Set osd memory config

Still seeing oom-killer trigger in Cinder Ceph CI
jobs with ceph-osd being a top memory consumer.

It appears to default to trying to use 4GB of memory,
change this to 2GB to see if it helps.

Increases the job timeout to 3h for a bit more
headroom since jobs are regularly taking more than 2h
to complete.

Change-Id: I71a46a452914256f36299623a29ed7eebf8e61d2

.zuul.yaml

@@ -16,7 +16,7 @@
       - ^.*\.rst$
       - ^doc/.*$
       - ^tox.ini$
-    timeout: 7200
+    timeout: 10800
     vars:
       configure_swap_size: 8192
       tempest_concurrency: 3

devstack/lib/cephadm

@@ -662,6 +662,14 @@ function set_min_client_version {
     fi
 }
 
+function set_memory_config {
+    $SUDO "$CEPHADM" shell --fsid $FSID --config $CEPH_CONFIG \
+        --keyring $CEPH_KEYRING -- ceph config get osd osd_memory_target
+    $SUDO "$CEPHADM" shell --fsid $FSID --config $CEPH_CONFIG \
+        --keyring $CEPH_KEYRING -- ceph config set osd osd_memory_target \
+        2147483648
+}
+
 # import_libvirt_secret_ceph() - Imports Cinder user key into libvirt
 # so it can connect to the Ceph cluster while attaching a Cinder block device
 function import_libvirt_secret_ceph {

devstack/plugin.sh

@@ -15,6 +15,7 @@ elif [[ "$1" == "stack" && "$2" == "install" ]]; then
         # Perform installation of service source
         echo_summary "[cephadm] Installing ceph"
         install_ceph
+        set_memory_config
         set_min_client_version
     else
         echo "[CEPHADM] Remote Ceph: Skipping install"