Creation of Git deployment key for user www-data on Debian

deployment_key.sh

# let's be root
su

# go the apache folder
cd /var/www

# create folder to store keys
mkdir .ssh
chown -R www-data:www-data .ssh
# create keys
sudo -u www-data ssh-keygen -t rsa
# rename keys
cd .ssh
mv id_rsa service_deployment_www-data
mv id_rsa.pub service_deployment_www-data.pub

# link key to our service host
nano config
# Host service.org
#    HostName service.org
#    User git
#    IdentityFile ~/.ssh/service_deployment_www-data
chown www-data:www-data config

# update a repository
cd /data/git/some-repository
sudo -u www-data git pull

To clone a repository as the www-data user:

 su - www-data -s /bin/bash -c 'cd /data/git/; git clone git@service.org:username/repo_name.git repo_name'

And to update it:

 su - www-data -s /bin/bash -c 'cd /data/git/repo_name; git pull'

---

If you have the following error:

Host key verification failed.
fatal: Could not read from remote repository.
Please make sure you have the correct access rights and the repository exists.

you probably need to add the Service.org server to the list of authorized hosts

su - www-data -s /bin/bash -c 'ssh-keyscan -t rsa service.org >> /var/www/.ssh/known_hosts'