Common: Lazy-load AWSInstance

This commit is contained in:
Mike Salvatore 2022-05-05 15:01:37 -04:00
parent ab136284dc
commit d977d19d9f
4 changed files with 124 additions and 154 deletions

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@ -1,25 +1,12 @@
import json
import logging
import re
from dataclasses import dataclass
from typing import Optional, Tuple
import threading
import requests
from common.aws.aws_metadata import fetch_aws_instance_metadata
AWS_INSTANCE_METADATA_LOCAL_IP_ADDRESS = "169.254.169.254"
AWS_LATEST_METADATA_URI_PREFIX = "http://{0}/latest/".format(AWS_INSTANCE_METADATA_LOCAL_IP_ADDRESS)
ACCOUNT_ID_KEY = "accountId"
logger = logging.getLogger(__name__)
AWS_TIMEOUT = 2
AWS_FETCH_METADATA_TIMEOUT = 10.0 # Seconds
@dataclass
class AWSInstanceInfo:
instance_id: Optional[str] = None
region: Optional[str] = None
account_id: Optional[str] = None
class AWSTimeoutError(Exception):
"""Raised when communications with AWS timeout"""
class AWSInstance:
@ -28,83 +15,42 @@ class AWSInstance:
"""
def __init__(self):
self._is_instance, self._instance_info = AWSInstance._fetch_instance_info()
self._instance_id = None
self._region = None
self._account_id = None
self._initialization_complete = threading.Event()
fetch_thread = threading.Thread(target=self._fetch_aws_instance_metadata, daemon=True)
fetch_thread.start()
def _fetch_aws_instance_metadata(self):
metadata = fetch_aws_instance_metadata()
self._instance_id = metadata[0]
self._region = metadata[1]
self._account_id = metadata[2]
self._initialization_complete.set()
@property
def is_instance(self) -> bool:
return self._is_instance
self._wait_for_initialization_to_complete()
return self._instance_id is not None
@property
def instance_id(self) -> str:
return self._instance_info.instance_id
self._wait_for_initialization_to_complete()
return self._instance_id
@property
def region(self) -> str:
return self._instance_info.region
self._wait_for_initialization_to_complete()
return self._region
@property
def account_id(self) -> str:
return self._instance_info.account_id
self._wait_for_initialization_to_complete()
return self._account_id
@staticmethod
def _fetch_instance_info() -> Tuple[bool, AWSInstanceInfo]:
try:
response = requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "meta-data/instance-id",
timeout=AWS_TIMEOUT,
)
if not response:
return False, AWSInstanceInfo()
info = AWSInstanceInfo()
info.instance_id = response.text if response else False
info.region = AWSInstance._parse_region(
requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "meta-data/placement/availability-zone",
timeout=AWS_TIMEOUT,
).text
)
except (requests.RequestException, IOError) as e:
logger.debug("Failed init of AWSInstance while getting metadata: {}".format(e))
return False, AWSInstanceInfo()
try:
info.account_id = AWSInstance._extract_account_id(
requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "dynamic/instance-identity/document",
timeout=AWS_TIMEOUT,
).text
)
except (requests.RequestException, json.decoder.JSONDecodeError, IOError) as e:
logger.debug(
"Failed init of AWSInstance while getting dynamic instance data: {}".format(e)
)
return False, AWSInstanceInfo()
return True, info
@staticmethod
def _parse_region(region_url_response):
# For a list of regions, see:
# https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts
# .RegionsAndAvailabilityZones.html
# This regex will find any AWS region format string in the response.
re_phrase = r"((?:us|eu|ap|ca|cn|sa)-[a-z]*-[0-9])"
finding = re.findall(re_phrase, region_url_response, re.IGNORECASE)
if finding:
return finding[0]
else:
return None
@staticmethod
def _extract_account_id(instance_identity_document_response):
"""
Extracts the account id from the dynamic/instance-identity/document metadata path.
Based on https://forums.aws.amazon.com/message.jspa?messageID=409028 which has a few more
solutions,
in case Amazon break this mechanism.
:param instance_identity_document_response: json returned via the web page
../dynamic/instance-identity/document
:return: The account id
"""
return json.loads(instance_identity_document_response)[ACCOUNT_ID_KEY]
def _wait_for_initialization_to_complete(self):
if not self._initialization_complete.wait(AWS_FETCH_METADATA_TIMEOUT):
raise AWSTimeoutError("Timed out while attempting to retrieve metadata from AWS")

