Logging
The Go SDK integrates with the
onelog
project, almost out of the box.
The project has chosen this library as:
- It works with WebAssembly binaries. Other popular logging solutions can't compile to target WebAssembly.
- It provides good performance.
- It supports structured logging.
Initialize logger​
You need to initialize a logger structure.
By performing this initialization in a global variable,
you can log from the two main policy entry points: validate
and
validate_settings
.
In the main package, main.go
there is initialization for the logger:
var (
logWriter = kubewarden.KubewardenLogWriter{}
logger = onelog.New(
&logWriter,
onelog.ALL, // shortcut for onelog.DEBUG|onelog.INFO|onelog.WARN|onelog.ERROR|onelog.FATAL
)
)
Consuming the logger​
Now, you can use the logger
object to log from wherever required your policy:
func validate(payload []byte) ([]byte, error) {
// ...
logger.Info("validating request")
// ...
}
You can add structured logging:
func validate(payload []byte) ([]byte, error) {
// ...
logger.WarnWithFields("logging something important", func(e onelog.Entry) {
e.String("one_field", "a value")
e.String("another_field", "another value")
})
// ...
}
You can refer to the
onelog
documentation
for more information.
Policy logging goes to the policy evaluator
(for example, kwctl
or policy-server
),
and they log on behalf of the policy.
They use mechanisms that are interoperable with other components that enable distributed tracing such as
Jaeger.