diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,82 @@ +# 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](https://github.com/owensmurray/legion#readme) framework. Since the +status of that framework is still experimental, the status of this service is +also experimental. + +- [API](#api) + - [`POST /v1/ping/:serviceId/:version`](#post-v1pingserviceidversion) + - [`GET /v1/services/:serviceId`](#get-v1servicesserviceid) + - [`GET /v1/services/:serviceId/:versionRange`](#get-v1servicesserviceidversionrange) + - [`GET /v1/graph`](#get-v1graph) +- [Content Types](#content-types) + - [`application/vnd.legion-discovery.instance-list+json`](#applicationvndlegion-discoveryinstance-listjson) + - [`application/vnd.legion-discovery.ping-request+json`](#applicationvndlegion-discoveryping-requestjson) + +## API + +### `POST /v1/ping/:serviceId/:version` + +Register a service. Registration expires in 30 seconds. + +- Request + - Content-Type: [`application/vnd.legion-discovery.ping-request+json`](#applicationvndlegion-discoveryping-requestjson) +- Response `204 No Content`: indicates a successful registration. + +### `GET /v1/services/:serviceId` + +Returns all current instances of a service, regardless of version. + +- Response `200 Ok` + - Content-Type: [`application/vnd.legion-discovery.instance-list+json`](#applicationvndlegion-discoveryinstance-listjson) + + +### `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. + +- Response `200 Ok` + - Content-Type: [`application/vnd.legion-discovery.instance-list+json`](#applicationvndlegion-discoveryinstance-listjson) + +### `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`](https://www.w3.org/TR/SVG11/) + - Content-Type [`text/vnd.graphviz`](http://www.graphviz.org/content/dot-language) + + +## 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" + } + + diff --git a/legion-discovery.cabal b/legion-discovery.cabal --- a/legion-discovery.cabal +++ b/legion-discovery.cabal @@ -1,7 +1,13 @@ name: legion-discovery -version: 0.2.2.1 -synopsis: Initial project template from stack -description: Please see README.md +version: 0.2.2.2 +synopsis: A discovery service based on Legion. + +description: 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. + homepage: https://github.com/owensmurray/legion-discovery#readme license: Apache-2.0 license-file: LICENSE @@ -10,7 +16,8 @@ copyright: 2016 Rick Owens category: value build-type: Simple --- extra-source-files: +extra-source-files: + README.md cabal-version: >=1.10 library @@ -31,7 +38,7 @@ SHA >= 1.6.4.1 && < 1.7, aeson >= 0.11.2.1 && < 0.12, attoparsec >= 0.13.1.0 && < 0.14, - base >= 4.8 && < 4.10, + base >= 4.9 && < 4.10, binary >= 0.7.5.0 && < 0.9, bytestring >= 0.10.6.0 && < 0.11, canteven-http >= 0.1.1.1 && < 0.2, @@ -39,6 +46,7 @@ conduit >= 1.2.7 && < 1.3, containers >= 0.5.6.2 && < 0.6, data-default-class >= 0.0.1 && < 0.2, + ekg >= 0.4.0.11 && < 0.5, graphviz >= 2999.18.1.2 && < 2999.19, http-types >= 0.9.1 && < 0.10, legion >= 0.8 && < 0.9, diff --git a/src/Network/Legion/Discovery.hs b/src/Network/Legion/Discovery.hs --- a/src/Network/Legion/Discovery.hs +++ b/src/Network/Legion/Discovery.hs @@ -9,6 +9,7 @@ import Canteven.HTTP (requestLogging, logExceptionsAndContinue, DecodeResult(Unsupported, BadEntity, Ok), FromEntity, decodeEntity) import Canteven.Log.MonadLog (getCantevenOutput) +import Control.Monad (void) import Control.Monad.IO.Class (MonadIO, liftIO) import Data.Aeson (encode, object, (.=), FromJSON, parseJSON, Value(Object), (.:), eitherDecode) @@ -38,7 +39,7 @@ ServiceId(ServiceId), toKey, Time(Time), unServiceAddr, version, ServiceAddr(ServiceAddr), InstanceInfo, Service, instances, name, unServiceId, State, Client(Client), cName, cVersion) -import Network.Legion.Discovery.Config (servicePort) +import Network.Legion.Discovery.Config (servicePort, ekgPort) import Network.Legion.Discovery.Graphviz (toDotGraph) import Network.Legion.Discovery.HttpError (HttpError) import Network.Legion.Discovery.LIO (runLIO, LIO) @@ -59,11 +60,13 @@ import qualified Data.Text.Lazy.Encoding as TLE import qualified Network.Legion.Discovery.Config as C import qualified Paths_legion_discovery as P +import qualified System.Remote.Monitoring as Ekg main :: IO () main = do (settings, startupMode, config) <- parseArgs logging <- getCantevenOutput (C.logging config) + void $ Ekg.forkServer "localhost" (ekgPort config) persist <- newMemoryPersistence :: IO (Persistence Input Output State) runLIO logging $ do legion <- forkLegionary persist settings startupMode