FT: Add python request example

Author: Bennett Buchanan

examples/python-V4Auth-example.py

@@ -0,0 +1,90 @@
+import sys, os, base64, datetime, hashlib, hmac, datetime, calendar, json
+import requests # pip install requests
+
+access_key = '9EQTVVVCLSSG6QBMNKO5'
+secret_key = 'T5mK/skkkwJ/mTjXZnHyZ5UzgGIN=k9nl4dyTmDH'
+
+method = 'POST'
+service = 's3'
+host = 'localhost:8100'
+region = 'us-east-1'
+canonical_uri = '/buckets'
+canonical_querystring = 'Action=ListMetrics&Version=20160815'
+content_type = 'application/x-amz-json-1.0'
+algorithm = 'AWS4-HMAC-SHA256'
+
+t = datetime.datetime.utcnow()
+amz_date = t.strftime('%Y%m%dT%H%M%SZ')
+date_stamp = t.strftime('%Y%m%d')
+
+# 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, date_stamp, regionName, serviceName):
+    kDate = sign(('AWS4' + key).encode('utf-8'), date_stamp)
+    kRegion = sign(kDate, regionName)
+    kService = sign(kRegion, serviceName)
+    kSigning = sign(kService, 'aws4_request')
+    return kSigning
+
+def get_start_time(t):
+    start = t.replace(minute=t.minute - t.minute % 15, second=0, microsecond=0)
+    return calendar.timegm(start.utctimetuple()) * 1000;
+
+def get_end_time(t):
+    end = t.replace(minute=t.minute - t.minute % 15, second=0, microsecond=0)
+    return calendar.timegm(end.utctimetuple()) * 1000 - 1;
+
+start_time = get_start_time(datetime.datetime(2016, 1, 1, 0, 0, 0, 0))
+end_time = get_end_time(datetime.datetime(2016, 2, 1, 0, 0, 0, 0))
+
+# Request parameters for listing Utapi bucket metrics--passed in a JSON block.
+bucketListing = {
+    'buckets': [ 'utapi-test' ],
+    'timeRange': [ start_time, end_time ],
+}
+
+request_parameters = json.dumps(bucketListing)
+
+payload_hash = hashlib.sha256(request_parameters).hexdigest()
+
+canonical_headers = \
+    'content-type:{0}\nhost:{1}\nx-amz-content-sha256:{2}\nx-amz-date:{3}\n' \
+    .format(content_type, host, payload_hash, amz_date)
+
+signed_headers = 'content-type;host;x-amz-content-sha256;x-amz-date'
+
+canonical_request = '{0}\n{1}\n{2}\n{3}\n{4}\n{5}' \
+    .format(method, canonical_uri, canonical_querystring, canonical_headers,
+            signed_headers, payload_hash)
+
+credential_scope = '{0}/{1}/{2}/aws4_request' \
+    .format(date_stamp, region, service)
+
+string_to_sign = '{0}\n{1}\n{2}\n{3}' \
+    .format(algorithm, amz_date, credential_scope,
+            hashlib.sha256(canonical_request).hexdigest())
+
+signing_key = getSignatureKey(secret_key, date_stamp, region, service)
+
+signature = hmac.new(signing_key, (string_to_sign).encode('utf-8'),
+                     hashlib.sha256).hexdigest()
+
+authorization_header = \
+    '{0} Credential={1}/{2}, SignedHeaders={3}, Signature={4}' \
+    .format(algorithm, access_key, credential_scope, signed_headers, signature)
+
+# The 'host' header is added automatically by the Python 'requests' library.
+headers = {
+    'Content-Type': content_type,
+    'X-Amz-Content-Sha256': payload_hash,
+    'X-Amz-Date': amz_date,
+    'Authorization': authorization_header
+}
+
+endpoint = 'http://' + host + canonical_uri + '?' + canonical_querystring;
+
+r = requests.post(endpoint, data=request_parameters, headers=headers)
+print (r.text)