Adhere to the style and best practices described in [Effective Go](https://golang.org/doc/effective_go.html). Read [Common Review Comments](https://github.com/golang/go/wiki/CodeReviewComments) for further information.
## Linting
This projects uses [golangci-lint](https://golangci-lint.run/) for linting.
You can [install golangci-lint](https://golangci-lint.run/usage/install/#linux-and-windows) locally,
but there is also a CI action to ensure compliance.
To locally run all configured linters, execute
```sh
golangci-lint run ./...
```
It is also recommended to use golangci-lint (and [gofumpt](https://github.com/mvdan/gofumpt) as formatter) in your IDE, by adding the recommended VS Code Settings or by [configuring it yourself](https://golangci-lint.run/usage/integrations/#editor-integration)
We use a [custom subset](/internal/logger/) of [zap](https://pkg.go.dev/go.uber.org/zap) to provide logging for Constellation's services and components.
Usage instructions can be found in the package documentation.
Certain components may further specify a subset of the logger for their use. For example, the CLI has a debug-only logger, restricting the use of the logger to only `Debugf()`.
Further we try to adhere to the following guidelines:
* Do not log potentially sensitive information, e.g. variables that contain keys, secrets or otherwise protected information.
* Start log messages in uppercase and end without a punctuation mark. Exclamation, question marks, or ellipsis may be used where appropriate.
Example:
```Go
log.Infof("This is a log message")
log.Infof("Waiting to do something...")
log.Error("A critical error occurred!")
```
* Use the `With()` method to add structured context to your log messages. The context tags should be easily searchable to allow for easy log filtering. Try to keep consistent tag naming!
Example:
```Go
log.With(zap.Error(someError), zap.String("ip", "192.0.2.1")).Errorf("Connecting to IP failed")
```
* Log messages may use format strings to produce human readable messages. However, the information should also be present as structured context fields if it might be valuable for debugging purposes.
Example:
```Go
log.Infof("Starting server on %s:%s", addr, port)
```
* Usage of the `Fatalf()` method should be constrained to the main package of an application only!
* Use log levels to configure how detailed the logs of you application should be.
*`Debugf()` for log low level and detailed information. This may include variable dumps, but should not disclose sensitive information, e.g. keys or secret tokens.
*`Infof()` for general information.
*`Warnf()` for information that may indicate unwanted behavior, but is not an application error. Commonly used by retry loops.
*`Errorf()` to log information about any errors that occurred.
*`Fatalf()` to log information about any errors that occurred and then exit the program. Should only be used in the main package of an application.
* Loggers passed to subpackages of an application may use the `Named()` method for better understanding of where a message originated.
As this project contains nested Go modules, we use a Go work file to ease integration with IDEs. You can find an introduction in the [Go workspace tutorial](https://go.dev/doc/tutorial/workspaces).
The following can be added to your personal `settings.json`, but it is recommended to add it to
the `<REPOSITORY>/.vscode/settings.json` repo, so the settings will only affect this repository.
```jsonc
// Use gofumpt as formatter.
"gopls": {
"formatting.gofumpt": true,
},
// Use golangci-lint as linter. Make sure you've installed it.
"go.lintTool":"golangci-lint",
"go.lintFlags": ["--fast"],
// You can easily show Go test coverage by running a package test.
"go.coverageOptions": "showUncoveredCodeOnly",
// Executing unit tests with race detection.
// You can add preferences like "-v" or "-count=1"
"go.testFlags": ["-race"],
// Enable language features for files with build tags.
// Attention! This leads to integration test being executed when
// running a package test within a package containing integration
// tests.
"go.buildTags": "integration",
```
Additionally, we use the [Redhat YAML formatter](https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml) to have uniform formatting in our `.yaml` files.
