glusterd/shared_storage: Provide a volume set option to create and mount the shared storage

Introducing a global volume set option(cluster.enable-shared-storage)
which helps create and set-up the shared storage meta volume.

gluster volume set all cluster.enable-shared-storage enable

On enabling this option, the system analyzes the number of peers
in the cluster, which are currently connected, and chooses three
such peers(including the node the command is issued from). From these
peers a volume(gluster_shared_storage) is created. Depending on the
number of peers available the volume is either a replica 3
volume(if there are 3 connected peers),  or a replica 2 volume(if there
are 2 connected peers). "/var/run/gluster/ss_brick" serves as the
brick path on each node for the shared storage volume. We also mount
the shared storage at "/var/run/gluster/shared_storage" on all the nodes
in the cluster as part of enabling this option. If there is only one node
in the cluster,  or only one node is up then the command will fail

Once the volume is created, and mounted the maintainance of the
volume like adding-bricks, removing bricks etc., is expected to
be the onus of the user.

On disabling the option, we provide the user a warning, and on
affirmation from the user we stop the shared storage volume, and unmount
it from all the nodes in the cluster.

gluster volume set all cluster.enable-shared-storage disable

Change-Id: Idd92d67b93f444244f99ede9f634ef18d2945dbc
BUG: 1222013
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/10793
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>

2 files changed, 125 insertions, 1 deletions

diff --git a/extras/hook-scripts/set/post/Makefile.am b/extras/hook-scripts/set/post/Makefile.am
index 3ec25d94134..99dfaa3eafb 100644
--- a/extras/hook-scripts/set/post/Makefile.am
+++ b/extras/hook-scripts/set/post/Makefile.am
@@ -1 +1 @@
-EXTRA_DIST = S30samba-set.sh S31ganesha-set.sh
+EXTRA_DIST = S30samba-set.sh S31ganesha-set.sh S32gluster_enable_shared_storage.sh
diff --git a/extras/hook-scripts/set/post/S32gluster_enable_shared_storage.sh b/extras/hook-scripts/set/post/S32gluster_enable_shared_storage.sh
new file mode 100755
index 00000000000..28fa0e53316
--- /dev/null
+++ b/extras/hook-scripts/set/post/S32gluster_enable_shared_storage.sh
@@ -0,0 +1,124 @@
+#!/bin/bash
+
+key=`echo $3 | cut -d '=' -f 1`
+val=`echo $3 | cut -d '=' -f 2`
+if [ "$key" != "cluster.enable-shared-storage" ]; then
+    exit;
+fi
+if [ "$val" != 'enable' ]; then
+    if [ "$val" != 'disable' ]; then
+        exit;
+    fi
+fi
+
+option=$val
+
+key_val_pair1=`echo $4 | cut -d ',' -f 1`
+key_val_pair2=`echo $4 | cut -d ',' -f 2`
+
+key=`echo $key_val_pair1 | cut -d '=' -f 1`
+val=`echo $key_val_pair1 | cut -d '=' -f 2`
+if [ "$key" != "is_originator" ]; then
+    exit;
+fi
+is_originator=$val;
+
+key=`echo $key_val_pair2 | cut -d '=' -f 1`
+val=`echo $key_val_pair2 | cut -d '=' -f 2`
+if [ "$key" != "local_node_hostname" ]; then
+    exit;
+fi
+local_node_hostname=$val;
+
+# Read gluster peer status to find the peers
+# which are in 'Peer in Cluster' mode and
+# are connected.
+
+number_of_connected_peers=0
+while read -r line
+do
+    # Already got two connected peers. Including the current node
+    # we have 3 peers which is enough to create a shared storage
+    # with replica 3
+    if [ "$number_of_connected_peers" == "2" ]; then
+        break;
+    fi
+
+    key=`echo $line | cut -d ':' -f 1`
+    if [ "$key" == "Hostname" ]; then
+        hostname=`echo $line | cut -d ':' -f 2 | xargs`
+    fi
+
+    if [ "$key" == "State" ]; then
+        peer_state=`echo $line | cut -d ':' -f 2 | cut -d '(' -f 1 | xargs`
+        conn_state=`echo $line | cut -d '(' -f 2 | cut -d ')' -f 1 | xargs`
+
+        if [ "$peer_state" == "Peer in Cluster" ]; then
+            if [ "$conn_state" == "Connected" ]; then
+                ((number_of_connected_peers++))
+                connected_peer[$number_of_connected_peers]=$hostname
+            fi
+        fi
+    fi
+
+done < <(gluster peer status)
+
+# Include current node in connected peer list
+((number_of_connected_peers++))
+connected_peer[$number_of_connected_peers]=$local_node_hostname
+
+# forming the create vol command
+create_cmd="gluster --mode=script --wignore volume create \
+            gluster_shared_storage replica $number_of_connected_peers"
+
+# Adding the brick names in the command
+for i in "${connected_peer[@]}"
+do
+    create_cmd=$create_cmd" "$i:/var/run/gluster/ss_brick
+done
+
+if [ "$option" == "disable" ]; then
+    # Unmount the volume on all the nodes
+    umount /var/run/gluster/shared_storage
+fi
+
+if [ "$is_originator" == 1 ]; then
+    if [ "$option" == "enable" ]; then
+        # Create and start the volume
+        $create_cmd
+        gluster --mode=script --wignore volume start gluster_shared_storage
+    fi
+
+    if [ "$option" == "disable" ]; then
+        # Stop and delete the volume
+        gluster --mode=script --wignore volume stop gluster_shared_storage
+        gluster --mode=script --wignore volume delete gluster_shared_storage
+    fi
+fi
+
+function check_volume_status()
+{
+    status=`gluster volume info gluster_shared_storage  | grep Status | cut -d ':' -f 2 | xargs`
+    echo $status
+}
+
+mount_cmd="mount -t glusterfs "$local_node_hostname":/gluster_shared_storage \
+           /var/run/gluster/shared_storage"
+
+if [ "$option" == "enable" ]; then
+    retry=0;
+    # Wait for volume to start before mounting
+    status=$(check_volume_status)
+    while [ "$status" != "Started" ]; do
+        sleep 5;
+        ((retry++))
+        if [ "$retry" == 3 ]; then
+            break;
+        fi
+        status = check_volume_status;
+    done
+    # Mount the volume on all the nodes
+    umount /var/run/gluster/shared_storage
+    mkdir -p /var/run/gluster/shared_storage
+    $mount_cmd
+fi