Install tools only in the jobs that need them

Keep lightweight discovery and validation jobs from paying for tools used only by other stages.

Prompt

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.

View all playbooks

How companies used this technique

Read what each company changed and follow the original sources.

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.

Current graph discovery uses a filtered tools install. Source

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.

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.

Ruby installation, about 2 minutes per the author, now runs only in the jobs that use Ruby. Source

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.

How companies used this technique

Install only what the change detector needs

Install tools only where they are used

Related techniques

Bake stable dependencies into runner images

Test supported runtimes concurrently

Build before starting the emulator

Company Playbooks

Related guides

Filter workflows by changed files

Cancel superseded CI runs