define config file for multiple image downloads and unpacking

[maxwellflitton]

As dockpack downloads and unpacks files from Docker images, we should enable users to create a config file for dockpack to read and download a collection of images and unpack them, like a generic package manager. Here we need to agree on fields and layout of a dockpack config file. After this, we can build the mechanism of reading and unpacking a list of these. I'll start by suggesting that the config file could take the following:

version: "1.0"
directory: "/path/to/your/project"
bucket_name: "bucket A"
docker_images:
  - name: "image1:tag1"
  - name: "image2:tag2"
  - name: "image3:tag3"

In later versions, we can be a bit more advanced but I think this is good enough to be useful. The bucket concept just refers to a collection of images to be downloaded. I think we can also override the directory field in the command that is reading the config file.

[TomBurdge]

Clarificatory:

• What work does "version" do here? Is the intention for it to be a field in the on-disk storage that you have mentioned will be used by the ls command? Would/could this (eventually) enable some form of caching?

• Is there one bucket per config file?

  • If it is one-to-one, I wonder if file name could serve as the bucket name? Or the bucket_name could be optional as a field in the config file and defaults to file name?

• When pulling multiple files, would one make a sub-directory in the directory specified by -d for each image? By which logic might one specify the sub-directory names? (Maybe this could go on a separate issue.)

Confirming:

• Do you plan for an arg for dockpack pull that has something like a --config/-c argument, that can substitute for -i to pull multiple images?