Add /health endpoint (#490)

Author: slinkydeveloper

packages/restate-sdk/src/endpoint/handlers/generic.ts

@@ -137,11 +137,21 @@ export class GenericHandler implements RestateHandler {
     }
 
     if (parsed.type === "unknown") {
-      const msg = `Invalid path: path doesn't end in /invoke/SvcName/handlerName and also not in /discover: ${path}`;
+      const msg = `Invalid path. Allowed are /health, or /discover, or /invoke/SvcName/handlerName, but was: ${path}`;
       this.endpoint.rlog.trace(msg);
       return this.toErrorResponse(404, msg);
     }
 
+    if (parsed.type === "health") {
+      return {
+        body: OnceStream(new TextEncoder().encode("OK")),
+        headers: {
+          "content-type": "application/text",
+          "x-restate-server": X_RESTATE_SERVER,
+        },
+        statusCode: 200,
+      };
+    }
     if (parsed.type === "discover") {
       return this.handleDiscovery(request.headers["accept"]);
     }

packages/restate-sdk/src/types/components.ts

@@ -269,6 +269,7 @@ export class WorkflowHandler implements ComponentHandler {
 export type PathComponents =
   | InvokePathComponents
   | { type: "discover" }
+  | { type: "health" }
   | { type: "unknown"; path: string };
 
 export type InvokePathComponents = {
@@ -292,5 +293,8 @@ export function parseUrlComponents(urlPath?: string): PathComponents {
   if (fragments.length > 0 && fragments[fragments.length - 1] === "discover") {
     return { type: "discover" };
   }
+  if (fragments.length > 0 && fragments[fragments.length - 1] === "health") {
+    return { type: "health" };
+  }
   return { type: "unknown", path: urlPath };
 }