In #14046 and #14089, we introduced new functionality to guard against running Logstash as root with the introduction of a new setting allow_superuser. The initial implementation set this to true to avoid a breaking change in a minor release, but we should set this setting to false by default to disallow running Logstash as root by default
### Tasks
- [x] on `main` (8.x), when `allow_superuser` is not set, log a deprecation advising how to resolve prior to upgrading to 9.x by _either_ (1) setting `allow_superuser: false` to opt in _or_ (2) setting `allow_superuser: true` to opt out
- [x] on `9.x`, set default value of `allow_superuser` to `false`
In #14046 and #14089, we introduced new functionality to guard against running Logstash as root with the introduction of a new setting
allow_superuser. The initial implementation set this totrueto avoid a breaking change in a minor release, but we should set this setting tofalseby default to disallow running Logstash as root by default