feat(VPCInstanceAuthenticator): add support for new VPC authentication flow

Authentication.md

@@ -3,6 +3,7 @@ The python-sdk-core project supports the following types of authentication:
 - Basic Authentication
 - Bearer Token Authentication
 - Identity and Access Management (IAM) Authentication
+- VPC Instance Authentication
 - Container Authentication
 - Cloud Pak for Data Authentication
 - No Authentication
@@ -13,13 +14,10 @@ so it is important for the SDK user to consult with the appropriate service docu
 to understand which authenticators are supported for that service.
 
 The python-sdk-core allows an authenticator to be specified in one of two ways:
-1. programmatically - the SDK user invokes the appropriate function(s) to create an instance of the 
-desired authenticator and then passes the authenticator instance when constructing an instance of the service client.
+1. programmatically - the SDK user invokes the appropriate function(s) to create an instance of the
+desired authenticator and then passes the authenticator instance when constructing an instance of the service.
 2. configuration - the SDK user provides external configuration information (in the form of environment variables
-or a credentials file) to indicate the type of authenticator, along with the configuration of the necessary properties
-for that authenticator.
-The SDK user then invokes the configuration-based service client constructor method
-to construct an instance of the authenticator and service client that reflect the external configuration information.
+or a credentials file) to indicate the type of authenticator, along with the configuration of the necessary properties for that authenticator. The SDK user then invokes the configuration-based service client constructor method to construct an instance of the authenticator and service client that reflect the external configuration information.
 
 The sections below will provide detailed information for each authenticator
 which will include the following:
@@ -296,6 +294,76 @@ service = ExampleServiceV1.new_instance(service_name='example_service')
 ```
 
 
+## VPC Instance Authentication
+The `VpcInstanceAuthenticator` is intended to be used by application code
+running inside a VPC-managed compute resource (virtual server instance) that has been configured
+to use the "compute resource identity" feature.
+The compute resource identity feature allows you to assign a trusted IAM profile to the compute resource as its "identity".
+This, in turn, allows applications running within the compute resource to take on this identity when interacting with
+IAM-secured IBM Cloud services.
+This results in a simplified security model that allows the application developer to:
+- avoid storing credentials in application code, configuraton files or a password vault
+- avoid managing or rotating credentials
+
+The `VpcInstanceAuthenticator` will invoke the appropriate operations on the compute resource's locally-available
+VPC Instance Metadata Service to (1) retrieve an instance identity token
+and then (2) exchange that instance identity token for an IAM access token.
+The authenticator will repeat these steps to obtain a new IAM access token whenever the current access token expires.
+The IAM access token is added to each outbound request in the `Authorization` header in the form:
+```
+   Authorization: Bearer <IAM-access-token>
+```
+
+### Properties
+
+- iam_profile_crn: (optional) the crn of the linked trusted IAM profile to be used when obtaining the IAM access token.
+
+- iam_profile_id: (optional) the id of the linked trusted IAM profile to be used when obtaining the IAM access token.
+
+- url: (optional) The VPC Instance Metadata Service's base URL.  
+The default value of this property is `http://169.254.169.254`, and should not need to be specified in normal situations.
+
+Usage Notes:
+1. At most one of `iam_profile_crn` or `iam_profile_id` may be specified.  The specified value must map
+to a trusted IAM profile that has been linked to the compute resource (virtual server instance).
+
+2. If both `iam_profile_crn` and `iam_profile_id` are specified, then an error occurs.
+
+3. If neither `iam_profile_crn` nor `iam_profile_id` are specified, then the default trusted profile linked to the compute resource will be used to perform the IAM token exchange.
+If no default trusted profile is defined for the compute resource, then an error occurs.
+
+
+### Programming example
+```python
+from ibm_cloud_sdk_core.authenticators import VPCInstanceAuthenticator
+from <sdk-package-name>.example_service_v1 import *
+
+# Create the authenticator.
+authenticator = VPCInstanceAuthenticator(iam_profile_crn='crn:iam-profile-123')
+
+# Construct the service instance.
+service = ExampleServiceV1(authenticator=authenticator)
+
+# 'service' can now be used to invoke operations.
+```
+
+### Configuration example
+External configuration:
+```
+export EXAMPLE_SERVICE_AUTH_TYPE=vpc
+export EXAMPLE_SERVICE_IAM_PROFILE_CRN=crn:iam-profile-123
+```
+Application code:
+```python
+from <sdk-package-name>.example_service_v1 import *
+
+# Construct the service instance.
+service = ExampleServiceV1.new_instance(service_name='example_service')
+
+# 'service' can now be used to invoke operations.
+```
+
+
 ##  Cloud Pak for Data
 The `CloudPakForDataAuthenticator` will accept a user-supplied username value, along with either a
 password or apikey, and will 
@@ -392,4 +460,3 @@ from <sdk-package-name>.example_service_v1 import *
 service = ExampleServiceV1.new_instance(service_name='example_service')
 
 # 'service' can now be used to invoke operations.
-```

ibm_cloud_sdk_core/__init__.py

@@ -42,6 +42,7 @@
 from .token_managers.jwt_token_manager import JWTTokenManager
 from .token_managers.cp4d_token_manager import CP4DTokenManager
 from .token_managers.container_token_manager import ContainerTokenManager
+from .token_managers.vpc_instance_token_manager import VPCInstanceTokenManager
 from .api_exception import ApiException
 from .utils import datetime_to_string, string_to_datetime, read_external_sources
 from .utils import datetime_to_string_list, string_to_datetime_list

ibm_cloud_sdk_core/authenticators/__init__.py

@@ -39,4 +39,5 @@
 from .container_authenticator import ContainerAuthenticator
 from .cp4d_authenticator import CloudPakForDataAuthenticator
 from .iam_authenticator import IAMAuthenticator
+from .vpc_instance_authenticator import VPCInstanceAuthenticator
 from .no_auth_authenticator import NoAuthAuthenticator

ibm_cloud_sdk_core/authenticators/authenticator.py

@@ -26,6 +26,7 @@ class Authenticator(ABC):
     AUTHTYPE_IAM = 'iam'
     AUTHTYPE_CONTAINER = 'container'
     AUTHTYPE_CP4D = 'cp4d'
+    AUTHTYPE_VPC = 'vpc'
     AUTHTYPE_NOAUTH = 'noAuth'
     AUTHTYPE_UNKNOWN = 'unknown'
 

ibm_cloud_sdk_core/authenticators/vpc_instance_authenticator.py

@@ -0,0 +1,124 @@
+# coding: utf-8
+
+# Copyright 2021 IBM All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Optional
+
+from requests import Request
+
+from ..token_managers.vpc_instance_token_manager import VPCInstanceTokenManager
+from .authenticator import Authenticator
+
+
+class VPCInstanceAuthenticator(Authenticator):
+    """VPCInstanceAuthenticator implements an authentication scheme in which it
+       retrieves an "instance identity token" and exchanges that
+       for an IAM access token using the VPC Instance Metadata Service API which is available
+       on the local compute resource (VM).
+       The instance identity token is similar to an IAM apikey, except that it is managed
+       automatically by the compute resource provider (VPC).
+       The resulting IAM access token is then added to outbound requests in an Authorization header of the form:
+
+           Authorization: Bearer <access-token>
+
+    Keyword Arguments:
+        iam_profile_crn (str, optional):
+            The CRN of the linked trusted IAM profile to be used as the identity of the compute resource.
+            At most one of iamProfileCrn or iamProfileId may be specified. If neither one is specified,
+            then the default IAM profile defined for the compute resource will be used. Defaults to None.
+        iam_profile_id (str, optional):
+            The ID of the linked trusted IAM profile to be used when obtaining the IAM access token.
+            At most one of iamProfileCrn or iamProfileId may be specified. If neither one is specified,
+            then the default IAM profile defined for the compute resource will be used. Defaults to None.
+        url (str, optional):
+            The VPC Instance Metadata Service's base endpoint URL. Defaults to 'http://169.254.169.254'.
+
+    Attributes:
+        iam_profile_crn (str, optional): The CRN of the linked trusted IAM profile.
+        iam_profile_id (str, optional): The ID of the linked trusted IAM profile.
+        url (str, optional): The VPC Instance Metadata Service's base endpoint URL.
+    """
+
+    DEFAULT_IMS_ENDPOINT = 'http://169.254.169.254'
+
+    def __init__(self,
+                 iam_profile_crn: Optional[str] = None,
+                 iam_profile_id: Optional[str] = None,
+                 url: Optional[str] = None) -> None:
+
+        if not url:
+            url = self.DEFAULT_IMS_ENDPOINT
+
+        self.token_manager = VPCInstanceTokenManager(
+            url=url, iam_profile_crn=iam_profile_crn, iam_profile_id=iam_profile_id)
+
+        self.validate()
+
+    def authentication_type(self) -> str:
+        """Returns this authenticator's type ('VPC')."""
+        return Authenticator.AUTHTYPE_VPC
+
+    def validate(self) -> None:
+        super().validate()
+
+        if self.token_manager.iam_profile_crn and self.token_manager.iam_profile_id:
+            raise ValueError(
+                'At most one of "iam_profile_id" or "iam_profile_crn" may be specified.')
+
+    def authenticate(self, req: Request) -> None:
+        """Adds IAM authentication information to the request.
+
+        The IAM access token will be added to the request's headers in the form:
+
+            Authorization: Bearer <bearer-token>
+
+        Args:
+            req: The request to add IAM authentication information too. Must contain a key to a dictionary
+            called headers.
+        """
+        headers = req.get('headers')
+        bearer_token = self.token_manager.get_token()
+        headers['Authorization'] = 'Bearer {0}'.format(bearer_token)
+
+
+    def set_iam_profile_crn(self, iam_profile_crn: str) -> None:
+        """Sets CRN of the IAM profile.
+
+        Args:
+            iam_profile_crn (str): the CRN of the linked trusted IAM profile to be used as
+                             the identity of the compute resource.
+
+        Raises:
+            ValueError: At most one of iam_profile_crn or iam_profile_id may be specified.
+                        If neither one is specified, then the default IAM profile defined
+                        for the compute resource will be used.
+        """
+        self.token_manager.set_iam_profile_crn(iam_profile_crn)
+        self.validate()
+
+    def set_iam_profile_id(self, iam_profile_id: str) -> None:
+        """Sets the ID of the IAM profile.
+
+        Args:
+            iam_profile_id (str): id of the linked trusted IAM profile to be used when obtaining
+                            the IAM access token
+
+        Raises:
+            ValueError: At most one of iam_profile_crn or iam_profile_id may be specified.
+                        If neither one is specified, then the default IAM profile defined
+                        for the compute resource will be used.
+        """
+        self.token_manager.set_iam_profile_id(iam_profile_id)
+        self.validate()

ibm_cloud_sdk_core/get_authenticator.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from ibm_cloud_sdk_core.authenticators.vpc_instance_authenticator import VPCInstanceAuthenticator
 from .authenticators import (Authenticator, BasicAuthenticator, BearerTokenAuthenticator, ContainerAuthenticator,
                              CloudPakForDataAuthenticator, IAMAuthenticator, NoAuthAuthenticator)
 from .utils import read_external_sources
@@ -91,6 +92,11 @@ def __construct_authenticator(config: dict) -> Authenticator:
             disable_ssl_verification=config.get(
                 'AUTH_DISABLE_SSL', 'false').lower() == 'true',
             scope=config.get('SCOPE'))
+    elif auth_type == Authenticator.AUTHTYPE_VPC.lower():
+        authenticator = VPCInstanceAuthenticator(
+            iam_profile_crn=config.get('IAM_PROFILE_CRN'),
+            iam_profile_id=config.get('IAM_PROFILE_ID'),
+            url=config.get('AUTH_URL'))
     elif auth_type == Authenticator.AUTHTYPE_NOAUTH.lower():
         authenticator = NoAuthAuthenticator()