Using ConfigMaps on GKE

Part of good cloud-native application design is separating configuration from the deployable artifact — i.e., the container image. In this lab, you will deploy a web app that can be dynamically reconfigured based on the existence of both environment variables and a configuration file. The variables and the file can be added at runtime with the use of Kubernetes ConfigMaps.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Create and Connect to a GKE Cluster

Using the main navigation menu, under COMPUTE, select Kubernetes Engine.
Click ENABLE.
Once enabled, click CREATE.
To the right of In the Standard: You manage your cluster, click CONFIGURE.
At the top, choose USE A SETUP GUIDE, and choose My first cluster.
Click CREATE NOW.
Once the cluster has been created, click the three vertical dots and choose Connect.
Under Command-line access, click Run in Cloud Shell.
When prompted, click Continue.
When the terminal has launched, hit Return to run the command.
When prompted, click Authorize.

Build the Container and Create the Deployment

In the Cloud Shell terminal, download the code for this lab from GitHub.
From the content-google-certified-pro-cloud-developer/flask-configmaps/ directory, use Cloud Build to create the container image. Note: Replace <your-project-id> with the ID of your project.

Create a deployment.yaml file to deploy the app. Note: Replace <your-project-id> with the ID of your project:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: flask-deployment
spec:
  selector:
    matchLabels:
      app: flask
  template:
    metadata:
      labels:
        app: flask
    spec:
      containers:
      - name: flask
        image: gcr.io/<your-project-id>/flask-configmaps
        ports:
        - containerPort: 8080

Create the deployment.
Create a load balancer service to expose the deployment.
After a few minutes, an external IP should be provisioned for the service. View the service and external IP.
Open the external IP in a browser tab to confirm the deployment is working.

Use a ConfigMap to Add Environment Variables

Create a new ConfigMap called animal-config using the literal values dogs=10 and cats=5.
Update the deployment YAML to create environment variables from this ConfigMap. Add the following under the container image, at the same indentation level. If you are using copy and paste, you may have to correct some indentation. Just make sure that env starts at the same indentation level as the image directive above it.
Re-apply the deployment.
Reload the web page, and the app should now display the environment variables.

Use a ConfigMap to Add a Configuration File

Create a file called animals.cfg with the following contents:

catfood=kibble
dogfood=mixer
fussy_dog=derek
latest_feed=10pm

Create a new ConfigMap called animal-configfile using the file you just created.
Update the deployment YAML to create a volume from this ConfigMap and mount it into the Pod. Add the following under the container image, at the same indentation level. If you are using copy and paste, you may have to correct some indentation. Just make sure that volumeMounts starts at the same indentation level as the image directive above it.
Now add the volume to the end of the YAML file. The volumes directive should start at the same indentation level as the containers directive:
Re-apply the deployment.
Reload the web page, and the app should now display the contents of the config file as well.

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Using ConfigMaps on GKE

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