From fa423ed722720c6dae22bc2197ffc4eb46f44f35 Mon Sep 17 00:00:00 2001
From: Frank Niessink <frank@niessink.com>
Date: Fri, 14 Jun 2024 11:46:31 +0200
Subject: [PATCH] Prevent zombie process in renderer.

Prevent zombie browser processes by starting Chromium only once and opening and closing a new page for each render.

Closes #8979.
---
 components/renderer/src/index.js | 30 +++++++++++++++++++-----------
 docs/src/changelog.md            |  3 ++-
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/components/renderer/src/index.js b/components/renderer/src/index.js
index d905764a5e..3982b01f53 100644
--- a/components/renderer/src/index.js
+++ b/components/renderer/src/index.js
@@ -6,21 +6,18 @@ const app = express();
 const RENDERER_PORT = process.env.RENDERER_PORT || 9000;
 const PROXY = `${process.env.PROXY_HOST || 'www'}:${process.env.PROXY_PORT || 80}`;
 const PROTOCOL = process.env.PROXY_PROTOCOL || 'http';
+let browser
 
 app.get("/api/health", async (_req, res) => {
-    res.status(200).send("OK")
+    const healthy = browser.connected ?? false
+    res.status(healthy ? 200 : 503).send(healthy ? "OK" : "Chromium not connected")
 })
 
 app.get("/api/render", async (req, res) => {
+    let webPage
     try {
         const url = sanitizeUrl(`${PROTOCOL}://${PROXY}/${req.query.path}`);
-        const browser = await puppeteer.launch({
-            defaultViewport: { width: 1500, height: 1000 },
-            args: ['--disable-dev-shm-usage', '--no-sandbox'],
-            // Opt in to new Chrome headless implementation, see https://developer.chrome.com/articles/new-headless/:
-            headless: "new",
-        });
-        const webPage = await browser.newPage();
+        webPage = await browser.newPage();
         await webPage.goto(url, {
             waitUntil: "networkidle2",
             timeout: 60000
@@ -42,15 +39,26 @@ app.get("/api/render", async (req, res) => {
             }
         });
         console.log(`URL ${url}: PDF created`);
-        await browser.close();
         res.contentType("application/pdf");
         res.send(pdf);
     } catch (error) {
         console.error(error)
         res.sendStatus(500)
+    } finally {
+        await webPage.close()
     }
 })
 
-app.listen(RENDERER_PORT, () => {
-    console.log(`Renderer started on port ${RENDERER_PORT}. Using proxy ${PROXY}`);
+app.listen(RENDERER_PORT, async () => {
+    try {
+        browser = await puppeteer.launch({
+            defaultViewport: { width: 1500, height: 1000 },
+            args: ['--disable-dev-shm-usage', '--no-sandbox'],
+            // Opt in to new Chrome headless implementation, see https://developer.chrome.com/articles/new-headless/:
+            headless: "new",
+        })
+        console.log(`Renderer started on port ${RENDERER_PORT}. Using proxy ${PROXY}`);
+    } catch (error) {
+        console.log(error)
+    }
 });
diff --git a/docs/src/changelog.md b/docs/src/changelog.md
index 1a17a1bb57..ac723dbf6d 100644
--- a/docs/src/changelog.md
+++ b/docs/src/changelog.md
@@ -17,7 +17,8 @@ If your currently installed *Quality-time* version is not v5.13.0, please first
 ### Fixed
 
 - In the dropdown of the "Add metric" button, keep the two checkboxes next to each other regardless of the width of the menu. Fixes [#8745](https://github.com/ICTU/quality-time/issues/8745).
-- The icon of the trend graph tab would not be shown. Closes [#8822](https://github.com/ICTU/quality-time/issues/8822).
+- The icon of the trend graph tab would not be shown. Fixes [#8822](https://github.com/ICTU/quality-time/issues/8822).
+- Prevent zombie browser processes in the renderer component when creating PDF fails by closing the browser regardless of whether generating the PDF succeeds or not. Fixes [#8979](https://github.com/ICTU/quality-time/issues/8979).
 
 ### Added