Ensure dashboard charts render in screenshot

apps/sht20/sht20_dashboard.py

@@ -19,6 +19,22 @@
 app = Flask(__name__)
 
 
+def find_chrome_executable():
+    """Return path to a Chrome/Chromium executable if installed."""
+    candidates = [
+        "chromium-browser",
+        "chromium",
+        "google-chrome",
+        "google-chrome-stable",
+        "chrome",
+    ]
+    for name in candidates:
+        path = shutil.which(name)
+        if path:
+            return path
+    return None
+
+
 def get_ip_address():
     """Return the host's primary IP address."""
     ip = "127.0.0.1"
@@ -182,7 +198,14 @@ async def _capture_with_pyppeteer(url, outfile):
     """Use headless Chrome to capture a screenshot of the dashboard."""
     from pyppeteer import launch
 
-    browser = await launch(args=["--no-sandbox"])
+    chrome_path = find_chrome_executable()
+    if not chrome_path:
+        raise RuntimeError(
+            "Chrome/Chromium not found. Please install it to capture screenshots."
+        )
+
+    browser = await launch(executablePath=chrome_path, args=["--no-sandbox"])
+
     page = await browser.newPage()
     await page.setViewport({"width": 1024, "height": 768})
     # Wait for all network activity (including Chart.js) to finish
@@ -212,8 +235,6 @@ def capture_and_send(url, outfile="dashboard.jpg"):
 
 
 if __name__ == "__main__":
-    import shutil
-
     influx_proc = start_influxdb()
     if influx_proc is not None:
         import atexit