Shell Script to simulate API requests for Load Tests

You can use below shell script to simulate a pre-defined load on an API.

       
#!/bin/bash

#########################################################
# This is simple shell script to simulate API load      #
# for given duration                                    #
# Eg: DURATION=60 and TPS=20, This script will trigger  #
# 20 requests per second for 1 minute.                  #
#########################################################


#define variables

set -x # run in debug mode
DURATION=60 # how long should load be applied ? - in seconds
TPS=20 # number of requests per second
end=$((SECONDS+$DURATION))

#start load
while [ $SECONDS -lt $end ];
do
    for ((i=1;i<=$TPS;i++)); do
        curl -X POST  -H 'Accept: application/json' -H 'Authorization: Bearer xxxxxxxxxxxxx' -H 'Content-Type: application/json' -d '{}' --cacert /path/to/cert/cert.crt -o /dev/null -s -w '%{time_starttransfer}\n' >> response-times.log &
    done
    sleep 1
done
wait

#end load
echo "Load test has been completed" 
       

Download the script from here.

Here while loop is to run this load for given time period
for loop is to fire given number of requests per second
cacert is optional - only used for https request, you can use -k option as well
-o /dev/null is to write the output to empty
-s is to silence the process
-w '%{timestarttransfer}%' is to retrieve the response time. This time will be written to a file
this request will run in background and script will initiate next request.

HTTPS connection using CURL command

When you need to try HTTP connection using CURL command you will return below error,

* Issuer certificate is invalid: 
* NSS error -8156
* Closing connection

Here you need to specify the cert in curl command using --cacert. before that you need to get the cert for your server. You can try below command to get cert.

openssl s_client -connect <host>:<port>

Eg: openssl s_client -connect localhost:8243

Now you can see the ssl certificate. You can extract the text between "-----BEGIN CERTIFICATE-----" and "-----END CERTIFICATE-----" including these two line and save as ssl.crt.

Now you can trigger HTTPS request according to below format

curl -X POST https://localhost:8243/xxxx/v1/test  -d '{}' --cacert /path/to/ssl.crt

Find if a SSL certificate is self signed or CA signed

Try below command for .pem certificate file

       
openssl x509 -in certificate.pem -inform PEM -noout -subject -issuer
       

If subject and issuer are same : It is self signed certificate
If subject and issuer are different : It is CA signed certificate and issuer will be CA

Simple HTTP Listener using Python

Here is a simple HTTP listener using Python BaseHTTPRequestHandler 
This Application will,

• listen to port 8000 on localhost
• respond to REST POST request 

from BaseHTTPServer import BaseHTTPRequestHandler
import urlparse, json
import shutil
import os

class GetHandler(BaseHTTPRequestHandler):

	def do_POST(self):

		content_len = int(self.headers.getheader('content-length'))
		req_token = self.headers.get('Authorization')
		post_body = self.rfile.read(content_len)
		data = json.loads(post_body)
		user_id = data['id']
		user_name = data['name']
		
		print ("Token "+str(req_token))
		print ("User Id "+str(user_id))
		print ("User Name "+str(user_name))
		 
		#Do something here
		
		self.send_response(200)
		return

if __name__ == '__main__':
	from BaseHTTPServer import HTTPServer
	server = HTTPServer(('localhost', 8000), GetHandler)
	print 'Starting server at http://localhost:8009'
	server.serve_forever()

    
 

Save the content as simple_http_server.py

Start Application : python simple_http_server.py

Sample Request:

curl -v -X POST -H 'Authorization: Bearer gcfdgckuyebku7t56FHGVBKJHKJTY6' -d '{"id":"1234","name":"Hasitha"}' http://localhost:8000

Sample Response:

* Rebuilt URL to: http://localhost:8000/
*   Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 8000 (#0)
> POST / HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/7.47.0
> Accept: */*
> Authorization: Bearer gcfdgckuyebku7t56FHGVBKJHKJTY6
> Content-Length: 30
> Content-Type: application/x-www-form-urlencoded
> 
* upload completely sent off: 30 out of 30 bytes
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Server: BaseHTTP/0.3 Python/2.7.12
< Date: Mon, 13 Aug 2018 15:21:06 GMT

* Closing connection 0

Application Logs:

Starting server at http://localhost:8000
Token Bearer gcfdgckuyebku7t56FHGVBKJHKJTY6
User Id 1234
User Name Hasitha

127.0.0.1 - - [13/Aug/2018 15:21:06] "POST / HTTP/1.1" 200 -