Creating a pre-receive hook environment

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

A pre-receive environment for GitHub Enterprise 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 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.

Ensure Docker is installed locally.
Create the file Dockerfile.alpine-3.3 that contains this information:
```
FROM gliderlabs/alpine:3.3
RUN apk add --no-cache git bash
```

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

Create a container:

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

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 appliance.

Creating a pre-receive hook environment using chroot

Create a Linux chroot environment.

Create a gzip compressed tar file of the chroot directory:

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

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 via the Admin Center

Sign in to your GitHub Enterprise instance at http(s)://[hostname]/login.
In the upper-right corner of any page, click .
In the left sidebar, click Admin center.
In the left sidebar, click Pre-receive hooks.
Click Manage environments.
Click Add environment.
Enter the desired name in the Environment name field.
Enter the URL of the *.tar.gz file that contains your environment.
Click Add environment.

Uploading a pre-receive hook environment via the administrative shell

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 appliance via scp. When using scp, you may need to adjust the *.tar.gz file permissions so that the file is world readable.
Connect to the administrative shell.
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.
```