Kubernetes ConfigMaps

A ConfigMap is an API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume. https://kubernetes.io/docs/concepts/configuration/configmap/

Commands

• kubectl create configmap

kubectl create configmap <map-name> <data-source>

• kubectl get configmaps
• kubectl describe configmaps YOUR_CONFIG_MAP_NAME
• kubectl edit configmap

EKS (aws-auth configmap)

• kubectl edit -n kube-system configmap/aws-auth
• kubectl describe -n kube-system configmap/aws-auth

Examples

• kube-root-ca.crt configMap
• aws-auth configMap
• nginx-controller, ingress-nginx-controller ConfigMap
• argocd-cm configMap
• Corefile from CoreDNS

Errors

helm list
Error: configmaps is forbidden: User "system:serviceaccount:kube-system:default" cannot list resource "configmaps" in API group "" in the namespace "kube-system"

Activities

• CKA v1.23: Use ConfigMaps and Secrets to configure applications
• CKA v1.15, CKA v1.21: Understand ConfigMaps
• Configure a Pod to Use a ConfigMap
• Configuring Redis using a ConfigMap

News

• Aug 2020 Kubernetes v1.19 Immutable Secrets and ConfigMaps

Errors

 Warning: resource configmaps/kube-root-ca.crt is missing the kubectl.kubernetes.io/last-applied-configuration annotation which is required by kubectl apply. kubectl apply should only be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically. secret/default-token-7z4zd created
Error from server (Conflict): error when applying patch:
.../...
to:
Resource: "/v1, Resource=configmaps", GroupVersionKind: "/v1, Kind=ConfigMap"
Name: "kube-root-ca.crt", Namespace: "your-namespace"
for: "your.yaml": Operation cannot be fulfilled on configmaps "kube-root-ca.crt": the object has been modified; please apply your changes to the latest version and try again

Related terms

• Deployment, Service, Secrets
• Terraform: kubernetes_config_map

https://registry.terraform.io/providers/hashicorp/kubernetes/latest/docs/resources/config_map (ConfigMap)

• Terraform resource: kubernetes config map v1 data
• kind: ConfigMap
• Terraform resource: kubernetes_config_map
• Sidecar container
• Kustomize
• configMapRef:
• data:
• Error: kind ConfigMap
• Error: UPGRADE FAILED: kind ConfigMap with the name "you-configmap-name" in "your-env" already exists
• Already exists in the cluster
• Kubernetes HostPath volume provider
• projected
• cattle-project

See also

• AWS IAM Authenticator for Kubernetes: aws-auth, kubectl edit -n kube-system configmap/aws-auth, eksctl create iamidentitymapping, mapUsers:, mapRoles:, mapAccounts:
• ConfigMaps: kubectl [ get | edit | describe | create | delete ] configmaps, aws-auth, Kustomize, kind: ConfigMap, ConfigMapRef, envFrom
• Kubectl information commands: cluster-info | view | pods | nodes | services | version | describe | logs

https://github.com/kubernetes/enhancements/issues/1412