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Pact server

The pact server is a stand-alone interactions recorder and verifier, aimed at clients that are non-JVM or non-Ruby based.

The pact client for that platform will need to be implemented, but it only be responsible for generating the JSON interactions, running the tests and communicating with the server.

The server implements a JSON REST Admin API with the following endpoints.

/         -> For diagnostics, currently returns a list of ports of the running mock servers.
/create   -> For initialising a test server and submitting the JSON interactions. It returns a port
/complete -> For finalising and verifying the interactions with the server.  It writes the `JSON` pact file to disk.

Running the server

Versions 2.2.6+

Pact server takes the following parameters:

Usage: pact-jvm-server [options] [port]

        port to run on (defaults to 29999)
        prints this usage text
  -h <value> | --host <value>
        host to bind to (defaults to localhost)
  -l <value> | --mock-port-lower <value>
        lower bound to allocate mock ports (defaults to 20000)
  -u <value> | --mock-port-upper <value>
        upper bound to allocate mock ports (defaults to 40000)
  -d | --daemon
        run as a daemon process
  -v <value> | --pact-version <value>
        pact version to generate for (2 or 3)
  -k <value> | --keystore-path <value>
        Path to keystore
  -p <value> | --keystore-password <value>
        Keystore password
  -s <value> | --ssl-port <value>   
        Ssl port the mock server should run on. lower and upper bounds are ignored
        run with debug logging

Using trust store 3.4.0+

Trust store can be used. However, it is limited to a single port for the time being.

Prior to version 2.2.6

Pact server takes one optional parameter, the port number to listen on. If not provided, it will listen on 29999. It requires an active console to run.

Using a distribution archive

You can download a distribution from maven central. There is both a ZIP and TAR archive. Unpack it to a directory of choice and then run the script in the bin directory.

Building a distribution bundle

You can build an application bundle with gradle by running (for 2.11 version):

$ ./gradlew :pact-jvm-server_2.11:installdist

This will create an app bundle in build/2.11/install/pact-jvm-server_2.11. You can then execute it with:

$ java -jar pact-jvm-server/build/2.10/install/pact-jvm-server_2.11/lib/pact-jvm-server_2.11-3.2.11.jar

or with the generated bundle script file:

$ pact-jvm-server/build/2.11/install/pact-jvm-server_2.11/bin/pact-jvm-server_2.11

By default will run on port 29999 but a port number can be optionally supplied.

Running it with docker

You can use a docker image to execute the mock server as a docker container.

$ docker run -d -p 8080:8080 -p 20000-20010:20000-20010 uglyog/pact-jvm-server

This will run the main server on port 8080, and each created mock server on ports 20000-20010. You can map the ports to any you require.

Life cycle

The following actions are expected to occur

  • The client calls /create to initialise a server with the expected JSON interactions and state
  • The admin server will start a mock server on a random port and return the port number in the response
  • The client will execute its interaction tests against the mock server with the supplied port
  • Once finished, the client will call `/complete' on the Admin API, posting the port number
  • The pact server will verify the interactions and write the JSON pact file to disk under /target
  • The mock server running on the supplied port will be shutdown.



The client will need POST to /create the generated JSON interactions, also providing a state as a query parameter and a path.

For example:

POST http://localhost:29999/create?state=NoUsers&path=/sub/ref/path '{ "provider": { "name": "Animal_Service"}, ... }'

This will create a new running mock service provider on a randomly generated port. The port will be returned in the 201 response:

{ "port" : 34423 }

But you can also reference the path from /sub/ref/path using the server port. The service will not strip the prefix path, but instead will use it as a differentiator. If your services do not have differences in the prefix of their path, then you will have to use the port method.


Once the client has finished running its tests against the mock server on the supplied port (in this example port 34423) the client will need to POST to /complete the port number of the mock server that was used.

For example:

POST http://localhost:29999/complete '{ "port" : 34423 }'

This will cause the Pact server to verify the interactions, shutdown the mock server running on that port and writing the pact JSON file to disk under the target directory.


The / endpoint is for diagnostics and to check that the pact server is running. It will return all the currently running mock servers port numbers.

For example:

GET http://localhost:29999/

    '{ "ports": [23443,43232] }'
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