• Frontend builds consumed ~5 minutes of a 10-minute E2E pipeline, even without frontend changes. • Hundreds of PRs per day caused thousands of redundant builds, generating terabytes of duplicate S3 data. • Slack’s DevXP team identified the bottleneck and targeted unnecessary frontend rebuilds. • Implemented selective build triggers and caching to skip unchanged frontend code. • Resulted in a 50% reduction in total build time and significant cost savings. • Engineers now experience faster feedback loops and more efficient resource usage.
Article Summaries:
- In the world of DevOps and Developer Experience (DevXP), speed and efficiency can make a big difference on an engineer’s day-to-day tasks. Today, we’ll dive into how Slack’s DevXP team took some existing tools and used them to optimize an end-to-end (E2E) testing pipeline. This lowered build times and reduced redundant processes, saving both time and resources for engineers at Slack. The Problem: Unnecessary Frontend Builds For one of our largest code repositories (a monolithic repository, or monorepo), Slack has a CI/CD pipeline that runs E2E tests before merging code into the main branch. Th
- Slack’s DevXP team has revamped its end‑to‑end (E2E) testing pipeline to cut redundant work and costs. By using Git’s diff to detect frontend changes, the team now skips building the frontend when no relevant code has changed, reusing a prebuilt version stored in AWS S3. An internal CDN serves these cached assets during tests, eliminating the ~5‑minute build step that previously ran on every pull request. The change reduces build time from about 10 minutes to roughly 5 minutes, saves thousands of hours of compute, and cuts terabytes of duplicate storage, improving overall pipeline efficiency.
Sources: