The latest articles on Forem by Rohit Kashyap (@rohitpotato). https://forem.com/rohitpotato https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F603142%2F873fdbaf-ac47-44c0-847e-d76d7cc72a43.jpeg https://forem.com/rohitpotato en Rohit Kashyap Mon, 29 Dec 2025 23:11:00 +0000 https://forem.com/rohitpotato/i-built-a-tool-to-master-promql-2p3l https://forem.com/rohitpotato/i-built-a-tool-to-master-promql-2p3l <p>My team recently moved from New Relic to OTEL. So, I decided to build a tool that teaches them PROMQL by going through several common scenarios. This could be a game-changer for teams that are migrating from paid SaaS observability tools to in-house monitoring.</p> <h2> Introducing <a href="https://github.com/rohitpotato/promql-playground" rel="noopener noreferrer">PROMQL Playground</a> </h2> <p>An interactive learning environment for Prometheus Query Language (PromQL). Write queries, visualize results, and learn PromQL concepts through hands-on examples.</p> <p><a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fhpyfmxexnvblbvck9yn0.png" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fhpyfmxexnvblbvck9yn0.png" alt="PROMQL Playground" width="800" height="401"></a></p> <h2> Features </h2> <ul> <li> <strong>Interactive Query Editor</strong> - Monaco-based editor with syntax highlighting and autocomplete</li> <li> <strong>Real Prometheus Data</strong> - Connects to demo.promlabs.com for real metrics</li> <li> <strong>Visualizations</strong> - Time series graphs with zoom, pan, and series filtering</li> <li> <strong>Learning Scenarios</strong> - Guided tutorials covering PromQL concepts</li> <li> <strong>Query Explanation</strong> - Step-by-step breakdown of query execution</li> <li> <strong>Function Reference</strong> - Documentation for all PromQL functions</li> </ul> <h2> Learning Scenarios </h2> <p>The playground includes guided scenarios to learn PromQL:</p> <ol> <li> <strong>Getting Started</strong> - Basic queries, metrics, and labels</li> <li> <strong>Error Rate Tracking</strong> - Monitor 4xx/5xx errors, calculate SLIs</li> <li> <strong>HTTP Request Analysis</strong> - Request rates, throughput, grouping</li> <li> <strong>Latency Analysis</strong> - Histograms, percentiles, p50/p95/p99</li> <li> <strong>Resource Usage</strong> - CPU, memory, disk monitoring</li> <li> <strong>Aggregation Deep Dive</strong> - sum, avg, max, min, count</li> <li> <strong>Top/Bottom Analysis</strong> - topk, bottomk for rankings</li> <li> <strong>Time Comparisons</strong> - Using offset for historical comparisons</li> <li> <strong>Rate Windows</strong> - Understanding rate() window sizes</li> </ol> <h2> Available Metrics </h2> <p>The demo server (demo.promlabs.com) provides these metrics:</p> <div class="table-wrapper-paragraph"><table> <thead> <tr> <th>Metric</th> <th>Type</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td><code>demo_api_request_duration_seconds</code></td> <td>Histogram</td> <td>HTTP request latency</td> </tr> <tr> <td><code>demo_api_http_requests_in_progress</code></td> <td>Gauge</td> <td>Current in-flight requests</td> </tr> <tr> <td><code>demo_cpu_usage_seconds_total</code></td> <td>Counter</td> <td>CPU time consumed</td> </tr> <tr> <td><code>demo_memory_usage_bytes</code></td> <td>Gauge</td> <td>Memory usage</td> </tr> <tr> <td><code>demo_disk_usage_bytes</code></td> <td>Gauge</td> <td>Disk space used</td> </tr> <tr> <td><code>demo_disk_total_bytes</code></td> <td>Gauge</td> <td>Total disk space</td> </tr> <tr> <td><code>demo_items_shipped_total</code></td> <td>Counter</td> <td>Business metric example</td> </tr> </tbody> </table></div> <p>Try here: <a href="https://promql-playground.vercel.app/" rel="noopener noreferrer">https://promql-playground.vercel.app/</a><br> Github: <a href="https://github.com/rohitpotato/promql-playground" rel="noopener noreferrer">https://github.com/rohitpotato/promql-playground</a></p> <h2> Acknowledgments </h2> <ul> <li> <a href="https://prometheus.io/" rel="noopener noreferrer">Prometheus</a> - Monitoring system</li> <li> <a href="https://promlabs.com/" rel="noopener noreferrer">PromLabs</a> - Demo Prometheus server</li> <li> <a href="https://github.com/prometheus-community/monaco-promql" rel="noopener noreferrer">monaco-promql</a> - PromQL language support</li> </ul> webdev devops opensource devex