Hamms is designed to elicit failures in your HTTP Client. Connection failures, malformed response data, slow servers, fat headers, and more!
You can either install hamms via pip:
pip install hamms
Or clone this project:
git clone https://github.com/kevinburke/hamms.git
-
Start hamms by running it from the command line:
python -m hamms
Or use the HammsServer class to start and stop the server on command.
from hamms import HammsServer class MyTest(object): def setUp(self): self.hs = HammsServer() self.hs.start(beginning_port=5500) def tearDown(self): self.hs.stop()
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Make requests and test your client. See the reference below for a list of supported failure modes.
By default, Hamms uses ports 5500-5600. You can customize the port range by
passing the beginning_port
parameter to HammsServer.start()
.
Connect to the ports listed below to enact the various failure modes.
-
5500 - Nothing is listening on the port. Note, your machine will likely send back a TCP reset (closing the connection) immediately.
To simulate a connection failure that just hangs forever (a connection timeout), connect to a bad host on a real server, for example
www.google.com:81
, or use a port in the10.*
range, for example10.255.255.1
. -
5501 - The port accepts traffic but never sends back data
-
5502 - The port sends back an empty string immediately upon connection
-
5503 - The port sends back an empty string after the client sends data
-
5504 - The port sends back a malformed response ("foo bar") immediately upon connection
-
5505 - The port sends back a malformed response ("foo bar") after the client sends data
-
5506 - The client accepts the request, and sends back one byte every 5 seconds
-
5507 - The client accepts the request, and sends back one byte every 30 seconds
-
5508 - Send a request to
localhost:5508?sleep=<float>
to sleep forfloat
number of seconds. If no value is provided, sleep for 5 seconds. -
5509 - Send a request to
localhost:5509?status=<int>
to return a response with HTTP status codestatus
. If no value is provided, return status code 200. -
5510 - The server will send a response with a
Content-Length: 3
header, however the response is actually 1 MB in size. This can break clients that reuse a socket. -
5511 - Send a request to
localhost:5511?size=<int>
to return aCookie
header that isn
bytes long. By default, return a 63KB header. 1KB larger will break many popular clients (curl, requests, for example) -
5512 - Use this port to test retry logic in your client - to ensure that it retries on failure.
The server maintains a counter for incoming requests. Each time a new request is made, a 500 error is served and the counter is decremented. When the counter reaches zero, a 200 response is served. This server accepts two query arguments:
- key - Specify a
key
to create a new counter. Continue making requests withkey=<key>
to decrement that particular counter. If no key is provided, 'default' is used. - tries - Specify the number of tries before success, as an integer. If no number is provided, you will get a success on the 3rd try.
The server will let you know the key and how many tries are remaining until you get a successful response. Example error response:
HTTP/1.1 500 INTERNAL SERVER ERROR Content-Length: 116 Content-Type: application/json Date: Wed, 19 Nov 2014 00:59:19 GMT Server: TwistedWeb/14.0.2 { "error": "The server had an error. Try again 1 more time", "key": "foobar", "success": false, "tries_remaining": 1 }
Example usage:
r = requests.get('http://localhost:5512?key=special-key') assert_equal(r.status_code, 500) r = requests.get('http://localhost:5512?key=special-key') assert_equal(r.status_code, 500) # Third time is the charm r = requests.get('http://localhost:5512?key=special-key') assert_equal(r.status_code, 200) # Set tries=1 to serve a 200 right away. r = requests.get('http://localhost:5512?key=my-key&tries=1') assert_equal(r.status_code, 200)
You can see the status of all available counters by making a GET request to
http://localhost:5512/counters
, or reset a counter by making a POST request tohttp://localhost:5512/counters
with thekey
you want to reset. - key - Specify a
-
5513 - Send a request to
localhost:5513?failrate=<float>
. The server will drop requests with a frequency offailrate
. -
5514 - The server will try as hard as it can to return a content type that is not parseable by the
Accept
header provided by the request. Specify aAccept: application/json
header in your request and the server will return data with thetext/morse
content type. The server will try these content-types in turn: -
text/morse
-
application/json
-
text/html
-
text/csv
If your Accept header indicates it can accept all of these content-types, the
server will return text/morse
.
-
5515 - The server will return a response with a content-type that matches the request, but it will be incomplete. The server will advertise an incorrect, too long Content-Length, and the response body will not be complete. The practical effect is that the server will hang halfway through the response download. The server can return partial responses with the following content-types:
-
application/json
-
text/html
-
text/plain
-
text/xml
If your server indicates an Accept header value of */*
, or the server cannot
find a matching content-type, the server will returnn an incomplete json
response.
- 5516 - Same semantics as port 5515, but the server will close the connection partway through, instead of hanging indefinitely.
- The server sends back a response without a content-type
- The server sends back a response with the wrong content-type
- The server randomly drops bytes from a valid response.
- Sending back byte data
- Handshake timeout
- Invalid certificate
- TLS v1.0 and higher only
- TLS v1.2 and higher only
- Server closes connection
Donations free up time to make improvements to the library, and respond to bug reports. You can send donations via Paypal's "Send Money" feature to [email protected]. Donations are not tax deductible in the USA.