Understand and apply continuous deployment Argo CD

Argo-CD yes Kubernetes A declarative 、GitOps Continuous delivery tools .argo-cd The advantage is that , Application definition 、 Configuration and environment are declarative , And subject to version control ; Application deployment and lifecycle management are automated .
argo-cd Be realized as kubernetes controller , The controller continuously monitors the running application , And the current active state and the desired target state ( stay git Specified in storage ) Compare . When the active state deviates from the target state and the deployed application is marked OutofSync. in addition ,argo-cd Report visual differences , At the same time, it provides the function of automatically or manually synchronizing the real-time state to the desired target state . And , stay Git Any changes made to the desired target state in the warehouse can be automatically applied and reflected in the specified target environment .

Next, we will demonstrate through practical examples argo-cd working process . First installation argo-cd.

kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

After installation argocd-server It is amended as follows NodePort Type of service, So that you can get through node node IP+ The port number is accessed and installed on the Internet argocd.

By looking at secret obtain argocd Login password for , User name is admin. The password you checked is through base64 Encrypted , You need to decrypt before logging in argocd Service .

  kubectl get secret -n argocd argocd-initial-admin-secret -oyaml
  echo '$password'|base64 --decode

  Sign in argocd after , establish project, Creating project You need to set the code warehouse git Address , To configure Destination, That is, the deployed cluster address namespace,git The code warehouse address is a Deployment Of yaml file .

  After the project is created , Click on Sync,argo-cd It will start from git Pull up depoyment Of yaml file , And complete the deployment .

At this time, if you do not modify git Medium deployment file , Instead, you can modify the deployment directly in the cluster deployment file , Change to a nonexistent image edition , After modification ,pod It should fail to start .

  At this point to see argo-cd, Will see argo-cd Automatically update version information , Get the latest deployment , You can see argo-cd It also shows new pod Failed to start .

here , If you want to go back to git Warehouse yaml File configuration information , Just in argo-cd Click on the Sync button .

see pod Information , You can see that the startup failed pod It has been deleted ,deployment Of yaml Restore files to and git The versions stored in are consistent .

Look again argo-cd, You can see that the project also obtains Sync After pod Deployment .

Demonstrate through the above practical example , You can see the introduction of argo-cd It can effectively avoid misoperation in production , When problems are found , It can be quickly rolled back to git Stored in warehouse yaml Defined deployment version .

perform kubectl scale command , For deployment httpserver Of pod Expand horizontally , Run after executing the command pod from 1 One becomes 2 individual .

kubectl scale deployment httpserver --replicas=2

At this point to see argo-cd Project , The project status will show OutOfSync state , Because when creating a project, you set it manually Sync.

  Do it manually Sync after , View deployment information , You can see argo-cd There is a 2 individual pod be in running state .

Of course, you can also set the project to automatic Sync Pattern , So in the production environment scale 了 deployment after ,argo-cd The latest deployment information will be automatically synchronized .