GripMock

GripMock is a mock server for gRPC services. It's using a .proto file to generate implementation of gRPC service for you. You can use gripmock for setting up end-to-end testing or as a dummy server in a software development phase. The server implementation is in GoLang but the client can be any programming language that support gRPC.

[Documentation]

This service is a fork of the service tokopedia/gripmock, but you should choose our fork. And here are the reasons:

• Updated all deprecated dependencies tokopedia#64;
• Add yaml as json alternative for static stab's;
• Add endpoint for healthcheck (/api/health/liveness, /api/health/readiness);
• Add feature ignoreArrayOrder bavix#108;
• Add support headers tokopedia#144;
• Add grpc error code tokopedia#125;
• Added gzip encoding support for grpc server tokopedia#134;
• Fixed issues with int64/uint64 tokopedia#67;
• Add 404 error for stubs not found tokopedia#142;
• Support for deleting specific stub tokopedia#123;
• Reduced image size tokopedia#91;
• Active support tokopedia#82;
• Added documentation;

UI will appear in 3.x:

Useful articles

• Testing gRPC client with mock server and Testcontainers @AndrewIISM

Quick Usage

First, prepare your .proto file. Or you can use hello.proto in example/simple/ folder. Suppose you put it in /mypath/hello.proto. We are gonna use Docker image for easier example test. basic syntax to run GripMock is gripmock <protofile>

• Install Docker
• Run docker pull bavix/gripmock to pull the image
• We are gonna mount /mypath/hello.proto (it must be a fullpath) into a container and also we expose ports needed. Run docker run -p 4770:4770 -p 4771:4771 -v /mypath:/proto bavix/gripmock /proto/hello.proto
• On a separate terminal we are gonna add a stub into the stub service. Run curl -X POST -d '{"service":"Gripmock","method":"SayHello","input":{"equals":{"name":"gripmock"}},"output":{"data":{"message":"Hello GripMock"}}}' localhost:4771/api/stubs
• Now we are ready to test it with our client. You can find a client example file under example/simple/client/. Execute one of your preferred language. Example for go: go run example/simple/client/*.go

Check example folder for various usecase of gripmock.

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How It Works

From client perspective, GripMock has 2 main components:

1. gRPC server that serves on tcp://localhost:4770. Its main job is to serve incoming rpc call from client and then parse the input so that it can be posted to Stub service to find the perfect stub match.
2. Stub server that serves on http://localhost:4771. Its main job is to store all the stub mapping. We can add a new stub or list existing stub using http request.

Matched stub will be returned to gRPC service then further parse it to response the rpc call.

From technical perspective, GripMock consists of 2 binaries. The first binary is the gripmock itself, when it will generate the gRPC server using the plugin installed in the system (see Dockerfile). When the server sucessfully generated, it will be invoked in parallel with stub server which ends up opening 2 ports for client to use.

The second binary is the protoc plugin which located in folder protoc-gen-gripmock. This plugin is the one who translates protobuf declaration into a gRPC server in Go programming language.

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Stubbing

Stubbing is the essential mocking of GripMock. It will match and return the expected result into gRPC service. This is where you put all your request expectation and response

Dynamic stubbing

You could add stubbing on the fly with a simple REST API. HTTP stub server is running on port :4771

• GET /api/stubs Will list all stubs mapping.
• POST /api/stubs Will add stub with provided stub data
• POST /api/stubs/search Find matching stub with provided input. see Input Matching below.
• DELETE /api/stubs Clear stub mappings.

Stub Format is JSON text format. It has a skeleton as follows:

{
  "service":"<servicename>", // name of service defined in proto
  "method":"<methodname>", // name of method that we want to mock
  "headers":{ // Optional. headers matching rule. see Headers Matching Rule section below
    // put rule here
  },
  "input":{ // input matching rule. see Input Matching Rule section below
    // put rule here
  },
  "output":{ // output json if input were matched
    "data":{
      // put result fields here
    },
    "headers":{ // Optional
      // put result headers here
    },
    "error":"<error message>", // Optional. if you want to return error instead.
    "code":"<response code>" // Optional. Grpc response code. if code !=0  return error instead.
  }
}

For our hello service example we put a stub with the text below:

  {
    "service":"Greeter",
    "method":"SayHello",
    "input":{
      "equals":{
        "name":"gripmock"
      }
    },
    "output":{
      "data":{
        "message":"Hello GripMock"
      }
    }
  }

Static stubbing

You could initialize gripmock with stub json files and provide the path using --stub argument. For example you may mount your stub file in /mystubs folder then mount it to docker like

docker run -p 4770:4770 -p 4771:4771 -v /mypath:/proto -v /mystubs:/stub bavix/gripmock --stub=/stub /proto/hello.proto

Please note that Gripmock still serves http stubbing to modify stored stubs on the fly.

