imagepullsecret-patcher

A simple Kubernetes client-go application that creates and patches imagePullSecrets to service accounts in all Kubernetes namespaces to allow cluster-wide authenticated access to private container registry.

A blog post: https://medium.com/titansoft-engineering/kubernetes-cluster-wide-access-to-private-container-registry-with-imagepullsecret-patcher-b8b8fb79f7e5

Installation and configuration

To install imagepullsecret-patcher, can refer to deploy-example as a quick-start.

Below is a table of available configurations:

Config name	ENV	Command flag	Default value	Description
force	CONFIG_FORCE	-force	true	overwrite secrets when not match
debug	CONFIG_DEBUG	-debug	false	show DEBUG logs
managedonly	CONFIG_MANAGEDONLY	-managedonly	false	only modify secrets which were created by imagepullsecret
runonce	CONFIG_RUNONCE	-runonce	false	run the update loop once, allowing for cronjob scheduling if desired
serviceaccounts	CONFIG_SERVICEACCOUNTS	-serviceaccounts	"default"	comma-separated list of serviceaccounts to patch
all service account	CONFIG_ALLSERVICEACCOUNT	-allserviceaccount	false	if true, list and patch all service accounts and the `-servicesaccounts` argument is ignored
dockerconfigjson	CONFIG_DOCKERCONFIGJSON	-dockerconfigjson	""	json credential for authenicating container registry
dockerconfigjsonpath	CONFIG_DOCKERCONFIGJSONPATH	-dockerconfigjsonpath	""	path for of mounted json credentials for dynamic secret management
secret name	CONFIG_SECRETNAME	-secretname	"image-pull-secret"	name of managed secrets
excluded namespaces	CONFIG_EXCLUDED_NAMESPACES	-excluded-namespaces	""	comma-separated namespaces excluded from processing
loop duration	CONFIG_LOOP_DURATION	-loop-duration	10 seconds	duration string which defines how often namespaces are checked, see https://golang.org/pkg/time/#ParseDuration for more examples

And here are the annotations available:

Annotation	Object	Description
k8s.titansoft.com/imagepullsecret-patcher-exclude	namespace	If a namespace is set this annotation with "true", it will be excluded from processing by imagepullsecret-patcher.

Providing credentials

You can provide the authentication credentials for imagepullsecret to populate across namespaces in a couple of ways.

You can provide a raw secret as an environment variable, or better yet, by mounting a volume into the container. Mounted secrets can be dynamically updated and are more secure. Please see the relevant docs for more information https://kubernetes.io/docs/concepts/configuration/secret/

Why

To deploy private images to Kubernetes, we need to provide the credential to the private docker registries in either

Pod definition (https://kubernetes.io/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod)
Default service account in a namespace (https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/#add-imagepullsecrets-to-a-service-account)

With the second approach, a Kubernetes cluster admin configures the default service accounts in each namespace, and a Pod deployed by developers automatically inherits the image-pull-secret from the default service account in Pod's namespace.

This is done manually by following command for each Kubernetes namespace.

kubectl create secret docker-registry image-pull-secret \
  -n <your-namespace> \
  --docker-server=<your-registry-server> \
  --docker-username=<your-name> \
  --docker-password=<your-pword> \
  --docker-email=<your-email>

kubectl patch serviceaccount default \
  -p "{\"imagePullSecrets\": [{\"name\": \"image-pull-secret\"}]}" \
  -n <your-namespace>

And it could be automated with a simple program like imagepullsecret-patcher.

Contribute

Development Environment

Go 1.13

License

titansoft-pte-ltd/imagepullsecret-patcher

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