Document Redis plugin and allow overruling the use of redis by the IDE.

Author: JanWielemaker

config-available/redis.pl

@@ -1,4 +1,58 @@
+/*  Part of SWISH
+
+    Author:        Jan Wielemaker
+    E-mail:        [email protected]
+    WWW:           http://www.swi-prolog.org
+    Copyright (C): 2020, SWI-Prolog Solutions b.v.
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in
+       the documentation and/or other materials provided with the
+       distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+    POSSIBILITY OF SUCH DAMAGE.
+*/
+
 :- module(config_redis, []).
+
+/** <module> Configure Redis
+
+SWISH may be configured to use the Redis key-value store for the various
+databases. This allows multiple SWISH instances to act as a cluster.
+
+Typically the configuration needs to be edited in two places:
+
+  - redis_server/3 must be called to address the Redis server
+  - redis_consumer may be set to identify this instance.  The
+    default is derived from the host name and port to which
+    this SWISH instance listens.  Clusters are advised to
+    assign a stable name to each cluster member.
+*/
+
+:- multifile swish_config:config/2.
+
+% Do not activate if `config(redis,false)` is present
+:- if(\+swish_config:config(ide,true)).
+
 :- use_module(swish(lib/config), []).
 :- use_module(library(redis)).
 :- use_module(library(settings)).
@@ -9,10 +63,9 @@
 
 :- redis_server(swish, localhost:6379, []).
 
-:- multifile swish_config:config/2.
 swish_config:config(redis, swish).
 swish_config:config(redis_prefix, swish).
-%swish_config:config(redis_consumer, alice).
+%swish_config:config(redis_consumer, peter).
 
 :- set_setting(user_profile:redis_server, swish).
 :- set_setting(user_profile:redis_prefix, 'swish:profiles').
@@ -22,3 +75,5 @@
 :- http_set_session_options([ redis_db(swish),
                               redis_prefix('swish:http:session')
                             ]).
+
+:- endif. % \+swish_config:config(ide,true)

ide.pl

@@ -65,6 +65,7 @@
 
 user:file_search_path(project, '.').
 
+swish_config:config(ide,		true).
 swish_config:config(show_beware,        false).
 swish_config:config(community_examples, true).