How to use a specific tag/version with composer and a private git repository?

Pull by git tag:

{
  "repositories": [
    {
      "type": "git",
      "url": "https://gitlab.xxx.com/some/repo.git"
    }
  ],
  "require": {
    "some/repo": "1.0.2"
  }
}

Pull by latest git commit:

{
  "repositories": [
    {
      "type": "git",
      "url": "https://gitlab.xxx.com/some/repo.git"
    }
  ],
  "require": {
    "some/repo": "dev-master"
  }
}

Pull by specific git commit:

{
  "repositories": [
    {
      "type": "git",
      "url": "https://gitlab.xxx.com/some/repo.git"
    }
  ],
  "require": {
    "some/repo": "dev-master#68696f39"
  }
}

Add repository via Composer Cli and pull latest git commit:

composer config repositories.repo git https://gitlab.xxx.com/some/repo.git
composer require "some/repo:dev-master"
composer update

How to require a specific Git tag?

Change the version requirement to dev-master, followed by a hash # and the Git tag name, e.g. v0.5.0, like so:

"require": {
    "vendor/package": "dev-master#v0.5.0"
}

How to require a specific Git commit?

Change the version requirement to dev-master, followed by a hash # and the Git commit reference, e.g. dd6ed3c8, like so:

"require": {
    "vendor/package": "dev-master#dd6ed3c8"
}

Referencing: https://getcomposer.org/doc/04-schema.md#package-links

---

Define your own package and set version and reference

An alternative to working with repositories of "type": "vcs" is to define a custom package "type": "package" inside repositories and work with a reference.

The reference is either a Git commit hash, or a tag or branch name, like origin/master.

This will tie the version to a specific commit reference, in this case dd6ed3c8.

"repositories": [
  # ...
  {
    "type": "package",
    "package": {
      "name": "vendor/package",
      "version": "v0.5.0",
      "source": {
        "url": "[email protected]:vendor/project.git",
        "type": "git",
        "reference": "dd6ed3c8"
      }
    }
  }
]