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77211e9f16
* messing around with benchmark.net.seems Ocelot adds about 2ms to a request..lets make this less? :) * #326 store json indented so it looks nice :P
91 lines
3.7 KiB
ReStructuredText
91 lines
3.7 KiB
ReStructuredText
Service Discovery
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=================
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Ocelot allows you to specify a service discovery provider and will use this to find the host and port
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for the downstream service Ocelot is forwarding a request to. At the moment this is only supported in the
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GlobalConfiguration section which means the same service discovery provider will be used for all ReRoutes
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you specify a ServiceName for at ReRoute level.
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Consul
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^^^^^^
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The following is required in the GlobalConfiguration. The Provider is required and if you do not specify a host and port the Consul default
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will be used.
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.. code-block:: json
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"ServiceDiscoveryProvider": {
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"Host": "localhost",
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"Port": 9500
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}
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In the future we can add a feature that allows ReRoute specfic configuration.
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In order to tell Ocelot a ReRoute is to use the service discovery provider for its host and port you must add the
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ServiceName, UseServiceDiscovery and load balancer you wish to use when making requests downstream. At the moment Ocelot has a RoundRobin
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and LeastConnection algorithm you can use. If no load balancer is specified Ocelot will not load balance requests.
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.. code-block:: json
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{
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"DownstreamPathTemplate": "/api/posts/{postId}",
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"DownstreamScheme": "https",
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"UpstreamPathTemplate": "/posts/{postId}",
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"UpstreamHttpMethod": [ "Put" ],
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"ServiceName": "product",
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"LoadBalancer": "LeastConnection",
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"UseServiceDiscovery": true
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}
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When this is set up Ocelot will lookup the downstream host and port from the service discover provider and load balance requests across any available services.
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ACL Token
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---------
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If you are using ACL with Consul Ocelot supports adding the X-Consul-Token header. In order so this to work you must add the additional property below.
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.. code-block:: json
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"ServiceDiscoveryProvider": {
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"Host": "localhost",
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"Port": 9500,
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"Token": "footoken"
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}
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Ocelot will add this token to the consul client that it uses to make requests and that is then used for every request.
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Eureka
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^^^^^^
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This feature was requested as part of `Issue 262 <https://github.com/TomPallister/Ocelot/issue/262>`_ . to add support for Netflix's
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Eureka service discovery provider. The main reason for this is it is a key part of `Steeltoe <https://steeltoe.io/>`_ which is something
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to do with `Pivotal <https://pivotal.io/platform>`_! Anyway enough of the background.
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In order to get this working add the following to ocelot.json..
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.. code-block:: json
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"ServiceDiscoveryProvider": {
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"Type": "Eureka"
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}
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And following the guide `Here <https://steeltoe.io/docs/steeltoe-discovery/>`_ you may also need to add some stuff to appsettings.json. For example the json below tells the steeltoe / pivotal services where to look for the service discovery server and if the service should register with it.
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.. code-block:: json
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"eureka": {
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"client": {
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"serviceUrl": "http://localhost:8761/eureka/",
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"shouldRegisterWithEureka": false,
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"shouldFetchRegistry": true
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}
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}
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I am told that if shouldRegisterWithEureka is false then shouldFetchRegistry will defaut to true so you don't need it explicitly but left it in there.
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Ocelot will now register all the necessary services when it starts up and if you have the json above will register itself with
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Eureka. One of the services polls Eureka every 30 seconds (default) and gets the latest service state and persists this in memory.
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When Ocelot asks for a given service it is retrieved from memory so performance is not a big problem. Please note that this code
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is provided by the Pivotal.Discovery.Client NuGet package so big thanks to them for all the hard work.
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