What is a ConfigMap?
- Docker & Kubernetes course
- Intermediate
- Lesson 43/82
- 4 min
Learn to separate configuration data with a ConfigMap.
What is a ConfigMap?
A ConfigMap is an object that keeps configuration data (key-value pairs or whole files) separate from the image. The same image runs in development, test and production with different ConfigMaps. Pods use a ConfigMap as environment variables or as files.
kubectl create configmap api-ayar --from-literal=LOG_LEVEL=info --from-literal=DB_HOST=db
kubectl get configmap api-ayar -o yamlConfigMaps are for non-secret data; Secrets are used for passwords and keys. A ConfigMap can be at most 1 MiB.
Inspecting a ConfigMap
ConfigMap data is in the data field. describe shows the keys and values readably; a single value is taken with jsonpath:
$ kubectl describe configmap api-ayar
Data
====
DB_HOST:
----
db
LOG_LEVEL:
----
info
$ kubectl get cm api-ayar -o jsonpath='{.data.LOG_LEVEL}'
infoPractice The first ConfigMap
Write two commands: create the api-ayar ConfigMap with the values LOG_LEVEL=info and DB_HOST=db; then print the LOG_LEVEL value with jsonpath='{.data.LOG_LEVEL}'.
Starter code
# buraya yazSample solution
kubectl create configmap api-ayar --from-literal=LOG_LEVEL=info --from-literal=DB_HOST=db
kubectl get configmap api-ayar -o jsonpath='{.data.LOG_LEVEL}'Expected output
configmap/api-ayar created info
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the benefit of keeping configuration in a ConfigMap instead of baking it into the image?
- The image shrinks
- Passwords are encrypted
- Pods get faster
- The same image is used in different environments without rebuilding Correct answer
Explanation: The build is done once; the configuration changes per environment.
2 Add a key-value from the command line.
kubectl create configmap api-ayar ____=LOG_LEVEL=infokubectl create configmap api-ayar --from-literal=LOG_LEVEL=infoExplanation: --from-literal takes NAME=value.
3 Match.
| Term | Meaning |
|---|---|
ConfigMap |
Non-secret config |
Secret |
Secret value |
data |
Key-value field |
1 MiB |
Size limit |