This post shows how to use git subtree commands to move git repositories around. Perfect if you’re indecisive about monorepo vs multirepo.

Move a repo in a different repo as a subfolder

Use case: you want to move a library into a monorepo (because you read a post that says it’s cool).

Before:

Source repo             Destination repo
|                       |
|-- src                 |-- packages
|   \-- index.ts        |   \-- bar
|-- package.json        \-- README.md
|-- package-lock.json    
\-- README.md

After:

Destination repo
|
|-- packages
|   |-- bar
|   \-- foo (**moved here from source repo**)
|       |-- src
|       |   \-- index.ts
|       |-- package.json
|       |-- package-lock.json
|       \-- README.md
\-- README.md

Steps:

  • Clone the source repo in a folder named source
  • Clone the destination repo in a sibling folder named destination
  • In the destination repo, run: git subtree add -P packages/foo ../source master (assuming the main branch is called master)
  • Delete the source repo (I’m sure you won’t regret it)

Move a subfolder to a new repo

Use case: you want to move a library out of a monorepo into its own dedicated repo (because you read a different post that says monorepos are actually not cool).

Before:

Source repo     
|
|-- packages
|   |-- bar
|   \-- foo
|       |-- package.json
|       \-- README.md
\-- README.md

After:

Destination repo (**keeping only the contents of foo**)
|-- package.json
\-- README.md

Steps:

  • Clone the source repo in a folder named source
  • Prepare a new empty bare repo in a folder named destination (with git init --bare)
  • In the source folder, run git subtree push -P packages/foo ../destination master
  • To double check everything went fine, you can clone the bare repo into a regular repo and inspect its contents.
  • Delete the library from the source repo

Move a subfolder to an existing repo

Use case: you have two monorepos and you want to move one library from one to the other (because the oxymoron of having multiple monorepos escapes you).

Before:

Source repo    Destination repo
|              |
|-- packages   |-- libs
    |-- bar        \-- bar
    \-- foo       

After:

Source repo    Destination repo
|              |
|-- packages   |-- libs
    \-- foo        |-- bar
                   \-- bar_v2 (** moved here from source repo where it was called bar **)
  • Clone the source repository into a folder named source
  • Clone the destination repository into a sibling folder named destination
  • In the source repo, keep only the desired library with git subtree split -P packages/bar -b temp (temp is the name of a branch we’ll use next)
  • Checkout the temp branch and double check the source repo folder only has the desired library
  • In the destination repo, add the library with git subtree add -P libs/bar_v2 ../source temp
  • Delete the library from the source repo