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Pre-Commit-GoLang

A set of git pre-commit hooks for Golang with support for multi-module monorepos, the ability to pass arguments and environment variables to all hooks, and the ability to invoke custom go tools.

Requires the Pre-Commit.com Hook Management Framework.

Installation

You can copy/paste the following snippet into your .pre-commit-config.yaml file.

NOTE A more fleshed-out version can be found in sample-config.yaml

    # ==========================================================================
    # Golang Pre-Commit Hooks | https://github.com/tekwizely/pre-commit-golang
    #
    # !! ALL Hooks enabled by default - Comment out hooks you are not using
    #
    # Visit the project home page to learn more about the available Hooks,
    # including useful arguments you might want to pass into them.
    #
    # NOTE: When passing options to hooks, if your options contain a reference
    #       to an existing file, then you will need to use a trailing '--'
    #       argument to separate the hook options from the modified-file list
    #       that Pre-Commit passes into the hook.
    #       For repo-based hooks, '--' is not needed.
    #
    # NOTE: You can pass environment variables to hooks using args with the 
    #       following format:
    #
    #           --hook:env:NAME=VALUE
    #
    # Consider adding aliases to longer-named hooks for easier CLI usage.
    # ==========================================================================
-   repo: https://github.com/tekwizely/pre-commit-golang
    rev: master
    hooks:
    #
    # Go Build
    #
    -   id: go-build-mod
    -   id: go-build-pkg
    -   id: go-build-repo-mod
    -   id: go-build-repo-pkg
    #
    # Go Mod Tidy
    #
    -   id: go-mod-tidy
    -   id: go-mod-tidy-repo
    #
    # Go Test
    #
    -   id: go-test-mod
    -   id: go-test-pkg
    -   id: go-test-repo-mod
    -   id: go-test-repo-pkg
    #
    # Go Vet
    #
    -   id: go-vet
    -   id: go-vet-mod
    -   id: go-vet-pkg
    -   id: go-vet-repo-mod
    -   id: go-vet-repo-pkg
    #
    # Revive
    #
    -   id: go-revive
    -   id: go-revive-mod
    -   id: go-revive-repo-mod
    #
    # GoSec
    #
    -   id: go-sec-mod
    -   id: go-sec-pkg
    -   id: go-sec-repo-mod
    -   id: go-sec-repo-pkg
    #
    # StaticCheck
    #
    -   id: go-staticcheck-mod
    -   id: go-staticcheck-pkg
    -   id: go-staticcheck-repo-mod
    -   id: go-staticcheck-repo-pkg
    #
    # StructSlop
    #
    -   id: go-structslop-mod
    -   id: go-structslop-pkg
    -   id: go-structslop-repo-mod
    -   id: go-structslop-repo-pkg
    #
    # Formatters
    #
    -   id: go-fmt
    -   id: go-fmt-repo
    -   id: go-fumpt        # replaces go-fmt
    -   id: go-fumpt-repo   # replaces go-fmt-repo
    -   id: go-imports      # replaces go-fmt
    -   id: go-imports-repo # replaces go-fmt-repo
    -   id: go-returns      # replaces go-imports & go-fmt
    -   id: go-returns-repo # replaces go-imports-repo & go-fmt-repo
    #
    # Style Checkers
    #
    -   id: go-lint
    -   id: go-critic
    #
    # GolangCI-Lint
    # - Fast Multi-Linter
    # - Can be configured to replace MOST other hooks
    # - Supports repo config file for configuration
    # - https://github.com/golangci/golangci-lint
    #
    -   id: golangci-lint
    -   id: golangci-lint-mod
    -   id: golangci-lint-pkg
    -   id: golangci-lint-repo-mod
    -   id: golangci-lint-repo-pkg
    #
    # Invoking Custom Go Tools
    # - Configured *entirely* through the `args` attribute, ie:
    #   args: [ go, test, ./... ]
    # - Use arg `--hook:error-on-output` to indicate that any output from the tool
    #   should be treated as an error.
    # - Use the `name` attribute to provide better messaging when the hook runs
    # - Use the `alias` attribute to be able to invoke your hook via `pre-commit run`
    #
    -   id: my-cmd
    -   id: my-cmd-mod
    -   id: my-cmd-pkg
    -   id: my-cmd-repo
    -   id: my-cmd-repo-mod
    -   id: my-cmd-repo-pkg

Overview

Hook Targets

File-Based Hooks

Some hooks run against matching staged files individually.

