@enmeshed/mesh-reflection

Allows members of a service mesh to obtain information about the available services in the mesh.

Architecture

Domain

All activity takes place in a ReflectionDomain, which is a root-level container for all of the below-mentioned resources.

API

import { ReflectionDomain } from '@enmeshed/mesh-reflection'

new ReflectionDomain(dataSource: DataSource)

Construct a new ReflectionDomain whose contents are provided by the given source.

environment: Environment = domain.getEnvironment(name: string)

Retrieves a named Environment contained within the domain.

DataSource

The domain has exactly one DataSource. A DataSource collects data from the cluster and prepares a collection of Resources that are available for consumers to inspect. The DataSource writes these resources into a local, non-persistent store contained within the domain. Only the DataSource is allowed to mutate the store, so a correctly implemented DataSource can guarantee consumers have a consistent view of the resources in the mesh.

Environment

Each domain has zero or more Environments identified by string names unique within the domain. An Environment is in turn a container for Resources which can be configured differently for each Environment. (Examples of Environments might be staging and live, where services would be configured differently for each.)

The Environment also contains a map associating each Service with zero or one Providers. This allows consumers to locate and connect to services on the mesh.

Consumers may enumerate and query resources, as well as listen for changes with node EventEmitter api. Further details below.

Resource

Resources come in two kinds, Services and Providers. Resources are identified by a string name which must be unique across the domain among resources of the same kind. Each Resource carries with it an arbitrary JSON metadata payload.

This library is unopinionated about the contents of the payload, but typically a Service would contain information about how it is expected to communicate with that service (for example, a service might idenitfy itself as gRPC and provide a list of acceptable protocol buffers) and a Provider would contain information about where to find that service (e.g. a cluster DNS address of the gRPC server)