Shulou(Shulou.com)06/02 Report--

One: brief introduction

The configuration of applications in many production environments is complex and may require a combination of multiple config files, command-line arguments, and environment variables. When using container deployment, the configuration should be decoupled from the application image to ensure the portability of the image.

ConfigMap is the kubernetes resource object used to store configuration files, and all configuration content is stored in etcd. ConfigMap allows us to decouple the configuration details from the container image. Through ConfigMap, we can pass the configuration to container or other system components (such as Controller) in the form of key-value pairs.

Second: the way to create ConfigMap

1.From Literal Values can use kubectl create to create a ConfigMap, and then get it through kubectl get

Click (here) to collapse or open

# Create the ConfigMap

$kubectl create configmap my-config-from-literal=key1=value1-from-literal=key2=value2

Configmap "my-config" created

# Get the ConfigMap Details for my-config

$kubectl get configmaps my-config-o yaml

ApiVersion: v1

Data:

Key1: value1

Key2: value2

Kind: ConfigMap

Metadata:

CreationTimestamp: 2017-05-31T07:21:55Z

Name: my-config

Namespace: default

ResourceVersion: "241345"

SelfLink: / api/v1/namespaces/default/configmaps/my-config

Uid: d35f0a3d-45d1-11e7-9e62-080027a460572.From Configuration File is created directly through the configuration file

Click (here) to collapse or open

ApiVersion: v1

Kind: ConfigMap

Metadata:

Name: special-config

Namespace: default

Data:

Special.how: very

Click (here) to collapse or open

ApiVersion: v1

Kind: ConfigMap

Metadata:

Name: env-config

Namespace: default

Data:

Log_level: INFO3. The current directory contains if there is a configuration file donkey.properties, you can use the kubectl command to create a ConfigMap containing the contents of the file.

Kubectl create configmap donkey.properties-from-file=donkey.properties

Third: the use of ConfigMap

1.Pod uses ConfigMap to define environment variables through env

Click (here) to collapse or open

ApiVersion: v1

Kind: Pod

Metadata:

Name: dapi-test-pod

Spec:

Containers:

-name: test-container

Image: gcr.io/google_containers/busybox

Command: ["/ bin/sh", "- c", "env"]

Env:

-name: SPECIAL_LEVEL_KEY

ValueFrom:

ConfigMapKeyRef:

Name: special-config

Key: special.how

-name: LOG_LEVEL

ValueFrom:

ConfigMapKeyRef:

Name: env-config

Key: log_level

RestartPolicy: Never starts with Kubernetes V1.6 and introduces a new field, envFrom, to automatically generate environment variables for key=value defined in ConfigMap in the Pod environment:

Click (here) to collapse or open

ApiVersion: v1

Kind: Pod

Metadata:

Name: dapi-test-pod

Spec:

Containers:

-name: test-container

Image: gcr.io/google_containers/busybox

Command: ["/ bin/sh", "- c", "env"]

EnvFrom:

-configMapRef:

Name: special-config

RestartPolicy: Never

two。 Use ConfigMap to set the startup parameters of the container startup command

Click (here) to collapse or open

ApiVersion: v1

Kind: Pod

Metadata:

Name: dapi-test-pod

Spec:

Containers:

-name: test-container

Image: k8s.gcr.io/busybox

Command: ["/ bin/sh", "- c", "echo $(SPECIAL_LEVEL_KEY) $(SPECIAL_TYPE_KEY)"]

Env:

-name: SPECIAL_LEVEL_KEY

ValueFrom:

ConfigMapKeyRef:

Name: special-config

Key: SPECIAL_LEVEL

-name: SPECIAL_TYPE_KEY

ValueFrom:

ConfigMapKeyRef:

Name: special-config

Key: SPECIAL_TYPE

RestartPolicy: Never3. Using ConfigMap in storage volumes

Click (here) to collapse or open

ApiVersion: v1

Kind: Pod

Metadata:

Name: busybox

Namespace: default

Spec:

Containers:

-image: 120.79.156.135/desktop/busybox:latest

Command:

-sleep

-"3600"

ImagePullPolicy: IfNotPresent

Name: busybox

VolumeMounts:

-name: donkeyconfig

MountPath: / configfiles

Volumes:

-name: donkeyconfig

ConfigMap:

Name: donkey.properties

Items:

-key: donkey.properties

Path: donkey.properties

RestartPolicy: Always

ImagePullSecrets:

-name: registry- secret4: restrictions on using ConfigMap

1.ConfigMap must be created before Pod

2.ConfigMap is restricted by Namespace, and only Pod in the same Namespaces can reference it.

Quota management in 3.ConfigMap has not been implemented yet

4.kubelet only supports ConfigMap for Pod that can be managed by API Server.

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