Support for Mounting Elastic File System Volumes

[cancan101]

http://aws.amazon.com/efs/

as an alternative to an NFS exported by the master.

[cariaso]

dependent on boto3

security group config doesn't yet allow one efs to be shared by multiple starclusters

addnode doesn't yet work, but I'm not sure why that is

the active security group connection work prevents the cluster from being fully terminated

but this works for me, and should be close enough to enable others to iteratively improve

# Copyright 2015 Michael Cariaso
#
# This file is a plugin for StarCluster.
#
# This EFS plugin is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# StarCluster is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with StarCluster. If not, see <http://www.gnu.org/licenses/>.

from starcluster import clustersetup
from starcluster.logger import log
import boto3

class EFSPlugin(clustersetup.DefaultClusterSetup):
    """Add EFS support

    Example config:

    [plugin efs]
    SETUP_CLASS = efs.EFSPlugin
    mount_point = /mnt/myefs
    dns_name = us-west-2a.fs-1234abcd.efs.us-west-2.amazonaws.com

    """

    def __init__(self, mount_point=None, dns_name=None,
                 **kwargs):
        self.mount_point = mount_point
        self.dns_name = dns_name
        super(EFSPlugin, self).__init__(**kwargs)

    def run(self, nodes, master, user, user_shell, volumes):
        log.info("Configuring EFS...")
        if self._authorize_efs(master):
            log.info("Installing nfs on all nodes")
            for node in nodes:
                self._install_efs_on_node(node)

    def on_add_node(self, node, nodes, master, user, user_shell, volumes):
        log.info("Adding %s to EFS" % node.alias)
        self._install_efs_on_node(node)

    def on_remove_node(self, node, nodes, master, user, user_shell, volumes):
        log.info("No need to remove %s from EFS" % node.alias)

    def _authorize_efs(self, master):
        parts = self.dns_name.split('.')
        filesystem = parts[1]

        b3client = boto3.client('efs')

        mount_target_id = None
        mtresponse = b3client.describe_mount_targets(FileSystemId=filesystem)
        for mt in mtresponse.get('MountTargets'):
            subnetid = mt.get('SubnetId')
            if subnetid == master.subnet_id:
                mount_target_id = mt.get('MountTargetId')
                break
        else:
            log.info('correct subnet not found')
            return False

        if mount_target_id:
            log.info('Authorizing EFS security group')
            sgresponse = b3client.modify_mount_target_security_groups(
                MountTargetId=mount_target_id,
                SecurityGroups=[master.cluster_groups[0].id],
            )
            return True
        return False

    def _install_efs_on_node(self, node):
        log.info("Installing nfs on %s" % node.alias)

        # in theory this is needed, but in practice it is already installed
        # and running this apt_install causes a crash
        #node.apt_install('nfs-common')

        if not node.ssh.isdir(self.mount_point):
            node.ssh.mkdir(self.mount_point)
        cmd = 'mount -t nfs4 %s:/ %s' % (self.dns_name, self.mount_point)
        log.info("run: %s" % cmd)
        node.ssh.execute(cmd)

[cariaso]

#564
solves it well enough