The Git Autoinstaller

TODO NOW:

* Migrate and upgrade the lone mediawiki-1.5.6 install
* Create the migration script

OVERALL PLAN:

* Some parts of the infrastructure will not be touched, although I plan
  on documenting them.  Specifically, we will be keeping:

    - parallel-find.pl, and the resulting
/mit/scripts/sec-tools/store/scriptslist

    - The current install scripts will be kept in place, sans changes
      necessary to make them use Git install of copying the script over.
      Porting these scripts to Python and making them modular would be
      nice, but is priority.  For the long term, seeing this scripts
      be packaged with rest of our code would be optimal.

* The new procedure for generating an update is as follows:

    1. Have the Git repository and working copy for the project on hand.

    2. Download the new tarball

    3. Extract the tarball over the working copy (`cp -R a/. b` works well)

    4. Check if there are any special update procedures, and update the
       .scripts/update shell script as necessary (this means that any
       application specific update logic will be kept with the actual
       source code.  The language of this update script will vary
       depending on context.)

    X. Check for empty directories and add stub files as necessary
       (use preserve-empty-dir)

    5. Commit your changes, and tag as v1.2.3-scripts

    6. Run the "dry-run script", which uses Git commands to check how many
       working copies apply the change cleanly, and writes out a logfile
       with the working copies that don't apply cleanly.

    7. Run the "limited run" script, which applies the update to our
       test-bed, and lets us check the basic functionality of the update.

    8. Run the "deploy" script, which applies the update to all working
       copies possible, and sends mail to users to whom the working copy
       did not apply cleanly. (It also frobs .scripts/version)

    Note: The last three scripts will need to be implemented, with an
          eye towards speed.

* How to migrate an old autoinstaller to the new autoinstaller

    - Find the oldest tarball/patch set for the application that still
      is in use and upgradable.

    - Untar, apply patch, place in a directory (unfurl) and git init

    - Commit this as the "pristine" version (branch "pristine")

    - Apply scripts patches

    - Create the .scripts directory and populate it with the interesting
      information (see below)

    - Commit this as the "scripts" version (branch "master")

* How to update the autoinstaller repository

    - Checkout pristine branch
    - Delete contents of pristine branch (excluding .git, try rm -Rf * and remove stragglers)
    - Unfurl tarball
    - Commit as new pristine branch
    - Checkout scripts branch
    - Merge pristine branch
    - Fix as necessary

* The repository for a given application will contain the following files:

    - The actual application's files, as from the official tarball

    - A .scripts directory, which contains the following information:

        * .scripts/update shell script (with the +x bit set appropriately),
          which performs the commands necessary to update a script.  This can
          be in any language.

        * .scripts/.htaccess to prevent this directory from being accessed
          from the web.

        * .scripts/database (generated) contains the database the
          user installed the script to, so scripts-remove can clean it

        * .scripts/version (generated) which contains the version
          last autoinstalled (as distinct from the actual version
          the script is) (This is the same as .scripts-version right
          now; probably want to keep that for now)

    - Because there will be no .gitignore file, you *must not* run
      `git add .` on an actual running copy of the application.
      `git add -u .` will generally be safe, but preferred mode
      of operation is to operate on a clean install.

* The migration process shall be as such:

    1. git init

    2. git remote add origin /foo

    3. git config branch.master.merge refs/heads/master

    4. git fetch origin

    5. git reset v1.2.3-scripts

    5. git checkout .scripts

    6. Setup .scripts/version (probably pipe the output of real-version)
        UNCLEAR if this is a good thing; if it is, make sure we add
        a .gitignore to the .scripts directory

* We will not add special code to handle .htaccess; thus the kernel patch
  for allowing Apache access to .htaccess sent to scripts-team@mit.edu
  must be handled first.

* The autoupgrade shall be the process of:

    # Make the directory not accessible by the outside world (htaccess, but be careful!)
    git add -u .
    git commit -m 'automatically generated backup'
    git pull origin master
    if [ $? ne 0 ]; then git reset --hard; echo 'conflicts during upgrade'; fi
    ./.scripts/update
    # Make it accessible

  (with some more robust error checking)

* Make install-statistics generate nice pretty graphs of installs by date
  (more histograms, will need to check actual .scripts-version files.)