Module-Based Hooks

Some hooks work on a per-module basis. The hooks run against module root folders containing one or more matching staged files.

Module Root Folder: A folder containing a go.mod file. Discovered by walking up the folder path from the staged file.

Module Mode

Module-based hooks enable module mode (GO111MODULE=on) before invoking their respective tools.

Package-Based Hooks

Some hooks work on a per-package basis. The hooks run against folders containing one or more staged files.

Package Folder: A folder containing one or more .go files.

Package Mode

Package-based hooks disable module mode (GO111MODULE=off) before invoking their respective tools.

Repo-Based Hooks

Some hooks run against the entire repo. The hooks only run once (if any matching files are staged), and are NOT provided the list of staged files,

Hook Suffixes

Hooks have suffixes in their name that indicate their targets:

Suffix	Target	Description
<none>	Files	Targets staged files directly
`-mod`	Module	Targets module root folders of staged `.go` files
`-pkg`	Package	Targets folders containing staged `.go` files
`-repo`	Repo Root	Targets the repo root folder
`-repo-mod`	All Modules	Targets all module root folders in the repo
`-repo-pkg`	All Packages	Targets all package folders in the repo

Multiple Hook Invocations

Due to OS command-line-length limits, Pre-Commit can invoke a hook multiple times if a large number of files are staged.

For file and repo-based hooks, this isn't an issue, but for module and package-based hooks, there is a potential for the hook to run against the same module or package multiple times, duplicating any errors or warnings.

Invoking Custom Tools

While this project includes builtin hooks for many popular go tools, it's not possible to include builtin hooks for every tool that users might want to use.

To help accommodate those users, this project includes the ability to invoke custom go tools.

See the my-cmd hooks for more information.

Useful Hook Parameters

-   id: hook-id
    args: [arg1, arg2, ..., '--'] # Pass options ('--' is optional)
    always_run: true              # Run even if no matching files staged
    alias: hook-alias             # Create an alias
    verbose: true                 # Display output, even if no errors

Passing Options To Hooks

You can pass options into individual hooks to customize tool behavior.

If your options contain a reference to an existing file, then you will need to use a trailing '--' argument to separate the hook options from the modified-file list that Pre-Commit passes into the hook.

NOTE: For repo-based hooks, '--' is not needed.

See each hook's description below for some popular options that you might want to use.

Additionally, you can view each tool's individual home page or help settings to learn about all the available options.

Passing Environment Variables To Hooks

You can pass environment variables to hooks to customize tool behavior.

NOTE: The Pre-Commit framework does not directly support the ability to pass environment variables to hooks.

This feature is enabled via support for a specially-formatted argument:

--hook:env:NAME=VALUE

The hook script will detect this argument and set the variable NAME to the value VALUE before invoking the configured tool.

You can pass multiple --hook:env: arguments.

The arguments can appear anywhere in the args: list.

Always Run

By default, hooks ONLY run when matching file types (usually *.go) are staged.

When configured to "always_run", a hook is executed as if EVERY matching file were staged.

