monopam#

A CLI tool that generates an opam repository and monorepo from a list of git repositories.

Overview#

monopam reads a text file containing git repository URLs and:

1. Clones each repository into a vendor/ directory
2. Generates an opam repository structure in opam-repository/
3. Creates a setup.sh script to pin packages and install dependencies
4. Sets up dune to build everything as a monorepo

This is useful for creating a local development environment with multiple interdependent packages that may not yet be published to opam.

Installation#

opam install . --deps-only
dune build
dune install

Or run directly:

dune exec monopam -- <args>

Usage#

monopam INPUT_FILE [-o OUTPUT_DIR] [-v]

Arguments#

• INPUT_FILE - Path to a text file containing git repository URLs (one per line)
• -o, --output DIR - Output directory (default: opam-repository)
• -v, --verbose - Enable verbose output

Input File Format#

# Comments start with #
https://github.com/user/repo1.git
https://github.com/user/repo2.git main
https://tangled.org/user/repo3

Each line contains a git URL, optionally followed by a branch name.

Output Structure#

output-dir/
├── dune-project           # Dune project file
├── dune                   # Top-level dune config
├── setup.sh               # Setup script for opam switch
├── opam-repository/
│   ├── repo               # opam repository metadata
│   └── packages/
│       └── <pkg>/
│           └── <pkg>.dev/
│               └── opam   # Package opam file with url stanza
└── vendor/
    ├── dune               # Lists vendor subdirectories
    ├── repo1/             # Cloned source code
    ├── repo2/
    └── ...

Setting Up the Monorepo#

After running monopam, set up the development environment:

cd output-dir
./setup.sh

The setup script will:

1. Create a local opam switch with OCaml 5.4.0
2. Pin all vendor packages
3. Install dependencies (including test dependencies)
4. Run dune build

Alternatively, run the steps manually:

cd output-dir
opam switch create . 5.4.0 -y
opam pin add -ny <pkg1> vendor/<repo1>
opam pin add -ny <pkg2> vendor/<repo2>
# ... for each package
opam install -y --deps-only --with-test <pkg1> <pkg2> ...
opam exec -- dune build --root .

Using the opam Repository as an Overlay#

You can also use just the generated opam repository as an overlay:

opam repository add local /path/to/output-dir/opam-repository
opam update
opam install <package-name>

Incremental Updates#

Running monopam again on an existing output directory will:

• Update existing repositories with git pull
• Clone any new repositories
• Regenerate the opam repository and setup script

Example#

# Create a repos.txt file
cat > repos.txt << EOF
https://github.com/user/ocaml-foo
https://github.com/user/ocaml-bar
https://tangled.org/user/ocaml-baz
EOF

# Generate the monorepo
monopam repos.txt -o my-monorepo -v

# Set up and build
cd my-monorepo
./setup.sh