docker-helper

Multi-stage builds reduce image size by using multiple FROM statements to compile or build in one stage, then copy only necessary artifacts to the final stage. This eliminates build dependencies and intermediate files from the production image, significantly lowering deployment footprint and startup time.

Health checks monitor container status by running periodic commands inside the container and marking it unhealthy if they fail. Configure them in Dockerfiles with HEALTHCHECK instructions or in Docker Compose with health check properties, enabling automatic restart policies and load balancer integration.

Order Dockerfile commands by frequency of change, placing stable commands early and volatile ones late. This ensures frequently-changed layers don't invalidate cached layers, speeding up rebuilds. Combine commands with && operators and use .dockerignore to exclude unnecessary files from the build context.

Yes, Docker Compose version 3+ automatically loads variables from .env files in the project directory, making them available for variable substitution in compose files. Use ${VARIABLE_NAME} syntax to reference them in service definitions, networks, and volumes.

Create a non-root user in the Dockerfile with RUN commands, then switch to it using the USER instruction before running the application. This prevents privilege escalation attacks and limits damage if the container is compromised, meeting production security standards.

Avoid running as root, omitting resource limits, missing health checks, and improper logging. Use restart policies with appropriate conditions, configure CPU and memory limits, implement proper volume and network management, and ensure containers fail fast with meaningful exit codes.