Skip to main content

Setting /etc/hosts entries during the initial deployment of an Application using k8s yaml file

Some times we have to enter specific hosts file entries to the container running inside the POD of a kubernetes deployment during the initial deployment stage itself.

If these entries are not in place, the application env variables mentioned in the yaml file , as hostnames , will not resolve to the IP address and the application will not start properly.

So to make sure the /etc/hosts file entries are already there after the spin up of the POD you can add the below entries in your yaml file.

cat > api-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
spec:
  template:
    metadata:
    spec:
      volumes:
      containers:
      - image: registryserver.jinojoseph.com:5000/jinojosephimage:v1.13
        lifecycle:
          postStart:
            exec:
              command: ["/bin/sh", "-c", "echo 10.0.1.10 namenode.jinojoseph.com >> /etc/hosts && echo 10.0.1.8 dn1.jinojoseph.com >> /etc/hosts && echo 10.0.1.4 dn2.jinojoseph.com >> /etc/hosts && echo 10.0.1.9 haproxy.jinojoseph.com >> /etc/hosts && echo 10.0.1.12 k8snn1.jinojoseph.com >> /etc/hosts && echo 10.0.1.13 haproxy1.jinojoseph.com >> /etc/hosts && echo 10.0.1.14 master.jinojoseph.com >> /etc/hosts  && echo 10.0.1.23 worker1.jinojoseph.com >> /etc/hosts && echo 10.0.1.6 worker2.jinojoseph.com >> /etc/hosts"]
        imagePullPolicy: IfNotPresent
        name: jinojoseph-api
        env:
        - name: spring.data.cassandra.contact-points
          value: "master.jinojoseph.com,worker1.jinojoseph.com,worker2.jinojoseph.com"
        - name: hive.url
          value: "jdbc:hive2://master.jinojoseph.com:2181,worker1.jinojoseph.com:2181,worker2.jinojoseph.com:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2"





Comments

Post a Comment

Popular posts from this blog

Password reset too simplistic/systematic issue

Some time when we try to reset the password of our user in linux it will show as simple and systematic as below: BAD PASSWORD: it is too simplistic/systematic no matter how hard password you give it will show the same. Solution: ######### Check if your password is Ok with the below command, jino@ndz~$ echo 'D7y8HK#56r89lj&8*&^%&^%#56rlKJ!789l' | cracklib-check D7y8HK#56r89lj&8*&^%&^%#56rlKJ!789l: it is too simplistic/systematic Now Create a password with the below command : jino@ndz~$ echo $(tr -dc '[:graph:]' 7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K; You can see that this password will be ok with the cracklib-check. jino@ndz~$ echo '7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K;' | cracklib-check                 7\xi%!W[y*S}g-H7W~gbEB4cv,9:E:K;: OK Thats all, Thanks.
Post a Comment
Read more

K8s External Secrets integration between AWS EKS and Secrets Manager(SM) using IAM Role.

What is K8s External Secrets and how it will make your life easier? Before saying about External Secrets we will say about k8s secrets and how it will work. In k8s secrets we will create key value pairs of the secrets and set this as either pod env variables or mount them as volumes to pods. For more details about k8s secrets you can check my blog http://jinojoseph.blogspot.com/2020/08/k8s-secrets-explained.html   So in this case if developers wants to change the ENV variables , then we have to edit the k8s manifest yaml file, then we have to apply the new files to the deployment. This is a tiresome process and also chances of applying to the wrong context is high if you have multiple k8s clusters for dev / stage and Prod deployments. So in-order to make this easy , we can add all the secrets that is needed in the deployment, in the AWS Secret Manager and with the help of External secrets we can fetch and create those secrets in the k8s cluster. So what is K8s external Secret? It is an
Post a Comment
Read more