#!/usr/bin/env python3 # # Copyright 2017-2018 Amazon.com, Inc. and its affiliates. All Rights Reserved. # # Licensed under the MIT License. See the LICENSE accompanying this file # for the specific language governing permissions and limitations under # the License. import logging import socket from efs_utils_common.cloudwatch import create_default_cloudwatchlog_agent_if_not_exist from efs_utils_common.constants import CONFIG_SECTION, FS_ID_REGEX_PATTERN from efs_utils_common.context import MountContext from efs_utils_common.error_reporting import fatal_error from efs_utils_common.exceptions import FallbackException from efs_utils_common.metadata import ( get_az_id_from_instance_metadata, get_dns_name_suffix, get_target_region, ) from efs_utils_common.network_utils import ( dns_name_can_be_resolved, mount_target_ip_address_can_be_resolved, ) from efs_utils_common.process_utils import add_field_in_options def get_dns_name_and_mount_target_ip_address(config, fs_id, options): def _validate_replacement_field_count(format_str, expected_ct): if format_str.count("{") != expected_ct or format_str.count("}") != expected_ct: raise ValueError( "DNS name format has an incorrect number of replacement fields" ) dns_name_format = config.get(CONFIG_SECTION, "dns_name_format") if "{fs_id}" not in dns_name_format: raise ValueError("DNS name format must include {fs_id}") format_args = {"fs_id": fs_id} expected_replacement_field_ct = 1 if "{az_id}" in dns_name_format: try: az_id = get_az_id_from_instance_metadata(config, options) expected_replacement_field_ct += 1 format_args["az_id"] = az_id except RuntimeError: err_msg = ( "Cannot retrieve AZ-ID from instance metadata service (IMDS). " "Ensure IMDS is reachable and that the instance has the correct IAM permissions. " "This is required for S3Files mounts using {az_id} in dns_name_format. " "You can also specify the AZ ID directly using the mount option: -o azid=." ) fatal_error(err_msg) region = None if "{region}" in dns_name_format: region = get_target_region(config, options) expected_replacement_field_ct += 1 format_args["region"] = region if "{dns_name_suffix}" in dns_name_format: expected_replacement_field_ct += 1 region = region or get_target_region(config, options) dns_name_suffix = get_dns_name_suffix(config, region) format_args["dns_name_suffix"] = dns_name_suffix logging.debug("Using dns_name_suffix %s", dns_name_suffix) _validate_replacement_field_count(dns_name_format, expected_replacement_field_ct) dns_name = dns_name_format.format(**format_args) if "mounttargetip" in options: ip_address = options.get("mounttargetip") logging.info( "Use the mount target ip address %s provided in the mount options to mount." % ip_address ) try: mount_target_ip_address_can_be_resolved( ip_address, passed_via_options=True, network_namespace=options.get("netns") if "netns" in options else None, ) return dns_name, options.get("mounttargetip") except FallbackException as e: fallback_message = e.message throw_ip_address_connect_failure( ip_address=ip_address, fallback_message=fallback_message ) if dns_name_can_be_resolved(dns_name): return dns_name, None logging.info( "Failed to resolve %s", dns_name, ) throw_dns_resolve_failure(dns_name) def throw_dns_resolve_failure(dns_name): message = ( 'Failed to resolve "%s" - check that your file system ID is correct, and ensure that the VPC has an S3Files mount ' "target for this file system ID.\nSee %s for more detail." ) % ( dns_name, "https://docs.aws.amazon.com/console/efs/mount-dns-name", ) fatal_error(message) def throw_ip_address_connect_failure( dns_name=None, ip_address=None, fallback_message=None ): dns_message = 'Failed to resolve "%s". ' % dns_name if dns_name else "" if not ip_address: ip_address_message = ( "The file system mount target ip address cannot be found, please pass mount target ip " "address via mount options. " ) else: ip_address_message = ( "Cannot connect to file system mount target ip address %s. " % ip_address ) fallback_message = "\n%s" % fallback_message if fallback_message else "" fatal_error("%s%s%s" % (dns_message, ip_address_message, fallback_message)) def match_device(config, device, options): context = MountContext() """Return the S3Files id, the remote path, and the az to mount""" try: remote, path = device.split(":", 1) except ValueError: remote = device path = "/" if FS_ID_REGEX_PATTERN.match(remote): return remote, path, None try: primary, secondaries, _ = socket.gethostbyname_ex(remote) hostnames = list(filter(lambda e: e is not None, [primary] + secondaries)) except socket.gaierror: create_default_cloudwatchlog_agent_if_not_exist(config, options) fatal_error( 'Failed to resolve "%s" - check that the specified DNS name is a CNAME record resolving to a valid S3Files DNS ' "name" % remote, 'Failed to resolve "%s"' % remote, ) if not hostnames: create_default_cloudwatchlog_agent_if_not_exist(config, options) fatal_error( 'The specified domain name "%s" did not resolve to an S3Files mount target' % remote ) for hostname in hostnames: fqdn_match = context.fqdn_regex_pattern.match(hostname) if fqdn_match: az_id = fqdn_match.group("az_id") fs_id = fqdn_match.group("fs_id") if az_id and "azid" in options and az_id != options["azid"]: fatal_error( 'The hostname "%s" resolved by the specified domain name "%s" does not match the azid provided in the ' "mount options, expected = %s, given = %s" % (hostname, remote, options["azid"], az_id) ) expected_dns_name, _ = get_dns_name_and_mount_target_ip_address( config, fs_id, add_field_in_options(options, "azid", az_id) ) # check that the DNS name of the mount target matches exactly the DNS name the CNAME resolves to if hostname == expected_dns_name: return fs_id, path, az_id else: create_default_cloudwatchlog_agent_if_not_exist(config, options) fatal_error( 'The specified CNAME "%s" did not resolve to a valid DNS name for an S3Files mount target. ' "Please refer to the documentation for mounting with DNS names for examples: %s" % ( remote, "https://docs.aws.amazon.com/efs/latest/ug/mounting-fs-mount-cmd-dns-name.html", ) )