101 lines
4.9 KiB
Markdown
101 lines
4.9 KiB
Markdown
# golangci-lint-action
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[](https://github.com/golangci/golangci-lint-action/actions)
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It's the official GitHub action for [golangci-lint](https://github.com/golangci/golangci-lint) from it's authors.
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The action runs [golangci-lint](https://github.com/golangci/golangci-lint) and reports issues from linters.
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## How to use
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Add `.github/workflows/golangci-lint.yml` with the following contents:
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```yaml
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name: golangci-lint
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on:
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push:
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tags:
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- v*
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branches:
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- master
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pull_request:
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jobs:
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golangci:
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name: lint
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v2
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- name: golangci-lint
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uses: golangci/golangci-lint-action@v0.1.7
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with:
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# Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.
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version: v1.26
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# Optional: golangci-lint command line arguments.
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# args: ./the-only-dir-to-analyze/...
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# Required: the token is used for fetching a list of releases of golangci-lint.
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# The secret `GITHUB_TOKEN` is automatically created by GitHub,
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# no need to create it manually.
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# https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token#about-the-github_token-secret
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github-token: ${{ secrets.GITHUB_TOKEN }}
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```
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## Comments and Annotations
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Currently, GitHub parses the action's output and creates [annotations](https://github.community/t5/GitHub-Actions/What-are-annotations/td-p/30770).
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The restrictions of annotations are the following:
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1. Currently, they don't support markdown formatting (see the [feature request](https://github.community/t5/GitHub-API-Development-and/Checks-Ability-to-include-Markdown-in-line-annotations/m-p/56704))
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2. They aren't shown in list of comments like it was with [golangci.com](https://golangci.com). If you would like to have comments - please, up-vote [the issue](https://github.com/golangci/golangci-lint-action/issues/5).
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## Performance
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The action was implemented with performance in mind:
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1. We cache data by [@actions/cache](https://github.com/actions/cache) between builds: Go build cache, Go modules cache, golangci-lint analysis cache.
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2. We don't use Docker because image pulling is slow.
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3. We do as much as we can in parallel, e.g. we download cache, go and golangci-lint binary in parallel.
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For example, in a repository of [golangci-lint](https://github.com/golangci/golangci-lint) running this action without the cache takes 50s, but with cache takes 14s:
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* in parallel:
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* 13s to download Go
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* 4s to restore 50 MB of cache
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* 1s to find and install `golangci-lint`
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* 1s to run `golangci-lint` (it takes 35s without cache)
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## Internals
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We use JavaScript-based action. We don't use Docker-based action because:
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1. docker pulling is slow currently
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2. it's easier to use caching from [@actions/cache](https://github.com/actions/cache) until GitHub team hasn't supported reusing actions from actions
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Inside our action we perform 3 steps:
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1. Setup environment running in parallel:
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* restore [cache](https://github.com/actions/cache) of previous analyzes
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* list [releases of golangci-lint](https://github.com/golangci/golangci-lint/releases) and find the latest patch version
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for needed version (users of this action can specify only minor version). After that install [golangci-lint](https://github.com/golangci/golangci-lint) using [@actions/tool-cache](https://github.com/actions/toolkit/tree/master/packages/tool-cache)
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* install the latest Go 1.x version using [@actions/setup-go](https://github.com/actions/setup-go)
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2. Run `golangci-lint` with specified by user `args`
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3. Save cache for later builds
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### Caching internals
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1. We save and restore the following directories: `~/.cache/golangci-lint`, `~/.cache/go-build`, `~/go/pkg`.
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2. The primary caching key looks like `golangci-lint.cache-{interval_number}-{go.mod_hash}`. Interval number ensures that we periodically invalidate
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our cache (every 7 days). `go.mod` hash ensures that we invalidate the cache early - as soon as dependencies have changed.
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3. We use [restore keys](https://help.github.com/en/actions/configuring-and-managing-workflows/caching-dependencies-to-speed-up-workflows#matching-a-cache-key): `golangci-lint.cache-{interval_number}-`, `golangci-lint.cache-`. GitHub matches keys by prefix if we have no exact match for the primary cache.
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This scheme is basic and needs improvements. Pull requests and ideas are welcome.
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## Development of this action
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1. Install [act](https://github.com/nektos/act#installation)
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2. Make a symlink for `act` to work properly: `ln -s . golangci-lint-action`
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3. Prepare deps once: `npm run prepare-deps`
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4. Run `npm run local` after any change to test it
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