configMapGenerator

Each entry in this list results in the creation of one ConfigMap resource (it’s a generator of n maps).

The example below creates four ConfigMaps:

• first, with the names and contents of the given files
• second, with key/value as data using key/value pairs from files
• third, also with key/value as data, directly specified using literals
• and a fourth, which sets an annotation and label via options for that single ConfigMap

Each configMapGenerator item accepts a parameter of behavior: [create|replace|merge]. This allows an overlay to modify or replace an existing configMap from the parent.

Also, each entry has an options field, that has the same subfields as the kustomization file’s generatorOptions field.

This options field allows one to add labels and/or annotations to the generated instance, or to individually disable the name suffix hash for that instance. Labels and annotations added here will not be overwritten by the global options associated with the kustomization file generatorOptions field. However, due to how booleans behave, if the global generatorOptions field specifies disableNameSuffixHash: true, this will trump any attempt to locally override it.

apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization  # These labels are added to all configmaps and secrets. generatorOptions:  labels:  fruit: apple  configMapGenerator: - name: my-java-server-props  behavior: merge  files:  - application.properties  - more.properties - name: my-java-server-env-file-vars  envs:  - my-server-env.properties  - more-server-props.env - name: my-java-server-env-vars  literals:  - JAVA_HOME=/opt/java/jdk  - JAVA_TOOL_OPTIONS=-agentlib:hprof  options:  disableNameSuffixHash: true  labels:  pet: dog - name: dashboards  files:  - mydashboard.json  options:  annotations:  dashboard: "1"  labels:  app.kubernetes.io/name: "app1" 

It is also possible to define a key to set a name different than the filename.

The example below creates a ConfigMap with the name of file as myFileName.ini while the actual filename from which the configmap is created is whatever.ini.

apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization  configMapGenerator: - name: app-whatever  files:  - myFileName.ini=whatever.ini 

ConfigMap from File

ConfigMap Resources may be generated from files - such as a java .properties file. To generate a ConfigMap Resource for a file, add an entry to configMapGenerator with the filename.

Example: Generate a ConfigMap with a data item containing the contents of a file.

The ConfigMaps will have data values populated from the file contents. The contents of each file will appear as a single data item in the ConfigMap keyed by the filename.

The example illustrates how you can create ConfigMaps from File using Generators.

File Input

# kustomization.yaml apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization configMapGenerator: - name: my-application-properties  files:  - application.properties  

# application.properties FOO=Bar 

Build Output

apiVersion: v1 data:  application.properties: |-   FOO=Bar kind: ConfigMap metadata:  name: my-application-properties-f7mm6mhf59 

ConfigMap from Literals

ConfigMap Resources may be generated from literal key-value pairs - such as JAVA_HOME=/opt/java/jdk. To generate a ConfigMap Resource from literal key-value pairs, add an entry to configMapGenerator with a list of literals.

Example: Create a ConfigMap with 2 data items generated from literals.

The example illustrates how you can create ConfigMaps from Literals using Generators.

File Input

# kustomization.yaml apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization configMapGenerator: - name: my-java-server-env-vars  literals:  - JAVA_HOME=/opt/java/jdk  - JAVA_TOOL_OPTIONS=-agentlib:hprof  

Build Output

apiVersion: v1 data:  JAVA_HOME: /opt/java/jdk  JAVA_TOOL_OPTIONS: -agentlib:hprof kind: ConfigMap metadata:  name: my-java-server-env-vars-44k658k8gk 

ConfigMap from env file

ConfigMap Resources may be generated from key-value pairs much the same as using the literals option but taking the key-value pairs from an environment file. These generally end in .env. To generate a ConfigMap Resource from an environment file, add an entry to configMapGenerator with a single envs entry, e.g. envs: [ 'config.env' ].

Example: Create a ConfigMap with 3 data items generated from an environment file.