Aliases / Names

pre-commit supports the ability to assign both an alias and a name to a configured hook:

config	description
alias	(optional) allows the hook to be referenced using an additional id when using `pre-commit run <hookid>`
name	(optional) override the name of the hook - shown during hook execution

These are beneficial for a couple of reasons:

Creating short names for long-named hooks for easier CLI usage:

# ...
      hooks:
        -   id: go-build-repo-mod
            alias: build

usage

$ pre-commit run build

Having variations of a given hook with different configurations:

# ...
    hooks:
      -   id: go-fmt

          # Add a second go-fmt hook with -w enabled
          # Configure so it only runs when manually invoked
      -   id: go-fmt
          args: [ -w ]
          alias: go-fmtw-alias
          name: go-fmtw-name
          stages: [manual]

NOTE: When creating variations, take note that the alias is used to execute the hook, but the the name is used in the hook report.

usage: alias vs name

 $ pre-commit run --hook-stage manual go-fmtw-alias

 go-fmtw-name................................Passed

Verbose Hook Output

When the "verbose" flag is enabled, all output generated by the hook will be displayed, even if there were no errors.

This can be useful, for example, for hooks that display warnings, but don't generate error codes for them.

Hooks

Build Tools
- go-build
- go-mod-tidy
Correctness Checkers
Formatters
- go-fmt
- go-fumpt
- go-imports
- go-returns
Style Checkers
GolangCI-Lint
- golangci-lint
Invoking Custom Tools
- my-cmd

go-build

Compiles packages, along with their dependencies, but does not install the results.

Hook ID	Description
`go-build-mod`	Run `'cd $(mod_root $FILE); go build -o /dev/null [$ARGS] ./...'` for each staged .go file
`go-build-pkg`	Run `'go build -o /dev/null [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-build-repo-mod`	Run `'cd $(mod_root); go build -o /dev/null [$ARGS] ./...'` for each module in the repo
`go-build-repo-pkg`	Run `'go build -o /dev/null [$ARGS] ./...'` in repo root folder

Install

Comes with Golang ( golang.org )

Help

https://golang.org/cmd/go/#hdr-Compile_packages_and_dependencies
go help build

go-mod-tidy

Makes sure go.mod matches the source code in the module.

Hook ID	Description
`go-mod-tidy`	Run `'cd $(mod_root $FILE); go mod tidy [$ARGS] ./...'` for each staged .go file
`go-mod-tidy-repo`	Run `'cd $(mod_root); go mod tidy [$ARGS] ./...'` for each module in the repo

Install

Comes with Golang ( golang.org )

Help

https://golang.org/ref/mod#go-mod-tidy
go mod help tidy

go-test

Automates testing, printing a summary of test results.

Hook ID	Description
`go-test-mod`	Run `'cd $(mod_root $FILE); go test [$ARGS] ./...'` for each staged .go file
`go-test-pkg`	Run `'go test [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-test-repo-mod`	Run `'cd $(mod_root); go test [$ARGS] ./...'` for each module in the repo
`go-test-repo-pkg`	Run `'go test [$ARGS] ./...'` in repo root folder

Install

Comes with Golang ( golang.org )

Help

https://golang.org/cmd/go/#hdr-Test_packages
go help test

go-sec

Inspects source code for security problems by scanning the Go AST.

Hook ID	Description
`go-sec-mod`	Run `'cd $(mod_root $FILE); gosec [$ARGS] ./...'` for each staged .go file
`go-sec-pkg`	Run `'gosec [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-sec-repo-mod`	Run `'cd $(mod_root); gosec [$ARGS] ./...'` for each module in the repo
`go-sec-repo-pkg`	Run `'gosec [$ARGS] ./...'` in repo root folder

Install (via bingo)

bingo install github.com/securego/gosec/v2/cmd/gosec

Help

https://github.com/securego/gosec#usage
gosec (no args)

go-staticcheck

A state of the art linter for the Go programming language. Using static analysis, it finds bugs and performance issues, offers simplifications, and enforces style rules.

