GitHub Actions caching for faster builds

<p>My GitHub Actions workflows take 10+ minutes mainly due to installing dependencies on every run. I need to cache dependencies, understand what to cache for Python and Node.js, and handle cache invalidation.</p>

<p>Dependency caching strategies:</p> <div class="highlight"><pre><span></span><code><span class="c1"># Python with uv (preferred):</span> <span class="nt">steps</span><span class="p">:</span> <span class="w"> </span><span class="p p-Indicator">-</span><span class="w"> </span><span class="nt">uses</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">astral-sh/setup-uv@v4</span> <span class="w"> </span><span class="nt">with</span><span class="p">:</span> <span class="w"> </span><span class="nt">enable-cache</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">true</span> <span class="w"> </span><span class="nt">cache-dependency-glob</span><span class="p">:</span><span class="w"> </span><span class="s">"**/uv.lock"</span><span class="w"> </span><span class="c1"># Invalidate on lockfile change</span> <span class="c1"># Python with pip (manual cache):</span> <span class="p p-Indicator">-</span><span class="w"> </span><span class="nt">uses</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">actions/cache@v4</span> <span class="w"> </span><span class="nt">with</span><span class="p">:</span> <span class="w"> </span><span class="nt">path</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">~/.cache/pip</span> <span class="w"> </span><span class="nt">key</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">pip-${{ runner.os }}-${{ hashFiles('**/requirements*.txt') }}</span> <span class="w"> </span><span class="nt">restore-keys</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">pip-${{ runner.os }}-</span><span class="w"> </span><span class="c1"># Fallback to older cache</span> <span class="c1"># Node.js with npm:</span> <span class="p p-Indicator">-</span><span class="w"> </span><span class="nt">uses</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">actions/setup-node@v4</span> <span class="w"> </span><span class="nt">with</span><span class="p">:</span> <span class="w"> </span><span class="nt">node-version</span><span class="p">:</span><span class="w"> </span><span class="s">'20'</span> <span class="w"> </span><span class="nt">cache</span><span class="p">:</span><span class="w"> </span><span class="s">'npm'</span><span class="w"> </span><span class="c1"># Built-in caching</span> <span class="c1"># Docker layer caching:</span> <span class="p p-Indicator">-</span><span class="w"> </span><span class="nt">uses</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">docker/build-push-action@v5</span> <span class="w"> </span><span class="nt">with</span><span class="p">:</span> <span class="w"> </span><span class="nt">cache-from</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">type=gha</span> <span class="w"> </span><span class="nt">cache-to</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">type=gha,mode=max</span> <span class="w"> </span><span class="c1"># Or registry-based:</span> <span class="w"> </span><span class="c1"># cache-from: type=registry,ref=ghcr.io/org/app:cache</span> <span class="w"> </span><span class="c1"># cache-to: type=registry,ref=ghcr.io/org/app:cache,mode=max</span> <span class="c1"># General file caching:</span> <span class="p p-Indicator">-</span><span class="w"> </span><span class="nt">uses</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">actions/cache@v4</span> <span class="w"> </span><span class="nt">with</span><span class="p">:</span> <span class="w"> </span><span class="nt">path</span><span class="p">:</span><span class="w"> </span><span class="p p-Indicator">|</span> <span class="w"> </span><span class="no">~/.cache/pre-commit</span> <span class="w"> </span><span class="no">.mypy_cache</span> <span class="w"> </span><span class="nt">key</span><span class="p">:</span><span class="w"> </span><span class="l l-Scalar l-Scalar-Plain">tools-${{ hashFiles('.pre-commit-config.yaml', 'mypy.ini') }}</span> </code></pre></div> <p>Key points: - Cache key with hashFiles() auto-invalidates when dependency files change - restore-keys provides fallback to partial cache (saves some time) - setup-node with cache: 'npm' handles npm caching automatically - Docker GHA cache shares layers between workflow runs on same branch - Cache size limit: 10GB per repo in GitHub Actions</p>