Month: January 2020

I am writing about how to configure AWS ECR to be used as my private docker container registry.

This can be done with a docker login command to authenticate to an ECR registry that provides an authorization token valid for 12 hours.

Because AWS ECR does not allow a docker login password to be valid for more than 12 hours. And thus even if I create a secret for kubernetes to use, it will be invalid after 12 hours

I want to use a CI-CD system like CircleCI or Jenkins which updates my pods automatically. So i don’t want to create this secret manually each time.

So, I need to keep the secret fresh and make sure I get the valid password from AWS. The solution for this is simple – just setting up a scheduled job or cron job to do this work for me.

Step 1. Create a Kubernetes cronjob

To create a Kubernetes cronjob , which will make sure my AWS ECR docker secret stays updated and valid to pull images whenever I update the pod images.

# aws-registry-credential-cron.yaml

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: aws-registry-credential-cron
spec:
  schedule: "* */8 * * *"
  successfulJobsHistoryLimit: 2
  failedJobsHistoryLimit: 2
  jobTemplate:
    spec:
      backoffLimit: 4
      template:
        spec:
          serviceAccountName: default
          terminationGracePeriodSeconds: 0
          restartPolicy: Never
          containers:
          - name: kubectl
            imagePullPolicy: IfNotPresent
            image: xynova/aws-kubectl:latest
            envFrom:
            - secretRef:
                name: aws-secret
            command:
            - "/bin/sh"
            - "-c"
            - |

              # create docker login information by aws ecr get-login command
DOCKER_REGISTRY_SERVER=https://${AWS_ACCOUNT}.dkr.ecr.${AWS_REGION}.amazonaws.com
              DOCKER_USER=AWS
              DOCKER_PASSWORD=$(aws ecr get-login --region ${AWS_REGION} --registry-ids ${AWS_ACCOUNT} | cut -d' ' -f6)
              # delete old secret
              kubectl delete secret aws-registry || true
              # create new one by run docker login information
              kubectl create secret docker-registry aws-registry \
              --docker-server=$DOCKER_REGISTRY_SERVER \
              --docker-username=$DOCKER_USER \
              --docker-password=$DOCKER_PASSWORD \
              --docker-email=no@email.local
              # set default pullSecret of service account default is aws-registry
              kubectl patch serviceaccount default -p '{"imagePullSecrets":[{"name":"aws-registry"}]}'

• schedule: “* */8 * * *” : The refresh cronjob script will be run every 8 hours.

✗ kubectl create -f ./aws-registry-credential-cron.yaml

Step 2. Create AWS secret

Create a Kubernetes secret aws-secret to save your AWS credential information by a command.

✗ kubectl create secret generic aws-secret \
--from-literal=AWS_ACCOUNT=YOUR_AWS_ACCOUNT_ID \
--from-literal=AWS_ACCESS_KEY_ID=YOUR_AWS_ACCESS_KEY_ID \
--from-literal=AWS_SECRET_ACCESS_KEY=YOUR_AWS_SECRET_ACCESS_KEY \
--from-literal=AWS_DEFAULT_REGION=ap-southeast-1 \
--from-literal=AWS_REGION=ap-southeast-1

Step 3. Add permission to service account default

I am using service account default (serviceAccountName: default) to run the cronjob, create and delete the secret. So, I will give default service account the admin access and my cronjob pod can then execute all the actions.

✗ kubectl create clusterrolebinding serviceaccounts-default-cluster-admin --clusterrole=cluster-admin --group=system:serviceaccounts

Step 4. Try to run cronjob manually

You can execute the cronjob by using bellow command.

 ✗ kubectl create job --from=cronjob/aws-registry-credential-cron aws-registry-credential-cron-manual-001

job.batch/aws-registry-credential-cron-manual-001 created

Verify execution result by checking the log of above job aws-registry-credential-cron-manual-001

✗ kubectl logs job/aws-registry-credential-cron-manual-001
secret "aws-registry" deleted
secret "aws-registry" created
serviceaccount "default" patched

Hope everything works for you too. Happy K8s!