BUG: Unable to view or browse dags in web UI after migrated airflow 1.9.0 to 1.10.10

[mmuru]

Apache Airflow version: airflow 1.10.10

Environment:

• OS (e.g. from /etc/os-release): Mac

What happened:
Ooops! throws exception File "/Users/muru/opensrc/py36/airflow_110/venv368/lib/python3.6/site-packages/airflow/www/templates/airflow/dags.html", line 84, in block "body" <a href="{{ url_for('airflow.'+ dag.get_default_view(), dag_id=dag.dag_id) }}" title="{{ dag.description[0:80] + '...' if dag.description|length > 80 else dag.description }}"> TypeError: object of type 'NoneType' has no len()

What you expected to happen:
Should able to load page without errors or exceptions.

The description column in dag table can be null. But in the dags.html, should check dag.decription is not null before perform length filter.

How to reproduce it:
migrate airflow 1.9.0 to 1.10.10
Perform airflow upgradedb
start airflow webserver
launch and open http://localhost:8080/

Anything else we need to know:
Line 84 in airflow/www/templates/airflow/dags.html file, replace the condition
if dag.description|length > 80 change to if dag.description and dag.description|length > 80

As a workaround, perform the following db update and open http://localhost:8080/
update dag set description=' ' where description is null;

[boring-cyborg]

Thanks for opening your first issue here! Be sure to follow the issue template!

[mik-laj]

Here is related PR: https://github.com/apache/airflow/pull/7593/files
@zhongjiajie Can you look at it?

[zhongjiajie]

Thanks @mik-laj to notice that, but is odd that #7593 not release in 1.10.10, and the reporter solution is also my PR's solution. And @kaxil milestone PR in 1.10.11, I think it will be fix after 1.10.11 release, cc: @mmuru

[zhongjiajie]

BTW, I will check which PR cause this error

[zhongjiajie]

@mmuru I find out the original pr is #7457, and I think it should not cause error because dag.description default value is ''(empty string),

airflow/airflow/models/dag.py

Line 218 in 42e9a29

description='', # type: str

unless you define description=None in DAG files. if so maybe you should just remove the description define.

And, BTW, we have #7593 to fix that will release in 1.10.11, will use description=None as default value, and fix your situation

[zhongjiajie]

Please mention me if you have further problem, I am sick recently and only check github twice a day, sorry about that.

[mmuru]

@zhongjiajie: I reviewed PR #7457, It checks only dag.description length limit but dag.description can be null. In my case, as I mentioned the 1.9.0 dags didn't have description. The description column was introduced in 1.10 and the default is null. I reviewed PR #7593 and it will fix this issue.

[kaxil]

Yes that PR will be cherry-picked in 1.10.11 and should fix the issue.

[zhongjiajie]

@mmuru In this case I prefer to close this issue, would reopen it if you still have further information.

[shawnngtq]

I face the same issue. Commenting here for record

[kaxil]

Cherry-picked to v1-10-test: d0de41c