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github-codespaces-efficiency

github-codespaces-efficiency

github.com/githubCloud & DevOps40.5k101 installsUpdated 1d ago
Repository

About github-codespaces-efficiency

A skill for auditing and improving GitHub Codespaces efficiency in repositories. It guides evidence-based changes to startup time and spend, with guardrails that preserve daily tools and balance cost against developer experience.

Key features

  1. 01Audit devcontainer and Codespaces usage
  2. 02Assess machine sizing and prebuild scope
  3. 03Tune idle timeout and image size
  4. 04Rank up to three evidence-backed fixes
  5. 05Verify changes and report expected impact

Use cases

  1. 01Investigate slow Codespaces startup
  2. 02Review Codespaces spending drivers
  3. 03Set up a repository devcontainer
  4. 04Evaluate an existing Codespaces configuration

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/github/awesome-copilot --skill github-codespaces-efficiency

After installing, type/github-codespaces-efficiencyin Claude Code to confirm it loaded.

Bundled filesreferences/codespaces.mdreferences/review-rubric.md

Details

From the project README

GitHub Codespaces Efficiency

Use this skill as a lean entrypoint for GitHub Codespaces efficiency work. Inspect the repo, identify waste, and load only needed references.

If no .devcontainer/ exists yet, load references/codespaces.md and define a baseline before proceeding with the steps below.

Use This Skill When

  • The user wants faster Codespaces startup or lower Codespaces spend.
  • The repo has a .devcontainer/ or explicit Codespaces configuration questions.
  • The user asks for devcontainer optimization, machine sizing, prebuild strategy, or idle-timeout guidance.
  • The user is setting up Codespaces for the first time or needs help creating a new .devcontainer/ from scratch.

Load Only What You Need

Core Workflow

1. Measure first
find .devcontainer -maxdepth 2 -type f
gh codespace list
repo=$(gh repo view --json nameWithOwner --jq .nameWithOwner)
gh api "/repos/$repo/codespaces/machines"

If gh auth fails or the user lacks repo admin scope, proceed with static analysis of .devcontainer/ files; mark machine-type and prebuild recommendations as unverified.

Look for: devcontainer image >2 GB or more than 10 features, machine type larger than usage data supports, missing devcontainer-lock.json (recommend adding — many repos predate lock-file support), prebuilds scoped too broadly, and idle timeout mismatched to usage patterns.

2. Apply guardrails

Check each proposed fix against these rules before recommending it:

  1. Does not remove tools the team uses every day — drop any fix that strips required development tools or extensions.
  2. Does not assume smaller is always better — balance machine cost against developer experience and throughput.
  3. Does not turn the devcontainer into a production image — drop any fix that adds production-only dependencies unless the team explicitly requires it.
  4. Incremental changes preferred — a greenfield baseline is appropriate only when no .devcontainer/ exists; flag (do not drop) changes that restructure an existing config.
  5. Repo changes stay separate from org settings — split any fix that mixes repo-editable files with org-level or user-level Codespaces settings into two distinct recommendations.
3. Select the top 3 fixes

From the six candidates below, keep only those supported by audit evidence from step 1 and passing all guardrails from step 2. Rank survivors by estimated monthly cost savings (USD). Select all candidates that meet both criteria, up to a maximum of 3.

  1. Trim devcontainer — remove features, packages, or extensions not needed for everyday development work; target image <2 GB and fewer than 10 features
  2. Right-size machine type — match to observed usage patterns; if data is unavailable, state assumptions explicitly
  3. Scope prebuilds — enable for the default branch, release/* branches active in the last 14 days, and branches with more than 5 Codespaces per week; disable for all others
  4. Tune idle timeout — 30 min default; 15 min if most sessions end before 30 min; 60 min if most sessions run longer
  5. Remove unused extensions or port-forwarding rules
  6. Reduce devcontainer image size and improve layer caching
4. Verify
  • Start a test Codespace to confirm devcontainer changes build and start as expected.
  • Validate machine sizing against observed usage when telemetry is available; otherwise mark as unverified.
  • Treat unexpected build or startup failures as real bugs even when the configuration looks correct.

Required Output

Waste sources: [top cost or startup-time drivers]

Proposed fixes: [top 3 changes supported by audit evidence and passing guardrails]

Validation: [proven live / static-only / remaining risk]

Impact:

  • Startup time: [expected] / [measured if available]
  • Monthly spend: [expected] / [measured if available]
  • Resource utilization: [expected] / [measured if available]

References

Comments

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