BLOGC-GIT-RECEIVER(1)

NAME
blogc-git-receiver - a simple login shell/git hook to deploy blogc websites

SYNOPSIS
chsh -s $(command -v blogc-git-receiver) user

DESCRIPTION
blogc-git-receiver provides a PaaS-like way to deploy blogc(1) websites. When used as a login shell, it will accept git payloads, creating bare repositories as needed, and installing a hook, that will take care of rebuilding the website each time someone push something to the master branch.

The git repository must provide a blogcfile(5) (if blogc-make(1) is installed), or a Makefile (or a GNUMakefile) that should accept the OUTPUT_DIR variable, and install built files into the directory pointed out by this variable.

blogc-git-receiver is part of blogc project, but isn't tied to blogc(1) or blogc-make(1). Any repository with Makefile that builds content and install it to OUTPUT_DIR should work with blogc-git-receiver.

SETUP
After creating an user (blogc for the examples), change its shell to blogc-git-receiver(1):

    # chsh -s $(command -v blogc-git-receiver) blogc

Now add ssh keys to /home/blogc/.ssh/authorized_keys. Every key in authorized_keys will be allowed to push to the git repositories, and even create new ones.

Also, make sure to install all the dependencies required by the websites, including a web server. blogc-git-receiver can't handle web server virtual hosts.

To deploy a website (e.g. blogc example repository):

    $ git clone https://github.com/blogc/blogc-example.git
    $ cd blogc-example
    $ git remote add blogc blogc@${SERVER_IP}:blogs/blogc-example.git
    $ git push blogc master

This will deploy the example to the server, creating a symlink to the built content in /home/blogc/repos/blogs/blogc-example.git/htdocs. This symlink should be used as the document root for the web server virtual host.

  Rebuild last successful build
If for some reason you want to rebuild the last successful build of a given website, you can run its pre-receive hook manually in the server:

    # su -s /bin/sh - blogc
    $ cd ~/repos/blogs/blogc-example.git
    $ ./hooks/pre-receive

This should re-run the last build as if it was pushed to git.

  Setup with SELinux enabled (Fedora)
Supposing the usage of nginx as webserver, running as the nginx user:

    # dnf install -y nginx policycoreutils-python-utils
    # useradd -m -s $(command -v blogc-git-receiver) blogc
    # gpasswd -a nginx blogc
    # chmod -R g+rx /home/blogc
    # su -c "mkdir /home/blogc/{builds,repos}" -s /bin/sh blogc
    # semanage fcontext -a -t httpd_sys_content_t "/home/blogc/(builds|repos)(/.*)?"
    # restorecon -R -v /home/blogc
    # systemctl restart nginx

After running these commands, the machine is ready to be used.

REPOSITORY MIRRORING
Users can rely on blogc-git-receiver to mirror repositories to a remote Git repository (e.g. a free Bitbucket private repository).

Please note that the blogc user must be able to push to the remote repository, and that any content manually pushed to the remote repository is overwritten by blogc-git-receiver.

Some reasonable ways to allow the blogc user to push to the remote repository are:

•   Create a password-less SSH key. The key must be password-less, because the push is automatic, and remote git hooks can't be interactive.

•   Create an oauth token in the hosting service (if it supports oauth authentication in git, e.g. GitHub) and add it to the git URL.

The mirroring feature wont't block a git push, it will just raise warnings. That means that if an error happens when mirroring the repository, the deploy will still succeed. Users should pay attention to the git hook logs, to avoid losing data due to repositories not being mirrored.

This feature just requires adding a remote called mirror to the bare repository in the server, or creating a configuration file (~/blogc-git-receiver.ini), that is a simple INI-style file where each repository is represented by a section and the value of the mirror variable is the URL that should be used to push.

To create the configuration file (recommended):

    # su -s /bin/sh - blogc
    $ cat > ~/blogc-git-receiver.ini <<EOF
    [repo:myblog.git]
    mirror=$YOUR_GIT_MIRROR_URL
    EOF

Or to add the mirror remote:

    # su -s /bin/sh - blogc
    $ cd repos
    $ git init --bare myblog.git  # if not created yet
    $ cd myblog.git
    $ git remote add --mirror=push mirror $YOUR_GIT_MIRROR_URL

Both examples assume that your repository is named myblog.git.

  Caveats of repository mirroring with SSH
The authentication must be done with a password-less SSH key created by the blogc user.

As the git push --mirror call is automated, users must disable SSH strict host checking in SSH's ~/.ssh/config file:

    Host bitbucket.org
        StrictHostKeyChecking no

The example uses bitbucket.org as remote host, that should be changed if needed.

To change this file, users must login with /bin/sh or any other "real" shell, as root:

    # su -s /bin/sh - blogc

  Push to mirror manually
If for some reason you want to push the repository of a given website to remote mirror, you can run its post-receive hook manually in the server:

    # su -s /bin/sh - blogc
    $ cd ~/repos/blogs/blogc-example.git
    $ ./hooks/post-receive

WARNING: If you push manually and your server's repository is empty, you'll clean your mirror repository.

ENVIRONMENT
The following variables can be set in the SSH Server (usually in ~/.ssh/environment) to change blogc-git-receiver behaviour:

BLOGC_GIT_RECEIVER_BASE_DIR
    Path to the base directory that should be used by blogc-git-receiver. Defaults to user's home directory. Useful for shared hosting environments that only provide one shell user.

BLOGC_GIT_RECEIVER_BUILDS_DIR
    Path to the directory that should be used to store the blogc builds. Defaults to $BLOGC_GIT_RECEIVER_BASE_DIR/builds. This directory must be readable by your webserver. This variable is useful to keep your git repositories unreadable, while letting your webserver access the built files. In this case, users need to also define custom symlinks for every repository in $BLOGC_GIT_RECEIVER_BASE_DIR/blogc-git-receiver.ini, because the default htdocs symlink inside the git repositories won't be acessible by the webserver.

The following variable is exported by blogc-git-receiver when building websites with make(1):

BLOGC_GIT_RECEIVER=1
    This variable can be used to enable building of content that should only be built when running in production environment, for example. This variable will not be exported when using blogc-make(1), whose builds are always considered to be "production" (blogc-make(1) is never called with -D).

BUGS
Please report any issues to: https://github.com/blogc/blogc

AUTHOR
Rafael G. Martins <rafael@rafaelmartins.eng.br>

SEE ALSO
blogc(1), git(1), git-shell(1), chsh(1), su(1), make(1)