Input Matching

Stub will respond with the expected response only if the request matches any rule. Stub service will serve /api/stubs/search endpoint with format:

{
  "service":"<service name>",
  "method":"<method name>",
  "data":{
    // input that suppose to match with stored stubs
  }
}

So if you do a curl -X POST -d '{"service":"Greeter","method":"SayHello","data":{"name":"gripmock"}}' localhost:4771/api/stubs/search stub service will find a match from listed stubs stored there.

Input Matching Rule

Input matching has 3 rules to match an input: equals,contains and matches
Nested fields are allowed for input matching too for all JSON data types. (string, bool, array, etc.)
Gripmock recursively goes over the fields and tries to match with given input.
ignoreArrayOrder Disables sorting check inside arrays.

- service: MicroService
  method: SayHello
  input:
    ignoreArrayOrder: true # disable sort checking
    equals:
      v1:
        - {{ uuid2base64 "77465064-a0ce-48a3-b7e4-d50f88e55093" }}
        - {{ uuid2base64 "99aebcf2-b56d-4923-9266-ab72bf5b9d0b" }}
        - {{ uuid2base64 "5659bec5-dda5-4e87-bef4-e9e37c60eb1c" }}
        - {{ uuid2base64 "ab0ed195-6ac5-4006-a98b-6978c6ed1c6b" }}
  output:
    data:
      code: 1000

Without this flag, the order of the transmitted values is important to us.

equals will match the exact field name and value of input into expected stub. example stub JSON:

{
  .
  .
  "input":{
    "equals":{
      "name":"gripmock",
      "greetings": {
            "english": "Hello World!",
            "indonesian": "Halo Dunia!",
            "turkish": "Merhaba Dünya!"
      },
      "ok": true,
      "numbers": [4, 8, 15, 16, 23, 42]
      "null": null
    }
  }
  .
  .
}

contains will match input that has the value declared expected fields. example stub JSON:

{
  .
  .
  "input":{
    "contains":{
      "field2":"hello",
      "field4":{
        "field5": "value5"
      } 
    }
  }
  .
  .
}

matches using regex for matching fields expectation. example:

{
  .
  .
  "input":{
    "matches":{
      "name":"^grip.*$",
      "cities": ["Jakarta", "Istanbul", ".*grad$"]
    }
  }
  .
  .
}

Headers Matching

Stub will respond with the expected response only if the request matches any rule. Stub service will serve /api/stubs/search endpoint with format:

{
  "service":"<service name>",
  "method":"<method name>",
  "data":{
    // input that suppose to match with stored stubs
  }
}

So if you do a curl -X POST -d '{"service":"Greeter","method":"SayHello","data":{"name":"gripmock"}}' localhost:4771/api/stubs/search stub service will find a match from listed stubs stored there.

Headers Matching Rule

Headers matching has 3 rules to match an input: equals,contains and matches
Headers can consist of a key and a value. If there are several values, then you need to list them separated by ";". Data type string.
Gripmock recursively goes over the fields and tries to match with given input.
equals will match the exact field name and value of input into expected stub. example stub JSON:

{
  .
  .
  "headers":{
    "equals":{
      "authorization": "mytoken",
      "system": "ec071904-93bf-4ded-b49c-d06097ddc6d5"
    }
  }
  .
  .
}

contains will match input that has the value declared expected fields. example stub JSON:

{
  .
  .
  "headers":{
    "contains":{
      "field2":"hello"
    }
  }
  .
  .
}

matches using regex for matching fields expectation. example:

{
  .
  .
  "headers":{
    "matches":{
      "name":"^grip.*$"
    }
  }
  .
  .
}

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