Merge lp:~tvansteenburgh/charms/precise/haproxy/sticky-sessions into lp:charms/haproxy

[Tim Van Steenburgh]

Enable sticky sessions by default

[lp:~tvansteenburgh/charms/precise/haproxy/sticky-sessions]

78. By Tim Van Steenburgh on 2014-04-30

Enable sticky sessions by default

[Marco Ceppi (marcoceppi)]

LGTM, +1

review: Approve

=== modified file 'config.yaml'
--- config.yaml	2014-01-07 18:44:15 +0000
+++ config.yaml	2014-04-30 21:49:17 +0000
@@ -101,8 +101,8 @@
               - service_name: haproxy_service
                 service_host: "0.0.0.0"
                 service_port: 80
-                service_options: [balance leastconn]
-                server_options: maxconn 100
+                service_options: [balance leastconn, cookie SRVNAME insert]
+                server_options: maxconn 100 cookie S{i} check
     type: string
     description: |
         Services definition(s). Although the variable type is a string, this is
@@ -112,6 +112,15 @@
         before the first variable, service_name, as above. Service options is a
         comma separated list, server options will be appended as a string to
         the individual server lines for a given listen stanza.
+
+        If your web application serves dynamic content based on users' login
+        sessions, a visitor will experience unexpected behaviour if each request
+        is proxied to a different backend web server. Session stickiness ensures
+        that a visitor 'sticks' to the backend web server which served their
+        first request. This is made possible by tagging each backend server
+        with a cookie. Session are sticky by default. To turn off sticky sessions,
+        remove the 'cookie SRVNAME insert' and 'cookie S{i}' stanzas from
+        `service_options` and `server_options`.
   sysctl:
     default: ""
     type: string

=== modified file 'hooks/hooks.py'
--- hooks/hooks.py	2014-01-21 15:46:29 +0000
+++ hooks/hooks.py	2014-04-30 21:49:17 +0000
@@ -298,8 +298,8 @@
             service_config.append(
                 "    errorfile %s %s" % (errorfile["http_status"], path))
     if isinstance(server_entries, (list, tuple)):
-        for (server_name, server_ip, server_port,
-             server_options) in server_entries:
+        for i, (server_name, server_ip, server_port,
+                server_options) in enumerate(server_entries):
             server_line = "    server %s %s:%s" % \
                 (server_name, server_ip, server_port)
             if server_options is not None:
@@ -307,6 +307,7 @@
                     server_line += " " + server_options
                 else:
                     server_line += " " + " ".join(server_options)
+            server_line = server_line.format(i=i)
             service_config.append(server_line)
     return '\n'.join(service_config)
 

=== modified file 'tests/10_deploy_test.py'
--- tests/10_deploy_test.py	2014-01-24 16:57:20 +0000
+++ tests/10_deploy_test.py	2014-04-30 21:49:17 +0000
@@ -53,6 +53,11 @@
 page.raise_for_status()
 print('Successfully got the Apache2 web page through haproxy IP address.')
 
+# Test that sticky session cookie is present
+if page.cookies.get('SRVNAME') != 'S0':
+    msg = 'Missing or invalid sticky session cookie value: %s' % page.cookies.get('SRVNAME')
+    amulet.raise_status(amulet.FAIL, msg=msg)
+
 # Test that the apache2 relation data is saved on the haproxy server.
 
 # Get the sentry for apache and get the private IP address.