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Setting Up a Local Kubernetes Cluster with Minikube and Deploying a Ruby on Rails Application with PostgreSQL

May 20, 2020 2020-05-20T09:00:00-03:00 by João Carlos Ottobboni (@jcottobboni)
3 min

Setting Up a Local Kubernetes Cluster with Minikube and Deploying a Ruby on Rails Application with PostgreSQL

This tutorial will guide you through setting up a local Kubernetes cluster using Minikube and deploying a Ruby on Rails application with a PostgreSQL database.

Prerequisites

  • A system with at least 4GB of RAM and 20GB of free disk space.
  • Docker installed on your system.
  • Basic knowledge of Kubernetes and Docker.
  • A Ruby on Rails application ready to be containerized.

Step-by-Step Guide

1. Install Minikube

Minikube is a tool that runs a single-node Kubernetes cluster locally.

  1. Download and install Minikube:

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    curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
chmod +x minikube
sudo mv minikube /usr/local/bin/

  2. Start Minikube:

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    minikube start --driver=docker

2. Install kubectl

kubectl is a command-line tool for interacting with Kubernetes clusters.

  1. Download and install kubectl:

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    curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
chmod +x kubectl
sudo mv kubectl /usr/local/bin/

  2. Verify kubectl installation:

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    kubectl version --client

3. Containerize Your Ruby on Rails Application

  1. Create a Dockerfile in the root directory of your Rails application:

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    FROM ruby:2.7
RUN apt-get update -qq && apt-get install -y nodejs postgresql-client
WORKDIR /myapp
COPY Gemfile /myapp/Gemfile
COPY Gemfile.lock /myapp/Gemfile.lock
RUN bundle install
COPY . /myapp
CMD ["rails", "server", "-b", "0.0.0.0"]

  2. Build the Docker image:

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    docker build -t myapp:latest .

4. Set Up PostgreSQL on Kubernetes

  1. Create a PostgreSQL Deployment:

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    apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
      - name: postgres
        image: postgres:latest
        env:
        - name: POSTGRES_USER
          value: postgres
        - name: POSTGRES_PASSWORD
          value: password
        ports:
        - containerPort: 5432

  2. Create a PostgreSQL Service:

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    apiVersion: v1
kind: Service
metadata:
  name: postgres
spec:
  ports:
  - port: 5432
  selector:
    app: postgres

  3. Apply the configurations:

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    kubectl apply -f postgres-deployment.yaml
kubectl apply -f postgres-service.yaml

5. Deploy Your Rails Application

  1. Create a Deployment for your Rails application:

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    apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:latest
        env:
        - name: DATABASE_HOST
          value: postgres
        - name: DATABASE_USER
          value: postgres
        - name: DATABASE_PASSWORD
          value: password
        ports:
        - containerPort: 3000

  2. Create a Service for your Rails application:

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    apiVersion: v1
kind: Service
metadata:
  name: myapp
spec:
  ports:
  - port: 3000
  selector:
    app: myapp

  3. Apply the configurations:

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    kubectl apply -f myapp-deployment.yaml
kubectl apply -f myapp-service.yaml

6. Access Your Application

  1. Get the URL of your Rails application:

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    minikube service myapp --url

  2. Open the URL in your browser to access your Rails application.

Conclusion

You have successfully set up a local Kubernetes cluster using Minikube and deployed a Ruby on Rails application with a PostgreSQL database. This setup allows you to develop and test your applications in an isolated environment similar to production.

If you encounter any issues, refer to the official Kubernetes documentation or seek help from communities like Stack Overflow.

Tutorials, Kubernetes
kubernetes minikube rails postgres devops
This post is licensed under CC BY 4.0 by the author.
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