Creating a pre-receive hook environment

To execute pre-receive hooks, use either the default pre-receive environment, or create a custom environment.

In this article

A pre-receive environment for GitHub Enterprise Server is a Linux chroot environment. Because pre-receive hooks execute on every push event, they should be fast and lightweight. The environment needed for such checks will typically be minimal.

GitHub Enterprise Server provides a default environment which includes these packages: awk, bash, coreutils, curl, find, gnupg, grep, jq, sed.

If you have a specific requirement that isn't met by this environment, such as support for a particular language, you can create and upload your own 64-bit Linux chroot environment.

The Git version used in the pre-receive hook environment must be at least 2.11, or if you are using libgit2 you must use at least version 0.18. If you are using another Git implementation, it must support relative paths in the info/alternates file.

Creating a pre-receive hook environment using Docker

You can use a Linux container management tool to build a pre-receive hook environment. This example uses Debian Linux and Docker.

  1. Ensure Docker is installed locally.

  2. Create the file Dockerfile.debian that contains this information:

    FROM --platform=linux/amd64 debian:stable
RUN apt-get update && apt-get install -y git bash curl
RUN rm -fr /etc/localtime /usr/share/zoneinfo/localtime

Note

The Debian image includes some symlinks by default, which if not removed, may cause errors when executing scripts in the custom environment. Symlinks are removed in the last line of the example above.

  1. From the working directory that contains Dockerfile.debian, build an image:

    $ docker build -f Dockerfile.debian -t pre-receive.debian .
> [+] Building 0.6s (6/6) FINISHED                                                                   docker:desktop-linux
> => [internal] load build definition from Dockerfile.debian
> => [1/2] FROM docker.io/library/debian:latest@sha256:80dd3c3b9c6cecb9f1667e9290b3bc61b78c2678c02cbdae5f0fea92cc6
> => [2/2] RUN apt-get update && apt-get install -y git bash curl
> => exporting to image
> => => exporting layers
> => => writing image sha256:b57af4e24082f3a30a34c0fe652a336444a3608f76833f5c5fdaf4d81d20c3cc
> => => naming to docker.io/library/pre-receive.debian

  2. Create a container:

    docker create --name pre-receive.debian pre-receive.debian /bin/true

  3. Export the Docker container to a gzip compressed tar file:

    docker export pre-receive.debian | gzip > debian.tar.gz

    This file debian.tar.gz is ready to be uploaded to the GitHub Enterprise Server appliance.

Creating a pre-receive hook environment using chroot

  1. Create a Linux chroot environment.

  2. Create a gzip compressed tar file of the chroot directory.

    cd /path/to/chroot
tar -czf /path/to/pre-receive-environment.tar.gz .

    Note

    • Do not include leading directory paths of files within the tar archive, such as /path/to/chroot.
    • /bin/sh must exist and be executable, as the entry point into the chroot environment.
    • Unlike traditional chroots, the dev directory is not required by the chroot environment for pre-receive hooks.

For more information about creating a chroot environment, see Chroot from the Debian Wiki.

Uploading a pre-receive hook environment on GitHub Enterprise Server

  1. In the top-right corner of GitHub Enterprise Server, click your profile picture, then click Enterprise settings.
  2. At the top of the page, click Settings.
  3. Under " Settings", click Hooks.
  4. Click Manage environments.
  5. Click Add environment.
  6. In the "Environment name" field, enter the desired name.
  7. In the "Upload environment from a URL" field, enter the URL of the *.tar.gz file that contains your environment.
  8. Click Add environment.

Uploading a pre-receive hook environment via the administrative shell

  1. Upload a readable *.tar.gz file that contains your environment to a web host and copy the URL or transfer the file to the GitHub Enterprise Server appliance via scp. When using scp, you may need to adjust the *.tar.gz file permissions so that the file is world readable.

  2. Connect to the administrative shell.

  3. Use the ghe-hook-env-create command and type the name you want for the environment as the first argument and the full local path or URL of a *.tar.gz file that contains your environment as the second argument.

    admin@ghe-host:~$ ghe-hook-env-create DebianTestEnv /home/admin/debian.tar.gz
> Pre-receive hook environment 'DebianTestEnv' (2) has been created.