Hook ID	Description
`go-staticcheck-mod`	Run `'cd $(mod_root $FILE); staticcheck [$ARGS] ./...'` for each staged .go file
`go-staticcheck-pkg`	Run `'staticcheck [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-staticcheck-repo-mod`	Run `'cd $(mod_root); staticcheck [$ARGS] ./...'` for each module in the repo
`go-staticcheck-repo-pkg`	Run `'staticcheck [$ARGS] ./...'` in repo root folder

Install (via bingo)

bingo install honnef.co/go/tools/cmd/staticcheck

Help

https://staticcheck.io/
staticcheck -h

go-structslop

Recommends struct field rearrangements to provide for maximum space/allocation efficiency.

Can modify files (see -apply)

Hook ID	Description
`go-structslop-mod`	Run `'cd $(mod_root $FILE); structslop [$ARGS] ./...'` for each staged .go file
`go-structslop-pkg`	Run `'structslop [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-structslop-repo-mod`	Run `'cd $(mod_root); structslop [$ARGS] ./...'` for each module in the repo
`go-structslop-repo-pkg`	Run `'structslop [$ARGS] ./...'` in repo root folder

Install (via bingo)

bingo install github.com/orijtech/structslop/cmd/structslop

Useful Args

-apply : apply suggested fixes

Help

https://github.com/orijtech/structslop#usage
structslop -h

go-vet

Examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string. Vet uses heuristics that do not guarantee all reports are genuine problems, but it can find errors not caught by the compilers.

Hook ID	Description
`go-vet`	Run `'go vet [$ARGS] $FILE'` for each staged .go file
`go-vet-mod`	Run `'cd $(mod_root $FILE); go vet [$ARGS] ./...'` for each staged .go file
`go-vet-pkg`	Run `'go vet [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`go-vet-repo-mod`	Run `'cd $(mod_root); go vet [$ARGS] ./...'` for each module in the repo
`go-vet-repo-pkg`	Run `'go vet [$ARGS] ./...'` in repo root folder

Install

Comes with Golang ( golang.org )

Help

https://golang.org/cmd/go/#hdr-Report_likely_mistakes_in_packages
go doc cmd/vet

go-fmt

Formats Go programs. It uses tabs for indentation and blanks for alignment. Alignment assumes that an editor is using a fixed-width font.

Can modify files (see -w)

Hook ID	Description
`go-fmt`	Run `'gofmt -l -d [$ARGS] $FILE'` for each staged .go file
`go-fmt-repo`	Run `'gofmt -l -d [$ARGS] .'` in repo root folder

Install

Comes with Golang ( golang.org )

Useful Args

-d=false : Hide diffs
-s       : Try to simplify code
-w       : Update source file directly

Help

https://godoc.org/github.com/golang/go/src/cmd/gofmt
gofmt -h

go-fumpt

Enforce a stricter format than gofmt, while being backwards compatible.

Replaces go-fmt
Can modify files (see -w)

Hook ID	Description
`go-fumpt`	Run `'gofumpt -l -d [$ARGS] $FILE'` for each staged .go file
`go-fumpt-repo`	Run `'gofumpt -l -d [$ARGS] .'` in repo root folder

Install (via bingo)

bingo install mvdan.cc/gofumpt

Useful Args

-d=false : Hide diffs
-extra   : Enable extra rules which should be vetted by a human
-s       : Try to simplify code
-w       : Update source file directly

Help

https://pkg.go.dev/mvdan.cc/gofumpt
gofumpt -h

go-imports

Updates your Go import lines, adding missing ones and removing unreferenced ones.

Replaces go-fmt
Can modify files (see -w)

Hook ID	Description
`go-imports`	Run `'goimports -l -d [$ARGS] $FILE'` for each staged .go file
`go-imports-repo`	Run `'goimports -l -d [$ARGS] .'` in repo root folder

Install (via bingo)

bingo install golang.org/x/tools/cmd/goimports

Useful Args

-d=false        : Hide diffs
-format-only    : Do not fix imports, act ONLY as go-fmt
-local prefixes : Add imports matching prefix AFTER 3rd party packages
                  (prefixes = comma-separated list)
-v              : Verbose logging
-w              : Update source file directly

Help

https://godoc.org/golang.org/x/tools/cmd/goimports
goimports -h

go-returns

Implements a Go pretty-printer (like go-fmt) that also adds zero-value return values as necessary to incomplete return statements.