File Input

# kustomization.yaml apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization configMapGenerator: - name: tracing-options  envs:  - tracing.env 

# tracing.env ENABLE_TRACING=true SAMPLER_TYPE=probabilistic SAMPLER_PARAMETERS=0.1 

Build Output

apiVersion: v1 kind: ConfigMap metadata:  # The name has had a suffix applied  name: tracing-options-6bh8gkdf7k # The data has been populated from each literal pair data:  ENABLE_TRACING: "true"  SAMPLER_TYPE: "probabilistic"  SAMPLER_PARAMETERS: "0.1" 

Overriding Base ConfigMap Values

ConfigMap values from bases may be overridden by adding another generator for the ConfigMap in the overlay and specifying the behavior field. behavior may be one of:

• create (default value): used to create a new ConfigMap. A name conflict error will be thrown if a ConfigMap with the same name and namespace already exists.
• replace: replace an existing ConfigMap from the base.
• merge: add or update the values in an existing ConfigMap from the base.

When updating an existing ConfigMap with the merge or replace strategies, you must ensure that both the name and namespace match the ConfigMap you’re targeting. For example, if the namespace is unspecified in the base, you should not specify it in the overlay. Conversely, if it is specified in the base, you must specify it in the overlay as well. This is true even if the overlay Kustomization includes a namespace, because configMapGenerator runs before the namespace transformer.

apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization  namespace: my-new-namespace  resources: - ../base  configMapGenerator:  - name: existing-name  namespace: existing-ns # needs to match target ConfigMap from base  behavior: replace  literals:  - ENV=dev 

Propagating the Name Suffix

Workloads that reference the ConfigMap or Secret will need to know the name of the generated Resource, including the suffix. Kustomize takes care of this automatically by identifying references to generated ConfigMaps and Secrets, and updating them.

In the following example, the generated ConfigMap name will be my-java-server-env-vars with a suffix unique to its contents. Changes to the contents will change the name suffix, resulting in the creation of a new ConfigMap, which Kustomize will transform Workloads to point to.

The PodTemplate volume references the ConfigMap by the name specified in the generator (excluding the suffix). Kustomize will update the name to include the suffix applied to the ConfigMap name.

Input: The kustomization.yaml and deployment.yaml files

# kustomization.yaml apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization configMapGenerator: - name: my-java-server-env-vars  literals:  - JAVA_HOME=/opt/java/jdk  - JAVA_TOOL_OPTIONS=-agentlib:hprof resources: - deployment.yaml 

# deployment.yaml apiVersion: apps/v1 kind: Deployment metadata:  name: test-deployment  labels:  app: test spec:  selector:  matchLabels:  app: test  template:  metadata:  labels:  app: test  spec:  containers:  - name: container  image: registry.k8s.io/busybox  command: [ "/bin/sh", "-c", "ls /etc/config/" ]  volumeMounts:  - name: config-volume  mountPath: /etc/config  volumes:  - name: config-volume  configMap:  name: my-java-server-env-vars 

Result: The output of the Kustomize build.

apiVersion: v1 kind: ConfigMap metadata:  # The name has been updated to include the suffix  name: my-java-server-env-vars-k44mhd6h5f data:  JAVA_HOME: /opt/java/jdk  JAVA_TOOL_OPTIONS: -agentlib:hprof --- apiVersion: apps/v1 kind: Deployment metadata:  labels:  app: test  name: test-deployment spec:  selector:  matchLabels:  app: test  template:  metadata:  labels:  app: test  spec:  containers:  - command:  - /bin/sh  - -c  - ls /etc/config/  image: registry.k8s.io/busybox  name: container  volumeMounts:  - mountPath: /etc/config  name: config-volume  volumes:  - configMap:  # The name has been updated to include the  # suffix matching the ConfigMap  name: my-java-server-env-vars-k44mhd6h5f  name: config-volume 

Feedback

Was this page helpful?

Glad to hear it! Please tell us how we can improve.

Sorry to hear that. Please tell us how we can improve.