Docker Health Checks and Useful Probes
How a HEALTHCHECK moves from starting to unhealthy, why plain Docker never restarts an unhealthy container, and what a good probe checks.
~5 min readread →
Developer interview notes & guides — Page 18
Focused explanations and longer guides, with worked scenarios, common mistakes and interview exercises across every chapter.
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Showing 409–432 of 825 articles
Docker Build Context and Ignore Rules
What the build context is, why COPY . . can ship your .env and .git, and how to write .dockerignore patterns that match nested folders.
~5 min readread →
Docker Images Versus Running Containers
An image is a read-only template; a container is that template plus a writable layer and a process. See what survives stop, start and rm.
~5 min readread →
Docker Base Image Maintenance and Dependency Updates
An image is frozen the day it's built. Keep bases patched with scheduled rebuilds, --pull, digest pins with automated bumps and EOL tracking.
~6 min readread →
Docker Image Tags and Reproducible Releases
Tags are movable pointers and digests are not. Learn why latest breaks rollbacks, how to tag releases, and when to pin images by sha256.
~5 min readread →
Docker Layers and Build Cache Invalidation
Why one edited source file can rerun npm install: how BuildKit's layer cache keys each step, and how to order a Dockerfile so rebuilds stay fast.
~5 min readread →
Docker Logs and Application Diagnostics
docker logs only shows stdout and stderr. Fix empty logs, Python buffering and unrotated json-file growth, then pick a logging driver.
~5 min readread →
Docker Multi-Stage Builds and Runtime Contents
Compile in one stage, ship only the output in the next: how a 400 MB build image became a 313 kB runtime, and what a scratch image gives up.
~5 min readread →
Docker Networks and Container DNS
Why containers can't resolve each other on the default bridge, how the 127.0.0.11 resolver works, and why nginx keeps a stale upstream IP.
~5 min readread →
Docker Nonroot Users and File Permissions
Switching a container to a nonroot USER breaks writes until ownership is right. Fix EACCES with chown, numeric UIDs and pre-created volume paths.
~5 min readread →
Docker Exposed Ports Versus Published Ports
EXPOSE documents a port; -p opens one on the host. Bind addresses, -P, the 127.0.0.1 trap inside containers and the ufw bypass on Linux.
~5 min readread →
Docker Read-Only Filesystems and Writable Paths
Run a container with --read-only, find the paths it still needs to write, and give each one a sized tmpfs or volume without reopening the rest.
~5 min readread →
Docker Resource Limits and Application Capacity
Memory limits end in a silent OOM kill and CPU limits in throttling. Size a container so the runtime inside it agrees with the cgroup outside.
~6 min readread →
Docker Secrets and Image Layer History
Build args and ENV values stay readable in docker history and image config. Pass build-time credentials with BuildKit secret mounts instead.
~5 min readread →
Docker Process Signals and Graceful Shutdown
Why docker stop sometimes takes the full timeout and ends in exit 137, and how PID 1, exec form and a SIGTERM handler fix shutdown.
~6 min readread →
Docker Volumes and Data Lifetimes
Named and anonymous volumes outlive containers in different ways. Trace which commands keep data, which delete it, and how to back it up.
~5 min readread →
Backtracking and Safe Pruning Rules
Backtracking and Safe Pruning Rules. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Big-O Complexity and Input Growth
Big-O Complexity and Input Growth. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Binary Search on an Answer Space
Binary Search on an Answer Space. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Binary Search and Explicit Boundaries
Binary Search and Explicit Boundaries. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Dynamic Programming and State Definition
Dynamic Programming and State Definition. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Graph DFS States and Cycle Detection
Graph DFS States and Cycle Detection. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Hash Maps for Frequency and Membership Problems
Hash Maps for Frequency and Membership Problems. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
Heaps for Top-K and Incremental Selection
Heaps for Top-K and Incremental Selection. Learn the reasoning, a practical example, common mistakes and an interview exercise.
~2 min readread →
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