--- title: "Install tools only in the jobs that need them" description: "Keep lightweight discovery and validation jobs from paying for tools used only by other stages." url: https://starsling.dev/ci-playbooks/techniques/install-consumed-tools canonicalUrl: https://starsling.dev/ci-playbooks/techniques/install-consumed-tools --- # Install tools only in the jobs that need them Keep lightweight discovery and validation jobs from paying for tools used only by other stages. ## How to choose an approach Compare the examples by repository setup, prerequisites, and risks before adopting one. Each company implemented this in its own environment; measure each change against your own baseline. - **[Mastra](https://starsling.dev/ci-playbooks/mastra#discovery-install)**: Use it when A metadata or graph-discovery job spends more on setup than its actual decision. Check before adopting: Pin the detector version and prove its dependency discovery works without install scripts. - **[Stripe](https://starsling.dev/ci-playbooks/stripe#install-only-consumed-tools)**: Use it when A shared setup step installs browsers, language runtimes or CLIs for every job. Check before adopting: Trace indirect script and action dependencies before moving setup, and declare every tool a job needs explicitly. ## Apply this technique ````text Evaluate and apply this CI technique to my repository: Install tools only in the jobs that need them. Keep lightweight discovery and validation jobs from paying for tools used only by other stages. Read the technique and its source-backed company examples: https://starsling.dev/ci-playbooks/techniques/install-consumed-tools.md Inspect this repository’s CI workflows, build and test commands, dependencies, and recent run timings. Identify where this technique applies and explain the expected benefit using this repository’s evidence. Measure a baseline from recent comparable runs: elapsed time, queue time, runner minutes and failures where available. If data is unavailable, say what cannot be measured. Compare relevant company approaches, checking prerequisites, platform differences and tradeoffs. Rank applicable options by evidence, fit and measurable opportunity; do not present company results as predictions for this repo. Recommend the smallest safe change, show what checks and fallback paths remain, and ASK ME WHICH CHANGE TO APPROVE BEFORE EDITING ANY FILES. Only after approval, work on a new feature branch, make one reversible change, and open a reviewable pull request. Never merge or push to a default or protected branch. Keep required checks, test coverage, deployment and release behavior intact. Validate the change and compare equivalent runs where possible; report limitations and what should be monitored after merge. ```` ## How companies used this technique Read what each company changed and follow the original sources. ### Mastra: Install only what the change detector needs Change-detection jobs disabled the workspace install and used a standalone Turbo executable. Later graph discovery installed only its root tools. Evidence: Source PR/commit evidence Current graph discovery uses a filtered tools install. ([Source](https://github.com/mastra-ai/mastra/blob/f92e947a448a47515acf14df1eddc5fd5c36f424/.github/workflows/prebuild.yml)) Use it when: A metadata or graph-discovery job spends more on setup than its actual decision. Before applying it: Pin the detector version and prove its dependency discovery works without install scripts. [Read more in the Mastra playbook](https://starsling.dev/ci-playbooks/mastra#discovery-install) [Primary source](https://github.com/mastra-ai/mastra/pull/12246) ### Stripe: Install tools only where they are used Stripe Android installed Ruby in its shared prepare step for every check. It moved the install into the screenshot and dependency-update jobs that actually run Ruby. Evidence: Source PR/commit evidence Ruby installation, about 2 minutes per the author, now runs only in the jobs that use Ruby. ([Source](https://github.com/stripe/stripe-android/pull/10184)) Use it when: A shared setup step installs browsers, language runtimes or CLIs for every job. Before applying it: Trace indirect script and action dependencies before moving setup, and declare every tool a job needs explicitly. [Read more in the Stripe playbook](https://starsling.dev/ci-playbooks/stripe#install-only-consumed-tools) [Primary source](https://github.com/stripe/stripe-android/pull/10184) ## CI optimization is continuous work. Apply this technique yourself, or use StarSling Runners for faster GitHub Actions and optional agent-driven optimization PRs, which teams on eligible paid plans can turn on. [Get self-improving CI](https://starsling.dev/products/runners) ## Related techniques ### [Bake stable dependencies into runner images](https://starsling.dev/ci-playbooks/techniques/prebuild-runner-images) Prepare versioned system dependencies and build downloads once in the runner image instead of installing them on every job. 2 implementations · 2 companies (Anthropic, Linear) ### [Test supported runtimes concurrently](https://starsling.dev/ci-playbooks/techniques/matrix-by-supported-runtime) Give each target framework its own job that installs only what it needs. 1 implementation · 1 company (Stripe) ### [Build before starting the emulator](https://starsling.dev/ci-playbooks/techniques/avoid-emulator-build-contention) Compile the app first, then boot the emulator and install the finished build. 1 implementation · 1 company (Stripe) ## Company Playbooks ### [Anthropic](https://starsling.dev/ci-playbooks/anthropic) Run only affected tests ### [DoorDash](https://starsling.dev/ci-playbooks/doordash) Run build and test in parallel, sharded across CI agents ### [Linear](https://starsling.dev/ci-playbooks/linear) Benchmark the same job on faster hardware ### [Mastra](https://starsling.dev/ci-playbooks/mastra) StarSling runners for the slowest test workflow ### [OpenAI](https://starsling.dev/ci-playbooks/openai) Rank CI fixes by the minutes they save ### [Ramp](https://starsling.dev/ci-playbooks/ramp) Move a CPU-bound test suite to a faster CPU ### [Shopify](https://starsling.dev/ci-playbooks/shopify) Let an agent iterate against one CI metric ### [Spotify](https://starsling.dev/ci-playbooks/spotify) Build arm64 on native arm64 runners ### [Stripe](https://starsling.dev/ci-playbooks/stripe) Run only the tests a change can reach ### [Uber](https://starsling.dev/ci-playbooks/uber) Build the merge-queue speculations most likely to be needed ## Related guides Implementation guides for this technique. ### [Filter workflows by changed files](https://starsling.dev/best-practices/github-actions/path-filter-workflows) Use paths and job conditions while keeping required checks reporting. ### [Cancel superseded CI runs](https://starsling.dev/best-practices/github-actions/cancel-superseded-runs) Cancel obsolete PR runs with a correctly scoped concurrency group.