Package traffic implements a predicate to control the matching probability for a given route by setting its weight.
The probability for matching a route is defined by the mandatory first parameter, that must be a decimal number between 0.0 and 1.0 (both exclusive).
The optional second argument is used to specify the cookie name for the traffic group, in case you want to use stickiness. Stickiness allows all subsequent requests from the same client to match the same route. Stickiness of traffic is supported by the optional third parameter, indicating whether the request being matched belongs to the traffic group of the current route. If yes, the predicate matches ignoring the chance argument.
You always have to specify one argument, if you do not need stickiness, and three arguments, if your service requires stickiness.
Predicates cannot modify the response, so the responsibility of setting the traffic group cookie remains to either a filter or the backend service.
The below example, shows a possible eskip document used for green-blue deployments of APIS, which usually don't require stickiness:
// hit by 10% percent chance v2: Traffic(.1) -> "https://api-test-green"; // hit by remaining chance v1: "https://api-test-blue";
The below example, shows a possible eskip document with two, independent traffic controlled route sets, which uses session stickiness:
// hit by 5% percent chance cartTest: Traffic(.05, "cart-test", "test") && Path("/cart") -> responseCookie("cart-test", "test") -> "https://cart-test"; // hit by remaining chance cart: Path("/cart") -> responseCookie("cart-test", "default") -> "https://cart"; // hit by 15% percent chance catalogTestA: Traffic(.15, "catalog-test", "A") -> responseCookie("catalog-test", "A") -> "https://catalog-test-a"; // hit by 30% percent chance catalogTestB: Traffic(.3, "catalog-test", "B") -> responseCookie("catalog-test", "B") -> "https://catalog-test-b"; // hit by remaining chance catalog: * -> responseCookie("catalog-test", "default") -> "https://catalog";
const ( // The eskip name of the predicate. PredicateName = "Traffic" )
Creates a new traffic control predicate specification.