Use PHP composer to clone git repo

That package in fact is available through packagist. You don't need a custom repository definition in this case. Just make sure you add a require (which is always needed) with a matching version constraint.

In general, if a package is available on packagist, do not add a VCS repo. It will just slow things down.

For packages that are not available via packagist, use a VCS (or git) repository, as shown in your question. When you do, make sure that:

The "repositories" field is specified in the root composer.json (it's a root-only field, repository definitions from required packages are ignored)

The repositories definition points to a valid VCS repo

If the type is "git" instead of "vcs" (as in your question), make sure it is in fact a git repo

You have a require for the package in question

The constraint in the require matches the versions provided by the VCS repo. You can use composer show to find the available versions. In this case ~2.3 would be a good option.

The name in the require matches the name in the remote composer.json. In this case, it is gedmo/doctrine-extensions.

Here is a sample composer.json that installs the same package via a VCS repo:

{
    "repositories": [
        {
            "url": "https://github.com/l3pp4rd/DoctrineExtensions.git",
            "type": "git"
        }
    ],
    "require": {
        "gedmo/doctrine-extensions": "~2.3"
    }
}

The VCS repo docs explain all of this quite well.

If there is a git (or other VCS) repository with a composer.json available, do not use a "package" repo. Package repos require you to provide all of the metadata in the definition and will completely ignore any composer.json present in the provided dist and source. They also have additional limitations, such as not allowing for proper updates in most cases.

Avoid package repos (see also the docs).

---

At the time of writing in 2013, this was one way to do it. Composer has added support for better ways: See @igorw 's answer

DO YOU HAVE A REPOSITORY?

Git, Mercurial and SVN is supported by Composer.

DO YOU HAVE WRITE ACCESS TO THE REPOSITORY?

Yes?

DOES THE REPOSITORY HAVE A composer.json FILE

If you have a repository you can write to: Add a composer.json file, or fix the existing one, and DON'T use the solution below.

Go to @igorw 's answer

ONLY USE THIS IF YOU DON'T HAVE A REPOSITORY
OR IF THE REPOSITORY DOES NOT HAVE A composer.json AND YOU CANNOT ADD IT

This will override everything that Composer may be able to read from the original repository's composer.json, including the dependencies of the package and the autoloading.

Using the package type will transfer the burden of correctly defining everything onto you. The easier way is to have a composer.json file in the repository, and just use it.

This solution really only is for the rare cases where you have an abandoned ZIP download that you cannot alter, or a repository you can only read, but it isn't maintained anymore.

"repositories": [
    {
        "type":"package",
        "package": {
          "name": "l3pp4rd/doctrine-extensions",
          "version":"master",
          "source": {
              "url": "https://github.com/l3pp4rd/DoctrineExtensions.git",
              "type": "git",
              "reference":"master"
            }
        }
    }
],
"require": {
    "l3pp4rd/doctrine-extensions": "master"
}

---

You can include git repository to composer.json like this:

"repositories": [
{
    "type": "package",
    "package": {
        "name": "example-package-name", //give package name to anything, must be unique
        "version": "1.0",
        "source": {
            "url": "https://github.com/example-package-name.git", //git url
            "type": "git",
            "reference": "master" //git branch-name
        }
    }
}],
"require" : {
  "example-package-name": "1.0"
}

---

Just tell composer to use source if available:

composer update --prefer-source

Or:

composer install --prefer-source

Then you will get packages as cloned repositories instead of extracted tarballs, so you can make some changes and commit them back. Of course, assuming you have write/push permissions to the repository and Composer knows about project's repository.

Disclaimer: I think I may answered a little bit different question, but this was what I was looking for when I found this question, so I hope it will be useful to others as well.

If Composer does not know, where the project's repository is, or the project does not have proper composer.json, situation is a bit more complicated, but others answered such scenarios already.

---

I try to join the solutions mention here as there are some important points to it needed to list.

As mentioned in the @igorw's answer the URL to repository must be in that case specified in the composer.json file, however since in both cases the composer.json must exist (unlike the 2nd way @Mike Graf) publishing it on the Packagist is not that much different (furthermore also Github currently provides packages services as npm packages), only difference instead of literally inputting the URL at the packagist interface once being signed up. Moreover, it has a shortcoming that it cannot rely on an external library that uses this approach as recursive repository definitions do not work in Composer. Furthermore, due to it, there seems to be a "bug" upon it, since the recursive definition failed at the dependency, respecifying the repositories explicitly in the root does not seem to be enough but also all the dependencies from the packages would have to be respecified.

With a composer file (answered Oct 18 '12 at 15:13 igorw)

{
    "repositories": [
        {
            "url": "https://github.com/l3pp4rd/DoctrineExtensions.git",
            "type": "git"
        }
    ],
    "require": {
        "gedmo/doctrine-extensions": "~2.3"
    }
}

Without a composer file (answered Jan 23 '13 at 17:28 Mike Graf)

"repositories": [
    {
        "type":"package",
        "package": {
          "name": "l3pp4rd/doctrine-extensions",
          "version":"master",
          "source": {
              "url": "https://github.com/l3pp4rd/DoctrineExtensions.git",
              "type": "git",
              "reference":"master"
            }
        }
    }
],
"require": {
    "l3pp4rd/doctrine-extensions": "master"
}

---

I was encountering the following error: The requested package my-foo/bar could not be found in any version, there may be a typo in the package name.

If you're forking another repo to make your own changes you will end up with a new repository.

E.g:

https://github.com/foo/bar.git
=>
https://github.com/my-foo/bar.git

The new url will need to go into your repositories section of your composer.json.

Remember if you want refer to your fork as my-foo/bar in your require section, you will have to rename the package in the composer.json file inside of your new repo.

{
    "name":         "foo/bar",

=>

{
    "name":         "my-foo/bar",

If you've just forked the easiest way to do this is edit it right inside github.

---

In my case, I use Symfony2.3.x and the minimum-stability parameter is by default "stable" (which is good). I wanted to import a repo not in packagist but had the same issue "Your requirements could not be resolved to an installable set of packages.". It appeared that the composer.json in the repo I tried to import use a minimum-stability "dev".

So to resolve this issue, don't forget to verify the minimum-stability. I solved it by requiring a dev-master version instead of master as stated in this post.

---

If you want to use a composer.json from GitHub you would look at this example (under the VCS section).

The package section is for packages that do not have the composer.json. However, you didn't follow that example as well or it would also have worked. Do read what it says about package repositories:

Basically, you define the same information that is included in the composer repository's packages.json, but only for a single package. Again, the minimum required fields are name, version, and either of dist or source.

---