Creating a pre-receive hook environment

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.

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 Alpine Linux and Docker.

1. Ensure Docker is installed locally.

2. Create the file Dockerfile.alpine-3.3 that contains this information:

   FROM gliderlabs/alpine:3.3 RUN apk add --no-cache git bash 

3. From the working directory that contains Dockerfile.alpine-3.3, build an image:

   $ docker build -f Dockerfile.alpine-3.3 -t pre-receive.alpine-3.3 . > Sending build context to Docker daemon 12.29 kB > Step 1 : FROM gliderlabs/alpine:3.3 > ---> 8944964f99f4 > Step 2 : RUN apk add --no-cache git bash > ---> Using cache > ---> 0250ab3be9c5 > Successfully built 0250ab3be9c5

4. Create a container:

   $ docker create --name pre-receive.alpine-3.3 pre-receive.alpine-3.3 /bin/true

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

   $ docker export pre-receive.alpine-3.3 | gzip > alpine-3.3.tar.gz

   This file alpine-3.3.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 .

   Notes:

   • 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, "BasicChroot" from the Ubuntu Community Help Wiki, or "Installing Alpine Linux in a chroot" from the Alpine Linux Wiki.

Uploading a pre-receive hook environment on GitHub Enterprise Server

1. In the top-right corner of GitHub Enterprise Server, click your profile photo, then click Enterprise settings.

2. In the enterprise account sidebar, click Settings.

3. Under " Settings", click Hooks.

4. Click Manage environments.

5. Click Add environment.

6. Enter the desired name in the Environment name field.

7. 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 AlpineTestEnv /home/admin/alpine-3.3.tar.gz > Pre-receive hook environment 'AlpineTestEnv' (2) has been created.