Mercurial to Git converter using git fast-import with multi repository import support

Legal

Dual-licensed under MIT or the UNLICENSE.

Features

  1. Import of single and multiple Mercurial repositories to Git repository.
  2. Import of new revisions from previously imported Mercurial repositories to Git repository.
  3. Tags.
  4. Closed branches.
  5. Verification of the end result with diff.

Installation

With cargo:

cargo install hg-git-fast-import

From source:

git clone https://github.com/kilork/hg-git-fast-import.git
cd hg-git-fast-import
cargo install --path .

Usage

hg-git-fast-import is a command-line utility, usage info can be access with --help argument:

$ hg-git-fast-import --help
hg-git-fast-import 1.1.0
Alexander Korolev <kilork@yandex.ru>
A utility to import single and multiple Mercurial repositories to Git.

USAGE:
    hg-git-fast-import <SUBCOMMAND>

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

SUBCOMMANDS:
    help      Prints this message or the help of the given subcommand(s)
    multi     Exports multiple Mercurial repositories to single Git repo in fast-import compatible format
    single    Exports single Mercurial repository to Git fast-import compatible format

Import of single repository:

$ hg-git-fast-import single --help
hg-git-fast-import-single 1.1.0
Alexander Korolev <kilork@yandex.ru>
Exports single Mercurial repository to Git fast-import compatible format

USAGE:
    hg-git-fast-import single [FLAGS] [OPTIONS] <hg_repo> [git_repo]

FLAGS:
        --clean                       Recreate Git repo before import if it exists.
        --cron                        Produce minimal output only if new revisions loaded or error happened.
        --fix-wrong-branch-names      Fix wrong Mercurial branch names (not compatible with git ref format).
    -h, --help                        Prints help information
        --no-clean-closed-branches    Do not clean closed Mercurial branches.
        --source-pull                 Pull source Mercurial repository before import.
        --target-pull                 Pull target Git repository before push.
        --target-push                 Push target Git repository after successful import.
    -V, --version                     Prints version information
        --verify                      Compares resulting Git repo with Mercurial.

OPTIONS:
    -a, --authors <authors>                            Authors remapping in toml format.
    -c, --config <config>                              Repository configuration in toml format.
        --git-active-branches <git-active-branches>    Git maximum number of branches to maintain active at once.
        --limit-high <limit-high>                      Limit high revision to import.
        --log <log>
            Log file. If present - additional log info would be printed to this file.


ARGS:
    <hg_repo>     The Mercurial repo for import to git
    <git_repo>    The Git repo to import to. Creates repo if it does not exist. Otherwise saved state must exist.

Import of multiple repositories:

$ hg-git-fast-import multi --help
hg-git-fast-import-multi 1.1.0
Alexander Korolev <kilork@yandex.ru>
Exports multiple Mercurial repositories to single Git repo in fast-import compatible format

USAGE:
    hg-git-fast-import multi [FLAGS] [OPTIONS] --config <config>

FLAGS:
        --clean                       Recreate Git repo before import if it exists.
        --cron                        Produce minimal output only if new revisions loaded or error happened.
        --fix-wrong-branch-names      Fix wrong Mercurial branch names (not compatible with git ref format).
    -h, --help                        Prints help information
        --no-clean-closed-branches    Do not clean closed Mercurial branches.
        --source-pull                 Pull source Mercurial repository before import.
        --target-pull                 Pull target Git repository before push.
        --target-push                 Push target Git repository after successful import.
    -V, --version                     Prints version information
        --verify                      Compares resulting Git repo with Mercurial.

OPTIONS:
    -a, --authors <authors>                            Authors remapping in toml format.
    -c, --config <config>                              Repositories configuration in toml format.
        --git-active-branches <git-active-branches>    Git maximum number of branches to maintain active at once.
        --log <log>
            Log file. If present - additional log info would be printed to this file.

Configuration syntax

For more advanced cases one may supply configuration in toml format.

