feat: updated email format for SQL-based email alerts (#10512)

* added sql statement and link to chart in alert email

* pylint

* updated email to include link to alert

* style changes

* pylint

* added todo and fixed formatting of email

Co-authored-by: Jason Davis <@dropbox.com>

superset/tasks/schedules.py

@@ -18,7 +18,6 @@
 """Utility functions used across Superset"""
 
 import logging
-import textwrap
 import time
 import urllib.request
 from collections import namedtuple
@@ -585,6 +584,9 @@ def deliver_alert(alert_id: int, recipients: Optional[str] = None) -> None:
         image_url = get_url_path(
             "ChartRestApi.screenshot", pk=alert.slice.id, digest=cache_key
         )
+        standalone_index = chart_url.find("/?standalone=true")
+        if standalone_index != -1:
+            image_url = chart_url[:standalone_index]
 
         user = security_manager.find_user(current_app.config["THUMBNAIL_SELENIUM_USER"])
         img_data = screenshot.compute_and_cache(
@@ -595,19 +597,17 @@ def deliver_alert(alert_id: int, recipients: Optional[str] = None) -> None:
         image_url = "https://media.giphy.com/media/dzaUX7CAG0Ihi/giphy.gif"
 
     # generate the email
+    # TODO add sql query results to email
     subject = f"[Superset] Triggered alert: {alert.label}"
     deliver_as_group = False
     data = None
     if img_data:
         images = {"screenshot": img_data}
-    body = __(
-        textwrap.dedent(
-            """\
-            <h2>Alert: %(label)s</h2>
-            <img src="cid:screenshot" alt="%(label)s" />
-        """
-        ),
+    body = render_template(
+        "email/alert.txt",
+        alert_url=get_url_path("AlertModelView.show", pk=alert.id),
         label=alert.label,
+        sql=alert.sql,
         image_url=image_url,
     )
 

superset/templates/email/alert.txt

@@ -0,0 +1,26 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License.  You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing,
+ software distributed under the License is distributed on an
+ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ KIND, either express or implied.  See the License for the
+ specific language governing permissions and limitations
+ under the License.
+-->
+<h2 style="color: red;">Alert: {{label}} &#x26A0;</h2>
+<p><b>SQL Statement:</b></p>
+<code><mark style="background-color: LightGrey; font-size: 1.1em">{{sql}}</mark></code>
+<p><a href="{{alert_url}}">View Alert Details</a></p>
+<p>Click <a href="{{image_url}}">here</a> or the image below to view the chart related to this alert.</p>
+<a href="{{image_url}}">
+    <img src="cid:screenshot" alt="{{label}}" />
+</a>