get dag's url to alert message In slack - airflow

Question

I'm using arflow 2.2.1.
I have a dag, that send alert message to slack, when its failed.
dag:
from alert.alert_slack import alert_slack
...
default_args = {
'owner': 'name',
'start_date': dt.datetime(2022, 11, 18),
'retries': 2,
'retry_delay': dt.timedelta(seconds=10),
'on_failure_callback': alert_slack('myslackid')
}
alert_slack:
from airflow.providers.slack.operators.slack import SlackAPIPostOperator
def alert_slack(channel: str):
def failure(context):
last_task = context.get('task_instance')
task_name = last_task.task_id
dag_name = last_task.dag_id
log_link = f"<{last_task.log_url}|{task_name}>"
error_message = context.get('exception') or context.get('reason')
execution_date = context.get('execution_date')
title = f':red_circle: DAG Failed.'
msg_parts = {
'*Dag*': dag_name,
'*Owner*': owner,
'*Task*': task_name,
'*Log*': log_link,
'*Error*': error_message,
'*Execution date*': execution_date
}
msg = "\n".join([title,
*[f"{key}: {value}" for key, value in msg_parts.items()]
]).strip()
SlackAPIPostOperator(
task_id="alert",
slack_conn_id="slack_alert",
text=msg,
channel=channel,
).execute(context=None)
return failure
I need to add an url of failed dag from airflow site (like https://myairflow.dev/code?dag_id=my_test_dag) to alert message
I tried to add the following code:
dagcode = context.get('dag_code')
dag_url = dagcode.source_code
dagcode return None.
But I think it's completely wrong and I don't know where to look for this url.
Can anyone please help me find where dag's url is and how do i pass it to alert message?

Answer 1

So the log link that you are including in the alert should take you to the Airflow UI. It will be the page with the log for that failed DAG run.
If you want a specific page in the UI for that DAG, say you want the 'Grid' view of a particular DAG like the picture I attach, you can simply hardcode the URL and include this URL in your slack message.
I.e.
last_task = context.get('task_instance')
dag_id = last_task.dag_id
# airflow_server_id is whatever the address
# to your Airflow webserver (e.g. myairflow.dev).
base_url = 'https://{airflow_server_id}/dags/{dag_id}/grid'
msg_parts = {
'*Dag*': dag_id,
'*Link to Dag grid page*': base_url
}
.
.
.
Or, say you want the Code UI page for this DAG,
last_task = context.get('task_instance')
dag_id = last_task.dag_id
# airflow_server_id is whatever the address
# to your Airflow webserver (e.g. myairflow.dev).
base_url = 'https://{airflow_server_id}/dags/{dag_id}/code'
msg_parts = {
'*Dag*': dag_id,
'*Link to Dag code page*': base_url
}
.
.
.
I will say, it is odd to want to include a link to a DAG page instead of the page of the logs of the failed DAG run. Usually, the person responding to slack alert would want to see more information about a DAG run NOT a DAG in itself. So if it were me, including the log URL of failed DAG run like you're already doing should be enough.
[![grid_dag_ui][1]][1]
[1]: https://i.stack.imgur.com/1IMII.png