Basic usage

The most basic operations when building an image are: starting with a given base image, copying local files to the image filesystem, and specifying some defaults for how to run a container based on the final image.

Blubber supports these operations and adds some basic constraints around who owns the files and runtime process.

Background

Given examples/hello-world as a working directory.

Copy in a script and run it as the container entry point

Given this "blubber.yaml"

version: v4
variants:
  hello:
    base: debian:bullseye    # start with a debian system
    copies: [local]          # copy our working directory to the default application path
    entrypoint: [./hello.sh] # run ./hello.sh when a container is started using this image

When you build the "hello" variant

Then the image will have the following files in the default working directory

README.md
hello.sh

And the image runtime user will be "900"

And the image entrypoint will be "./hello.sh"

And the image will not include default arguments.

Blubber respects .dockerignore files

Given this "blubber.yaml"

version: v4
variants:
  hello:
    base: debian:bullseye
    copies: [local]

And this ".dockerignore"

/README.md

When you build the "hello" variant

Then the image will have the following files in the default working directory

hello.sh

And the image will not have the following files in the default working directory

README.md

Files are excluded using explicit glob patterns

Given this "blubber.yaml"

version: v4
variants:
  hello:
    base: debian:bullseye
    copies:
      - from: local
        exclude:
          - "*.md"

When you build the "hello" variant

Then the image will have the following files in the default working directory

hello.sh

And the image will not have the following files in the default working directory

README.md

Variants can include one another

Given this "blubber.yaml"

version: v4
variants:
  hello:
    base: debian:bullseye
    copies: [local]
  hey:
    includes: [hello]

When you build the "hey" variant

Then the image will have the following files in the default working directory

README.md
hello.sh