How to cache node_modules in GitHub Actions?

Use actions/cache with a path to node_modules and a key based on your lockfile hash, e.g., `key: ${{ runner.os }}-${{ hashFiles('package-lock.json') }}`. This ensures the cache updates only when dependencies change, skipping redundant npm installs.

actions/cache vs GitHub artifacts for saving build outputs?

Cache is optimized for speed and reuse within the same workflow or branch, with automatic eviction policies. Artifacts are better for retaining outputs longer-term or sharing between workflows, but are slower to upload/download.

Why does my GitHub Actions cache miss so often?

Common causes include overly specific cache keys that change too frequently or cache version mismatches due to different OS runners. Review your key strategy and ensure consistent paths across jobs.

How to clear or delete a specific cache in GitHub Actions?

Caches are managed automatically by GitHub, but you can use the GitHub API to delete entries or override them by creating a new cache with the same key. There's no built-in UI for selective deletion.

Can actions/cache share caches between different workflows?

Yes, caches are scoped to the repository and branch, so they can be shared across workflows if keys match. Use branch-specific or default branch caches for cross-workflow reuse.

How to cache Python virtual environments in GitHub Actions?

Cache the venv directory (e.g., `~/.cache/pip` or a custom venv path) with a key derived from requirements.txt hash. Example: `key: ${{ runner.os }}-pip-${{ hashFiles('requirements.txt') }}`.

What tools are needed for self-hosted runners with actions/cache?

Ensure runners meet minimum version requirements (e.g., 2.327.1 for v5) and have POSIX-compliant tar installed. For cross-OS caching, Windows runners need GNU tar and zstd.

cache

MITTypeScriptv5.0.5

A GitHub Action for caching dependencies and build outputs to speed up workflow execution.

GitHub

What is cache?

actions/cache is an official GitHub Action that provides caching capabilities for GitHub Actions workflows. It allows developers to save and restore dependencies, build outputs, and other files between workflow runs, dramatically reducing execution time by avoiding redundant operations. The action integrates directly with GitHub's caching service and supports a wide range of programming languages and package managers.

Target Audience

Developers and DevOps engineers using GitHub Actions for CI/CD who want to optimize workflow performance by caching dependencies and build artifacts. It's particularly valuable for projects with large dependency trees or lengthy build processes.

Value Proposition

As an official GitHub-maintained action, it offers reliable, platform-native caching with seamless integration, regular updates, and strong backward compatibility. Its granular control through separate restore/save actions and flexible key strategies provides more optimization options than basic caching approaches.

Overview

Cache dependencies and build outputs in GitHub Actions

Use Cases

Best For

Caching npm or Yarn dependencies in Node.js projects

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Storing pip or Poetry dependencies for Python workflows

Caching Maven or Gradle dependencies in Java builds

Saving compiled binaries or Docker layers to speed up subsequent runs

Sharing cache between jobs in monorepo workflows

Optimizing CI times for projects with large dependency graphs

Not Ideal For

Projects using alternative CI/CD platforms like GitLab CI or Jenkins
Workflows with dependency installation times under a minute where caching overhead negates benefits
Environments with strict on-premises data storage requirements
Monorepos or large projects that consistently exceed the 10GB per-repository cache limit

Pros & Cons

Pros

Official Platform Integration

As a GitHub-maintained action, it benefits from direct support and seamless updates, evidenced by the managed migration to v2 cache APIs with backward compatibility.

Granular Control Strategies

Separate restore and save actions enable advanced caching logic, such as conditional saves or partial restores, detailed in the caching strategies document.

Cross-OS Cache Sharing

Optional cross-platform caching allows caches to be reused across different runner operating systems, though it requires specific setup like GNU tar on Windows.

Dynamic Cache Key Flexibility

Keys can leverage GitHub Actions contexts and functions like hashFiles, enabling precise cache invalidation based on file changes, as shown in the examples.

Cons

Configuration Complexity

Crafting effective cache keys and paths requires deep understanding of GitHub Actions syntax; misconfigurations lead to cache misses, as noted in the cache version differences.

Storage Capacity Constraints

The 10GB per repository limit and automatic eviction of older caches can force manual management or workflow breaks for data-heavy projects.

Platform Lock-in Risks

Tight coupling to GitHub's infrastructure means service changes, like the v2 API migration, mandate timely updates to avoid workflow failures, as warned in the 'Important changes' section.

Limited Community Contributions

The project explicitly states it is not accepting external contributions, which may delay fixes or features not prioritized by GitHub's internal roadmap.

Frequently Asked Questions

Home

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upload-artifact

`@actions/upload-artifact` is an official GitHub Action that allows developers to upload files, directories, or files matching wildcard patterns as artifacts from their workflow runs. These artifacts are stored by GitHub and can be downloaded later or used by other jobs in the same workflow, facilitating data persistence and sharing across CI/CD steps. ## Key Features - **Flexible Path Specification** — Upload individual files, entire directories, or use wildcard patterns and exclusions to select specific files. - **Performance and Control** — Manually adjust compression levels for speed or size, and customize behavior when no files are found. - **Artifact Management** — Set custom retention periods, overwrite existing artifacts, and include or exclude hidden files from uploads. - **Output Integration** — Provides artifact IDs, URLs, and digests as outputs for use in subsequent steps or with the GitHub REST API. - **Immutable Archives** — Each upload creates a unique, immutable artifact, preventing accidental corruption from concurrent modifications. ## Philosophy The action is designed to be a reliable, performant, and secure method for persisting workflow data, with sensible defaults that prioritize safety (like excluding hidden files) while offering granular control for advanced use cases.

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download-artifact

The `@actions/download-artifact` action enables GitHub Actions workflows to retrieve stored artifacts from workflow runs. It provides flexible options for downloading single or multiple artifacts, filtering by patterns, and accessing artifacts across different repositories and runs. ## Key Features - **Single Artifact Download** — Download a specific artifact by name or unique ID to a specified directory. - **Bulk Artifact Retrieval** — Download all artifacts from a run, with options to merge them into a single directory or keep them separate. - **Cross-Repository Access** — Download artifacts from other repositories or workflow runs using a GitHub token with appropriate permissions. - **Pattern Filtering** — Use glob patterns to download only matching artifacts, useful in multi-architecture build scenarios. - **Flexible Output Control** — Choose whether to automatically decompress artifacts or maintain them as-is for manual handling. - **File Permission Preservation** — Supports workflows that require maintaining executable permissions via tar archives. ## Philosophy The action is designed to be a reliable, configurable tool for artifact retrieval within GitHub's ecosystem, prioritizing compatibility with the platform's artifact system and providing clear, predictable behavior for common use cases.

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#devops

#caching

#workflow-optimization

#build-automation

#dependency-management