Single mode configuration example

```toml

Allows to start import in of hanged heads in repository

(currently has no effect, default value is true). Optional.

allowunnamedheads = true

Offset for git fast-import marks in Git repository. Optional, default is 0.

offset = 1000

Path prefix in target repository. If path_prefix = 'test',

all files will be under test folder in target Git repository.

Optional.

path_prefix = 'prefix1'

Tag prefix in target repository. Optional.

tag_prefix = 'prefix2-'

Branch prefix in target repository. Optional.

branch_prefix = 'prefix3-'

By default master branch is not prefixed by branch_prefix.

This behavior can be changed by specifying this as true.

Optional.

prefixdefaultbranch = false

Mapping between authors in Mercurial and authors in Git.

Required mainly because of Git asks for particular format "Somename ".

But also can be used to fix typos and etc.

[authors] 'aaa 1' = 'Bbb bbb@company.xyz' aaa = 'Bbb bbb@company.xyz' ccc = 'Qqq qqq@another.dom' 'My my_typo@wrong.xyz' = 'My my@normal.xyz'

Mapping between branches in Mercurial and branches in Git.

Required mainly because Git does not allow some characters,

which allowed in Mercurial, for example - spaces.

Branches taken from mapping will not have branch_prefix,

so it must be added to mapped values.

[branches] 'branch in hg' = 'branch-in-git' 'anotherhg' = 'othergit' ```

See single.toml.

With authors and branches subsections one can rename authors and branches during import. Offset creates marks in Git repository. Can be useful if all marks files from imported repositories planned to be analyzed together. allow_unnamed_heads allows to start import in case of hanged heads in repository, currently this feature has no effect.

Multi mode configuration example

```toml

Path to target git repository.

pathgit = "000git"

This is subsection with list of repositories to be aggregated into single repo.

Each subsection start like this (see toml format for arrays).

[[repositories]]

Mercurial repository path.

pathhg = "001hg"

Child Git repository path.

pathgit = "001git"

Child repository configuration for 001hg/001git.

Fields are the same as on root level in single mode configuration.

[repositories.config] allowunnamedheads = true offset = 1000 pathprefix = 'prefix1' tagprefix = 'prefix2-' branchprefix = 'prefix3-' prefixdefault_branch = true

Same as authors section in single mode, but for this child repository.

[repositories.config.authors] 'aaa' = 'Bbb bbb@company.xyz'

Same as branches section in single mode, but for this child repository.

[repositories.config.branches] 'branch1' = 'branch2'

This sections specify to which branches would be merged migrated

branches from this child Git repository.

[repositories.mergedbranches] branchin_git = 'branch2'

Explanation: in this case branchingit will be a branch in 000_git repo

and it will contain branch2 merged from remote child repository.

This is second child repository.

[[repositories]]

Here we can also specify alias, this field used to add reference in target 000_git repository.

Otherwise path_prefix is used from config section.

alias = "another002" pathhg = "002hg" pathgit = "002_git"

[repositories.mergedbranches] branchingit = 'branchin_hg'

Actually this branchinhg is from second migrated Git repository.

Interesting to note - both child repository branches are merged

into single branchingit branch in target 000_git repository.

```

Each of child repositories will be imported in corresponding path_git from configuration, then single repository from top level path_git will reference child repositories as remote. For remote name either alias either path_prefix is taken.

See multi.toml.

Authors list configuration example

toml 'aaa 1' = 'Bbb <bbb@company.xyz>' aaa = 'Bbb <bbb@company.xyz>' ccc = 'Qqq <qqq@another.dom>' 'My <my_typo@wrong.xyz>' = 'My <my@normal.xyz>'

See authors.toml.

Requirements

Docker support

To setup all dependencies can be a tricky task - it is possible to use docker for running hg-git-fast-import.

Docker installation

git clone https://github.com/kilork/hg-git-fast-import.git
cd hg-git-fast-import/docker
./build.sh

Docker running

docker run -it --rm kilork/hg-git-fast-import hg-git-fast-import --help

To mount current directory with repositories and run hg-git-fast-import command with docker one can use wrapper hg-git-fast-import/docker/run.sh:

cd hg-git-fast-import/docker
./run.sh

By default this will mount current directory to /repositories dir inside docker container. This can be overriden by usage of env variable:

HG_GIT_FAST_IMPORT_VOLUME=~/sandbox:/sandbox ./run.sh single /sandbox/source_hg /sandbox/target_git