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 that contains this information:

   FROM alpine:latest
   RUN apk add --no-cache git bash
   

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

   $ docker build -f Dockerfile.alpine -t pre-receive.alpine .
   > Sending build context to Docker daemon 12.29 kB
   > Step 1 : FROM alpine:latest
   >  ---> 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 pre-receive.alpine /bin/true
   

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

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

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