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Kubernetes Level 03 Day 02: Deploy LAMP Stack on Kubernetes Cluster

This document outlines the solution for Kubernetes Level 03 Day 02. The objective was to provision a dynamic PHP website backed by a MySQL database, all running within a single multi-container Pod (the LAMP stack).

Table of Contents

Task Overview

Objective: Deploy a WordPress-ready LAMP stack using Kubernetes native objects.

  • Deployment Name: lamp-wp
  • Containers: * httpd-php-container: webdevops/php-apache:alpine-3-php7
    • mysql-container: mysql:5.6
  • ConfigMap: php-config (sets variables_order = "EGPCS")
  • Services:
    • lamp-service: NodePort 30008 (HTTP)
    • mysql-service: Port 3306 (Internal)
  • Secrets Handling: Pull database credentials from existing secrets into environment variables for both containers.

Step-by-Step Solution

1. Create the ConfigMap

PHP needs the variables_order set to "EGPCS" to ensure it correctly populates the $_ENV superglobal from environment variables.

Command: 

kubectl create configmap php-config --from-literal=php.ini='variables_order = "EGPCS"'

2. Define the Unified Manifest

We will create a YAML file defining the Deployment and both Services.

Create generic secret: 

kubectl create secret generic database \
--from-literal=MYSQL_ROOT_PASSWORD=admin123 \
--from-literal=MYSQL_DATABASE=kodekloud \
--from-literal=MYSQL_USER=kodekloud \
--from-literal=MYSQL_PASSWORD=admin123 \
--from-literal=MYSQL_HOST=mysql-service

Edit index.php file: 

<?php
$dbname = $_ENV["MYSQL_DATABASE"];
$dbuser = $_ENV["MYSQL_USER"];
$dbpass = $_ENV["MYSQL_PASSWORD"];
$dbhost = $_ENV["MYSQL_HOST"];

$connect = mysqli_connect($dbhost, $dbuser, $dbpass) or die("Unable to Connect to '$dbhost'");

$test_query = "SHOW TABLES FROM $dbname";
$result = mysqli_query($test_query);

if ($result->connect_error) {
   die("Connection failed: " . $conn->connect_error);
}
  echo "Connected successfully";

Command: 

vi lamp-stack.yaml

Content: 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: lamp-wp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: lamp-app
  template:
    metadata:
      labels:
        app: lamp-app
    spec:
      volumes:
      - name: php-config-volume
        configMap:
          name: php-config
      containers:
      - name: httpd-php-container
        image: webdevops/php-apache:alpine-3-php7
        ports:
        - containerPort: 80
        volumeMounts:
        - name: php-config-volume
          mountPath: /opt/docker/etc/php/php.ini
          subPath: php.ini
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom: { secretKeyRef: { name: mysql-root-pass, key: password } }
        - name: MYSQL_DATABASE
          valueFrom: { secretKeyRef: { name: mysql-db-url, key: database } }
        - name: MYSQL_USER
          valueFrom: { secretKeyRef: { name: mysql-user-pass, key: username } }
        - name: MYSQL_PASSWORD
          valueFrom: { secretKeyRef: { name: mysql-user-pass, key: password } }
        - name: MYSQL_HOST
          valueFrom: { secretKeyRef: { name: mysql-host, key: host } }

      - name: mysql-container
        image: mysql:5.6
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom: { secretKeyRef: { name: mysql-root-pass, key: password } }
        - name: MYSQL_DATABASE
          valueFrom: { secretKeyRef: { name: mysql-db-url, key: database } }
        - name: MYSQL_USER
          valueFrom: { secretKeyRef: { name: mysql-user-pass, key: username } }
        - name: MYSQL_PASSWORD
          valueFrom: { secretKeyRef: { name: mysql-user-pass, key: password } }
        - name: MYSQL_HOST
          valueFrom: { secretKeyRef: { name: mysql-host, key: host } }
---
apiVersion: v1
kind: Service
metadata:
  name: lamp-service
spec:
  type: NodePort
  selector:
    app: lamp-app
  ports:
    - port: 80
      targetPort: 80
      nodePort: 30008
---
apiVersion: v1
kind: Service
metadata:
  name: mysql-service
spec:
  selector:
    app: lamp-app
  ports:
    - port: 3306
      targetPort: 3306

Apply: 

kubectl apply -f lamp-stack.yaml

3. Deploy the PHP Application

Copy the provided index.php from the jump host into the running container's document root (/app).

Command: 

kubectl cp /tmp/index.php lamp-wp-<POD_ID>:/app/index.php -c httpd-php-container

Note: Ensure the index.php utilizes getenv('MYSQL_USER') etc., rather than hardcoded strings.

4. Verification

Verify the pods are running and test the database connection.

Check Status: 

kubectl get pods
# Wait for 2/2 READY

Test Accessibility: Open the web browser and access the NodePort 30008. * Expected Result: "Connected successfully"

Deep Dive: Multi-Container Architectures

Shared Network Namespace

In this task, MySQL and Apache/PHP reside in the same Pod. * Networking: They share the same IP address and localhost interface. * Connectivity: Even though we created a mysql-service, the PHP application should ideally connect to 127.0.0.1:3306. If the MYSQL_HOST secret points to the service name, Kubernetes DNS handles the resolution, but localhost is more efficient for intra-pod communication.

ConfigMap Mounting with subPath

When mounting a ConfigMap to a path that already contains files (like /opt/docker/etc/php/), using a standard mount would overwrite the entire directory, potentially deleting other configuration files. * subPath: By specifying subPath: php.ini, we only project that single specific file into the directory, leaving the rest of the target folder's contents intact.