Can plugin configurations support "inheritance" from higher levels with partial property overrides, instead of complete replacement?

[hlg212]

Description

I want to define a common configuration template for certain plugins (e.g., limit-count) that includes basic connection information (such as Redis host and port). When enabling the plugin on a route, I expect these basic properties to be automatically filled, while allowing the route to override specific properties (such as rate-limiting rules), rather than completely rewriting the entire plugin configuration.

I have tried using Plugin Config and Plugin Metadata, but their behavior does not meet expectations:

• Plugin Metadata: Requires internal plugin support and is not a general solution.
• Conflict between Plugin Config and Route Configuration: According to the official documentation, when the same plugin is configured across multiple objects (e.g., Route and Plugin Config), merging follows the priority order Consumer > Route > Plugin Config > Service. However, only the complete configuration of the highest-priority plugin instance is executed. This means the route configuration entirely replaces the Plugin Config configuration, rather than performing intelligent property-level merging and overriding.

Reproduction Steps and Current Result:

1. Create a Plugin Config containing limit-count connection information.
2. Create a route that references plugin_config_id: test-plugin_config_id and configures the limit-count plugin in the plugins field, specifying only different rate-limiting properties.

Example Configuration:

{
  "time_window": 60,
  "redis_host": "local",
  "count": 5
}

Plugin Config Configuration:

{
  "rejected_msg": "plugin configs !",
  "time_window": 60,
  "redis_host": "local",
  "count": 2
}

3. Test the route and observe that the plugin uses the route configuration but loses the "rejected_msg" information defined in the Plugin Config, resulting in a direct 503 error page (see screenshot: [image placeholder]).

Expected Behavior:
I expect plugin configurations to support an "inheritance" or "default value filling" model. For example, with Redis plugins, the expected merging logic would be:

• Higher level (e.g., Plugin Config): Defines default/basic properties (host, port, password).
• Lower level (e.g., Route): Defines extended or overridden properties (database, timeout).

Final effective configuration: Properties specified at the lower level override those of the same name at the higher level, while unique properties from the higher level are automatically included. Example:
{host, port, password} + {database, timeout} → {host, port, password, database, timeout}.

My Questions:

1. In the current APISIX design, is there a way to achieve the "property-level merging" described above?
2. If not currently available, does the official team plan to support such functionality in future versions (e.g., enhancing the merging strategy for Plugin Config)?