OpenShift BuildConfig Tutorial

✅ What is OpenShift BuildConfig?

BuildConfig in OpenShift is a Kubernetes-native custom resource provided by OpenShift that defines how to build a container image from source code. It automates the end-to-end image build process — from fetching source code to producing and storing container images — using build strategies like Source-to-Image (S2I), Docker, or custom workflows.

📘 BuildConfig Definition

A BuildConfig is a declarative configuration object in OpenShift that defines the strategy, source, triggers, and output for building container images automatically or on-demand.

It’s like a recipe for converting application source code into a deployable container image.

⭐ Key Features of BuildConfig

🔧 Example Use Cases

📦 BuildConfig vs Dockerfile vs Pipelines

🚀 BuildConfig Lifecycle

1. Developer pushes code to Git
2. OpenShift triggers a build (via webhook or manually)
3. Code is fetched and built using specified strategy
4. Final image is stored (ImageStream or registry)
5. App is deployed or updated automatically

✅ Works on OpenShift 4.13+ (including Azure Red Hat OpenShift)

🎯 Goal

Build a Node.js application using:

• ✅ Git source
• ✅ External Red Hat base image (ubi8/nodejs-16)
• ✅ OpenShift S2I strategy (using DockerImage)
• ✅ No need for preloaded ImageStreams

🧱 Prerequisites

🧾 Option 1: YAML Method (CLI or Web Console YAML Editor)

✅ Step-by-Step (Using YAML)

1. Create/Open a project oc new-project nodejs-s2i-demo
2. Apply this working BuildConfig YAML:

apiVersion: build.openshift.io/v1
kind: BuildConfig
metadata:
  name: nodejs-sample-build
  labels:
    app: nodejs-sample
spec:
  source:
    type: Git
    git:
      uri: https://github.com/sclorg/nodejs-ex.git
      ref: main
    contextDir: .
  strategy:
    type: Source
    sourceStrategy:
      from:
        kind: DockerImage
        name: registry.access.redhat.com/ubi8/nodejs-16
      forcePull: true
  output:
    to:
      kind: ImageStreamTag
      name: nodejs-sample:latest
  triggers:
    - type: ConfigChange
    - type: ImageChange
  runPolicy: Serial
Code language: JavaScript (javascript)

3. Start the build manually: oc start-build nodejs-sample-build --follow
4. Deploy the built image: oc new-app nodejs-sample oc expose svc/nodejs-sample
5. Access the app: oc get route

🖱️ Option 2: Using the OpenShift Developer Console UI

Based on your screenshots — modern and guided flow

✅ Step-by-Step (Using Developer Web Console)

1. Go to Developer → +Add → From Git
2. Fill Git Repository info:
   • Git Repo URL: https://github.com/sclorg/nodejs-ex.git
   • Git Reference: main (or leave blank)
   • Context Dir: .
3. Builder Image Selection (Build from):
   • Select “Docker Image” from the build option dropdown
   • Input Docker Image: registry.access.redhat.com/ubi8/nodejs-16
4. Deployment Settings:
   • App Name: nodejs-sample
   • Resources: Deployment (leave default)
   • Create Route: ✅ (enabled)
5. Click “Create”

OpenShift will:

• Create BuildConfig, ImageStream, Deployment, and Route
• Trigger an initial build
• Watch progress from Builds or Topology

🧪 How to Monitor

• Build logs:
  Developer → Builds → nodejs-sample-build → View Logs
• Application route:
  Developer → Topology → Click route link
• BuildConfig YAML:
  Admin → Builds → nodejs-sample-build → YAML

🔁 Updating Code

Just push code to GitHub and trigger a build manually:

oc start-build nodejs-sample-build

Or setup GitHub webhook using:

oc describe bc nodejs-sample-build

✅ Summary

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.