🚇 metro

Fast and reliable message transport between microservices!

🚧 Disclaimer: metro is under active development currently. The first release is expected soon. Watch this space for updates.

What is metro?

metro is an asynchronous pub-sub messaging platform that decouples producers and consumers of messages and forms the backbone for event-driven applications. metro offers durable message storage and real-time message delivery with high availability, fault-tolerance and consistent performance at scale.

Local setup

Clone the repo with submodules

git clone --recurse-submodules -j8 https://github.com/razorpay/metro
cd metro

Building the binary

Install dependencies

make deps

Generate go bindings from proto definitions

make proto-generate

Build the binary

make go-build-metro

The binary can be found at bin/ directory

Running the binary

Before running metro components, bring up the dependent datastores

make dev-docker-datastores-up

The datastores can be brough down as well with this command

make dev-docker-datastores-down

Various metro components can now be run. metro has 4 components, all components are part of same binary and can be ran using a cmd param component

Running Metro Web component

bin/metro -component web

Running Metro Worker component

bin/metro -component worker

Running OpenAPI Server

bin/metro -component openapi-server

Building the metro docker image

After cloning the repository, run

make docker-build-metro

Running metro docker image

The first step is to bring the dependent datastores up (kafka, zookeeper, consul and pulsar)

make dev-docker-datastores-up

The metro image along with the monitoring stack, prometheus and jaeger, can be run as

make dev-docker-up

To bring the setup down

 make dev-docker-down

To rebuild

make dev-docker-rebuild

Running metro components WITHOUT docker

Make sure dependents datastores(consul, kafka, zookeeper) are running and accessible via localhost. Refer above section on how to bring up datastores using docker.

Copy dev.toml.sample to dev.toml

 cp config/dev.toml.sample config/dev.toml

Run metro web

 make dev-up app=web

Run metro worker

make dev-up app=worker 

Contributing guidelines

Style checking and unit tests

metro runs unit tests, golint and goimports check in the continuous integration (CI) pipeline.

You can locally test these changes by running the following make targets

golint check

make lint-check

goimports check

make goimports-check

You can also apply goimports changes locally by doing the following

make goimports

Running unit tests

make test-unit

Integration tests

Integration tests are run as part of continuous integration on github actions. They test end to end integration of various metro components along with datastores.

Integration tests can also be run locally

Before running them locally, make sure metro is running locally. After which, run the following make target

make test-integration

Compatibility tests

Compatibility tests are also run as part of continuous integration to test compatibility against google pub/sub.

To run them locally, make sure metro is running locally along with google pub/sub emulator.

To bring up the google pub/sub emulator, run the following

make dev-docker-emulator-up

After which, run the following make target

make test-compat

Updating the metro-proto submodule

To update the submodule to the latest remote commit

git submodule update --remote --merge

Accessing the APIs

The default ports for various services in metro

• gRPC endpoint on port 8081
• grpc-gateway HTTP endpoint on port 8082
• swagger docs on port 3000