Remove host update code which can be non performant

[gamuniz]

SUMMARY

#14231

Inventory deletion causes unnecessary queries to the database to update fields which isn't necessary. This removes that update before deletion.

ISSUE TYPE

• Bug, Docs Fix or other nominal change

COMPONENT NAME

• API

AWX VERSION

make VERSION
awx: 22.5.1.dev3+g77c32c8a60

ADDITIONAL INFORMATION

[AlanCoding]

Manually testing to booster confidence.

• ran Demo Job Template a few more times
• Inspected /api/v2/jobs/60/job_events/
• Deleted demo inventory
• Compared the job events after deletion

before deletion

{
            "id": 104,
            "type": "job_event",
            "url": "[/api/v2/job_events/104/](https://localhost:8043/api/v2/job_events/104/)",
            "related": {
                "job": "[/api/v2/jobs/60/](https://localhost:8043/api/v2/jobs/60/)",
                "children": "[/api/v2/job_events/104/children/](https://localhost:8043/api/v2/job_events/104/children/)",
                "host": "[/api/v2/hosts/1/](https://localhost:8043/api/v2/hosts/1/)"
            },
            "summary_fields": {
                "host": {
                    "id": 1,
                    "name": "localhost",
                    "description": ""
                },
                "job": {
                    "id": 60,
                    "name": "Demo Job Template",
                    "description": "",
                    "status": "successful",
                    "failed": false,
                    "elapsed": 5.219,
                    "type": "job",
                    "job_template_id": 7,
                    "job_template_name": "Demo Job Template"
                },
                "role": {}
            },
            "created": "2023-07-12T20:23:02.413242Z",
            "modified": "2023-07-12T20:23:02.657922Z",
            "job": 60,
            "event": "runner_on_start",
            "counter": 4,
            "event_display": "Host Started",
            "event_data": {
                "playbook": "hello_world.yml",
                "playbook_uuid": "50a201ec-a817-4b94-a71a-9388c68f1b1c",
                "play": "Hello World Sample",
                "play_uuid": "92042dfb-5402-072f-efd8-000000000002",
                "play_pattern": "all",
                "task": "Gathering Facts",
                "task_uuid": "92042dfb-5402-072f-efd8-000000000008",
                "task_action": "gather_facts",
                "resolved_action": "ansible.builtin.gather_facts",
                "task_args": "",
                "task_path": "/runner/project/hello_world.yml:1",
                "host": "localhost",
                "uuid": "5f39f0d0-8400-4c44-b085-b76949402a1d",
                "guid": "84b0ee1ffa5f4c3f81310913953da1be"
            },
            "event_level": 3,
            "failed": false,
            "changed": false,
            "uuid": "5f39f0d0-8400-4c44-b085-b76949402a1d",
            "parent_uuid": "92042dfb-5402-072f-efd8-000000000008",
            "host": 1,
            "host_name": "localhost",
            "playbook": "hello_world.yml",
            "play": "Hello World Sample",
            "task": "Gathering Facts",
            "role": "",
            "stdout": "",
            "start_line": 4,
            "end_line": 4,
            "verbosity": 0
        },

after

{
            "id": 104,
            "type": "job_event",
            "url": "[/api/v2/job_events/104/](https://localhost:8043/api/v2/job_events/104/)",
            "related": {
                "job": "[/api/v2/jobs/60/](https://localhost:8043/api/v2/jobs/60/)",
                "children": "[/api/v2/job_events/104/children/](https://localhost:8043/api/v2/job_events/104/children/)",
                "host": "[/api/v2/hosts/1/](https://localhost:8043/api/v2/hosts/1/)"
            },
            "summary_fields": {
                "job": {
                    "id": 60,
                    "name": "Demo Job Template",
                    "description": "",
                    "status": "successful",
                    "failed": false,
                    "elapsed": 5.219,
                    "type": "job",
                    "job_template_id": 7,
                    "job_template_name": "Demo Job Template"
                },
                "role": {}
            },
            "created": "2023-07-12T20:23:02.413242Z",
            "modified": "2023-07-12T20:23:02.657922Z",
            "job": 60,
            "event": "runner_on_start",
            "counter": 4,
            "event_display": "Host Started",
            "event_data": {
                "playbook": "hello_world.yml",
                "playbook_uuid": "50a201ec-a817-4b94-a71a-9388c68f1b1c",
                "play": "Hello World Sample",
                "play_uuid": "92042dfb-5402-072f-efd8-000000000002",
                "play_pattern": "all",
                "task": "Gathering Facts",
                "task_uuid": "92042dfb-5402-072f-efd8-000000000008",
                "task_action": "gather_facts",
                "resolved_action": "ansible.builtin.gather_facts",
                "task_args": "",
                "task_path": "/runner/project/hello_world.yml:1",
                "host": "localhost",
                "uuid": "5f39f0d0-8400-4c44-b085-b76949402a1d",
                "guid": "84b0ee1ffa5f4c3f81310913953da1be"
            },
            "event_level": 3,
            "failed": false,
            "changed": false,
            "uuid": "5f39f0d0-8400-4c44-b085-b76949402a1d",
            "parent_uuid": "92042dfb-5402-072f-efd8-000000000008",
            "host": 1,
            "host_name": "localhost",
            "playbook": "hello_world.yml",
            "play": "Hello World Sample",
            "task": "Gathering Facts",
            "role": "",
            "stdout": "",
            "start_line": 4,
            "end_line": 4,
            "verbosity": 0
        },

This legit gives a 404 when clicking on the host link. I don't think I care.

[AlanCoding]

Also checked running the cleanup jobs management job effectively removes the job with a deleted inventory. It does. Also confirmed I am left with 0 job events in the system. I am.

Done with manual testing, I'm fine with this.

[john-westcott-iv]

I don't see anywhere that we set cascade on this field which is probably why the host sticks in Alans testing but yields a 404. But I am also fine with that.

[AlanCoding]

I wanted to formalize the shape of the query we're looking at removing here, because this is really helpful if someone is looking at SQL statements and trying to map them to the source. I had to dig into the Django source code because I can't just do str(qs.query) with updates.

https://github.com/django/django/blob/89c7454dbdae3e0df6d96aa6132205d05e4a9b3d/django/db/models/query.py#L1192-L1197

So to test this query, I do:

from django.db.models import sql

j = Job.objects.order_by('-created').first()
h = j.inventory.hosts.first()
h.job_events_as_primary_host.all()

qs = h.job_events_as_primary_host.all()
qs._not_support_combined_queries("update")
qs._for_write = True
query = qs.query.chain(sql.UpdateQuery)
query.add_update_values({'host': None})

print(str(query))

Doing this, I get:

UPDATE "main_jobevent" SET "host_id" = NULL WHERE "main_jobevent"."host_id" = 1

So this is a query that should no longer be seen after this merge. It should probably never be done.