Add variable SWIFT_STORAGE_IPS

If the variable SWIFT_STORAGE_IPS contains a space-separated list of
IPs, we can use this to create consistent rings across all proxy and
storage nodes.

Change-Id: If9307196dc7e74e4a842c95503958ae2d7f7acc7

doc/source/configuration.rst

@@ -513,6 +513,18 @@ If you only want to do some testing of a real normal swift cluster
 with multiple replicas you can do so by customizing the variable
 ``SWIFT_REPLICAS`` in your ``localrc`` section (usually to 3).
 
+You can manually override the ring building to use specific storage
+nodes, for example when you want to test a multinode environment. In
+this case you have to set a space-separated list of IPs in
+``SWIFT_STORAGE_IPS`` in your ``localrc`` section that should be used
+as Swift storage nodes.
+Please note that this does not create a multinode setup, it is only
+used when adding nodes to the Swift rings.
+
+::
+
+    SWIFT_STORAGE_IPS="192.168.1.10 192.168.1.11 192.168.1.12"
+
 Swift S3
 ++++++++
 

lib/swift

@@ -149,6 +149,11 @@ SWIFT_TEMPURL_KEY=${SWIFT_TEMPURL_KEY:-}
 # Toggle for deploying Swift under HTTPD + mod_wsgi
 SWIFT_USE_MOD_WSGI=${SWIFT_USE_MOD_WSGI:-False}
 
+# A space-separated list of storage node IPs that
+# should be used to create the Swift rings
+SWIFT_STORAGE_IPS=${SWIFT_STORAGE_IPS:-}
+
+
 # Functions
 # ---------
 
@@ -693,14 +698,35 @@ function init_swift {
         swift-ring-builder container.builder create ${SWIFT_PARTITION_POWER_SIZE} ${SWIFT_REPLICAS} 1
         swift-ring-builder account.builder create ${SWIFT_PARTITION_POWER_SIZE} ${SWIFT_REPLICAS} 1
 
-        for node_number in ${SWIFT_REPLICAS_SEQ}; do
+        # The ring will be created on each node, and because the order of
-            swift-ring-builder object.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( OBJECT_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+        # nodes is identical we can use a seed for rebalancing, making it
-            swift-ring-builder container.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( CONTAINER_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+        # possible to get a ring on each node that uses the same partition
-            swift-ring-builder account.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( ACCOUNT_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+        # assignment.
-        done
+        if [[ -n $SWIFT_STORAGE_IPS ]]; then
-        swift-ring-builder object.builder rebalance
+            local node_number
-        swift-ring-builder container.builder rebalance
+            node_number=1
-        swift-ring-builder account.builder rebalance
+
+            for node in ${SWIFT_STORAGE_IPS}; do
+                swift-ring-builder object.builder add z${node_number}-${node}:${OBJECT_PORT_BASE}/sdb1 1
+                swift-ring-builder container.builder add z${node_number}-${node}:${CONTAINER_PORT_BASE}/sdb1 1
+                swift-ring-builder account.builder add z${node_number}-${node}:${ACCOUNT_PORT_BASE}/sdb1 1
+                let "node_number=node_number+1"
+            done
+
+        else
+
+            for node_number in ${SWIFT_REPLICAS_SEQ}; do
+                swift-ring-builder object.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( OBJECT_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+                swift-ring-builder container.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( CONTAINER_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+                swift-ring-builder account.builder add z${node_number}-${SWIFT_SERVICE_LOCAL_HOST}:$(( ACCOUNT_PORT_BASE + 10 * (node_number - 1) ))/sdb1 1
+            done
+        fi
+
+        # We use a seed for rebalancing. Doing this allows us to create
+        # identical rings on multiple nodes if SWIFT_STORAGE_IPS is the same
+        swift-ring-builder object.builder rebalance 42
+        swift-ring-builder container.builder rebalance 42
+        swift-ring-builder account.builder rebalance 42
     } && popd >/dev/null
 
     # Create cache dir