feat: healthz page (#25)

Description
---
Add healthz page that just return 200 with `{status:"ok"}`

Motivation and Context
---

How Has This Been Tested?
---
Just run it manually a check healthz

What process can a PR reviewer use to test or verify this change?
---
same as above

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Breaking Changes
---

- [x] None
- [ ] Requires data directory on base node to be deleted
- [ ] Requires hard fork
- [ ] Other - Please specify

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app.js

@@ -14,6 +14,7 @@ var blocksRouter = require("./routes/blocks");
 var mempoolRouter = require("./routes/mempool");
 var searchCommitmentsRouter = require("./routes/search_commitments");
 var searchKernelsRouter = require("./routes/search_kernels");
+var healthz = require("./routes/healthz");
 
 var assetsRouter = require("./routes/assets");
 
@@ -97,6 +98,7 @@ app.use("/assets", assetsRouter);
 app.use("/mempool", mempoolRouter);
 app.use("/search_commitments", searchCommitmentsRouter);
 app.use("/search_kernels", searchKernelsRouter);
+app.use("/healthz", healthz);
 
 // catch 404 and forward to error handler
 app.use(function (req, res, next) {

routes/healthz.js

@@ -0,0 +1,50 @@
+//  Copyright 2021. The Tari Project
+//
+//  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+//  following conditions are met:
+//
+//  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+//  disclaimer.
+//
+//  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+//  following disclaimer in the documentation and/or other materials provided with the distribution.
+//
+//  3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
+//  products derived from this software without specific prior written permission.
+//
+//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+//  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+//  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+//  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+//  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+//  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+var { createClient } = require("../baseNodeClient");
+
+var express = require("express");
+var router = express.Router();
+
+router.get("/", async function (req, res) {
+  let client = createClient();
+  let result;
+  try {
+    result = await client.getVersion({});
+  } catch (error) {
+    res.status(404);
+    if (req.query.json !== undefined) {
+      res.json({ error: error });
+    } else {
+      res.render("error", { error: error });
+    }
+    return;
+  }
+  let json = { version: result.value };
+  if (req.query.json !== undefined) {
+    res.json(json);
+  } else {
+    res.render("healthz", json);
+  }
+});
+
+module.exports = router;

views/healthz.hbs

@@ -0,0 +1,5 @@
+<a href="/">Home</a>
+<div>
+  Version:
+  <b>{{this.version}}</b>
+</div>