Dockerfile best practices. What do you use?

Main best practices for Dockerfile:

• Use minimal base images (e.g., Alpine) to reduce the final image size.
• Minimize the number of layers by combining RUN commands with &&.
• Cache dependencies separately from copying source code to speed up builds when only code changes.
• Use .dockerignore to exclude unnecessary files from the build context.
• Explicitly specify versions of packages and base images for reproducibility.
• Run containers as non-privileged users for security.
• Use multi-stage builds to separate the build stage from the final image to reduce size.

Example:

FROM golang:1.20-alpine AS builder
WORKDIR /app
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN go build -o myapp

FROM alpine:latest
RUN adduser -D appuser
USER appuser
WORKDIR /app
COPY --from=builder /app/myapp .
CMD ["./myapp"]

This approach allows creating a compact and secure image with minimal layers.