init-containers.md

Init Containers

This lab will show how to use Kubernetes Init Containers to run scripts and load data prior to the initialization of the primary container.

I'm not going to lie, things are going to get a little weird.

We are going to pull data from a remote source, and then populate the database from that source file. All before the primary container is initialized.

I told you it was going to be weird.

For reference, take a look at the Kubernetes.io docs on Init Containers by clicking here

Download and pre-populate data with init containers

Take note of the two files in this directory, init-db-sample.yaml and init-web-api-sample.yaml. We'll use these as our reference points for deployment.

1. Clear anything out of your cluster by deleting your deployments

   $ kubectl delete -f heroes-db.yaml
   $ kubectl delete -f heroes-web-api.yaml

2. Modify init-db-sample.yaml in the helper-files directory to add your imagePullSecrets as well as reference your container registry and db image

   spec:
   imagePullSecrets:
       - name: acr-secret
   containers:
   - image:  <login server>/azureworkshop/rating-db:v1

3. Deploy the db to your cluster with the modified db yaml

   cd ~/blackbelt-aks-hackfest/labs/helper-files
   
   $ kubectl create -f init-db-sample.yaml

4. Modify the init-web-api-sample.yaml to add your imagePullSecrets as well as reference your container registry and db image,

   note that you only need to add your login info to the top level container(s) - the init containers pull from docker hubs public repo

   change

         name:  heroes-api
       spec:
         containers:
         - image: sonofjorel/rating-api:v1

   to

         name:  heroes-api
       spec:
         imagePullSecrets:
         - name: acr-secret
         containers:
           - image:  <login server>/azureworkshop/rating-api:v1

   and change

         name:  heroes-web
       spec:
         containers:
         - image: sonofjorel/rating-web:v1

   to

         name:  heroes-web
       spec:
         imagePullSecrets:
         - name: acr-secret
         containers:
           - image:  <login server>/azureworkshop/rating-web:v1

5. Deploy the db to your cluster with the modified db yaml

   $ kubectl create -f init-web-api-sample.yaml