Airflow 2 - debugging why dag is not loading - airflow

On Airflow 2 my dag is not showing on the UI, and I'm getting DAG Import Errors (...) for it.
The error message is insufficient for me to debug (it's a custom operator, with a lot of custom logic - so I don't want to get into details of the error itself).
On Airflow 1.X I could use cli:
airflow list_dags
to get more elaborated debug message, is there anything analogical on airflow 2 ?
I'm looking for a cli command/UI option that will provide me with more elaborated error message, than the one I'm getting on the main screen of the webserver.

As described in the Airlfow's documentation, to test DAG loading you can simply run:
python your-dag-file.py
If there is any problem during the DAG loading phase you will get a stack trace here.
The later sections also describe how to test custom operators.

As explained in the upgrading manual the
airflow list_dags has been changed to airflow dags list
The full syntax is:
airflow dags list [-h] [-o table, json, yaml] [-S SUBDIR]
for more information see docs

Related

airflow experimental api , how to set dag that is running as failed

I'm using experimental api of airflow
and would like to failed running DAG
i didn't see it in documentation
i tried the below, but it creating new running dag/task
would be glad to get the right experimental api/method/payload for it
thanks in advnace
'''session.post(
url=f'{airflow_env}/api/experimental/dags/{dag_name}/dag_runs',
json={'state':'failed',
"dag_run_id":"scheduled__2022-03-13T20:30:32.887761+00:00"})
'''

Apache Airflow problem - "a task with task_id create_tag_template_field_result is already in the DAG"

So, I have a problem with even the blank Airflow installation.
As soon as I try to run
airflow test tutorial print_date 2015-06-01
I get a raised exception which says
PendingDeprecationWarning: The requested task could not be added to the DAG because a task with task_id create_tag_template_field_result is already in the DAG. Starting in Airflow 2.0, trying to overwrite a task will raise an exception.
What is the reason for this (as I made literally no changes to the installation whatsoever)?
I also got that when, in a previous installation, I tried to run my own dag... but the "create_tag_template_field_result" was nowhere to be found in my code.
you can set the config arg load_examples = False to solve it.
This is the test command will call get_dag function which will construct a DagBag object, in the construction function will call collect_dags function.
The collect_dags function when the conf arg LOAD_EXAMPLES=True(default True), will collect all the dags in the example path, that's where the task create_tag_template_field_result comes from.
And in the collect_dags function will call add_task function of every example task, that's where you add the create_tag_template_field_result task again.
And maybe it's quickstart when you added this task before for the first time while you didn't realize.
you can set the config arg load_examples = False to solve it
This warning is occuring in
/usr/local/lib/python3.7/dist-packages/airflow/example_dags/example_complex.py
so i remove or rename (for example, to not working name *.py.back ) this.
I had the same error with a fresh install.
Then I don't know if this helps, but I downgraded Airflow to version 1.10.10 (with python3.7) and the error was gone.

Dag Seems to be missing

I have a dag which checks for new workflows to be generated (Dynamic DAG) at a regular interval and if found, creates them. (Ref: Dynamic dags not getting added by scheduler )
The above DAG is working and the dynamic DAGs are getting created and listed in the web-server. Two issues here:
When clicking on the DAG in web url, it says "DAG seems to be missing"
The listed DAGs are not listed using "airflow list_dags" command
Error:
DAG "app01_user" seems to be missing.
The same is for all other dynamically generated DAGs. I have compiled the Python script and found no errors.
Edit1:
I tried clearing all data and running "airflow run". It ran successfully but no Dynamic generated DAGs were added to "airflow list_dags". But when running the command "airflow list_dags", it loaded and executed the DAG, (which generated Dynamic DAGs). The dynamic DAGs are also listed as below:
[root#cmnode dags]# airflow list_dags
sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8\nLANG=en_US.UTF-8)
sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8\nLANG=en_US.UTF-8)
[2019-08-13 00:34:31,692] {settings.py:182} INFO - settings.configure_orm(): Using pool settings. pool_size=15, pool_recycle=1800, pid=25386
[2019-08-13 00:34:31,877] {__init__.py:51} INFO - Using executor LocalExecutor
[2019-08-13 00:34:32,113] {__init__.py:305} INFO - Filling up the DagBag from /root/airflow/dags
/usr/lib/python2.7/site-packages/airflow/operators/bash_operator.py:70: PendingDeprecationWarning: Invalid arguments were passed to BashOperator (task_id: tst_dyn_dag). Support for passing such arguments will be dropped in Airflow 2.0. Invalid arguments were:
*args: ()
**kwargs: {'provide_context': True}
super(BashOperator, self).__init__(*args, **kwargs)
-------------------------------------------------------------------
DAGS
-------------------------------------------------------------------
app01_user
app02_user
app03_user
app04_user
testDynDags
Upon running again, all the above generated 4 dags disappeared and only the base DAG, "testDynDags" is displayed.
When I was getting this error, there was an exception showing up in the webserver logs. Once I resolved that error and I restarted the webserver it went through normally.
From what I can see this is the error that is thrown when the webserver tried to parse the dag file and there is an error. In my case it was an error importing a new operator I added to a plugin.
Usually, I check in Airflow UI, sometimes the reason of broken DAG appear in there. But if it is not there, I usually run the .py file of my DAG, and error (reason of DAG cant be parsed) will appear.
I never got to work on dynamic DAG generation but I did face this issue when DAG was not present on all nodes ( scheduler, worker and webserver ). In case you have airflow cluster, please make sure that DAG is present on all airflow nodes.
Same error, the reason was I renamed my dag_id in uppercase. Something like "import_myclientname" into "import_MYCLIENTNAME".
I am little late to the party but I faced the error today:
In short: try executing airflow dags report and/or airflow dags reserialize
Check out my comment here:
https://stackoverflow.com/a/73880927/4437153
I found that airflow fails to recognize a dag defined in a file that does not have from airflow import DAG in it, even if DAG is not explicitly used in that file.
For example, suppose you have two files, a.py and b.py:
# a.py
from airflow import DAG
from airflow.operators.dummy_operator import DummyOperator
def makedag(dag_id="a"):
with DAG(dag_id=dag_id) as dag:
DummyOperator(task_id="nada")
dag = makedag()
and
# b.py
from a import makedag
dag = makedag(dag_id="b")
Then airflow will only look at a.py. It won't even look at b.py at all, even to notice if there's a syntax error in it! But if you add from airflow import DAG to it and don't change anything else, it will show up.

