SPARK-2333 - spark_ec2 script should allow option for existing security group

    - Uses the name tag to identify machines in a cluster.
    - Allows overriding the security group name so it doesn't need to coincide with the cluster name.
    - Outputs the request id's of up to 10 pending spot instance requests.

Author: Vida Ha <vida@databricks.com>

Closes #1899 from vidaha/vida/ec2-reuse-security-group and squashes the following commits:

c80d5c3 [Vida Ha] wrap retries in a try catch block
b2989d5 [Vida Ha] SPARK-2333: spark_ec2 script should allow option for existing security group

docs/ec2-scripts.md

@@ -12,14 +12,16 @@ on the [Amazon Web Services site](http://aws.amazon.com/).
 
 `spark-ec2` is designed to manage multiple named clusters. You can
 launch a new cluster (telling the script its size and giving it a name),
-shutdown an existing cluster, or log into a cluster. Each cluster is
-identified by placing its machines into EC2 security groups whose names
-are derived from the name of the cluster. For example, a cluster named
+shutdown an existing cluster, or log into a cluster. Each cluster
+launches a set of instances, which are tagged with the cluster name,
+and placed into EC2 security groups.  If you don't specify a security
+group, the `spark-ec2` script will create security groups based on the
+cluster name you request. For example, a cluster named
 `test` will contain a master node in a security group called
 `test-master`, and a number of slave nodes in a security group called
-`test-slaves`. The `spark-ec2` script will create these security groups
-for you based on the cluster name you request. You can also use them to
-identify machines belonging to each cluster in the Amazon EC2 Console.
+`test-slaves`.  You can also specify a security group prefix to be used
+in place of the cluster name.  Machines in a cluster can be identified
+by looking for the "Name" tag of the instance in the Amazon EC2 Console.
 
 
 # Before You Start

ec2/spark_ec2.py

@@ -124,7 +124,7 @@ def parse_args():
         help="The SSH user you want to connect as (default: root)")
     parser.add_option(
         "--delete-groups", action="store_true", default=False,
-        help="When destroying a cluster, delete the security groups that were created")
+        help="When destroying a cluster, delete the security groups that were created.")
     parser.add_option(
         "--use-existing-master", action="store_true", default=False,
         help="Launch fresh slaves, but use an existing stopped master if possible")
@@ -138,7 +138,9 @@ def parse_args():
     parser.add_option(
         "--user-data", type="string", default="",
         help="Path to a user-data file (most AMI's interpret this as an initialization script)")
-
+    parser.add_option(
+        "--security-group-prefix", type="string", default=None,
+        help="Use this prefix for the security group rather than the cluster name.")
 
     (opts, args) = parser.parse_args()
     if len(args) != 2:
@@ -285,8 +287,12 @@ def launch_cluster(conn, opts, cluster_name):
             user_data_content = user_data_file.read()
 
     print "Setting up security groups..."
-    master_group = get_or_make_group(conn, cluster_name + "-master")
-    slave_group = get_or_make_group(conn, cluster_name + "-slaves")
+    if opts.security_group_prefix is None:
+        master_group = get_or_make_group(conn, cluster_name + "-master")
+        slave_group = get_or_make_group(conn, cluster_name + "-slaves")
+    else:
+        master_group = get_or_make_group(conn, opts.security_group_prefix + "-master")
+        slave_group = get_or_make_group(conn, opts.security_group_prefix + "-slaves")
     if master_group.rules == []:  # Group was just now created
         master_group.authorize(src_group=master_group)
         master_group.authorize(src_group=slave_group)
@@ -310,12 +316,11 @@ def launch_cluster(conn, opts, cluster_name):
         slave_group.authorize('tcp', 60060, 60060, '0.0.0.0/0')
         slave_group.authorize('tcp', 60075, 60075, '0.0.0.0/0')
 
-    # Check if instances are already running in our groups
+    # Check if instances are already running with the cluster name
     existing_masters, existing_slaves = get_existing_cluster(conn, opts, cluster_name,
                                                              die_on_error=False)
     if existing_slaves or (existing_masters and not opts.use_existing_master):
-        print >> stderr, ("ERROR: There are already instances running in " +
-                          "group %s or %s" % (master_group.name, slave_group.name))
+        print >> stderr, ("ERROR: There are already instances for name: %s " % cluster_name)
         sys.exit(1)
 
