CHEATSHEET FOR USING GIT FOR WEB SITES HOSTED BY BASIC SLAC WEB SERVER
                 
                 Greg White, 21-Nov-2019
             v0.1  21-Nov-2019, First version
 

This cheatsheet helps authors of web accessible static web pages at SLAC, to manage the files of their
web sites using git, and use git to automatically publish to the SLAC web server.

Three directories are relevant for developing web sites using Git at SLAC.

1. SLAC's Apache web server serves out of /afs/slac/www/. Anything under that is at the symmetrical URL address
   under https://www.slac.stanford.edu/. Eg This file, whose URL is: 
      https://www.slac.stanford.edu/grp/ad/docs/model/swdev/wwwslaccheatsheet.txt, would be found at 
                      /afs/slac/www/grp/ad/docs/model/swdev/wwwslaccheatsheet.txt.

2. Git Repos. Our repos for accelerator related software, are hosted at:
      /afs/slac/g/cd/swe/git/repos/. Specifically, repos of web sites SHOULD be under:
      /afs/slac/g/cd/swe/git/repos/sites/.

3. Your development directory. Personally I clone repos from above into ~/sites/. 

Basic publication mechanism
===========================

This section describes setting up a git repo under /afs/slac.stanford.edu/g/cd/swe/git/repos/sites/, so that
it automatically publishes anything got pushed to it, into its concomitant web site under 
https://www.slac.stanford.edu/.

This example made the web site corresponding to the URL 
   https://www.slac.stanford.edu/grp/ad/docs/model/swdev/

Note the directory design of repos for web sites under https://www.slac.stanford.edu/grp/ad/docs/. These repos
are hosted at /afs/slac.stanford.edu/g/cd/swe/git/repos/sites/www.slac.stanford.edu/grp/ad/docs/: 

Setting up the repo for your web site:

    cd  /afs/slac/g/cd/swe/git/repos/sites  # Where (I propose) we keep web site golden master repos
    mkdir -p www.slac.stanford.edu/grp/ad/docs/model/     # Make a directory for the golden master of the repo
                                                          # corresponding to its URL at SLAC.


Make the repo in the right place in the directory hierarchy:

    cd www.slac.stanford.edu/grp/ad/docs/model/
    git init --bare swdev.git                             # Make our golden master bare repo for the files of a 
                                                          # site or subsite. 

Make the git post-receive hook that publishes all pushed changes, directly to the web site:
      
      [Experts will note there is no ssh setup done here, which is often part of the auto publication process. That's 
      because the repo and the publication area are both in AFS, and so accessible from the same SLAC host. So all 
      that is needed is to tell git to where to make its work checkout (GIT_WORK_TREE).]
                    
      Write the post-receive hook right in the bare repo hooks dir:
      cd /afs/slac/g/cd/swe/git/repos/sites/www.slac.stanford.edu/grp/ad/docs/model/swdev.git
      gwt=/afs/slac/www/grp/ad/docs/model/swdev/           # Set to where git will auto-checkout pushes made to it
      echo '#!/bin/sh' > hooks/post-receive
      echo "GIT_WORK_TREE=$gwt git checkout -f" >> hooks/post-receive
      chmod +x hooks/post-receive   #Give execute permission to the script

Ensure the directory to which you want your post-receive hook to checkout any updates, exists (in the
web site space). If not make it:
      
      cd /afs/slac/www/grp/ad/docs/model
      mkdir swdev

Having completed the above steps just once, any time you git push to swdev.git, /afs/slac/www/grp/ad/docs/model/swdev/ 
will be automatically updated, and hence also the web site https://www.slac.stanford.edu/grp/ad/docs/model/swdev/.


Basic Workflow
==============

1. Optionally, make a directory where you'll do your edit, that has the same directory structure
as the web site and the repos;

     [greg@rhel6-64e git]$ pwd            
     /u/cd/greg/Sites/git
     [greg@rhel6-64e git]$ mkdir -p www.slac.stanford.edu/grp/ad/docs/model          
     [greg@rhel6-64e git]$ cd www.slac.stanford.edu/grp/ad/docs/model

2. Clone the repo of the web site you're interested in,
   If on an AFS machine:

     [greg@rhel6-64e model]$ git clone       /afs/slac.stanford.edu/g/cd/swe/git/repos/sites/www.slac.stanford.edu/grp/ad/docs/model/matlab.git
     Cloning into 'matlab'...
     warning: You appear to have cloned an empty repository.
     done.

Or if on your own machine:

 git clone greg@rhel6-64.slac.stanford.edu:/afs/slac/g/cd/swe/git/repos/sites/www.slac.stanford.edu/grp/ad/docs/model/swdev.git

3. Edit files

4. Then git add and git commit. maybe in one line:

   git commit -am 'Removed arcfour256'

5. Finally git push. If the setup above in Basic Publication Mechanism has been done properly, the
web site will update automatically.

   git push

Iterate steps 3 (edit) to 5 (push) as much as you like.