App Architecture & Build Flow¶

Summary¶

This guide defines:

Overview¶

RDK Broadband (RDK-B) applications designed for prplLCM and Dobby are packaged as OCI (Open Container Initiative) images.

An OCI image is a standardized container format that includes:

Application binaries
Runtime dependencies
Metadata (labels, versioning)
Execution instructions (entrypoint / CMD)

These images are:

Built once (cross-platform if needed)
Stored in a container registry (e.g., GitHub Container Registry (GHCR))
Pulled and executed by container runtimes like prplLCM or DAC

High-Level Architecture¶

flowchart TD;
    A["Source Code Repo"];
    B["CI/CD Pipeline<br/>(GitHub Actions / Jenkins)"];
    C["OCI Image Build<br/>(Docker / Buildx)"];
    D["OCI Registry<br/>(e.g. ghcr.io)"];
    E["RDK Device<br/>(App Runtime)"];

    A --> B;
    B --> C;
    C --> D;
    D --> E;

Expected Vendor Workflow¶

1. Build Trigger¶

Triggered on Git tag (e.g., v1.2.3)
Ensures semantic versioning

on:
  push:
    tags:
      - 'v[0-9]+.[0-9]+.[0-9]+'

2. Version Extraction¶

APP_VERSION=$(git describe --tags --exact-match HEAD | sed 's/^v//')

Used for:

Image tagging
OCI metadata labels

3. Multi-Architecture Build¶

Typical targets:

arm64 (aarch64)
armv7
amd64

4. Image Tagging Strategy¶

Each build produces:

ghcr.io/org/app:arm64
ghcr.io/org/app:arm64-1.2.3
ghcr.io/org/app:latest
ghcr.io/org/app:1.2.3

5. Multi-Platform Manifest¶

A final manifest combines all architectures:

docker manifest create ghcr.io/org/app:1.2.3 ghcr.io/org/app:arm64-1.2.3 ghcr.io/org/app:armv7-1.2.3 ghcr.io/org/app:amd64-1.2.3
docker manifest push ghcr.io/org/app:1.2.3

This allows you to automatically pull the correct architecture:

docker pull ghcr.io/org/app:1.2.3

Key Takeaways¶

OCI images are the standard deployment artifact
CI/CD pipelines handle build, test, and distribution
Multi-arch support is strongly recommended
Images must be lightweight and secure