Allow viewing of .log.gz files

I'm not sure why, but previously we have not passed .log.gz files
through to the htmlify web-app.  This means clicking on it in the
browser prompts to download the file.  This is unlikley to be what
devlopers investigating logs interactively want.

Traditionally in devstack-gate there's been a bunch of renaming
log->log.txt that happens to make the files presentable [1].  With
zuulv3 native jobs this happens less and everyone has to be aware of
this behaviour (e.g. Ia7415d2fbbb320f8eddc4e46c3a055414df5f997 is a
good example of raw .log files being added).  I think it is fine to
assume a .log file is text that is safe to pass through os-loganalyze.

From my reading of os-loganalyze [2], a .log.gz file would get mached
by util.use_passthrough_view and by default be filtered via a HTMLView
-- thus the file_conditions.yaml update is perhaps unnecessary, but
provided just to keep things in sync with .txt which has always been
there (I9cda9c05f42c5658d1c1dde8aa2efbc0abcc48a2)

[1] https://git.openstack.org/cgit/openstack-infra/devstack-gate/tree/functions.sh#n869
[2] https://git.openstack.org/cgit/openstack-infra/os-loganalyze/tree/os_loganalyze/view.py#n237

Change-Id: I72e4f752713e7947bd66dfe8164976f0a4e3af24

files/os-loganalyze-file_conditions.yaml

@@ -2,6 +2,9 @@ conditions:
  - filename_pattern: ^.*\.txt(\.gz)?$
    filter: SevFilter
    view: HTMLView
+ - filename_pattern: ^.*\.log(\.gz)?$
+   filter: SevFilter
+   view: HTMLView
  - filename_pattern: ^.*console\.html(\.gz)?$
    filter: SevFilter
    view: HTMLView

templates/logs.vhost.erb

@@ -84,15 +84,15 @@ NameVirtualHost <%= @vhost_name %>:<%= @port %>
   RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME}.gz -f
   RewriteRule ^/(.*)$ %{REQUEST_URI}.gz
 
-  # rewrite txt.gz & console.html[.gz] files to map to our internal htmlify
-  # wsgi app
+  # rewrite (txt|log).gz & console.html[.gz] files to map to our
+  # internal htmlify wsgi app
   # PT, Pass-through:  to come back around and get picked up by the
   #                    WSGIScriptAlias
   # NS, No-subrequest: on coming back through, mod-autoindex may have added
   #                    index.html which would match the !-f condition. We
   #                    therefore ensure the rewrite doesn't trigger by
   #                    disallowing subrequests.
-  RewriteRule ^/(.*\.txt\.gz)$ /htmlify/$1 [QSA,L,PT,NS]
+  RewriteRule ^/(.*\.(txt|log)\.gz)$ /htmlify/$1 [QSA,L,PT,NS]
   RewriteRule ^/(.*console\.html(\.gz)?)$ /htmlify/$1 [QSA,L,PT,NS]
 
   # Check if the request exists as a file, directory or symbolic link