πŸš€ DevOps & SRE Certification Program πŸ“… Starting: 1st of Every Month 🀝 +91 8409492687 πŸ” Contact@DevOpsSchool.com

Upgrade & Secure Your Future with DevOps, SRE, DevSecOps, MLOps!

We spend hours on Instagram and YouTube and waste money on coffee and fast food, but won’t spend 30 minutes a day learning skills to boost our careers.
Master in DevOps, SRE, DevSecOps & MLOps!

Learn from Guru Rajesh Kumar and double your salary in just one year.


Get Started Now!

Limitation with OpenShift with Docker Images compare to Vanilla Kubernetes

Let me explain very clearly, so you fully understand why some images work, some don’t in OpenShift πŸš€:


🎯 Big Picture: OpenShift Is Different from Vanilla Kubernetes

TopicKubernetesOpenShift
Can run root containers?βœ… Allowed by default❌ Not allowed by default (Security!)
Need special non-root images?❌ Noβœ… Yes, or modify yourself
Handles normal Docker images easily?βœ… Yes🟑 Sometimes extra care needed
FocusFlexibleSecure by Design

βœ… OpenShift enforces Security Context Constraints (SCC)
βœ… OpenShift forces containers to run non-root by default.


πŸ›  Why nginx-unprivileged worked but others failed?

ImageWhy it Worked / Failed
nginxinc/nginx-unprivilegedβœ… Built specifically to run as non-root, listens on 8080
registry.redhat.io/rhscl/nginx-116-rhel7πŸ›‘ It’s a S2I base image, not runnable directly
nginx:latest (official)πŸ›‘ Tries to bind port 80, needs root
bitnami/nginxβœ… Works if you map to 8080
Any random DockerHub NGINXπŸ›‘ Fails unless it listens >1024 and runs non-root

πŸ“‹ The 3 Problems You Face with Most Docker Images in OpenShift

IssueWhy HappensHow to Solve
Image expects to run as rootOpenShift blocks root by defaultUse non-root images (unprivileged) or modify Dockerfile
Image tries to bind port 80Only root can bind ports <1024Configure container to listen on 8080 or higher
Image is an S2I base (not normal app)Meant for building apps, not direct runUse oc new-app + --strategy=source or use proper image

🧠 In simple words:

  • Normal Kubernetes: You can pull almost any DockerHub image and it runs.
  • OpenShift: You must care about non-root and correct ports, or your app won’t run.

πŸš€ How to Choose Images for OpenShift:

βœ… Prefer images labeled as β€œOpenShift Ready”, β€œnon-root”, or β€œunprivileged”.
βœ… If using random DockerHub images:

  • Make sure they don’t require root user.
  • Make sure they listen on port >1024 (like 8080, 8443).

βœ… For NGINX specifically:

  • Use nginxinc/nginx-unprivileged (best for OpenShift).
  • Or customize your own nginx Dockerfile to listen on port 8080 and remove user nginx; line.

πŸ”₯ Quick Visual:

Image TypeWorks Directly in OpenShift?Extra Work Needed?
nginxinc/nginx-unprivilegedβœ… YesNo
bitnami/nginxβœ… MostlyAdjust port sometimes
nginx:latest❌ NoMust modify (port, user)
registry.redhat.io/rhscl/nginx-116-rhel7πŸ›‘ Not directUse S2I build process
Your own custom Docker imageπŸ›‘ If rootModify to non-root

πŸ“’ Final Cheat Sheet for You

What to CheckWhy Important
Running user (root or non-root)OpenShift only allows random high UID (non-root)
Listening PortMust be >1024 (8080, 8443, etc.)
Image typeIs it runnable app image or just a S2I builder base?
OpenShift SCCs (Security Context Constraints)Forces strict security on containers

✨ In one line:

In OpenShift, containers must be non-root, non-privileged, and ports >1024 β€” otherwise they fail!


πŸš€ Bonus

Would you also like me to give you:

  • πŸ“¦ How to convert any Docker image into OpenShift-ready by adjusting Dockerfile?
  • πŸ”₯ Full tutorial: Best practices for building OpenShift-compliant containers?


Subscribe
Notify of
guest


0 Comments
Newest
Oldest Most Voted
Inline Feedbacks
View all comments

Certification Courses

DevOpsSchool has introduced a series of professional certification courses designed to enhance your skills and expertise in cutting-edge technologies and methodologies. Whether you are aiming to excel in development, security, or operations, these certifications provide a comprehensive learning experience. Explore the following programs:

DevOps Certification, SRE Certification, and DevSecOps Certification by DevOpsSchool

Explore our DevOps Certification, SRE Certification, and DevSecOps Certification programs at DevOpsSchool. Gain the expertise needed to excel in your career with hands-on training and globally recognized certifications.

0
Would love your thoughts, please comment.x
()
x