init

Author: satr

docs/amazon-lex-access-with-rest-api.py

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+# AWS Version 4 signing example
+
+# Based on example from the source: http://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html
+
+# Amazon Lex API request
+
+# See: http://docs.aws.amazon.com/general/latest/gr/sigv4_signing.html
+# This version makes a POST request and passes request parameters
+# in the body (payload) of the request. Auth information is passed in
+# an Authorization header.
+import datetime
+import hashlib
+import hmac
+import os
+import sys
+
+import requests
+
+# easy_install pip
+# pip install requests
+
+# ************* REQUEST VALUES *************
+method = 'POST'
+service = 'lex'
+host = 'runtime.lex.us-east-1.amazonaws.com'
+region = 'us-east-1'
+endpoint = 'https://runtime.lex.us-east-1.amazonaws.com'
+
+request_text = 'this is the request text' # request text
+
+request_parameters =  '{"inputText": "' + request_text + '", "sessionAttributes": {"attr_name" : "value"}}' #request text (and optional session attributes) to the Lex bot
+# for post_action 'content' - sessionAttributes are passed as the x-amz-lex-session-attributes HTTP header.
+
+bot_name = 'TestBotForRequest'  # bot name
+bot_alias = 'testbotforrequest' # bot's alias
+user_id = 'myUserId' # some user-id - not used for authentication
+# for text request (json); {"inputText": "string", "sessionAttributes": {"string" : "string" }})
+post_action = 'text'
+# for stream request (text or audio stream)
+#post_action = 'content'
+
+# POST requests use a content type header. For Lex,
+# the content is JSON or stream.
+# for post_action = 'text':
+content_type = 'application/json'
+# for post_action = 'content', audio stream in PCM format:
+#content_type = 'audio/l16;rate=16000;channels=1'
+#content_type = 'audio/x-l16;sample-rate=16000;channel-count=1'
+# for post_action = 'content', audio stream in Opus format:
+#content_type = 'audio/x-cbr-opus-with-preamble;preamble-size=0;bit-rate=256000;frame-size-milliseconds=4'
+# for post_action = 'content', text:
+#content_type = 'text/plain;charset=utf-8'
+
+# 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
+
+# Read AWS access key from env. variables or configuration file. Best practice is NOT
+# to embed credentials in code.
+access_key = os.environ.get('AWS_ACCESS_KEY_ID')
+secret_key = os.environ.get('AWS_SECRET_ACCESS_KEY')
+if access_key is None or secret_key is None:
+    print 'No access key is available.'
+    sys.exit()
+
+# Create a date for headers and the credential string
+t = datetime.datetime.utcnow()
+amz_date = t.strftime('%Y%m%dT%H%M%SZ')#'20170714T010101Z'
+date_stamp = t.strftime('%Y%m%d') # Date w/o time, used in credential scope  '20170714'
+
+
+# ************* 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: Create canonical URI--the part of the URI from domain to query
+# string (use '/' if no path)
+canonical_uri = '/bot/' + bot_name + '/alias/' + bot_alias + '/user/' + user_id + '/' + post_action
+
+## Step 3: Create the canonical query string. In this example, request
+# parameters are passed in the body of the request and the query string
+# is blank.
+canonical_querystring = ''
+
+# Step 4: Create the canonical 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 = 'content-type:' + content_type + '\n' + 'host:' + host + '\n' + 'x-amz-date:' + amz_date + '\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 include those that you want to be included in the
+# hash of the request. "Host" and "x-amz-date" are always required.
+# For Lex, content-type and x-amz-target are also required.
+signed_headers = 'content-type;host;x-amz-date'
+
+# Step 6: Create payload hash. In this example, the payload (body of
+# the request) contains the request parameters.
+payload_hash = hashlib.sha256(request_parameters).hexdigest()
+
+# Step 7: Combine elements to create 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 = date_stamp + '/' + region + '/' + service + '/' + 'aws4_request'
+string_to_sign = algorithm + '\n' +  amz_date + '\n' +  credential_scope + '\n' +  hashlib.sha256(canonical_request).hexdigest()
+
+
+# ************* TASK 3: CALCULATE THE SIGNATURE *************
+# Create the signing key using the function defined above.
+signing_key = getSignatureKey(secret_key, date_stamp, 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 *************
+# Put the signature information in a header named Authorization.
+authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' +  'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature
+
+# For Lex, the request can include any headers, but MUST include "host", "x-amz-date",
+# "x-amz-target", "content-type", and "Authorization". Except for the authorization
+# header, the headers must be included in the canonical_headers and signed_headers values, as
+# noted earlier. Order here is not significant.
+# # Python note: The 'host' header is added automatically by the Python 'requests' library.
+headers = {'Content-Type':content_type,
+           'X-Amz-Date':amz_date,
+           'Authorization':authorization_header}
+
+
+# ************* SEND THE REQUEST *************
+print '\nBEGIN REQUEST++++++++++++++++++++++++++++++++++++'
+print 'Request URL = ' + endpoint
+
+r = requests.post(endpoint + canonical_uri, data=request_parameters, headers=headers)
+
+print '\nRESPONSE++++++++++++++++++++++++++++++++++++'
+print 'Response code: %d\n' % r.status_code
+print r.text