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PostgreSQL Deployment in Kubernetes | The Complete Guide

Gursimran Singh | 17 July 2022

Deploying PostgreSQL on Kubernetes

What is PostgreSQL?

PostgreSQL is a powerful, open-source Relational Database Management System. Any organization or any individual does not control PostgreSQL. Its source code is available free of charge. PostgreSQL has earned a strong reputation for its reliability, data integrity, and correctness.
  1. Runs on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, macOS, Solaris, Tru64), and Windows.
  2. Being Fully ACID compliant, it has full support for foreign keys, joins, views, triggers, and stored procedures (in multiple languages).
  3. Includes most SQL:2008 data types, including INTEGER, NUMERIC, BOOLEAN, CHAR, VARCHAR, DATE, INTERVAL, and TIMESTAMP.
  4. Supports the storage of binary large objects, including pictures, sounds, or video.
  5. It has native programming interfaces for C/C++, Java, .Net, Perl, Python, Ruby, Tcl, ODBC, among others, and exceptional documentation.
This article gives an overview of How PostgreSQL Deployment works on Kubernetes with Blue Green Strategy. Let's understand what is Blue-Green Deployment Strategy first.

Blue-Green Deployment Database

Blue-Green Deployment Strategy is a special strategy that reduces the risk and minimizes downtime. It uses two production environments, Blue and Green. Only one of these environments is alive at the moment, and deployment is done on the inactive one. For example, if Green is a live environment, deployment to the Blue (inactive) environment occurs, and a switchover occurs after verification, which renders the Blue environment as the live environment and the Green environment inactive. Let's go ahead to know how we make use of this strategy in deploying PostgreSQL on Kubernetes.

How use PostgreSQL on Kubernetes?

Following are the Prerequisites for PostgreSQL Deployment on Kubernetes.

Step 1 - Create a PostgreSQL Container Image with Docker

Create a file name “Dockerfile” for PostgreSQL. This image contains our custom config dockerfile, which will look like this:
FROM ubuntu: latest

RUN apt - key adv--keyserver hkp: //p80.pool.sks-keyservers.net:80 --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8

RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ xenial-pgdg main" > /etc/apt / sources.list.d / pgdg.list

RUN apt - get update && apt - get install - y python - software - properties software - properties - common postgresql - 9.6 postgresql - client - 9.6 postgresql - contrib - 9.6

RUN / etc / init.d / postgresql start && \
psql--command "CREATE USER root WITH SUPERUSER PASSWORD 'xenonstack';" && \
createdb - O root xenonstack

RUN echo "host all  all  md5" >> /etc/postgresql / 9.6 / main / pg_hba.conf

RUN echo "listen_addresses='*'" >> /etc/postgresql / 9.6 / main / postgresql.conf

# Expose the PostgreSQL port

# Add VOLUMEs to allow backup of databases

# Set the
default command to run when starting the container
CMD["/usr/lib/postgresql/9.6/bin/postgres", "-D", "/var/lib/postgresql", "-c", "config_file=/etc/postgresql/9.6/main/postgresql.conf"]
This Postgres image has a base image of ubuntu xenial. After that, we create Super User and default databases. Exposing the 5432 port will help the external system to connect to the PostgreSQL server.

Step 2 - Build PostgreSQL Docker Image

$ docker build - t dr.xenonstack.com: 5050 / postgres: v9 .6

Step 3 - Create a Storage Volume (Using GlusterFS)

Using the below-mentioned command creates a volume in GlusterFS for PostgreSQL and start it. As we don’t want to lose our PostgreSQL Database data just because a Gluster server dies in the cluster, so we put replica 2 or more for higher availability of data.
$ gluster volume create postgres - disk replica 2 transport tcp k8 - master: /mnt/brick
1 / postgres - disk k8 - 1: /mnt/brick
1 / postgres - disk
$ gluster volume start postgres - disk
$ gluster volume info postgres - disk

Step 4 - Deploy PostgreSQL with Docker on Kubernetes

Deploying PostgreSQL on Kubernetes has the following prerequisites:
  1. Docker Image: We have created a Docker Image for Postgres in Step 2
  2. Persistent Shared Storage Volume: We have created a Persistent Shared Storage Volume in Step 3
  3. Deployment & Service Files: Next, we will create Deployment & Service Files
Create a file name “deployment.yml” for PostgreSQL. This deployment file will look like this:
apiVersion: extensions / v1beta1
kind: Deployment
 name: postgres
namespace: production
 replicas: 1
 k8s - app: postgres
 -name: postgres
image: dr.xenonstack.com: 5050 / postgres: v9 .6
imagePullPolicy: "IfNotPresent"
 -containerPort: 5432
value: postgres - name: POSTGRES_PASSWORD
value: superpostgres - name: PGDATA
value: /var/lib / postgresql / data / pgdata
 -mountPath: /var/lib / postgresql / data
name: postgredb
 -name: postgredb
 endpoints: glusterfs - cluster
path: postgres - disk
readOnly: false
We need to Define the Environment Variables for PostgreSQL: 1. POSTGRES_USER (Super Username for PostgreSQL) 2. POSTGRES_PASSWORD (SuperUser password for PostgreSQL) 3. PGDATA (Data Directory for PostgreSQL Database) Now we need to create a file named “service.yml” for PostgreSQL. This deployment file will look like this:
apiVersion: v1
kind: Service
 k8s - app: postgres
name: postgres
namespace: production
 type: NodePort
 -port: 5432
 k8s - app: postgres
Now let's deploy PostgreSQL using the following commands:
$ kubectl create - f deployment.yml
$ kubectl create - f service.yml

You have now successfully Deployed PostgreSQL on Kubernetes.

Summarizing PostgreSQL Deployment

PostgreSQL on Kubernetes helped to utilize resources even better than virtual machines and provide isolation from other apps deployed on the same machine.

Interested in reading about Deploying Kotlin Application on Docker and Kubernetes?

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