Replaces go-fmt and go-imports
Can modify files (see -w)

Hook ID	Description
`go-returns`	Run `'goreturns -l -d [$ARGS] $FILE'` for each staged .go file
`go-returns-repo`	Run `'goreturns -l -d [$ARGS] .'` in repo root folder

Install (via bingo)

bingo install github.com/sqs/goreturns

Useful Args

-b              : Remove bare returns
-d=false        : Hide diffs
-i=false        : Disable go-imports
-local prefixes : Add imports matching prefix AFTER 3rd party packages
                  (prefixes = comma-separated list)
-p              : Print non-fatal type-checking errors to STDERR
-s              : Try to simplify code
-w              : Update source file directly

Help

https://godoc.org/github.com/sqs/goreturns
goreturns -h

go-lint

A linter for Go source code, meant to carry out the stylistic conventions put forth in Effective Go and CodeReviewComments.

Hook ID	Description
`go-lint`	Run `'golint -set_exit_status [$ARGS] $FILE'` for each staged .go file

Install (via bingo)

bingo install golang.org/x/lint/golint

Help

go-revive

~6x faster, stricter, configurable, extensible, and beautiful drop-in replacement for golint.

Hook ID	Description
`go-revive`	Run `'revive [$ARGS] $FILE'` for each staged .go file
`go-revive-mod`	Run `'cd $(mod_root $FILE); revive [$ARGS] ./...'` for each staged .go file
`go-revive-repo-mod`	Run `'cd $(mod_root); revive [$ARGS] ./...'` for each module in the repo

Support for Repository-Level Config

As of time of writing, revive only auto-checks for configs in ${HOME}/revive.toml, and doesn't check the local folder (ie. ${REPO_ROOT}/revive.toml).

To make revive more useful, these hooks add built-in support for a repository-level config file.

Auto-Configured

These hooks are configured to auto-add -config=revive.toml when the file is present in the repository root.

Triggerred When Modified

These hooks are configured to run when the repo-level revive.toml file is modified (and staged).

NOTE: Although configured to run, the file-based go-revive hook will, by default, effectively do nothing if there are no staged .go files to run against.

Install (via bingo)

bingo install github.com/mgechev/revive

Useful Args

-config [PATH]     : Path to config file (TOML)
-exclude [PATTERN] : Pattern for files/directories/packages to be excluded from linting
-formatter [NAME]  : formatter to be used for the output

Displaying Warnings

By default, revive doesn't generate errors on warnings, so warning messages may not be displayed if there are no accompanying error messages.

You can use the "verbose: true" hook configuration to always show hook output.

Help

https://github.com/mgechev/revive#usage
revive -h

go-critic

The most opinionated Go source code linter for code audit.

Hook ID	Description
`go-critic`	Run `'gocritic check [$ARGS] $FILE'` for each staged .go file

Install

https://github.com/go-critic/go-critic#installation

Useful Args

-enableAll        : Enable ALL checkers
-enable checkers  : comma-separated list of checkers to be enabled
                    (can include #tags)
-disable checkers : comma-separated list of checkers to be disabled
                    (can include #tags)

Tags

#diagnostic
#style
#opinionated
#performance
#experimental

Help

https://go-critic.github.io/overview
gocritic check -help

golangci-lint

A FAST linter aggregator, with colored output, fewer false-positives, and support for yaml/toml configuration.

