Add airflow_dag_last_status

[nvn01234]

Related to PR69, follow the comment of @elephantum

[nvn01234]

Hypotheses: Maybe it'll be more straight forward to add airflow_dag_last_status{status="xxx"} = 0/1 ?

What about if we add airflow_last_dagrun_status(...) = -1/0/1

• -1 for failed
• 0 for running
• 1 for success

[elephantum]

@nvn01234 I updated your PR to the latest version of code, can you please check that everything works?

[nvn01234]

Nice, it worked. Result look like this:

I also consider to add airflow_last_dagrun_task_status (tasks's status of the last dagrun for each dag), will submit another PR later.

[elephantum]

I renamed metric for consistency.

[nvn01234]

I changed the PR title too