[v2.1.0] Tree View "Refresh" uses Wrong Endpoint

[fraciril]

Apache Airflow version:
v2.1.0

Environment:

• Cloud provider or hardware configuration: GCP
• OS (e.g. from /etc/os-release): Ubuntu 20.04
• Server: nginx 1.19.10

What happened:

When refreshing the tree view, both with auto-refresh and with the refresh button, the tree view is not refreshed and the empty message "error:" is displayed.

The issue is that the request being made when refreshing the tree view is:

GET https://{IP}/object/tree_data?dag_id={DAG_ID}

However, I'm serving Airflow in

https://{IP}/airflow
(See the added /airflow endpoint, read how to reproduce for more info)

So the correct request should be:

GET https://{IP}/airflow/object/tree_data?dag_id={DAG_ID}
(with the base /airflow/ endpoint)

I believe my configuration is correct, as the graph view however does use the correct request when refreshing:

GET https://{IP}/airflow/object/task_instances?dag_id={DAG_ID}...

What you expected to happen:

The tree view refresh request uses the correct base url so the tree view is refreshed

How to reproduce it:

Serve Airflow v2.1.0 using Ngninx as a reverse proxy with and docker-compose, with these configurations:

nginx.conf:

...
location /airflow/ {
        proxy_pass http://<airflow-webserver-container-name>:8080;
...

docker-compose.yml:

...
airflow-webserver:
    environment:
      AIRFLOW__WEBSERVER__ENABLE_PROXY_FIX: 'true'
      AIRFLOW__WEBSERVER__BASE_URL: 'http://${AIRFLOW_URL}/airflow'
    ports:
      - 8080:8080
...

Anything else we need to know:

• This started happening with version 2.1.0
• The Graph Refresh works correctly

[boring-cyborg]

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

[uranusjr]

Already fixed in #16018.