Logging format argument - logfmt / json

[nfaust-edb]

I use json formatted log messages and I would like to add a command argument for logging format between logfmt and json. My thought is something like what is used by thanos-receive.

--log.format=logfmt        Log format to use. Possible options: logfmt or json.

Thank you.

[nfaust-edb]

My golang isn't great, but this accomplishes my request with minimal effort.

diff --git a/main.go b/main.go
index 0da18ea..01fb67b 100644
--- a/main.go
+++ b/main.go
@@ -76,6 +76,7 @@ type CmdConfig struct {
        ScaleTimeout           time.Duration
        useAzAwareHashRing     bool
        podAzAnnotationKey     string
+       LogFormat              string
 }
 
 func parseFlags() CmdConfig {
@@ -98,18 +99,26 @@ func parseFlags() CmdConfig {
        flag.DurationVar(&config.ScaleTimeout, "scale-timeout", defaultScaleTimeout, "A timeout to wait for receivers to really start after they report healthy")
        flag.BoolVar(&config.useAzAwareHashRing, "use-az-aware-hashring", false, "A boolean to use az aware hashring to comply with Thanos v0.32+")
        flag.StringVar(&config.podAzAnnotationKey, "pod-az-annotation-key", "", "pod annotation key for AZ Info, If not specified or key not found, will use sts name as AZ key")
+       flag.StringVar(&config.LogFormat, "log.format", "logfmt", "Log format to use. Possible options: logfmt or json.")
        flag.Parse()
 
        return config
 }
 
 func main() {
-       logger := log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
-       logger = log.WithPrefix(logger, "ts", log.DefaultTimestampUTC)
-       logger = log.WithPrefix(logger, "caller", log.DefaultCaller)
-
        config := parseFlags()
 
+       var logger log.Logger
+       if config.LogFormat == "json" {
+               logger = log.NewJSONLogger(log.NewSyncWriter(os.Stderr))
+               logger = log.WithPrefix(logger, "ts", log.DefaultTimestampUTC)
+               logger = log.WithPrefix(logger, "caller", log.DefaultCaller)
+       } else {
+               logger = log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
+               logger = log.WithPrefix(logger, "ts", log.DefaultTimestampUTC)
+               logger = log.WithPrefix(logger, "caller", log.DefaultCaller)
+       }
+
        var tmpControllerLabel string
        if len(config.StatefulSetLabel) > 0 {
                tmpControllerLabel = config.StatefulSetLabel

% kubectl get pods -n thanos thanos-receive-controller-6f89bdfc99-ngtk2
NAME                                         READY   STATUS    RESTARTS   AGE
thanos-receive-controller-6f89bdfc99-ngtk2   1/1     Running   0          12s

% kubectl logs -n thanos thanos-receive-controller-6f89bdfc99-ngtk2
W1021 19:24:19.767848       1 client_config.go:618] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
{"caller":"main.go:210","level":"info","msg":"starting the controller","ts":"2024-10-21T19:24:19.768880714Z"}
{"caller":"main.go:526","level":"debug","msg":"successfully synced ConfigMap cache","ts":"2024-10-21T19:24:20.266325225Z"}
{"caller":"main.go:526","level":"debug","msg":"successfully synced StatefulSet cache","ts":"2024-10-21T19:24:20.367139036Z"}
{"caller":"main.go:534","level":"info","msg":"successfully synced all caches","ts":"2024-10-21T19:24:20.36724654Z"}
{"caller":"main.go:606","hashring":"default","level":"info","msg ":"hashring got a new statefulset","statefulset":"thanos-receive-ingestor","ts":"2024-10-21T19:24:20.367636454Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-0.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:25.382775Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-1.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:25.391109574Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-2.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:25.403918641Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-3.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:25.411709703Z"}
{"caller":"main.go:612","hashring":"[{Hashring:default Tenants:[] Endpoints:[{Address:thanos-receive-ingestor-0.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-1.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-2.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-3.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:}] Algorithm: ExternalLabels:map[]}]","level":"info","msg":"hashring populated","ts":"2024-10-21T19:24:25.411784205Z"}
{"caller":"main.go:606","hashring":"default","level":"info","msg ":"hashring got a new statefulset","statefulset":"thanos-receive-ingestor","ts":"2024-10-21T19:24:25.763651238Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-0.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:30.776491447Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-1.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:30.784822607Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-2.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:30.791457715Z"}
{"AZ":"","caller":"main.go:692","endpoint:":"thanos-receive-ingestor-3.thanos-receive-ingestor.thanos.svc.cluster.local:10901","hashring":"default","level":"info","msg":"Hashring got an endpoint","ts":"2024-10-21T19:24:30.801930042Z"}
{"caller":"main.go:612","hashring":"[{Hashring:default Tenants:[] Endpoints:[{Address:thanos-receive-ingestor-0.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-1.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-2.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:} {Address:thanos-receive-ingestor-3.thanos-receive-ingestor.thanos.svc.cluster.local:10901 AZ:}] Algorithm: ExternalLabels:map[]}]","level":"info","msg":"hashring populated","ts":"2024-10-21T19:24:30.802098647Z"}