Change to debian:bookworm-slim as base image for the controller

The current controller image is around 853MB in size at the moment. This is because we are using golang:1.21-bookworm as base image. For the controller itself this image provides way more than actually needed, therefore this MR switches to a minimized image as base (debian:bookworm-slim).

It should also be possible to use scratch or alpine but this would need some adjustments in combination with the generated plugins. The image used in this MR is already quite small in size (~113mb with the controller) and does not need any further adjustments.

Reducing the size even further would be something for a real production setup.

Description

Changed from golang:1.21-bookworm to debian:bookworm-slim as base image for the controller

Related Issue

Motivation and Context

Everyone loves smaller images

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

controller/controller.Dockerfile

@@ -9,7 +9,7 @@ RUN --mount=type=cache,target=/root/go/pkg/mod \
     --mount=type=cache,target=/root/.cache/go-build \
     make build-gosdn
 
-FROM ${GITLAB_PROXY}golang:$GOLANG_VERSION-bookworm
+FROM ${GITLAB_PROXY}debian:bookworm-slim
 WORKDIR /app/
 COPY --from=builder /gosdn/controller/configs/development-gosdn.toml.example ./configs/development-gosdn.toml
 COPY --from=builder /gosdn/controller/configs/containerlab-gosdn.toml.example ./configs/containerlab-gosdn.toml