legion-discovery

A simple service discovery service based on Legion, that natively supports the idea of interface versions, and the idea that clients may only be interested in finding certain (compatible) versions of the services they are looking for.

The initial motivation for this project is to act as a test driver for the Legion framework. Since the status of that framework is still experimental, the status of this service is also experimental.

• API
  • POST /v1/ping
  • GET /v1/services/:serviceId
  • GET /v1/services/:serviceId/:versionRange
  • GET /v1/graph
• Content Types
  • application/vnd.legion-discovery.instance-list+json
  • application/vnd.legion-discovery.ping-request+json

API

POST /v1/ping

Register a service. The service name and version are obtained via the User-Agent header field. Registration expires in 30 seconds.

• Request
  • Content-Type: application/vnd.legion-discovery.ping-request+json
  • Headers:
    • User-Agent: The User-Agent request header is mandatory, and must conform to the grammar specified in RFC-2616 and, further, must provide the product version that RFC-2616 describes as optional.
• Response 204 No Content: indicates a successful registration.

GET /v1/services/:serviceId

Returns all current instances of a service, regardless of version.

• Request

  • Headers:
    • User-Agent: The User-Agent request header is mandatory, and must conform to the grammar specified in RFC-2616

• Response 200 Ok

  • Content-Type: application/vnd.legion-discovery.instance-list+json

GET /v1/services/:serviceId/:versionRange

Returns the service instances that match the requested version range. The version range syntax is the same as what cabal understands (e.g. >= 0.1 && < 0.2). You are really going to want to make sure and url encode this segment of the url.

• Request

  • Headers:
    • User-Agent: The User-Agent request header is mandatory, and must conform to the grammar specified in RFC-2616

• Response 200 Ok

  • Content-Type: application/vnd.legion-discovery.instance-list+json

GET /v1/graph

Returns a visualization of the service interactions. This endpoint supports multiple content types via the Accept header.

• Response 200 Ok
  • Content-Type image/svg+xml
  • Content-Type text/vnd.graphviz

Content Types

application/vnd.legion-discovery.instance-list+json

{
    "https://host1:8080": {
        "version": "1.0.2.0"
    },
    "https://host2:8080": {
        "version": "1.0.2.0"
    },
    "https://host3:8080": {
        "version": "1.0.2.0"
    }
}

application/vnd.legion-discovery.ping-request+json

{
    "serviceAddress": "https://host3:8080"
}