[ILM] Unable to remove Index priority value on existing index lifecycle policy

[hendry-lim]

Kibana version: 7.7.0

Elasticsearch version: 7.7.0

Server OS version: RHEL 8

Browser version: 83.0.4103.61

Browser OS version: Windows 10

Original install method (e.g. download page, yum, from source, etc.): Docker

Describe the bug:
Index priority reverted back to 100 even though value was removed before saving the policy.
In some cases, the index priority value became 1 instead of 100.

Steps to reproduce:

1. Create a new index lifecycle policy mypolicy
2. Leave all fields to be default
3. Save policy
4. Edit mypolicy
5. Remove Hot phase - Index priority value
6. Save policy
7. Edit mypolicy

Expected behavior:
Index priority field value is blank

Screenshots (if relevant):

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context:
This issue also occurs in Warm and Cold phases.

Discuss URL: https://discuss.elastic.co/t/ilm-unable-to-remove-index-priority-on-existing-index-lifecycle-policy/235271

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[hendry-lim]

The same issue persists in 7.7.1.

Noticed that the Index priority value was set to 100 when saving.

{
    "name": "mypolicy",
    "phases": {
        "hot": {
            "min_age": "0ms",
            "actions": {
                "rollover": {
                    "max_age": "30d",
                    "max_size": "50gb"
                },
                "set_priority": {
                    "priority": 100
                }
            }
        }
    }
}

[cjcenizal]

Thanks for reporting this @hendry-lim! Looking into this now.

[hendry-lim]

Issue persists in 7.8.0.

[alisonelizabeth]

Thanks for the update @hendrikmuhs! I was able to reproduce and opened #70154 with a fix.

[hendry-lim]

Thank you @alisonelizabeth