add healthUtil

Makefile

@@ -1,6 +1,5 @@
 TEST_FILES := $(shell find ./**/*.ts)
 
-
 test: $(TEST_FILES)
 	deno test test.ts
-	deno check mod.ts
+	deno check mod.ts

healthUtil.ts

@@ -0,0 +1,33 @@
+import { Effects, ExpectedExports, ResultType } from "./types.ts";
+
+export const checkWebUrl: (
+  url: string,
+) => (effects: Effects, duration: number) => Promise<ResultType<null | void>> =
+  (url) => {
+    return async (effects, duration) => {
+      await guardDurationAboveMinimum({ duration, minimumTime: 5000 });
+
+      return await effects.fetch(url)
+        .then((_) => ok)
+        .catch((e) => {
+          effects.warn(`Error while fetching URL: ${url}`);
+          effects.error(JSON.stringify(e));
+          effects.error(e.toString());
+          return error(`Error while fetching URL: ${url}`);
+        });
+    };
+  };
+
+// Ensure the starting duration is pass a minimum
+const guardDurationAboveMinimum = (
+  input: { duration: number; minimumTime: number },
+) =>
+  (input.duration <= input.minimumTime)
+    ? Promise.reject(errorCode(60, "Starting"))
+    : null;
+
+const errorCode = (code: number, error: string) => ({
+  "error-code": [code, error] as const,
+});
+const error = (error: string) => ({ error });
+const ok = { result: null };

mod.ts

@@ -1,6 +1,6 @@
 export { matches, YAML } from "./dependencies.ts";
 export * as types from "./types.ts";
-
 export * as compat from "./compat/mod.ts";
 export * as migrations from "./migrations.ts";
+export * as healthUtil from "./healthUtil.ts";
 export * as util from "./util.ts";