Testing Airflow Dag in command line

From Airflow manual at https://airflow.apache.org/tutorial.html#testing, I found that I can run something like following to test a specific task:
airflow test dag_id task_id
When I did, I only got this message:
[2018-07-10 18:29:54,346] {driver.py:120} INFO - Generating grammar tables from /usr/lib/python2.7/lib2to3/Grammar.txt
[2018-07-10 18:29:54,367] {driver.py:120} INFO - Generating grammar tables from /usr/lib/python2.7/lib2to3/PatternGrammar.txt
[2018-07-10 18:29:54,477] {__init__.py:45} INFO - Using executor SequentialExecutor
[2018-07-10 18:29:54,513] {models.py:189} INFO - Filling up the DagBag from /var/lib/airflow/dags
It doesn't look like it is really running it. Am I misunderstood? Or is there another way to run a DAG locally?
I copied this example call from the paragraph in the page you have linked to:
# command layout: command subcommand dag_id task_id date
# testing print_date
airflow test tutorial print_date 2015-06-01
# testing sleep
airflow test tutorial sleep 2015-06-01
So just include the date as shown above and the DAG task should run as expected.
for airflow version 2.4.0
airflow tasks test tutorial sleep 2015-06-01

How to find the number of upstream tasks failed in Airflow?

I am having a tough time in figuring out how to find the failed task for the same dag run running twice on same day(same execution day).
Consider an example when a dag with dag_id=1 has failed on the first run (due to any reason lets say connection timeout maybe) and task got failed. TaskInstance table will contain the entry of the failed task when we try to query it. GREAT!!
But, If I re-run the same dag(note that dag_id is still 1) then in the last task(it has the rule of ALL_DONE so irrespective of the whether upstream task was failed or was successful it will be executed) I want to calculate the number of tasks failed in the current dag_run ignoring the previous dag_runs. I came across dag_run id which could be useful if we can relate it to TaskInstance but I could not. Any suggestions/help is appreciated.
In Airflow 1.10.x the same result can be achieved by much simpler code that avoids touching ORM directly.
from airflow.utils.state import State
def your_python_operator_callable(**context):
tis_dagrun = context['ti'].get_dagrun().get_task_instances()
failed_count = sum([True if ti.state == State.FAILED else False for ti in tis_dagrun])
print(f"There are {failed_count} failed tasks in this execution"
The one unfortunate problem is that context['ti'].get_dagrun() does not return instance of DAGRun when running test of a single task from CLI. In the effect, manual testing of that single task will fail but the standard run will work as expected.
You could create a PythonOperator task which queries the Airflow database to find the information you're looking for. This has the added benefit of passing along the information you need to query for the data you want:
from contextlib import closing
from airflow import models, settings
from airflow.utils.state import State
def your_python_operator_callable(**context):
with closing(settings.Session()) as session:
print("There are {} failed tasks in this execution".format(
session.query(
models.TaskInstance
).filter(
models.TaskInstance.dag_id == context["dag"].dag_id,
models.TaskInstance.execution_date == context["execution_date"],
models.TaskInstance.state == State.FAILED).count()
)
Then add the task to your DAG with a PythonOperator.
(I have not tested the above, but hopefully will send you on the right path)

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