From 588865b71ea20593e3359b502c20f4f7c013294e Mon Sep 17 00:00:00 2001
From: Charles Morin <charles.mor@outlook.fr>
Date: Tue, 5 Sep 2023 10:23:08 -0400
Subject: [PATCH] Added health endpoint and fixed headers

---
 package-lock.json | 22 +++++++++++-----------
 package.json      |  2 +-
 src/config.ts     |  2 +-
 src/health.ts     | 33 +++++++++++++++++++++++++++++++++
 src/setup.ts      |  4 ++++
 5 files changed, 50 insertions(+), 13 deletions(-)
 create mode 100644 src/health.ts

diff --git a/package-lock.json b/package-lock.json
index c6ad143..57d8852 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
     "name": "substreams-sink",
-    "version": "0.9.4",
+    "version": "0.9.5",
     "lockfileVersion": 3,
     "requires": true,
     "packages": {
         "": {
             "name": "substreams-sink",
-            "version": "0.9.4",
+            "version": "0.9.5",
             "license": "MIT OR Apache-2.0",
             "dependencies": {
                 "@substreams/core": "^0.1.18",
@@ -314,9 +314,9 @@
             "dev": true
         },
         "node_modules/@types/node": {
-            "version": "20.5.8",
-            "resolved": "https://registry.npmjs.org/@types/node/-/node-20.5.8.tgz",
-            "integrity": "sha512-eajsR9aeljqNhK028VG0Wuw+OaY5LLxYmxeoXynIoE6jannr9/Ucd1LL0hSSoafk5LTYG+FfqsyGt81Q6Zkybw=="
+            "version": "20.5.9",
+            "resolved": "https://registry.npmjs.org/@types/node/-/node-20.5.9.tgz",
+            "integrity": "sha512-PcGNd//40kHAS3sTlzKB9C9XL4K0sTup8nbG5lC14kzEteTNuAFh9u5nA0o5TWnSG2r/JNPRXFVcHJIIeRlmqQ=="
         },
         "node_modules/@types/set-cookie-parser": {
             "version": "2.4.3",
@@ -384,9 +384,9 @@
             }
         },
         "node_modules/fast-check": {
-            "version": "3.12.0",
-            "resolved": "https://registry.npmjs.org/fast-check/-/fast-check-3.12.0.tgz",
-            "integrity": "sha512-SqahE9mlL3+lhjJ39joMLwcj6F+24hfZdf/tchlNO8sHcTdrUUdA5P/ZbSFZM9Xpzs36XaneGwE0FWepm/zyOA==",
+            "version": "3.12.1",
+            "resolved": "https://registry.npmjs.org/fast-check/-/fast-check-3.12.1.tgz",
+            "integrity": "sha512-aRN6WrO+q3TZV8CjXnpebx9bTHrpYIOVi6v3ttxciZiWqS739yy8b1oVx+qNEyV1b8RdVjlp/+miTY6yAp90HA==",
             "funding": [
                 {
                     "type": "individual",
@@ -493,9 +493,9 @@
             }
         },
         "node_modules/pure-rand": {
-            "version": "6.0.2",
-            "resolved": "https://registry.npmjs.org/pure-rand/-/pure-rand-6.0.2.tgz",
-            "integrity": "sha512-6Yg0ekpKICSjPswYOuC5sku/TSWaRYlA0qsXqJgM/d/4pLPHPuTxK7Nbf7jFKzAeedUhR8C7K9Uv63FBsSo8xQ==",
+            "version": "6.0.3",
+            "resolved": "https://registry.npmjs.org/pure-rand/-/pure-rand-6.0.3.tgz",
+            "integrity": "sha512-KddyFewCsO0j3+np81IQ+SweXLDnDQTs5s67BOnrYmYe/yNmUhttQyGsYzy8yUnoljGAQ9sl38YB4vH8ur7Y+w==",
             "funding": [
                 {
                     "type": "individual",
diff --git a/package.json b/package.json
index d5f53a1..e1ca5d8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "substreams-sink",
-    "version": "0.9.4",
+    "version": "0.9.5",
     "description": "Substreams Sink",
     "type": "module",
     "exports": "./dist/index.js",
diff --git a/src/config.ts b/src/config.ts
index 9ab3744..af5d144 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -11,5 +11,5 @@ export const DEFAULT_COLLECT_DEFAULT_METRICS = false;
 export const DEFAULT_START_BLOCK = "-1";
 export const DEFAULT_SUBSTREAMS_API_TOKEN = "";
 export const DEFAULT_PARAMS = [];
-export const DEFAULT_HEADERS = [];
+export const DEFAULT_HEADERS = new Headers();
 export const DEFAULT_AUTH_ISSUE_URL = "https://auth.pinax.network/v1/auth/issue";
diff --git a/src/health.ts b/src/health.ts
new file mode 100644
index 0000000..f1522d1
--- /dev/null
+++ b/src/health.ts
@@ -0,0 +1,33 @@
+import type { IncomingMessage, ServerResponse } from "http";
+
+import * as prometheus from "./prometheus.js";
+import * as http from "./http.js";
+
+export function health() {
+    http.server.on("request", async (req, res) => {
+        if (!req.url) return;
+        try {
+            if (req.method == "GET") {
+                if (req.url === "/health") {
+                    const messages = await getSingleMetric("substreams_sink_data_message")
+                    if (messages) return toText(res, "OK");
+                    return toText(res, "no messages received yet", 503);
+                }
+            }
+        } catch (err: any) {
+            res.statusCode = 400;
+            return res.end(err.message);
+        }
+    });
+}
+
+async function getSingleMetric(name: string) {
+    const metric = prometheus.registry.getSingleMetric(name);
+    const get = await metric?.get();
+    return get?.values[0].value;
+}
+
+function toText(res: ServerResponse<IncomingMessage>, data: any, status = 200) {
+    res.writeHead(status, { 'Content-Type': 'text/plain; charset=utf-8' });
+    return res.end(data);
+}
\ No newline at end of file
diff --git a/src/setup.ts b/src/setup.ts
index 976826a..5c8bc82 100644
--- a/src/setup.ts
+++ b/src/setup.ts
@@ -10,6 +10,7 @@ import * as prometheus from "./prometheus.js";
 import { logger } from "./logger.js";
 import { onRestartInactivitySeconds } from "./restartInactivitySeconds.js";
 import { applyParams } from "./applyParams.js";
+import { health } from "./health.js";
 
 export async function setup(options: RunOptions) {
     // Configure logging with TSLog
@@ -37,6 +38,9 @@ export async function setup(options: RunOptions) {
     // Adding default headers
     headers.set("User-Agent", "substreams-sink");
 
+    // Health check
+    health();
+
     // Apply params
     if (params.length && substreamPackage.modules) {
         applyParams(params, substreamPackage.modules.modules);