Implementation Steps of Docker Constructing kubectl Image

If the application service is deployed using k8s integration gitlab ci/cd, the kubeclt image is required in the gitlab-ci process
There are two ways to build an kubectl image using docker

Mode 1 (the mirror image is relatively small by 1 point, about 45.8 M)

Installing kubectl executable files on Linux using curl

cd /usr/local/bin
curl -LO https://storage.googleapis.com/kubernetes-release/release/v1.20.1/bin/linux/amd64/kubectl
chmod +x ./kubectl

Refer to the official installation documentation for details

Next, create a new Dockerfile file in the/usr/local/bin directory, and write the following contents

FROM alpine:latest
COPY kubectl /usr/local/bin/
RUN chmod +x /usr/local/bin/kubectl

After the Dockerfile file is built, execute the build command in the same directory

docker build -t registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1 .

Wait for the image build to complete

Mode 2 (the mirror image is relatively large, about 48.9 M)

This method is relatively convenient, but the construction is slow, and the kubectl executable file needs to be downloaded during the construction process
Create a new Dockerfile file directly, and write the following contents

FROM alpine:latest

RUN apk add --update -t deps curl

RUN curl -L https://storage.googleapis.com/kubernetes-release/release/v1.20.1/bin/linux/amd64/kubectl -o /usr/local/bin/kubectl \
  && chmod +x /usr/local/bin/kubectl

RUN apk del --purge deps \
  && rm /var/cache/apk/*

Execute the build command in the same directory

docker build -t registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1 .

Finally

1. Test whether the built image can be used normally

docker run -it registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1 kubectl version --client

The output is as follows, that is, the constructed image can be used normally

Client Version: version.Info{Major:"1", Minor:"20", GitVersion:"v1.20.1", GitCommit:"c4d752765b3bbac2237bf87cf0b1c2e307844666", GitTreeState:"clean", BuildDate:"2020-12-18T12:09:25Z", GoVersion:"go1.15.5", Compiler:"gc", Platform:"linux/amd64"}

2. Pull the image from Registry

docker pull registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1

3. Push the mirror image to Registry, and replace [ImageId] with the corresponding mirror image ID

docker login --username= User name  registry.cn-hangzhou.aliyuncs.com

docker tag [ImageId] registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1

docker push registry.cn-hangzhou.aliyuncs.com/sanchar/kubectl:v1.20.1