Allow ceilometer-api to run under mod_wsgi

If CEILOMETER_USE_MOD_WSGI is True then the API app will
run under mod wsgi. The default is false (for now).

The changes are modeled on keystone's use of apache.

Note that these changes are dependent on
https://review.openstack.org/#/c/121823/ in ceilometer.

Using mod_wsgi allows the ceilometer api to handle "concurrent"
requests. This is extremely useful when trying to benchmark
various aspects of the service.

Change-Id: I4c220c3b52804cd8d9123b47780a98e0346ca81e

Author: Chris Dent

files/apache-ceilometer.template

@@ -0,0 +1,15 @@
+Listen %PORT%
+
+<VirtualHost *:%PORT%>
+    WSGIDaemonProcess ceilometer-api processes=2 threads=10 user=%USER% display-name=%{GROUP}
+    WSGIProcessGroup ceilometer-api
+    WSGIScriptAlias / %WSGIAPP%
+    WSGIApplicationGroup %{GLOBAL}
+    <IfVersion >= 2.4>
+        ErrorLogFormat "%{cu}t %M"
+    </IfVersion>
+    ErrorLog /var/log/%APACHE_NAME%/ceilometer.log
+    CustomLog /var/log/%APACHE_NAME%/ceilometer_access.log combined
+</VirtualHost>
+
+WSGISocketPrefix /var/run/%APACHE_NAME%

lib/ceilometer

@@ -41,6 +41,7 @@ CEILOMETER_CONF_DIR=/etc/ceilometer
 CEILOMETER_CONF=$CEILOMETER_CONF_DIR/ceilometer.conf
 CEILOMETER_API_LOG_DIR=/var/log/ceilometer-api
 CEILOMETER_AUTH_CACHE_DIR=${CEILOMETER_AUTH_CACHE_DIR:-/var/cache/ceilometer}
+CEILOMETER_WSGI_DIR=${CEILOMETER_WSGI_DIR:-/var/www/ceilometer}
 
 # Support potential entry-points console scripts
 CEILOMETER_BIN_DIR=$(get_python_exec_prefix)
@@ -52,6 +53,7 @@ CEILOMETER_BACKEND=${CEILOMETER_BACKEND:-mysql}
 CEILOMETER_SERVICE_PROTOCOL=http
 CEILOMETER_SERVICE_HOST=$SERVICE_HOST
 CEILOMETER_SERVICE_PORT=${CEILOMETER_SERVICE_PORT:-8777}
+CEILOMETER_USE_MOD_WSGI=$(trueorfalse False $CEILOMETER_USE_MOD_WSGI)
 
 # To enable OSprofiler change value of this variable to "notifications,profiler"
 CEILOMETER_NOTIFICATION_TOPICS=${CEILOMETER_NOTIFICATION_TOPICS:-notifications}
@@ -105,12 +107,39 @@ create_ceilometer_accounts() {
 }
 
 
+# _cleanup_keystone_apache_wsgi() - Remove wsgi files, disable and remove apache vhost file
+function _cleanup_ceilometer_apache_wsgi {
+    sudo rm -f $CEILOMETER_WSGI_DIR/*
+    sudo rm -f $(apache_site_config_for ceilometer)
+}
+
 # cleanup_ceilometer() - Remove residual data files, anything left over from previous
 # runs that a clean run would need to clean up
 function cleanup_ceilometer {
     if [ "$CEILOMETER_BACKEND" != 'mysql' ] && [ "$CEILOMETER_BACKEND" != 'postgresql' ] ; then
         mongo ceilometer --eval "db.dropDatabase();"
     fi
+    if [ "$CEILOMETER_USE_MOD_WSGI" == "True" ]; then
+        _cleanup_ceilometer_apache_wsgi
+    fi
+}
+
+function _config_ceilometer_apache_wsgi {
+    sudo mkdir -p $CEILOMETER_WSGI_DIR
+
+    local ceilometer_apache_conf=$(apache_site_config_for ceilometer)
+    local apache_version=$(get_apache_version)
+
+    # copy proxy vhost and wsgi file
+    sudo cp $CEILOMETER_DIR/ceilometer/api/app.wsgi $CEILOMETER_WSGI_DIR/app
+
+    sudo cp $FILES/apache-ceilometer.template $ceilometer_apache_conf
+    sudo sed -e "
+        s|%PORT%|$CEILOMETER_SERVICE_PORT|g;
+        s|%APACHE_NAME%|$APACHE_NAME|g;
+        s|%WSGIAPP%|$CEILOMETER_WSGI_DIR/app|g;
+        s|%USER%|$STACK_USER|g
+    " -i $ceilometer_apache_conf
 }
 
 # configure_ceilometer() - Set config files, create data dirs, etc
@@ -163,6 +192,11 @@ function configure_ceilometer {
         iniset $CEILOMETER_CONF vmware host_username "$VMWAREAPI_USER"
         iniset $CEILOMETER_CONF vmware host_password "$VMWAREAPI_PASSWORD"
     fi
+
+    if [ "$CEILOMETER_USE_MOD_WSGI" == "True" ]; then
+        iniset $CEILOMETER_CONF api pecan_debug "False"
+        _config_ceilometer_apache_wsgi
+    fi
 }
 
 function configure_mongodb {
@@ -223,7 +257,16 @@ function start_ceilometer {
     run_process ceilometer-acentral "ceilometer-agent-central --config-file $CEILOMETER_CONF"
     run_process ceilometer-anotification "ceilometer-agent-notification --config-file $CEILOMETER_CONF"
     run_process ceilometer-collector "ceilometer-collector --config-file $CEILOMETER_CONF"
-    run_process ceilometer-api "ceilometer-api -d -v --log-dir=$CEILOMETER_API_LOG_DIR --config-file $CEILOMETER_CONF"
+
+    if [[ "$CEILOMETER_USE_MOD_WSGI" == "False" ]]; then
+        run_process ceilometer-api "ceilometer-api -d -v --log-dir=$CEILOMETER_API_LOG_DIR --config-file $CEILOMETER_CONF"
+    else
+        enable_apache_site ceilometer
+        restart_apache_server
+        tail_log ceilometer /var/log/$APACHE_NAME/ceilometer.log
+        tail_log ceilometer-api /var/log/$APACHE_NAME/ceilometer_access.log
+    fi
+
 
     # Start the compute agent last to allow time for the collector to
     # fully wake up and connect to the message bus. See bug #1355809
@@ -248,6 +291,10 @@ function start_ceilometer {
 
 # stop_ceilometer() - Stop running processes
 function stop_ceilometer {
+    if [ "$CEILOMETER_USE_MOD_WSGI" == "True" ]; then
+        disable_apache_site ceilometer
+        restart_apache_server
+    fi
     # Kill the ceilometer screen windows
     for serv in ceilometer-acompute ceilometer-acentral ceilometer-anotification ceilometer-collector ceilometer-api ceilometer-alarm-notifier ceilometer-alarm-evaluator; do
         stop_process $serv