Documentation: Add prolog submit-rule example 'Master and Apprentice'.
Bug: Issue 703
Change-Id: I3e0d64457adefd78a4bdcb1ac9c779e41da9f269
diff --git a/Documentation/prolog-cookbook.txt b/Documentation/prolog-cookbook.txt
index 08626ba..c4a0589 100644
--- a/Documentation/prolog-cookbook.txt
+++ b/Documentation/prolog-cookbook.txt
@@ -684,6 +684,43 @@
S =.. [submit | Labels].
====
+Example 13: Master and apprentice
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The master and apprentice example allow you to specify a user (the `master`)
+that must approve all changes done by another user (the `apprentice`).
+
+The code first checks if the commit author is in the apprentice database.
+If the commit is done by an apprentice, it will check if there is a +2
+review by the associated `master`.
+
+.rules.pl
+[caption=""]
+====
+ % master_apprentice(Master, Apprentice).
+ % Extend this with appropriate user-id's for your master/apprentice setup.
+ master_apprentice(user(1000064), user(1000000)).
+
+ submit_rule(S) :-
+ gerrit:default_submit(In),
+ In =.. [submit | Ls],
+ add_apprentice_master(Ls, R),
+ S =.. [submit | R].
+
+ check_master_approval(S1, S2, Master) :-
+ gerrit:commit_label(label('Code-Review', 2), R),
+ R = Master, !,
+ S2 = [label('Master-Approval', ok(R)) | S1].
+ check_master_approval(S1, [label('Master-Approval', need(_)) | S1], _).
+
+ add_apprentice_master(S1, S2) :-
+ gerrit:commit_author(Id),
+ master_apprentice(Master, Id),
+ !,
+ check_master_approval(S1, S2, Master).
+
+ add_apprentice_master(S, S).
+====
+
GERRIT
------
Part of link:index.html[Gerrit Code Review]
