Go Micro 
Go Micro is a standard library for microservices.
Overview
Go Micro provides the core requirements for distributed systems development including RPC and Event driven communication. The Micro philosophy is sane defaults with a pluggable architecture. We provide defaults to get you started quickly but everything can be easily swapped out.
Features
Go Micro abstracts away the details of distributed systems. Here are the main features.
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Authentication - Auth is built in as a first class citizen. Authentication and authorization enable secure zero trust networking by providing every service an identity and certificates. This additionally includes rule based access control.
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Dynamic Config - Load and hot reload dynamic config from anywhere. The config interface provides a way to load application level config from any source such as env vars, file, etcd. You can merge the sources and even define fallbacks.
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Data Storage - A simple data store interface to read, write and delete records. It includes support for memory, file and CockroachDB by default. State and persistence becomes a core requirement beyond prototyping and Micro looks to build that into the framework.
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Service Discovery - Automatic service registration and name resolution. Service discovery is at the core of micro service development. When service A needs to speak to service B it needs the location of that service. The default discovery mechanism is multicast DNS (mdns), a zeroconf system.
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Load Balancing - Client side load balancing built on service discovery. Once we have the addresses of any number of instances of a service we now need a way to decide which node to route to. We use random hashed load balancing to provide even distribution across the services and retry a different node if there's a problem.
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Message Encoding - Dynamic message encoding based on content-type. The client and server will use codecs along with content-type to seamlessly encode and decode Go types for you. Any variety of messages could be encoded and sent from different clients. The client and server handle this by default. This includes protobuf and json by default.
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gRPC Transport - gRPC based request/response with support for bidirectional streaming. We provide an abstraction for synchronous communication. A request made to a service will be automatically resolved, load balanced, dialled and streamed.
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Async Messaging - PubSub is built in as a first class citizen for asynchronous communication and event driven architectures. Event notifications are a core pattern in micro service development. The default messaging system is a HTTP event message broker.
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Synchronization - Distributed systems are often built in an eventually consistent manner. Support for distributed locking and leadership are built in as a Sync interface. When using an eventually consistent database or scheduling use the Sync interface.
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Pluggable Interfaces - Go Micro makes use of Go interfaces for each distributed system abstraction. Because of this these interfaces are pluggable and allows Go Micro to be runtime agnostic. You can plugin any underlying technology. Find plugins in github.com/micro/go-plugins.
Getting Started
See pkg.go.dev for usage.
License
Go Micro is Apache 2.0 licensed.