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Initializing PostgreSQL Database with Kubernetes ConfigMaps

Objective​

In the realm of container orchestration and cloud-native applications, initializing databases securely and efficiently is crucial. Kubernetes ConfigMaps offer a way to manage configuration data and scripts, like our init.sh, separate from the container image for better modularity and security. This lab walks you through the process of creating a Kubernetes ConfigMap for the init.sh script in the 'my-cool-app' namespace.

Prerequisites​

Initial Setup​

Navigate to the root directory of the python-fastapi-demo-docker project where your environment variables are sourced:

cd ~/environment/python-fastapi-demo-docker

1. Creating the Kubernetes ConfigMap for Database Initialization​

Our PostgreSQL database requires custom initialization, which is why we use an init.sh script. This script creates the database, user, and table. To manage this script, we create a Kubernetes ConfigMap. This ensures that the script is executed when the PostgreSQL container starts, initializing the database as required.

From the root directory of the 'python-fastapi-demo-docker' project, generate the Kubernetes ConfigMap:

kubectl create configmap db-init-script --from-file=init.sh=server/db/init.sh -n my-cool-app

The expected output should look like this:

configmap/db-init-script created

2. Verifying the ConfigMap Creation​

To ensure that your Kubernetes ConfigMap has been successfully created, you can use the kubectl get configmap command. This command lists all ConfigMaps in the current namespace:

kubectl get configmap -n my-cool-app

The expected output should look like this:

NAME               DATA   AGE
db-init-script     1      4m47s
kube-root-ca.crt   1      5m36s

3. Inspecting the ConfigMap Details​

For a deeper understanding of your created ConfigMap, you can use the following command to obtain detailed information about the specified ConfigMap:

kubectl describe configmap db-init-script -n my-cool-app

The expected output should look like this:

Name:         db-init-script
Namespace:    my-cool-app
Labels:       <none>
Annotations:  <none>

Data
====
init.sh:
----
#!/bin/bash
...

Conclusion​

This lab guided you through the process of creating a Kubernetes ConfigMap that securely initializes your PostgreSQL database within a Minikube environment.