Skip to content

Defining A Dockerfile For The OCI Image

Overview

This guide defines best practices for creating Dockerfiles for RDK-B containerized applications.

Base Image Selection

FROM scratch
Pros Cons
- Minimal size
- No attack surface		 - Requires fully static binaries

Option 2: FROM alpine (Minimal Linux base, much smaller than Debian)

FROM alpine:3.20
Pros Cons
- Small (~5MB)
- Includes package manager		 - Uses musl libc (not glibc)

Static Linking with musl

To support scratch, compile binaries statically:

Rust Example

target: x86_64-unknown-linux-musl

Install toolchain:

rustup target add x86_64-unknown-linux-musl

Minimal Runtime Dockerfile Example

FROM scratch

LABEL org.opencontainers.image.source="https://github.com/org/repo"
LABEL org.opencontainers.image.description="RDK-B OCI Application"

WORKDIR /app

COPY target/release/my-app /app/my-app
COPY templates /app/templates
COPY static /app/static

EXPOSE 8080

CMD ["/app/my-app"]

ENTRYPOINT vs CMD

CMD ["/app/my-app"]
  • Default command
  • Easily overridden

ENTRYPOINT (Optional)

ENTRYPOINT ["/app/my-app"]
  • Harder to override
  • Good for fixed-function containers

File Layout Best Practices

/app
 ├── binary
 ├── templates/
 ├── static/
 └── config/

OCI Metadata Labels

Include standard labels in your Dockerfile:

LABEL org.opencontainers.image.version="1.2.3"
LABEL org.opencontainers.image.revision="abc1234"
LABEL org.opencontainers.image.source="https://github.com/org/repo"
LABEL org.opencontainers.image.description="RDK App"

Key Recommendations

  • Prefer FROM scratch + static binaries
  • Use alpine only if dynamic dependencies are required
  • Keep images small (<50MB ideally)
  • Avoid unnecessary tools (curl, bash, etc.)