Downloading the Source

The Android source tree is located in a Git repository hosted by Google. The Git repository includes metadata for the Android source, including those related to changes to the source and the date they were made. This document describes how to download the source tree for a specific Android code-line.

To instead start with a factory image for a specific device, see Selecting a device build.

Installing Repo

Repo is a tool that makes it easier to work with Git in the context of Android. For more information about Repo, see the Developing section.

To install Repo:

  1. Make sure you have a bin/ directory in your home directory and that it is included in your path:

    mkdir ~/bin
  2. Download the Repo tool and ensure that it is executable:

    curl > ~/bin/repo
    chmod a+x ~/bin/repo

For version 1.21, the SHA-1 checksum for repo is b8bd1804f432ecf1bab730949c82b93b0fc5fede

For version 1.22, the SHA-1 checksum for repo is da0514e484f74648a890c0467d61ca415379f791

For version 1.23, the SHA-256 checksum for repo is e147f0392686c40cfd7d5e6f332c6ee74c4eab4d24e2694b3b0a0c037bf51dc5

Initializing a Repo client

After installing Repo, set up your client to access the Android source repository:

  1. Create an empty directory to hold your working files. If you're using MacOS, this has to be on a case-sensitive filesystem. Give it any name you like:

  2. Configure git with your real name and email address. To use the Gerrit code-review tool, you will need an email address that is connected with a registered Google account. Make sure this is a live address at which you can receive messages. The name that you provide here will show up in attributions for your code submissions.

    git config --global "Your Name"
    git config --global ""
  3. Run repo init to bring down the latest version of Repo with all its most recent bug fixes. You must specify a URL for the manifest, which specifies where the various repositories included in the Android source will be placed within your working directory.

    repo init -u

    To check out a branch other than "master", specify it with -b. For a list of branches, see Source Code Tags and Builds.

    repo init -u -b android-4.0.1_r1

A successful initialization will end with a message stating that Repo is initialized in your working directory. Your client directory should now contain a .repo directory where files such as the manifest will be kept.

Downloading the Android Source Tree

To pull down the Android source tree to your working directory from the repositories as specified in the default manifest, run

repo sync

The Android source files will be located in your working directory under their project names. The initial sync operation will take an hour or more to complete. For more about repo sync and other Repo commands, see the Developing section.

Using Authentication

By default, access to the Android source code is anonymous. To protect the servers against excessive usage, each IP address is associated with a quota.

When sharing an IP address with other users (e.g. when accessing the source repositories from beyond a NAT firewall), the quotas can trigger even for regular usage patterns (e.g. if many users sync new clients from the same IP address within a short period).

In that case, it is possible to use authenticated access, which then uses a separate quota for each user, regardless of the IP address.

The first step is to create a password with the password generator and follow the instructions on the password generator page.

The second step is to force authenticated access, by using the following manifest URI: Notice how the /a/ directory prefix triggers mandatory authentication. You can convert an existing client to use mandatory authentication with the following command:

repo init -u

Troubleshooting network issues

When downloading from behind a proxy (which is common in some corporate environments), it might be necessary to explicitly specify the proxy that is then used by repo:

export HTTP_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>
export HTTPS_PROXY=http://<proxy_user_id>:<proxy_password>@<proxy_server>:<proxy_port>

More rarely, Linux clients experience connectivity issues, getting stuck in the middle of downloads (typically during "Receiving objects"). It has been reported that tweaking the settings of the TCP/IP stack and using non-parallel commands can improve the situation. You need root access to modify the TCP setting:

sudo sysctl -w net.ipv4.tcp_window_scaling=0
repo sync -j1

Using a local mirror

When using several clients, especially in situations where bandwidth is scarce, it is better to create a local mirror of the entire server content, and to sync clients from that mirror (which requires no network access). The download for a full mirror is smaller than the download of two clients, while containing more information.

These instructions assume that the mirror is created in /usr/local/aosp/mirror. The first step is to create and sync the mirror itself. Notice the --mirror flag, which can be specified only when creating a new client:

mkdir -p /usr/local/aosp/mirror
cd /usr/local/aosp/mirror
repo init -u --mirror
repo sync

Once the mirror is synced, new clients can be created from it. Note that it's important to specify an absolute path:

mkdir -p /usr/local/aosp/master
cd /usr/local/aosp/master
repo init -u /usr/local/aosp/mirror/platform/manifest.git
repo sync

Finally, to sync a client against the server, the mirror needs to be synced against the server, then the client against the mirror:

cd /usr/local/aosp/mirror
repo sync
cd /usr/local/aosp/master
repo sync

It's possible to store the mirror on a LAN server and to access it over NFS, SSH or Git. It's also possible to store it on a removable drive and to pass that drive around between users or between machines.

Verifying Git Tags

Load the following public key into your GnuPG key database. The key is used to sign annotated tags that represent releases.

gpg --import

Copy and paste the key below, then enter EOF (Ctrl-D) to end the input and process the keys.

Version: GnuPG v1.4.2.2 (GNU/Linux)


After importing the keys, you can verify any tag with

git tag -v TAG_NAME

If you haven't set up ccache yet, now would be a good time to do it.