Kubernetes how to make Deployment to update image

Docker Problem Overview

I do have deployment with single pod, with my custom docker image like:

containers:
  - name: mycontainer
    image: myimage:latest

During development I want to push new latest version and make Deployment updated. Can't find how to do that, without explicitly defining tag/version and increment it for each build, and do

kubectl set image deployment/my-deployment mycontainer=myimage:1.9.1

Docker Solutions

Solution 1 - Docker

You can configure your pod with a grace period (for example 30 seconds or more, depending on container startup time and image size) and set "imagePullPolicy: "Always". And use kubectl delete pod pod_name. A new container will be created and the latest image automatically downloaded, then the old container terminated.

Example:

spec:
  terminationGracePeriodSeconds: 30
  containers:
  - name: my_container
    image: my_image:latest
    imagePullPolicy: "Always"

I'm currently using Jenkins for automated builds and image tagging and it looks something like this:

kubectl --user="kube-user" --server="https://kubemaster.example.com"  --token=$ACCESS_TOKEN set image deployment/my-deployment mycontainer=myimage:"$BUILD_NUMBER-$SHORT_GIT_COMMIT"

Another trick is to intially run:

kubectl set image deployment/my-deployment mycontainer=myimage:latest

and then:

kubectl set image deployment/my-deployment mycontainer=myimage

It will actually be triggering the rolling-update but be sure you have also imagePullPolicy: "Always" set.

Update:

another trick I found, where you don't have to change the image name, is to change the value of a field that will trigger a rolling update, like terminationGracePeriodSeconds. You can do this using kubectl edit deployment your_deployment or kubectl apply -f your_deployment.yaml or using a patch like this:

kubectl patch deployment your_deployment -p \
  '{"spec":{"template":{"spec":{"terminationGracePeriodSeconds":31}}}}'

Just make sure you always change the number value.

Solution 2 - Docker

UPDATE 2019-06-24

Based on the @Jodiug comment if you have a 1.15 version you can use the command:

kubectl rollout restart deployment/demo

First

1.Prepare deployment

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: demo
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - name: demo
        image: registry.example.com/apps/demo:master
        imagePullPolicy: Always
        env:
        - name: FOR_GODS_SAKE_PLEASE_REDEPLOY
          value: 'THIS_STRING_IS_REPLACED_DURING_BUILD'

2.Deploy

sed -ie "s/THIS_STRING_IS_REPLACED_DURING_BUILD/$(date)/g" deployment.yml
kubectl apply -f deployment.yml

Second (one liner):

kubectl patch deployment web -p \
  "{\"spec\":{\"template\":{\"metadata\":{\"labels\":{\"date\":\"`date +'%s'`\"}}}}}"

Of course the imagePullPolicy: Always is required on both cases.

Solution 3 - Docker

kubectl rollout restart deployment myapp

This is the current way to trigger a rolling update and leave the old replica sets in place for other operations provided by kubectl rollout like rollbacks.

Solution 4 - Docker

I use Gitlab-CI to build the image and then deploy it directly to GCK. If use a neat little trick to achieve a rolling update without changing any real settings of the container, which is changing a label to the current commit-short-sha.

My command looks like this:

kubectl patch deployment my-deployment -p "{\"spec\":{\"template\":{\"metadata\":{\"labels\":{\"build\":\"$CI_COMMIT_SHORT_SHA\"}}}}}}"

Where you can use any name and any value for the label as long as it changes with each build.

Have fun!

Solution 5 - Docker

It seems that k8s expects us to provide a different image tag for every deployment. My default strategy would be to make the CI system generate and push the docker images, tagging them with the build number: xpmatteo/foobar:456.

For local development it can be convenient to use a script or a makefile, like this:

# create a unique tag    
VERSION:=$(shell date +%Y%m%d%H%M%S)
TAG=xpmatteo/foobar:$(VERSION)

deploy:
	npm run-script build
	docker build -t $(TAG) . 
	docker push $(TAG)
	sed s%IMAGE_TAG_PLACEHOLDER%$(TAG)% foobar-deployment.yaml | kubectl apply -f - --record

The sed command replaces a placeholder in the deployment document with the actual generated image tag.

Solution 6 - Docker

Another option which is more suitable for debugging but worth mentioning is to check in revision history of your rollout:

$ kubectl rollout history deployment my-dep
deployment.apps/my-dep
 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>
3         <none>

To see the details of each revision, run:

 kubectl rollout history deployment my-dep --revision=2

And then returning to the previous revision by running:

 $kubectl rollout undo deployment my-dep --to-revision=2

And then returning back to the new one.
Like running ctrl+z -> ctrl+y (:

(*) The CHANGE-CAUSE is <none> because you should run the updates with the --record flag - like mentioned here:

kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record

(**) There is a discussion regarding deprecating this flag.

Solution 7 - Docker

We could update it using the following command:

kubectl set image deployment/<<deployment-name>> -n=<<namespace>> <<container_name>>=<<your_dockerhub_username>>/<<image_name you want to set now>>:<<tag_of_the_image_you_want>>

For example,

kubectl set image deployment/my-deployment -n=sample-namespace my-container=alex/my-sample-image-from-dockerhub:1.1

where:

kubectl set image deployment/my-deployment - we want to set the image of the deployment named my-deployment
-n=sample-namespace - this deployment belongs to the namespace named as sample-namespace. If your deployment belongs to the default namespace, no need to mention this part in your command.
my-container is the container name which was previously mentioned in the YAML file of your deployment configuration.
alex/my-sample-image-from-dockerhub:1.1 is the new image which you want to set for the deployment and run the container for. Here, alex is the username of the dockerhub image(if applicable), my-sample-image-from-dockerhub:1.1 the image and tag you want to use.

Solution 8 - Docker

I am using Azure DevOps to deploy the containerize applications, I am easily manage to overcome this problem by using the build ID

Everytime its builds and generate the new Build ID, I use this build ID as tag for docker image here is example

imagename:buildID

once your image is build (CI) successfully, in CD pipeline in deployment yml file I have give image name as

imagename:env:buildID

here evn:buildid is the azure devops variable which having value of build ID.

so now every time I have new changes to build(CI) and deploy(CD).

please comment if you need build definition for CI/CD.

Content Type	Original Author	Original Content on Stackoverflow
Question	Andriy Kopachevskyy	View Question on Stackoverflow
Solution 1 - Docker	Camil	View Answer on Stackoverflow
Solution 2 - Docker	Przemek Nowak	View Answer on Stackoverflow
Solution 3 - Docker	Martin Peter	View Answer on Stackoverflow
Solution 4 - Docker	David Faber	View Answer on Stackoverflow
Solution 5 - Docker	xpmatteo	View Answer on Stackoverflow
Solution 6 - Docker	RtmY	View Answer on Stackoverflow
Solution 7 - Docker	vagdevi k	View Answer on Stackoverflow
Solution 8 - Docker	Noman Sadiq	View Answer on Stackoverflow