forge

forge is a CLI tool for generating Moldfile from Dockerfile.

What is Moldfile?

Moldfile is a Dockerfile compatible file format proposed in CDCM. It strictly records versions of all dependencies in Dockerfile, e.g. base image and packages, and provides high configuration reproducibility. Its recommended file name is Moldfile or Dockerfile.mold.

Dockerfile

For writing Dockerfile, developers usually use loose version specification. latest or a meaningful named tag for a base image and no version specification for installing packages in RUN instructions. It provides high readability and maintainability.

FROM ubuntu:latest

RUN apt-get update && apt-get install -y \
    curl

Moldfile

Moldfile is generated from Dockerfile and pins versions of all dependencies. Digest for a base image and version pinning for packages. It provides high configuration reproducibility for building Docker image and records the configuration at the time of its generation.

FROM ubuntu@sha256:e6173d4dc55e76b87c4af8db8821b1feae4146dd47341e4d431118c7dd060a74

RUN apt-get update && apt-get install -y \
    curl=7.81.0-1ubuntu1.15

Usage

Warning

Currently it doesn't support new Docker image format.

Use forge with Docker Engine older version than v25.0.

mold

forge mold PATH [flags]

Generate Moldfile from Dockerfile.

Note

For version pinning of packages, it currently supports only packages installed via apt.

vdiff

forge vdiff FILE_PATH1 FILE_PATH2 [flags]

Extract specified version differences between two files (Moldfile/Dockerfile).

It only supports comparison between the same structure instruction files. It is expected to use for Dockerfile and Moldfile generated from the Dockerfile, or Moldfiles generated from the same Dockerfile.

Example

Moldfile1:

FROM ubuntu@sha256:ed4a42283d9943135ed87d4ee34e542f7f5ad9ecf2f244870e23122f703f91c2

RUN apt-get update && apt-get install -y \
    wget=1.20.3-1ubuntu2

Moldfile2:

FROM ubuntu@sha256:4c32aacd0f7d1d3a29e82bee76f892ba9bb6a63f17f9327ca0d97c3d39b9b0ee

RUN apt-get update && apt-get install -y \
    wget=1.21.3-1ubuntu1

Output:

{
  "buildStages": [
    {
      "stageName": "",
      "baseImage": {
        "name": "ubuntu",
        "moldfile1": "@sha256:ed4a42283d9943135ed87d4ee34e542f7f5ad9ecf2f244870e23122f703f91c2",
        "moldfile2": "@sha256:4c32aacd0f7d1d3a29e82bee76f892ba9bb6a63f17f9327ca0d97c3d39b9b0ee"
      },
      "packages": [
        {
          "packageManager": "apt",
          "name": "wget",
          "moldfile1": "1.20.3-1ubuntu2",
          "moldfile2": "1.21.3-1ubuntu1"
        }
      ]
    }
  ]
}

check

forge check FILE_PATH [flags]

Check if the Dockerfile/Moldfile is appropriate format to parse with forge. If FILE_PATH is "-", the file content is read from stdin.

Installation

Go tools

go install github.com/tklab-group/forge@latest

Binary

Download from release page.