     # Figure out Spark AMI
@@ -371,9 +376,13 @@ def launch_cluster(conn, opts, cluster_name):
                 for r in reqs:
                     id_to_req[r.id] = r
                 active_instance_ids = []
+                outstanding_request_ids = []
                 for i in my_req_ids:
-                    if i in id_to_req and id_to_req[i].state == "active":
-                        active_instance_ids.append(id_to_req[i].instance_id)
+                    if i in id_to_req:
+                        if id_to_req[i].state == "active":
+                            active_instance_ids.append(id_to_req[i].instance_id)
+                        else:
+                            outstanding_request_ids.append(i)
                 if len(active_instance_ids) == opts.slaves:
                     print "All %d slaves granted" % opts.slaves
                     reservations = conn.get_all_instances(active_instance_ids)
@@ -382,8 +391,8 @@ def launch_cluster(conn, opts, cluster_name):
                         slave_nodes += r.instances
                     break
                 else:
-                    print "%d of %d slaves granted, waiting longer" % (
-                        len(active_instance_ids), opts.slaves)
+                    print "%d of %d slaves granted, waiting longer for request ids including %s" % (
+                        len(active_instance_ids), opts.slaves, outstanding_request_ids[0:10])
         except:
             print "Canceling spot instance requests"
             conn.cancel_spot_instance_requests(my_req_ids)
@@ -440,14 +449,29 @@ def launch_cluster(conn, opts, cluster_name):
         print "Launched master in %s, regid = %s" % (zone, master_res.id)
 
     # Give the instances descriptive names
+    # TODO: Add retry logic for tagging with name since it's used to identify a cluster.
     for master in master_nodes:
-        master.add_tag(
-            key='Name',
-            value='{cn}-master-{iid}'.format(cn=cluster_name, iid=master.id))
+        name = '{cn}-master-{iid}'.format(cn=cluster_name, iid=master.id)
+        for i in range(0, 5):
+            try:
+                master.add_tag(key='Name', value=name)
+            except:
+                print "Failed attempt %i of 5 to tag %s" % ((i + 1), name)
+                if (i == 5):
+                    raise "Error - failed max attempts to add name tag"
+                time.sleep(5)
+
+
     for slave in slave_nodes:
-        slave.add_tag(
-            key='Name',
-            value='{cn}-slave-{iid}'.format(cn=cluster_name, iid=slave.id))
+        name = '{cn}-slave-{iid}'.format(cn=cluster_name, iid=slave.id)
+        for i in range(0, 5):
+            try:
+                slave.add_tag(key='Name', value=name)
+            except:
+                print "Failed attempt %i of 5 to tag %s" % ((i + 1), name)
+                if (i == 5):
+                    raise "Error - failed max attempts to add name tag"
+                time.sleep(5)
 
     # Return all the instances
     return (master_nodes, slave_nodes)
@@ -463,10 +487,10 @@ def get_existing_cluster(conn, opts, cluster_name, die_on_error=True):
     for res in reservations:
         active = [i for i in res.instances if is_active(i)]
         for inst in active:
-            group_names = [g.name for g in inst.groups]
-            if group_names == [cluster_name + "-master"]:
+            name = inst.tags.get(u'Name', "")
+            if name.startswith(cluster_name + "-master"):
                 master_nodes.append(inst)
-            elif group_names == [cluster_name + "-slaves"]:
+            elif name.startswith(cluster_name + "-slave"):
                 slave_nodes.append(inst)
     if any((master_nodes, slave_nodes)):
         print ("Found %d master(s), %d slaves" % (len(master_nodes), len(slave_nodes)))
@@ -474,7 +498,7 @@ def get_existing_cluster(conn, opts, cluster_name, die_on_error=True):
         return (master_nodes, slave_nodes)
     else:
         if master_nodes == [] and slave_nodes != []:
-            print >> sys.stderr, "ERROR: Could not find master in group " + cluster_name + "-master"
+            print >> sys.stderr, "ERROR: Could not find master in with name " + cluster_name + "-master"
         else:
             print >> sys.stderr, "ERROR: Could not find any existing cluster"
         sys.exit(1)
@@ -816,7 +840,10 @@ def real_main():
             # Delete security groups as well
             if opts.delete_groups:
                 print "Deleting security groups (this will take some time)..."
-                group_names = [cluster_name + "-master", cluster_name + "-slaves"]
+                if opts.security_group_prefix is None:
+                    group_names = [cluster_name + "-master", cluster_name + "-slaves"]
+                else:
+                    group_names = [opts.security_group_prefix + "-master", opts.security_group_prefix + "-slaves"]
 
                 attempt = 1
                 while attempt <= 3: