Amazon Neptune
User Guide (API Version 2017-11-29)

Connect to Neptune Using Python with Version 4 Signing (Example)

This section shows an example program written in Python that illustrates how to work with Signature Version 4 for Amazon Neptune. This example is based on the examples in the Signature Version 4 Signing Process section in the Amazon Web Services General Reference.

In order to work with this example program, you need the following:

  • Python 3.x installed on your computer, which you can get from the Python site. These programs were tested using Python 3.6.

  • The Python requests library, which is used in the example script to make web requests. A convenient way to install Python packages is to use pip, which gets packages from the Python package index site. You can then install requests by running pip install requests at the command line.

  • An access key (access key ID and secret access key) in environment variables named AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY. As a best practice, we recommend that you do not embed credentials in code. For more information, see Best Practices for Managing AWS Access Keys in the Amazon Web Services General Reference.

    The region of your Neptune DB cluster in envirnment variable named SERVICE_REGION.

    If you are using temporary credentials, you must specify AWS_SESSION_TOKEN in addition to AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and SERVICE_REGION.

    Note

    If you are using temporary credentials, they expire after a specified interval, including the session token.

    You will need to update your session token when you request new credentials. For more information, see Using Temporary Security Credentials to Request Access to AWS Resources.

The following example shows how to make signed requests to Neptune using Python. The request makes a either a GET or POST request. Authentication information is passed using the Authorization request header.

This example also works as an AWS Lambda function. For more information, see Setup AWS Lambda for Neptune IAM Authentication.

To make signed requests to the Gremlin and SPARQL Neptune endpoints

  1. Create a new file named neptunesigv4.py, and open it in a text editor.

  2. Copy and paste the following code into the neptunesigv4.py file.

    # Amazon Neptune version 4 signing example (version v2) # The following script requires python 3.6+ (sudo yum -y install python3) # => the reason is that we're using urllib.parse() to manually encode URL # parameters: the problem here is that SIGV4 encoding requires whitespaces # to be encoded as %20 rather than not or using '+', as done by previous/ # default versions of the library. # See: http://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html # This version makes a GET request and passes the signature # in the Authorization header. import sys, datetime, hashlib, hmac import requests # pip3 install requests import urllib import os import json from argparse import RawTextHelpFormatter from argparse import ArgumentParser # Configuration. http is required. protocol = 'http' # The following lines enable debugging at httplib level (requests->urllib3->http.client) # You will see the REQUEST, including HEADERS and DATA, and RESPONSE with HEADERS but without DATA. # # The only thing missing will be the response.body which is not logged. # # import logging # http_client.HTTPConnection.debuglevel = 1 # logging.basicConfig() # logging.getLogger().setLevel(logging.DEBUG) # requests_log = logging.getLogger("requests.packages.urllib3") # requests_log.setLevel(logging.DEBUG) # requests_log.propagate = True # Read AWS access key from env. variables. Best practice is NOT # to embed credentials in code. access_key = os.getenv('AWS_ACCESS_KEY_ID', '') secret_key = os.getenv('AWS_SECRET_ACCESS_KEY', '') region = os.getenv('SERVICE_REGION', '') # AWS_SESSION_TOKEN is optional enviornment variable. Specify a session token only if you are using temporary # security credentials. session_token = os.getenv('AWS_SESSION_TOKEN', '') ### Note same script can be used for AWS Lambda (runtime = python3.6). ## Steps to use this python script for AWS Lambda # 1. AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_SESSION_TOKEN and AWS_REGION variables are already part of Lambda's Exeuction envionment # No need to set them up explicitly. # 3. Create Lambda deployment package https://docs.aws.amazon.com/lambda/latest/dg/lambda-python-how-to-create-deployment-package.html # 4. Create a Lambda function in the same VPC and assign an IAM role with neptune access def lambda_handler(event, context): # sample_test_input = { # "host": "END_POINT:8182", # "method": "GET", # "query_type": "gremlin", # "query": "g.V().count()" # } # Lambda uses AWS_REGION instead of SERVICE_REGION global region region = os.getenv('AWS_REGION', '') host = event['host'] method = event['method'] query_type = event['query_type'] query = event['query'] return make_signed_request(host, method, query_type, query) # Key derivation functions. See: # http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4-examples-python def sign(key, msg): return hmac.new(key, msg.encode('utf-8'), hashlib.sha256).digest() def getSignatureKey(key, dateStamp, regionName, serviceName): kDate = sign(('AWS4' + key).encode('utf-8'), dateStamp) kRegion = sign(kDate, regionName) kService = sign(kRegion, serviceName) kSigning = sign(kService, 'aws4_request') return kSigning def validate_input(method, query_type): # Supporting GET and POST for now: if (method != 'GET' and method != 'POST'): print('First parameter must be "GET" or "POST", but is "' + method + '".') sys.exit() # SPARQL UPDATE requires POST if (method == 'GET' and query_type == 'sparqlupdate'): print('SPARQL UPDATE is not supported in GET mode. Please choose POST.') sys.exit() # Note: it looks like Gremlin POST requires the query to be encoded in a JSON # struct; we haven't implemented this in the python script, so let's for now # disable Gremlin POST requests. if (method == 'POST' and query_type == 'gremlin'): print('POST is currently not supported for Gremlin in this python script.') sys.exit() def get_canonical_uri_and_payload(query_type, query): # Set the stack and payload depending on query_type. if (query_type == 'sparql'): canonical_uri = '/sparql/' payload = {'query': query} elif (query_type == 'sparqlupdate'): canonical_uri = '/sparql/' payload = {'update': query} elif (query_type == 'gremlin'): canonical_uri = '/gremlin/' payload = {'gremlin': query} elif (query_type == "loader"): canonical_uri = "/loader/" payload = json.loads(query) elif (query_type == "status"): canonical_uri = "/status/" payload = {} else: print( 'Third parameter should be from ["gremlin", "sparql", "sparqlupdate", "loader", "status] but is "' + query_type + '".') sys.exit() ## return output as tuple return canonical_uri, payload def make_signed_request(host, method, query_type, query): service = 'neptune-db' endpoint = protocol + '://' + host print() print('+++++ USER INPUT +++++') print('host = ' + host) print('method = ' + method) print('query_type = ' + query_type) print('query = ' + query) # validate input validate_input(method, query_type) # get canonical_uri and payload canonical_uri, payload = get_canonical_uri_and_payload(query_type, query) # ************* REQUEST VALUES ************* # do the encoding => quote_via=urllib.parse.quote is used to map " " => "%20" request_parameters = urllib.parse.urlencode(payload, quote_via=urllib.parse.quote) # ************* TASK 1: CREATE A CANONICAL REQUEST ************* # http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # Step 1 is to define the verb (GET, POST, etc.)--already done. # Create a date for headers and the credential string. t = datetime.datetime.utcnow() amzdate = t.strftime('%Y%m%dT%H%M%SZ') datestamp = t.strftime('%Y%m%d') # Date w/o time, used in credential scope # ************* TASK 1: CREATE A CANONICAL REQUEST ************* # http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # Step 1 is to define the verb (GET, POST, etc.)--already done. # Step 2: is to define the canonical_uri--already done. # Step 3: Create the canonical query string. In this example (a GET request), # request parameters are in the query string. Query string values must # be URL-encoded (space=%20). The parameters must be sorted by name. # For this example, the query string is pre-formatted in the request_parameters variable. if (method == 'GET'): canonical_querystring = request_parameters elif (method == 'POST'): canonical_querystring = '' else: print('Request method is neither "GET" nor "POST", something is wrong here.') sys.exit() # Step 4: Create the canonical headers and signed headers. Header names # must be trimmed and lowercase, and sorted in code point order from # low to high. Note that there is a trailing \n. canonical_headers = 'host:' + host + '\n' + 'x-amz-date:' + amzdate + '\n' # Step 5: Create the list of signed headers. This lists the headers # in the canonical_headers list, delimited with ";" and in alpha order. # Note: The request can include any headers; canonical_headers and # signed_headers lists those that you want to be included in the # hash of the request. "Host" and "x-amz-date" are always required. signed_headers = 'host;x-amz-date' # Step 6: Create payload hash (hash of the request body content). For GET # requests, the payload is an empty string (""). if (method == 'GET'): post_payload = '' elif (method == 'POST'): post_payload = request_parameters else: print('Request method is neither "GET" nor "POST", something is wrong here.') sys.exit() payload_hash = hashlib.sha256(post_payload.encode('utf-8')).hexdigest() # Step 7: Combine elements to create canonical request. canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash # ************* TASK 2: CREATE THE STRING TO SIGN************* # Match the algorithm to the hashing algorithm you use, either SHA-1 or # SHA-256 (recommended) algorithm = 'AWS4-HMAC-SHA256' credential_scope = datestamp + '/' + region + '/' + service + '/' + 'aws4_request' string_to_sign = algorithm + '\n' + amzdate + '\n' + credential_scope + '\n' + hashlib.sha256( canonical_request.encode('utf-8')).hexdigest() # ************* TASK 3: CALCULATE THE SIGNATURE ************* # Create the signing key using the function defined above. signing_key = getSignatureKey(secret_key, datestamp, region, service) # Sign the string_to_sign using the signing_key signature = hmac.new(signing_key, (string_to_sign).encode('utf-8'), hashlib.sha256).hexdigest() # ************* TASK 4: ADD SIGNING INFORMATION TO THE REQUEST ************* # The signing information can be either in a query string value or in # a header named Authorization. This code shows how to use a header. # Create authorization header and add to request headers authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' + 'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature # The request can include any headers, but MUST include "host", "x-amz-date", # and (for this scenario) "Authorization". "host" and "x-amz-date" must # be included in the canonical_headers and signed_headers, as noted # earlier. Order here is not significant. # Python note: The 'host' header is added automatically by the Python 'requests' library. if (method == 'GET'): headers = {'x-amz-date': amzdate, 'Authorization': authorization_header} elif (method == 'POST'): headers = {'content-type': 'application/x-www-form-urlencoded', 'x-amz-date': amzdate, 'Authorization': authorization_header} else: print('Request method is neither "GET" nor "POST", something is wrong here.') sys.exit() # https://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html # The process for temporary security credentials is the same as using long-term credentials and # for temporary security credentials should be added as parameter name is X-Amz-Security-Token. if session_token: headers['x-amz-security-token'] = session_token # ************* SEND THE REQUEST ************* request_url = endpoint + canonical_uri print() if (method == 'GET'): print('++++ BEGIN GET REQUEST +++++') print('Request URL = ' + request_url) r = requests.get(request_url, headers=headers, verify=False, params=request_parameters) print() print('+++++ RESPONSE +++++') print('Response code: %d\n' % r.status_code) print(r.text) elif (method == 'POST'): print('\n+++++ BEGIN POST REQUEST +++++') print('Request URL = ' + request_url) r = requests.post(request_url, headers=headers, verify=False, data=request_parameters) print() print('+++++ RESPONSE +++++') print('Response code: %d\n' % r.status_code) print(r.text) else: print('Request method is neither "GET" nor "POST", something is wrong here.') sys.exit() help_msg = ''' export AWS_ACCESS_KEY_ID=[MY_ACCESS_KEY_ID] export AWS_SECRET_ACCESS_KEY=[MY_SECRET_ACCESS_KEY] export AWS_SESSION_TOKEN=[MY_AWS_SESSION_TOKEN] export SERVICE_REGION=[us-east-1|us-east-2|us-west-2|eu-west-1] python version >=3.6 is required. Examples: For help python3 program_name.py -h Examples: Queries python3 program_name.py -ho your-neptune-endpoint -p 8182 -a GET -q status python3 program_name.py -ho your-neptune-endpoint -p 8182 -a GET -q sparql -d "SELECT ?s WHERE { ?s ?p ?o }" python3 program_name.py -ho your-neptune-endpoint -p 8182 -a POST -q sparql -d "SELECT ?s WHERE { ?s ?p ?o }" python3 program_name.py -ho your-neptune-endpoint -p 8182 -a POST -q sparqlupdate -d "INSERT DATA { <http://s> <http://p> <http://o> }" python3 program_name.py -ho your-neptune-endpoint -p 8182 -a GET -q gremlin -d "g.V().count()" python3 program_name.py -ho your-neptune-endpoint -p 8182 -a GET -q loader -d \'{"loadId": "68b28dcc-8e15-02b1-133d-9bd0557607e6"}\' python3 program_name.py -ho your-neptune-endpoint -p 8182 -a GET -q loader -d '{}' python3 program_name.py -ho your-neptune-endpoint -p 8182 -a POST -q loader -d \'{"source": "source", "format" : "csv", "failOnError": "fail_on_error", "iamRoleArn": "iam_role_arn", "region": "region"}\' Environment variables must be defined as AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and SERVICE_REGION. You should also set AWS_SESSION_TOKEN environment variable if you are using temporary credentials (ex. IAM Role or EC2 Instance profile). Current Limitations: - Query mode "sparqlupdate" requires POST (as per the SPARQL 1.1 protocol) - The python script currently does not support POST for Gremlin ''' def exit_and_print_help(): print(help_msg) exit() def parse_input_and_query_neptune(): parser = ArgumentParser(description=help_msg, formatter_class=RawTextHelpFormatter) group_host = parser.add_mutually_exclusive_group() group_host.add_argument("-ho", "--host", type=str) group_port = parser.add_mutually_exclusive_group() group_port.add_argument("-p", "--port", type=int, help="port ex. 8182, default=8182", default=8182) group_action = parser.add_mutually_exclusive_group() group_action.add_argument("-a", "--action", type=str, help="http action, default = GET", default="GET") group_endpoint = parser.add_mutually_exclusive_group() group_endpoint.add_argument("-q", "--query_type", type=str, help="query_type, default = status ", default="status") group_data = parser.add_mutually_exclusive_group() group_data.add_argument("-d", "--data", type=str, help="data required for the http action", default="") args = parser.parse_args() print("parsed input: ") print(args) # Read command line parameters host = args.host port = args.port method = args.action query_type = args.query_type query = args.data if (access_key == ''): print('!!! ERROR: Your AWS_ACCESS_KEY_ID environment variable is undefined.') exit_and_print_help() if (secret_key == ''): print('!!! ERROR: Your AWS_SECRET_ACCESS_KEY environment variable is undefined.') exit_and_print_help() if (region == ''): print('!!! ERROR: Your SERVICE_REGION environment variable is undefined.') exit_and_print_help() if host is None: print('!!! ERROR: Neptune dns is missing') exit_and_print_help() host = host + ":" + str(port) make_signed_request(host, method, query_type, query) if __name__ == "__main__": parse_input_and_query_neptune()
  3. In a terminal, navigate to the location of the neptunesigv4.py file.

  4. Type the following commands, replacing the access key, secret key, and region with the correct values.

    export AWS_ACCESS_KEY_ID=MY_ACCESS_KEY_ID export AWS_SECRET_ACCESS_KEY=MY_SECRET_ACCESS_KEY export SERVICE_REGION=us-east-1|us-east-2|us-west-2|eu-west-1|eu-west-2|eu-central-1

    If you are using temporary credentials, you must specify AWS_SESSION_TOKEN in addition to AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and SERVICE_REGION.

    export AWS_SESSION_TOKEN=MY_AWS_SESSION_TOKEN

    Note

    If you are using temporary credentials, they expire after a specified interval, including the session token.

    You will need to update your session token when you request new credentials. For more information, see Using Temporary Security Credentials to Request Access to AWS Resources.

  5. Type one of the following commands to send a signed request to the Neptune DB instance. These examples use Python version 3.6.

    Endpoint Status

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -a GET -q status

    Gremlin

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a GET -q gremlin -d "g.V().count()"

    SPARQL

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a GET -q sparql -d "SELECT ?s WHERE { ?s ?p ?o }"

    SPARQL UPDATE

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a POST -q sparql -d "SELECT ?s WHERE { ?s ?p ?o }" -p 8182 -a POST -q sparqlupdate -d "INSERT DATA { <http://s> <http://p> <http://o> }"

    Loader

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a GET -q loader -d \'{"loadId": "68b28dcc-8e15-02b1-133d-9bd0557607e6"}\'
    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a GET -q loader -d '{}'
    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p 8182 -a POST -q loader -d \'{"source": "source", "format" : "csv", "failOnError": "fail_on_error", "iamRoleArn": "iam_role_arn", "region": "region"}\'
  6. The syntax for running the Python script is as follows:

    python3.6 neptunesigv4.py -ho your-neptune-endpoint -p port -a GET|POST -q gremlin|sparql|sparqlupdate|loader|status -d "string0data"

    Gremlin traversals only support GET. SPARQL UPDATE requires POST.