Docker installation doc improved and switchable debugging

Using a Docker container, login was failing with no error or ok
message.  After a lengthy debugging session on irc with alxjsn
assisted by taggnostr realised it was the web setting in config.ini.

Install doc for docker now mentions that the web setting must end in
/issues/.

SHELL_DEBUG environment variable enabled set -xv in startp script.a

Author: rouilj

doc/installation.txt

@@ -291,8 +291,12 @@ If the tracker directory is empty, the docker container will prompt
 you to install a tracker template and prompt you for the database
 type.
 
-Once you have edited and configured ``template/config.ini``, (see
-`Configuring your first tracker`) run another interactive session
+Then you need to configure the tracker by editing
+``template/config.ini``.  Make sure that the tracker web setting ends
+in ``/issues/`` See `Configuring your first tracker` and the top of
+``config.ini`` for other settings.
+
+Once you have configured the tracker, run another interactive session
 with::
 
     docker run --rm -it -p 9017:8080 \
@@ -316,6 +320,10 @@ can use::
 where ``c0d5`` is the id prefix for the running container obtained
 from ``docker container ls``.
 
+If you add ``-e SHELL_DEBUG=1`` to the docker command, it sets the
+``SHELL_DEBUG`` environment variable which will enable debugging
+output from the startup script.
+
 Non-Guided Installation
 '''''''''''''''''''''''
 

scripts/Docker/roundup_start

@@ -6,7 +6,9 @@
 
 # "$@" should be a set of tracker=directory pairs.
 
-set -xv
+if ! [ -z "$SHELL_DEBUG" ]; then
+    set -xv
+fi
 
 trap exit INT
 
@@ -22,7 +24,7 @@ for tracker_spec in "$@"; do
     # ^ is a tab for use with <<-
 
     # was $tracker_spec in the form of a=b, if not ignore it.
-    # allows setting CMD to -p 9090 issue=tracker for example.
+    # allows setting CMD to -i index_template issue=tracker for example.
     if [ -z "$directory" ]; then continue; fi
 
     # something is specified or built wrong. Don't start.