According to the official Airflow docs,
The task instances directly upstream from the task need to be in a success state. Also, if you have set depends_on_past=True, the previous task instance needs to have succeeded (except if it is the first run for that task).
As all know, the task is kind of 'instantiated & parameteriazed' operator.
Now this is what confuse me. For example:
DAG: {op_1} -> {op_2} -> {op_3}
{op_2} is a simple PythonOperator that takes 1 parameter from {op_1} and do stuff;
To my understanding, op_2(param_1) & op_2(param_2) are considered as 2 different tasks.
Given depends_on_past is set to True, then:
From the official docs for trigger rules:
depends_on_past (boolean) when set to True, keeps a task from getting triggered if the previous schedule for the task hasn’t succeeded.
So unless a previous run of your DAG has failed, the depends_on_past should not be a factor, it will not affect the current run at all if the previous run executed the tasks successfully.