Add documentation for git hosting

.wordlist.txt

@@ -4,6 +4,7 @@ APIs
 balancer
 bugfix
 callables
+cgit
 Charmhub
 CLI
 conf
@@ -18,14 +19,17 @@ dropdown
 EBS
 EKS
 favicon
+filesystem
 FIXME
 fmt
 formatters
 garbo
+git
 Grafana
 IAM
 innerHTML
 installable
+haproxy
 Jira
 JS
 JSON
@@ -55,6 +59,7 @@ RSS
 RTD
 sampledata
 scss
+SSL
 stylesheets
 subdirectories
 subfolders

reference/index.rst

@@ -50,6 +50,14 @@ Ubuntu-related
 
    services/mirror-prober.rst
 
+Git-related
+~~~~~~~~~~~~~~
+
+.. toctree::
+   :maxdepth: 1
+
+   services/git-hosting.rst
+
 Possibly out-of-date
 --------------------
 

reference/services/git-hosting.rst

@@ -0,0 +1,90 @@
+Git hosting
+===============
+
+Description
+-----------
+
+Launchpad has direct Git hosting support alongside its existing Bazaar hosting support. 
+The major subsystems involved are:
+
+* The git client
+* Hosting service
+* The underlying object model
+* The web application
+* Repository source code browser 
+
+Git client
+----------
+
+This is what users install on their systems to use Git. 
+It is also installed on the hosting backend to support the ``receive-pack`` and ``upload-pack`` protocols.
+
+Hosting service
+---------------
+
+The outside world connects to the Git hosting service using one of several protocols:
+
+* ``git://``
+* ``git+ssh://``
+* ``https://``
+
+The Git "dumb" HTTP transport will not be supported, as it has largely been considered 
+deprecated since the provision of "smart" HTTP transport in Git v1.6.6 (released January, 2010).
+
+SSL is terminated by haproxy for HTTPS, and all the other protocols also pass through 
+haproxy for load balancing (although at the moment we only have a single backend).  
+The underlying protocol endpoints live in `lp:turnip <https://code.launchpad.net/turnip>`_, 
+which invokes ``git upload-pack`` and ``git receive-pack`` to implement the git protocol itself.
+
+``turnip`` also provides an internal API used by the Launchpad web application to manipulate and inspect repositories; 
+and in turn the Launchpad web application provides an internal XML-RPC interface used by ``turnip`` to translate logical 
+repository paths to filesystem paths and to notify Launchpad of repository changes.
+
+``turnip`` is deployed using Juju, using the `turnip charm <https://git.launchpad.net/turnip/tree/charm>`_.  
+
+See more at `turnip documentation <https://turnip.readthedocs.io/en/latest/index.html>`_ 
+
+The web application
+-------------------
+
+Code that is executed as part of the Launchpad web application.  Major features:
+
+ * general information
+ * listings for various registry objects - people, teams, projects, packages
+ * default repositories for projects and packages
+ * privacy
+
+Repository source code browser
+------------------------------
+
+Launchpad uses the external `cgit <http://git.zx2c4.com/cgit/about/>`_ project to provide a web view of the repository contents.  
+This is invoked by ``turnip`` when it receives HTTPS requests that don't correspond 
+to git smart HTTP protocol, and ``turnip``` deals with configuring ``cgit`` appropriately for each repository.
+
+Log files
+---------
+See `FreshLogs documentation <https://wiki.canonical.com/Launchpad/FreshLogs>`_.
+
+Production
+~~~~~~~~~~
+
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-access.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-api-access.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-api-error.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-pack-backend.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-pack-frontend-git.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-pack-frontend-http.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-pack-frontend-ssh.log``
+* ``rless turnip-pack-{1,2,3,4}.lp.internal::turnip-logs/turnip-pack-virt.log``
+
+Staging
+~~~~~~~
+
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-access.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-api-access.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-api-error.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-pack-backend.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-pack-frontend-git.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-pack-frontend-http.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-pack-frontend-ssh.log``
+* ``rless turnip-pack-{1,2}.qastaging.lp.internal::turnip-logs/turnip-pack-virt.log``