Include level in JSON log messages (useful for automatic status mapping in DataDog)

[cbugneac-nex]

What would you like to be added:
Include the level in the JSON log messages.

Why is this needed:
So that it's clear what type of log messages are these, e.g info, warning, error, etc.
At the moment these JSON log messages:

{"ts":1708343903247.908,"caller":"options/serving.go:374","msg":"Generated self-signed cert (/tmp/apiserver.crt, /tmp/apiserver.key)","v":0}                                                                                   │
{"ts":1708343906442.6155,"caller":"aggregated/handler.go:275","msg":"Adding GroupVersion metrics.k8s.io v1beta1 to ResourceManager","v":0}                                                                                     │
{"ts":1708343906652.7542,"caller":"server/secure_serving.go:213","msg":"Serving securely on :10250","v":0}                                                                                                                     │
{"ts":1708343906652.7927,"caller":"headerrequest/requestheader_controller.go:169","msg":"Starting RequestHeaderAuthRequestController","v":0}                                                                                   │
{"ts":1708343906652.8008,"caller":"cache/shared_informer.go:311","msg":"Waiting for caches to sync for RequestHeaderAuthRequestController","v":0}                                                                              │
{"ts":1708343906652.823,"caller":"dynamiccertificates/dynamic_serving_content.go:132","msg":"Starting controller","v":0,"name":"serving-cert::/tmp/apiserver.crt::/tmp/apiserver.key"}                                         │
{"ts":1708343906652.873,"caller":"dynamiccertificates/tlsconfig.go:240","msg":"Starting DynamicServingCertificateController","v":0}                                                                                            │
{"ts":1708343906652.9602,"caller":"dynamiccertificates/configmap_cafile_content.go:202","msg":"Starting controller","v":0,"name":"client-ca::kube-system::extension-apiserver-authentication::client-ca-file"}                 │
{"ts":1708343906738.6284,"caller":"cache/shared_informer.go:311","msg":"Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::client-ca-file","v":0}                                      │
{"ts":1708343906738.739,"caller":"dynamiccertificates/configmap_cafile_content.go:202","msg":"Starting controller","v":0,"name":"client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file"}    │
{"ts":1708343906738.7761,"caller":"cache/shared_informer.go:311","msg":"Waiting for caches to sync for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file","v":0}                        │
{"ts":1708343906838.8875,"caller":"cache/shared_informer.go:318","msg":"Caches are synced for client-ca::kube-system::extension-apiserver-authentication::client-ca-file","v":0}                                               │
{"ts":1708343906838.9417,"caller":"cache/shared_informer.go:318","msg":"Caches are synced for client-ca::kube-system::extension-apiserver-authentication::requestheader-client-ca-file","v":0}                                 │
{"ts":1708343906839.1077,"caller":"cache/shared_informer.go:318","msg":"Caches are synced for RequestHeaderAuthRequestController","v":0}

are detected in DataDog as errors. Adding level would allow automatic mapping to correct status.

Used args:

            args:
              - --secure-port=10250
              - --cert-dir=/tmp
              - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
              - --kubelet-use-node-status-port
              - --metric-resolution=15s
              - --logging-format=json

/kind feature

[dashpole]

/assign @dgrisonnet
/triage accepted

[yashvardhan-kukreja]

Hi folks, I looked a bit into this issue.
This would be easy to solve but seems to be impossible to solve from metrics-server.
That's because the inclusion of level field is actually a configurable attribute of the zapr logger library used under-the-hood.
But metrics-server doesn't use it directly, instead it uses the k8s.io/component-base as a wrapper to initialize and apply logging configurations and the whole zapr configuration and implementation lies under component-base instead.

The sad part is that k8s.io/component-base doesn't expose relevant options to configure the level key and as of now, it just omits the "level" key when initializing the JSON logger as a default case irrespective of what the invoker/client (for eg: metrics-server) wants.

References:

• component-base using the zapcore EncoderConfig without LevelKey: "level" as the default EncoderConfig when constructing the JSOLogger
• component-base hardcoded to only go through the code-path of choosing the default zapcore EncoderConfig when creating a JSON logger for a client like metrics-server - notice the last nil arg

What could be the fix then?

• Smallest one, yet not so clean one: Modify the component-base's NewJSONLogger to include LevelKey as well in its default EncoderConfig i.e. the following two lines of code to be added here

		LevelKey:       "level",
		EncodeLevel:    zapcore.LowercaseLevelEncoder,

Working example

• Larger but cleaner and extensible one: Modify component-base to allow clients like metrics-server to provide more granular options like providing EncoderConfig for the underlying JSON logger to use instead of blatantly using nil (causing it to forcefully use the default encoderconfig)

[yashvardhan-kukreja]

Update: I have raised an issue in component-base to address this issue as well as linked just before this comment

[yashvardhan-kukreja]

@dashpole @dgrisonnet would you folks mind re-assigning this issue to me, just considering no updates on before my comments?

[dashpole]

I believe the component-base repo is synced from kubernetes/kubernetes/staging. I would open an issue in k/k itself

[yashvardhan-kukreja]

I believe the component-base repo is synced from kubernetes/kubernetes/staging. I would open an issue in k/k itself

Sure @dashpole

Would you mind assigning me the issue when you open that issue considering I have already navigated the component-base fairly enough to realise where the changes would potentially be needed to be made.

Would love to contribute on this one!

[gmarcot]

Hello folks,

any news about this request?

Many thanks for your support