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Docker Images vs Containers, Explained
Sep 11, 2026

Docker Images vs Containers, Explained

Confused by Docker images versus containers? An image is the read-only template; a container is a running copy of it. See it proven with real output: one image, three containers, each with its own writable layer, plus what image layers actually are.

Fix: Permission Denied on the Docker Daemon Socket
Sep 11, 2026

Fix: Permission Denied on the Docker Daemon Socket

Got 'permission denied while trying to connect to the Docker daemon socket' on Linux? Here is why it happens, the one-line fix to keep working now, the permanent docker-group fix, and the insecure chmod you should never copy. Real captured output.

Docker Security Basics: Non-Root, Read-Only, Image Scanning, and Secrets
Sep 11, 2026

Docker Security Basics: Non-Root, Read-Only, Image Scanning, and Secrets

Harden a Docker container without breaking it: scan for CVEs with Trivy, run as non-root, make the root filesystem read-only, drop Linux capabilities, and keep secrets out of the image. Real captured output.

Operating Containers: Healthchecks, Resource Limits, Restart Policies, and Env Config
Sep 11, 2026

Operating Containers: Healthchecks, Resource Limits, Restart Policies, and Env Config

Make Docker containers behave in production: healthchecks and health-gated startup, memory and CPU limits (and the OOM exit 137), restart policies that self-heal, and clean env config. Real captured output.

Where Your Data Lives: Docker Volumes, Bind Mounts, and Networks
Sep 10, 2026

Where Your Data Lives: Docker Volumes, Bind Mounts, and Networks

Make container data survive restarts and let containers talk to each other: named volumes vs bind mounts, backing up and restoring a volume, and user-defined networks with DNS by name. Real captured output.

Lean Docker Images: Multi-Stage Builds and Layer Caching
Sep 10, 2026

Lean Docker Images: Multi-Stage Builds and Layer Caching

Build the same Node app two ways and measure it: a naive 1.62GB image versus a 233MB multi-stage Alpine image. Real numbers for image size, layer caching, and docker history, with a working Dockerfile you can copy.

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