gRoxy is a gRPC mocking server that allows you to mock gRPC services and responses easily by specifying the message content alongside the message definition. gRoxy is designed to be used in development and testing environments to help you test your gRPC clients and services without having to rely on the actual gRPC server.

---

• todos
• installation
• usage
  • example
  • configuration
  • groxypb
    • nested messages
    • enums
    • repeated fields
    • maps
• project status

todos

• currently service supports only mocking unary methods, but we plan to support streaming methods as well
• serving the gRPC reflection service
• support for the gRPC health check service
• passthrough mode for proxying and modifying real gRPC services

installation

You can install gRoxy using the following command:

go install github.com/Semior001/groxy/cmd/groxy@latest

Or you can pull the docker image from ghcr.io:

docker pull ghcr.io/semior001/groxy:latest

Or from the docker hub:

docker pull semior/groxy:latest

usage

Usage:
  groxy [OPTIONS]

Application Options:
  -a, --addr=                Address to listen on (default: :8080) [$ADDR]
      --json                 Enable JSON logging [$JSON]
      --debug                Enable debug mode [$DEBUG]

file:
      --file.name=           Config file name (default: groxy.yml) [$FILE_NAME]
      --file.check-interval= Check interval for the config file (default: 3s) [$FILE_CHECK_INTERVAL]
      --file.delay=          Delay before applying the changes (default: 500ms) [$FILE_DELAY]

Help Options:
  -h, --help                 Show this help message

example

The simplest configuration for a method "Stub" would look like this:

version: 1

rules:
  - match: { uri: "com.github.Semior001.groxy.example.mock.ExampleService/Stub" }
    respond:
      body: |
        message StubResponse {
            option              (groxypb.target) = true; // this option specifies that the message is a response 
            string message = 1 [(groxypb.value)  = "Hello, World!"];
            int32 code     = 2 [(groxypb.value)  = "200"];
        }

That's it. You just need to define the response message, mark it as a target response message via the option, and set values via the value option. The response message will be sent to the client when the client calls the "Stub" method. No need for providing protosets, no need for providing the whole set of definitions, just the message you want to send.

More importantly, if your response message contains lots of fields, which are not important for the test, you can just ignore them. gRoxy will leave them empty, and the client will not be able to distinguish between the real server and the mock server. That's ensured by the protobuf's backward compatibility.

Field is backward compatible if it's of the same type and the same number. Names of the fields and messages are not important.

configuration

gRoxy uses a YAML configuration file to define the rules for the gRPC mocking server. The configuration file consists of the following sections:

Section	Description
version	The version of the configuration file. The current version is 1, and any other version will raise an error.
not-matched	The not-matched section contains the default response if the request didn't match to any rule. Not-matched section may contain a request body, or a gRPC status. See respond type section
rules	The rules section contains the rules for the gRPC mocking server.

Rules are defined in the rules section. Each rule consists of the following fields:

Field	Required	Description
match	true	The match section contains the matchers for the request.
match.uri	true	The URI matcher for the request. The URI matcher is a regular expression that matches the URI of the request.
match.header	optional	a map of headers that should be present in the request.
match.body	optional	The body matcher for the request. This must be a protobuf snippet that defines the request message with values to be matched.
respond	true	The respond section contains the response for the request.

The Respond section contains the response for the request. The respond section may contain the following fields:

Field	Required	Description
body	optional	The body of the response. This must be a protobuf snippet that defines the response message with values to be sent.
metadata	optional	The metadata to be sent as a response.
status	optional	The gRPC status to be sent as a response.
status.code	true, if status is present	The gRPC status code to be sent as a response.
status.msg	true, if status is present	The gRPC status message to be sent as a response.

The configuration file is being watched for changes, and the server will reload the configuration file if it changes.

You can also take a look at examples for more information.

groxypb

gRoxy uses the groxypb annotations to define values in protobuf message snippets. It compiles protobuf in a runtime, checking the target via the groxypb.target option and interpreting values via the groxypb.value option.

Example of the snippet:

message SomeMessage {
    option              (groxypb.target) = true; 
    string message = 1 [(groxypb.value) = "Hello, World!"];
    int32 code = 2     [(groxypb.value) = "200"];
}

nested messages

In case of nested messages, there are two options how to set values:

1. Set the value in the nested message:

message SomeMessage {
    option                    (groxypb.target) = true; 
    string parent_value = 1   [(groxypb.value) = "parent"];
    NestedMessage nested = 2;
}

message NestedMessage {
    string nested_value = 1 [(groxypb.value) = "nested"];
}

2. Set the JSON value in the annotation to the parent's field:

message SomeMessage {
    option                    (groxypb.target) = true; 
    string parent_value = 1  [(groxypb.value) = "parent"];
    NestedMessage nested = 2 [(groxypb.value) = "{\"nested_value\": \"nested\"}"];
}

enums

For enums, the value should be set as a string name of the enum value:

enum SomeEnum { 
    EMPTY = 0; 
    NEEDED_VALUE = 2; 
}

message StubResponse {
    option (groxypb.target) = true;
    SomeEnum some_enum = 9 [(groxypb.value) = 'NEEDED_VALUE'];
}

repeated fields

For repeated fields, the value should be set as a JSON array of the values:

message StubResponse {
    option (groxypb.target) = true;
    repeated string repeated_field = 1 [(groxypb.value) = '["value1", "value2"]'];
}

maps

For maps, the value should be set as a JSON object of the key-value pairs:

message StubResponse {
    option (groxypb.target) = true;
    map<string, string> map_field = 1 [(groxypb.value) = '{"key1": "value1", "key2": "value2"}'];
}

status

The project is currently in active development, and breaking changes may occur until the release of version 1.0. However, we strive to minimize disruptions and will only introduce breaking changes when there is a compelling reason to do so.