notifications: add low disk space notification

src/mailer.js

@@ -13,6 +13,7 @@ exports = module.exports = {
     oomEvent,
     rebootRequired,
     boxUpdateError,
+    lowDiskSpace,
 
     sendTestMail,
 
@@ -279,6 +280,22 @@ async function rebootRequired(mailTo) {
     await sendMail(mailOptions);
 }
 
+async function lowDiskSpace(mailTo, message) {
+    assert.strictEqual(typeof mailTo, 'string');
+    assert.strictEqual(typeof message, 'string');
+
+    const mailConfig = await getMailConfig();
+
+    const mailOptions = {
+        from: mailConfig.notificationFrom,
+        to: mailTo,
+        subject: `[${mailConfig.cloudronName}] Server is running low on disk space`,
+        text: render('low_disk_space-text.ejs', { message, notificationsUrl: mailConfig.notificationsUrl })
+    };
+
+    await sendMail(mailOptions);
+}
+
 async function boxUpdateError(mailTo, message) {
     assert.strictEqual(typeof mailTo, 'string');
     assert.strictEqual(typeof message, 'string');