Unit 6: CI/CD, Interviews & 90-Day Roadmap

Part L: Registry, Docker Hub & CI/CD

1. Push & Pull Images

A common naming pattern is registry/namespace/repository:tag.

docker login
docker build -t myapp:1.0 .
docker tag myapp:1.0 USER/myapp:1.0
docker push USER/myapp:1.0

To pull on another machine: docker pull USER/myapp:1.0

2. CI/CD Pipeline Flow

3. Docker vs Kubernetes

Docker packages/runs containers; Kubernetes orchestrates container workloads across clusters. They solve different layers. Learn Docker first, then Kubernetes.

Part N: Interview Preparation Scenarios

Scenario: App Works Locally but Not in Docker

Inspect environment variables, bind address (must be 0.0.0.0, not localhost inside container), dependencies, ports, filesystem paths and logs.

Scenario: Database Data Disappears

Verify that a named volume is mounted at the correct database data path. Do not rely on a container's writable layer for persistent production data.

Scenario: Browser Cannot Connect

Check docker ps, docker port, host/container port mapping, application listening address and logs.

Scenario: DB Connection Refused

Check service name, network membership, credentials, port, logs and readiness. Do not assume depends_on means the DB is fully booted.

Part S: Final Golden Rules

Container ko VM mat samjho; container process isolation provide karta hai.
Production data ko container writable layer par depend mat karo; persistent storage use karo.
Compose mein localhost ka matlab same container hota hai; another service ke liye service name use karo.
Secrets Dockerfile mein hard-code mat karo.
Build context ko .dockerignore se control karo.
Logs + inspect + exec are your first debugging tools.
One Command to Remember: docker COMMAND --help

Part O: 90-Day Roadmap

Hinglish: Is roadmap ko follow karke aap Docker zero se pro ban sakte ho.

Days 1–15: Fundamentals + CLI (Run, ps, logs, exec, inspect).
Days 16–30: Dockerfile + Images (Build context, layers, cache, tags, multi-stage).
Days 31–45: Volumes + Networks (Bind mounts, bridge networks, port mapping).
Days 46–60: Compose + Databases (Multi-container stacks, env vars).
Days 61–75: Security + Optimization + CI/CD (Non-root, scanning, small images).
Days 76–90: Cloud + Projects + Interviews (AWS/ECR/ECS, Kubernetes comparison).

Unit 6: Career & Next