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zazkia is a tool that simulates all kinds of connection problems with a tcp connection (reset,delay,throttle,corrupt).

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How does it work ?

In order to apply misbehavior, zazkia must be used as a proxy between a client and service. It will accept tcp connections from a client and for each new one, will create a connection to the target service.


By specifying routes, you can tell zazkia on what ports to listen and what target to connect to (host and port).

Minimal zazkia-routes.json example

        "label": "oracle",
        "service-hostname": "",
        "service-port": 1521,
        "listen-port": 49997

With this route definition, your application should use "localhost:49997" instead of "" in the connection specification. Your application (the client) will setup a tcp connection with zazkia which will setup another tcp connection to oracle (the service).

Initial transport behavior

The transport part of a route configuration can be used to setup the initial behavior of a new connection pair (called link). Using a REST api, the transport behavior can be changed on a per-link basis.

Full zazkia-routes.json example

        "label": "postgresql",
        "service-hostname": "",
        "service-port": 5432,
        "listen-port": 49998,
        "transport": {
			"accept-connections": true,
			"throttle-service-response": 1000,
			"delay-service-response": 100,
			"service-response-corrupt-method": "randomize",
			"sending-to-client": true,
			"receiving-from-client": true,
			"sending-to-service": true,
			"receiving-from-service": true,
			"verbose": true
transport property comment effective values
accept-connections whether connections from the client are accepted true, false
throttle-service-response bytes per second non-negative integer
delay-service-response milliseconds delay non-negative integer
service-response-corrupt-method how the bytes are mangled empty, randomize
sending-to-client whether a response from the service is sent back to the client true, false
receiving-from-client whether a request from the client is read true, false
sending-to-service whether a request from the client is sent to the service true, false
receiving-from-service whether a response from the service is read true, false
verbose log each message that is transported between client and service true, false

Default transport behavior

"transport": {
	"accept-connections": true,
	"throttle-service-response": 0,
	"delay-service-response": 0,
	"service-response-corrupt-method": "",
	"sending-to-client": true,
	"receiving-from-client": true,
	"sending-to-service": true,
	"receiving-from-service": true,
	"verbose": false


To build the project locally and test it.

go get -u

Make sure $GOPATH/bin is on your $PATH.

go generate
go test
go build


Defaults (-p 9191 -f zazkia-routes.json)



A simple HTML dashboard is available to change the transport behavior of individual links. See the Swagger tab for documentation of the REST API.



A Docker image is available on Docker Hub.


docker run -d -p 9200-9300:9200-9300 -p 9191:9191 -v $(pwd):/data emicklei/zazkia

Zazkia will look for a file called zazkia-routes.json. The web UI will be running on http://localhost:9191 When using Docker, routes must use listener ports in the range 9200-9300 or 3306 (mysql) or 5432 (postgres) or 8080 (tomcat,jboss).


See the examples folder for simple usecase examples.

Build your own image

GOOS=linux go build && docker build -t emicklei/zazkia:latest .

© 2017, Apache v2 License. Contributions welcome.

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