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@ -0,0 +1,74 @@
import json
import logging
import re
import requests
AWS_INSTANCE_METADATA_LOCAL_IP_ADDRESS = "169.254.169.254"
AWS_LATEST_METADATA_URI_PREFIX = f"http://{AWS_INSTANCE_METADATA_LOCAL_IP_ADDRESS}/latest/"
ACCOUNT_ID_KEY = "accountId"
logger = logging.getLogger(__name__)
AWS_TIMEOUT = 2
def fetch_aws_instance_metadata():
instance_id = None
region = None
account_id = None
try:
response = requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "meta-data/instance-id",
timeout=AWS_TIMEOUT,
)
if not response:
return (None, None, None)
instance_id = response.text
region = _parse_region(
requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "meta-data/placement/availability-zone",
timeout=AWS_TIMEOUT,
).text
)
account_id = _extract_account_id(
requests.get(
AWS_LATEST_METADATA_URI_PREFIX + "dynamic/instance-identity/document",
timeout=AWS_TIMEOUT,
).text
)
except (requests.RequestException, IOError, json.decoder.JSONDecodeError) as err:
logger.debug(f"Failed init of AWSInstance while getting metadata: {err}")
return (None, None, None)
return (instance_id, region, account_id)
def _parse_region(region_url_response):
# For a list of regions, see:
# https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Concepts
# .RegionsAndAvailabilityZones.html
# This regex will find any AWS region format string in the response.
re_phrase = r"((?:us|eu|ap|ca|cn|sa)-[a-z]*-[0-9])"
finding = re.findall(re_phrase, region_url_response, re.IGNORECASE)
if finding:
return finding[0]
else:
return None
def _extract_account_id(instance_identity_document_response):
"""
Extracts the account id from the dynamic/instance-identity/document metadata path.
Based on https://forums.aws.amazon.com/message.jspa?messageID=409028 which has a few more
solutions,
in case Amazon break this mechanism.
:param instance_identity_document_response: json returned via the web page
../dynamic/instance-identity/document
:return: The account id
"""
return json.loads(instance_identity_document_response)[ACCOUNT_ID_KEY]

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@ -1,7 +1,5 @@
import logging
from functools import wraps
from threading import Event
from typing import Callable, Optional
from typing import Optional
import boto3
import botocore
@ -30,53 +28,29 @@ def filter_instance_data_from_aws_response(response):
aws_instance: Optional[AWSInstance] = None
AWS_INFO_FETCH_TIMEOUT = 10.0 # Seconds
init_done = Event()
def initialize():
global aws_instance
aws_instance = AWSInstance()
init_done.set()
def wait_init_done(fnc: Callable):
@wraps(fnc)
def inner():
awaited = init_done.wait(AWS_INFO_FETCH_TIMEOUT)
if not awaited:
logger.error(
f"AWS service couldn't initialize in time! "
f"Current timeout is {AWS_INFO_FETCH_TIMEOUT}, "
f"but AWS info took longer to fetch from metadata server."
)
return
fnc()
return inner
@wait_init_done
def is_on_aws():
return aws_instance.is_instance
@wait_init_done
def get_region():
return aws_instance.region
@wait_init_done
def get_account_id():
return aws_instance.account_id
@wait_init_done
def get_client(client_type):
return boto3.client(client_type, region_name=aws_instance.region)
@wait_init_done
def get_instances():
"""
Get the information for all instances with the relevant roles.

