What it is

reviewdog is an automated code review tool written in Go and released under the MIT license. It lives in the version control and collaboration space of the developer tooling ecosystem, and it integrates with code analysis tools regardless of programming language. Rather than performing analysis itself, reviewdog consumes the output of existing linters and static analysis tools and turns those findings into review comments on code hosting services. The project has been published for roughly ten years, carries more than nine thousand stars and close to five hundred forks, and its topic list covers CI, linting, static analysis, code quality, and the GitHub, GitLab and Bitbucket platforms.

The concrete problem it solves is noise and placement. A linter run in continuous integration typically emits a long report over an entire codebase, which is difficult to act on during review. reviewdog takes that output, filters it to findings that fall inside the diff of the patch under review, and posts the surviving findings as comments anchored to the relevant lines. The same filtering works locally, so a developer can run a linter over a whole project and see only issues introduced by the current change. reviewdog also supports code suggestions, a configuration file, and exit codes that let a pipeline fail when problems remain.

Key capabilities

• Consumes any linter output through configurable errorformat, pre-defined errorformats, Reviewdog Diagnostic Format (RDFormat), checkstyle format, SARIF format, or a supplied diff.
• Posts findings as comments on GitHub, GitLab and Bitbucket through dedicated reporters.
• Offers multiple GitHub reporters, including pull request checks, checks, pull request review comments, annotations, and pull request annotations.
• Provides GitLab MergeRequest discussion and MergeRequest commit reporters, plus a Bitbucket Code Insights report reporter.
• Runs in a local reporter mode, which is the default, to filter lint output by diff on a developer machine.
• Attaches code suggestions to review comments.
• Reads a reviewdog configuration file to define how tools and reporters are invoked.

Who uses it and how

• Teams wire reviewdog into GitHub Actions, Travis CI, Circle CI, GitLab CI, or Bitbucket Pipelines to comment on merge and pull requests automatically.
• Jenkins users run it through the common reporter path, including with the GitHub pull request builder plugin.
• Developers run it locally to reduce a full-repository lint report to only the lines changed in the working patch.
• Maintainers configure filter mode and exit codes so a pipeline can surface findings without necessarily failing the build.
• Users wanting newer behaviour run the separate nightly reviewdog releases.

Getting started

The README installs reviewdog with a shell script fetched over curl, defaulting to a local ./bin/ directory, with flags for an alternative installation directory and a specific version. Alpine Linux users use wget instead, since curl is not present by default, and nightly releases are available as an alternative channel.

When to use it — and when not to

reviewdog fits projects that already run linters and want their findings placed inline on pull requests without writing per-tool review integrations. It is not an analyser: an operator still chooses, installs, and configures every linter, sets the matching input format, and selects a reporter for each hosting service. The install path is a shell script or a nightly build rather than a package manager, and

# Install the latest version. (Install it into ./bin/ by default).
$ curl -sfL https://raw.githubusercontent.com/reviewdog/reviewdog/fd59714416d6d9a1c0692d872e38e7f8448df4fc/install.sh | sh -s

# Specify installation directory ($(go env GOPATH)/bin/) and version.
$ curl -sfL https://raw.githubusercontent.com/reviewdog/reviewdog/fd59714416d6d9a1c0692d872e38e7f8448df4fc/install.sh | sh -s -- -b $(go env GOPATH)/bin [vX.Y.Z]

# In alpine linux (as it does not come with curl by default)
$ wget -O - -q https://raw.githubusercontent.com/reviewdog/reviewdog/fd59714416d6d9a1c0692d872e38e7f8448df4fc/install.sh | sh -s [vX.Y.Z]

$ curl -sfL https://raw.githubusercontent.com/reviewdog/nightly/30fccfe9f47f7e6fd8b3c38aa0da11a6c9f04de7/install.sh | sh -s -- -b $(go env GOPATH)/bin

steps:
- uses: reviewdog/action-setup@d8edfce3dd5e1ec6978745e801f9c50b5ef80252 # v1.4.0
  with:
    reviewdog_version: latest # Optional. [latest,nightly,v.X.Y.Z]

$ brew install --cask reviewdog/tap/reviewdog
$ brew upgrade --cask reviewdog/tap/reviewdog

> scoop install reviewdog

$ go install github.com/reviewdog/reviewdog/cmd/reviewdog@latest

$ golint ./...
comment_iowriter.go:11:6: exported type CommentWriter should have comment or be unexported
$ golint ./.