What is your experience with dynamic parameterization of Docker files?

Developed template Dockerfiles using environment variables and build arguments.

Applied the following methods:

1. ARG instructions for build arguments:

   FROM ubuntu:latest
   ARG APP_VERSION
   RUN echo "Building version: $APP_VERSION"
   

2. ENV instructions for runtime environment variables:

   FROM alpine:latest
   ENV PORT=8080
   CMD ["sh", "-c", "echo Listening on port $PORT"]
   

3. Passing ARG and ENV via --build-arg and -e during build/run:

   docker build --build-arg APP_VERSION=1.2.0 .
   docker run -e PORT=9000 my_image
   

4. Using multi-stage builds to pass values between stages:

   # builder stage
   FROM golang:1.20 as builder
   ARG BUILD_TAG
   WORKDIR /app
   RUN go build -ldflags "-X main.version=$BUILD_TAG" -o app .
   
   # final stage
   FROM alpine:latest
   COPY --from=builder /app/app /
   CMD ["/app"]
   

5. Integration with CI/CD systems (e.g., GitLab CI, Jenkins) for automatic substitution of parameters (application version, environment, API keys) during image build or container deployment.

This approach allows creating more flexible and reusable Docker images, adaptable to various environments and requirements, without modifying the Dockerfile itself.