Kubernetes ConfigMap Operations

Internal

• Kubernetes Operations
• Kubernetes Cluster Configuration Concepts

Inspect a ConfigMap

kubectl get cm <name> -o yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: example
  ...
data:
  color: red
  shape: square

Read the Content of a File Stored in ConfigMap

kubectl get cm <configmap-name> -o jsonpath='{.data.<key>}'

Create a ConfigMap with CLI

All three options presented below can be combined on one single command line:

Specify Key/Value Pairs on Command Line

kubectl create configmap example \
  --from-literal=COLOR=red \
  --from-literal=SHAPE=square \
  --from-literal=PHRASE="something and something else"

Multiple --from-literal= entries are allowed.

Use the Content of a File

The entire content of the file is keyed by default under the file name.

kubectl create configmap example --from-file=some-config-file.txt

apiVersion: v1
kind: ConfigMap
metadata:
  name: example
  ...
data:
  some-config-file.txt: |
    color=blue
    shape=circle

An arbitrary key, different from the file name, can be specified:

kubectl create configmap example --from-file=mykey=some-config-file.txt

Multiple --from-file= can be used.

Import all Files from a Directory

kubectl can be used to inspect a directory and create an individual ConfigMap entry for each file in the directory whose name is a valid ConfigMap key. In the example below, /tmp/config-dir contains two files: A.txt and B.txt.

kubectl create configmap example --from-file=/tmp/config-dir

apiVersion: v1
kind: ConfigMap
metadata:
  name: example
  ...
data:
  A.txt: |
    color=red
  B.txt: |
    shape=square

Edit an Already Deployed ConfigMap

Interactively

kubectl edit configmap myconfigmap

Non-Interactively

This sequence adds a key/value (shape=square) to an existing ConfigMap, leaving the other keys unchanged:

kubectl create configmap <existing-configmap-name> --from-literal=shape=square --dry-run --save-config=true -o yaml | k apply -f -