docker plugin

A source implementation for pulling from Docker Registry instances.

Usage:

# Specify the docker source kind
kind: docker

# Specify the registry endpoint, defaults to Docker Hub (optional)
registry-url: https://registry.hub.docker.com

# Image path (required)
image: library/alpine

# Image tag to follow (optional)
track: latest

# Specify the digest of the exact image to use (required)
ref: 6c9f6f68a131ec6381da82f2bff978083ed7f4f7991d931bfa767b7965ebc94b

# Some images are built for multiple platforms. When tracking a tag, we
# will choose which image to use based on these settings. Default values
# are chosen based on the output of `uname -m` and `uname -s`, but you
# can override them.
#architecture: arm64
#os: linux

Note that Docker images may contain device nodes. BuildStream elements cannot contain device nodes so those will be dropped. Any regular files in the /dev directory will also be dropped.