Manages multiple linters
Can replace many/most other hooks
Can report only new issues (see --new)
Can modify files (see --fix)

Hook ID	Description
`golangci-lint`	Run `'golangci-lint run [$ARGS] $FILE'` for each staged .go file
`golangci-lint-mod`	Run `'cd $(mod_root $FILE); golangci-lint run [$ARGS] ./...'` for each staged .go file
`golangci-lint-pkg`	Run `'golangci-lint run [$ARGS] ./$(dirname $FILE)'` for each staged .go file
`golangci-lint-repo-mod`	Run `'cd $(mod_root); golangci-lint run [$ARGS] ./...'` for each module in the repo
`golangci-lint-repo-pkg`	Run `'golangci-lint run [$ARGS] ./...'` in repo root folder

Install (via bingo)

bingo install github.com/golangci/golangci-lint/cmd/golangci-lint

Useful Args

   --config PATH     : Specify config file
   --disable linters : Disable specific linter(s)
   --enable-all      : Enable ALL linters
   --enable linters  : Enable specific linter(s)
   --fast            : Run only fast linters (from enabled linters sets)
   --fix             : Fix found issues (if supported by linter)
   --new             : Show only new issues (see help for further details)
   --no-config       : don't read config file
   --presets presets : Enable presets of linters

Presets

bugs
complexity
format
performance
style
unused

Help

https://github.com/golangci/golangci-lint#quick-start
golangci-lint run -h

Config File Help:

https://github.com/golangci/golangci-lint#config-file
golangci-lint config -h

my-cmd

Using the my-cmd-* hooks, you can invoke custom go tools in various contexts.

Hook ID	Description
`my-cmd`	Run `'$ARGS[0] [$ARGS[1:]] $FILE'` for each staged .go file
`my-cmd-mod`	Run `'cd $(mod_root $FILE); GO111MODULE=on $ARGS[0] [$ARGS[1:]]'` for each staged .go file
`my-cmd-pkg`	Run `'GO111MODULE=off $ARGS[0] [$ARGS[1:]] ./$(dirname $FILE)'` for each staged .go file
`my-cmd-repo`	Run `'$ARGS[0] [$ARGS[1:]]'` in the repo root folder
`my-cmd-repo-mod`	Run `'cd $(mod_root); GO111MODULE=on $ARGS[0] [$ARGS[1:]]'` for each module in the repo
`my-cmd-repo-pkg`	Run `'GO111MODULE=off $ARGS[0] [$ARGS[1:]]` in repo root folder

Configuring the hooks

The my-cmd hooks are configured entirely through the pre-commit args attribute, including specifying which tool to run (ie $ARGS[0] above).

This includes the need to manually add the ./... target for module-based tools that require it.

Examples

Here's an example of what it would look like to use the my-cmd hooks to invoke go test if it wasn't already included:

.pre-commit-config.yaml

# ...
      hooks:
            # Run 'cd $(mod_root $FILE); go test ./...' for each staged .go file
        -   id: my-cmd-mod
            name: go-test-mod
            alias: go-test-mod
            args: [ go, test, ./... ]

Names & Aliases

It is recommended that you use both name and alias attributes when defining my-cmd hooks.

The name will provide better messaging when the hook runs.

The alias will enable you to invoke the hook manually from the command-line when needed (see pre-commit help run)

error-on-output

Some tools, like gofmt, goimports, and goreturns, don't generate error codes, but instead expect the presence of any output to indicate warning/error conditions.

The my-cmd hooks accept a --hook:error-on-output argument to indicate this behavior.

Here's an example of what it would look like to use the my-cmd hooks to invoke gofmt if it wasn't already included:

.pre-commit-config.yaml

# ...
      hooks:
            # Run 'gofmt -l -d $FILE' for each staged .go file
            # Treat any output as indication of failure
        -   id: my-cmd
            name: go-fmt
            alias: go-fmt
            args: [ gofmt, -l, -d, --hook:error-on-output]

NOTE: The plain --error-on-output option is now deprecated, but still supported, as long as it's the very first entry in the args: list.

License

The tekwizely/pre-commit-golang project is released under the MIT License. See LICENSE file.