go-lint-cerrl

README

go-lint-cerrl

go-lint-cerrl is a golang linter that helps finding unlogged errors created by the cerror package from your project.

Description

There are number of cases when errors are created with a cerror.New... call but not logged with a Log... method.

For example:

err := cerror.NewF(...) - bad, error is not logged err := cerror.NewF(...).LogError() - good, error is logged

It's so easy to forget about the Log... and very hard to catch this during a code review. Moreover this defect is totally invisible for the end user. Highly likely we'll find out it only when catch a bug and try to find some useful inforamtion in logs. These aspects make such kind of bugs quite dangerous and should be a motivation to use the linter.

Note that the linter expects the .Log() in chain, so the following cases:

err := cerror.New()
_ = err.Log()

will be highlited as errors. Fill free to use //nolint:cerrl if you use the linter as golangci-lint pluign.

The linter checks only files that contain cerror package import. The import must have the /pkg/cerror suffix. The linter also understands import aliases. For example:

import cerr "my_proj/pkg/cerror"
...
err := cerr.New(...).LogError()
...

Installation

It's very important to remember that plugins programs that load them must be built with the same configuration (go version, os, arch, ...).

All the golangci-lint builds and docker images have CGO_ENABLED=0 that breaks the go plugin system requirements CGO_ENABLED=1. So most likely you'll have to install golangci-lint from source:

go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.45.0

Before installation ensure that you have CGO_ENABLED=1 locally:

go env | grep CGO_ENABLED

Use as a golangci-lint plugin locally

Clone or download the repo:

git clone https://github.com/edenlabllc/go-lint-cerrl

Switch to the root directory and build the plugin:

#build into the current directory
make build-plugin

#or into a custom directory
go build --buildmode plugin --output {custom dir path} plugin/cerrl.go

Finally you'll get the *.so file that you can add to your golangci-lint config file. See the .golangci.yml configuration example with the plugin in our repo.

Known issues

If you see an error during golangci-lint run that looks similar too:

... unable to load plugin: plugin.Open(...): plugin was built with a different version of ...

Solution - try to remove all the installed versions of golangci-lint and install it again:

#see the path to golangci-lint
which golangci-lint

#remove it
rm $(which golangci-lint)

#ensure that you don't have another copy
which golangci-lint
#should see golangci-lint not found. If no delete this copy too

#install
go install github.com/golangci/golangci-lint/cmd/golangci-lint@v1.45.0

If some of your teammate haven't manage to install the plugin you can keep two golangci-lint configs - with and without plugin and refer them inside your IDE individually. For example for vscode add the following lines to settings.json:

"go.lintFlags": [
    "-c",
    "/path/to/.golangci-no-plugin.yml",
]

And use them from cli as we did in our repo.

Use as a golangci-lint plugin in docker

If you don't want to install the plugin locally and you don't need online linter issues discovering, you can run golangci-lint inside the docker.

As it was mentioned here we can't use one of the golangci-lint docker images. So we have to run the golang image and install golangci-lint and build the plugin inside the container. You can see an example of docker-compose file in our repo

Use in github workflows

Unfortunately we can't use the original golangci-lint github action because of CGO_ENABLED=0. We have to install the plugin and golangci-lint by our own during the github action and then run the linter. See an example of such action inside our repo. You can use this approach for the entire linting process or separate the linting into two jobs (as wee deed):

• lint using config without plugins and use the original golangci-lint github action
• lint using config with plugins only and use a custom action

Known issues

If you want to use only plugins in your .golangci.yml config you'll need to add at least one default linter (e.g. bodyclose) too because golangci-lint crashes otherwise.

Use as a standalone

Rememeber that nolint directives won't work outside the golangci-lint.

Install using go:

go install github.com/edenlabllc/go-lint-cerrl/cmd/cerrl

then use like:

cerrl ./...

Also you can integrate the binary into go vet:

go vet -vettool=$(which cerrl) ./...

Links

If you want to read more about how to build your own linter and integrate it into golangci-lint see the following resources:

• build a custom linter from scratch and integrate it into go vet and golangci-lint
• a simple example of golangci-lint plugin
• how to add a new linter into golangci-lint
• golang AST visualizer