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@ -4,7 +4,7 @@ import pytest
import requests
import requests_mock
from common.aws.aws_instance import AWS_LATEST_METADATA_URI_PREFIX, AWSInstance
from common.aws.aws_metadata import AWS_LATEST_METADATA_URI_PREFIX, fetch_aws_instance_metadata
INSTANCE_ID_RESPONSE = "i-1234567890abcdef0"
@ -59,8 +59,7 @@ def get_test_aws_instance(
url, exc=exception["account_id"]
)
test_aws_instance_object = AWSInstance()
return test_aws_instance_object
return fetch_aws_instance_metadata()
# all good data
@ -77,20 +76,16 @@ def good_data_mock_instance():
del instance
def test_is_instance_good_data(good_data_mock_instance):
assert good_data_mock_instance.is_instance
def test_instance_id_good_data(good_data_mock_instance):
assert good_data_mock_instance.instance_id == EXPECTED_INSTANCE_ID
assert good_data_mock_instance[0] == EXPECTED_INSTANCE_ID
def test_region_good_data(good_data_mock_instance):
assert good_data_mock_instance.region == EXPECTED_REGION
assert good_data_mock_instance[1] == EXPECTED_REGION
def test_account_id_good_data(good_data_mock_instance):
assert good_data_mock_instance.account_id == EXPECTED_ACCOUNT_ID
assert good_data_mock_instance[2] == EXPECTED_ACCOUNT_ID
# 'region' bad data
@ -107,20 +102,16 @@ def bad_region_data_mock_instance():
del instance
def test_is_instance_bad_region_data(bad_region_data_mock_instance):
assert bad_region_data_mock_instance.is_instance
def test_instance_id_bad_region_data(bad_region_data_mock_instance):
assert bad_region_data_mock_instance.instance_id == EXPECTED_INSTANCE_ID
assert bad_region_data_mock_instance[0] == EXPECTED_INSTANCE_ID
def test_region_bad_region_data(bad_region_data_mock_instance):
assert bad_region_data_mock_instance.region is None
assert bad_region_data_mock_instance[1] is None
def test_account_id_bad_region_data(bad_region_data_mock_instance):
assert bad_region_data_mock_instance.account_id == EXPECTED_ACCOUNT_ID
assert bad_region_data_mock_instance[2] == EXPECTED_ACCOUNT_ID
# 'account_id' bad data
@ -137,20 +128,16 @@ def bad_account_id_data_mock_instance():
del instance
def test_is_instance_bad_account_id_data(bad_account_id_data_mock_instance):
assert not bad_account_id_data_mock_instance.is_instance
def test_instance_id_bad_account_id_data(bad_account_id_data_mock_instance):
assert bad_account_id_data_mock_instance.instance_id is None
assert bad_account_id_data_mock_instance[0] is None
def test_region_bad_account_id_data(bad_account_id_data_mock_instance):
assert bad_account_id_data_mock_instance.region is None
assert bad_account_id_data_mock_instance[1] is None
def test_account_id_data_bad_account_id_data(bad_account_id_data_mock_instance):
assert bad_account_id_data_mock_instance.account_id is None
assert bad_account_id_data_mock_instance[2] is None
# 'region' bad requests
@ -168,24 +155,19 @@ def bad_region_request_mock_instance(region_exception):
del instance
@pytest.mark.parametrize("region_exception", [requests.RequestException, IOError])
def test_is_instance_bad_region_request(bad_region_request_mock_instance):
assert not bad_region_request_mock_instance.is_instance
@pytest.mark.parametrize("region_exception", [requests.RequestException, IOError])
def test_instance_id_bad_region_request(bad_region_request_mock_instance):
assert bad_region_request_mock_instance.instance_id is None
assert bad_region_request_mock_instance[0] is None
@pytest.mark.parametrize("region_exception", [requests.RequestException, IOError])
def test_region_bad_region_request(bad_region_request_mock_instance):
assert bad_region_request_mock_instance.region is None
assert bad_region_request_mock_instance[1] is None
@pytest.mark.parametrize("region_exception", [requests.RequestException, IOError])
def test_account_id_bad_region_request(bad_region_request_mock_instance):
assert bad_region_request_mock_instance.account_id is None
assert bad_region_request_mock_instance[2] is None
# not found request
@ -204,22 +186,16 @@ def not_found_request_mock_instance():
url = f"{AWS_LATEST_METADATA_URI_PREFIX}dynamic/instance-identity/document"
m.get(url)
not_found_aws_instance_object = AWSInstance()
yield not_found_aws_instance_object
del not_found_aws_instance_object
def test_is_instance_not_found_request(not_found_request_mock_instance):
assert not_found_request_mock_instance.is_instance is False
return fetch_aws_instance_metadata()
def test_instance_id_not_found_request(not_found_request_mock_instance):
assert not_found_request_mock_instance.instance_id is None
assert not_found_request_mock_instance[0] is None
def test_region_not_found_request(not_found_request_mock_instance):
assert not_found_request_mock_instance.region is None
assert not_found_request_mock_instance[1] is None
def test_account_id_not_found_request(not_found_request_mock_instance):
assert not_found_request_mock_instance.account_id is None
assert not_found_request_mock_instance[2] is None