User Story

As a developer, I want to override management attribute values using environment variables

Purpose

EAP on the cloud relies on container environment variables to customize its configuration to the container platform.
This feature lets a cloud deployer override an existing attribute value in the management model using an environment variable.

This feature is not specific to the cloud target platform but this is where this will make the most of sense and implore the most the developer experience.

Content Location

In a developer guide.
Where should this content go? New guide? Existing guides or processes this content should go with/relate to?

Prerequisites

N/A

Procedures 

For example, if the user wants to update the cache-size attribute on the /subsystem=foo/resource=my-resource, the cache-size attribute must be configured with an expression and a default value:
cache-size=${my-resource-cache-size:1234}
so that the user can use a system property (or an env var with EAP7-1728) to resolve the expression with a new value.
However if the attribute is not configured with an expression, the user has no way to simply modify it.

With this feature, for the same example above, the user could set an env var before starting EAP to change the value of the cache size with something like:
SUBSYSTEM_CACHE_RESOURCE_MY_RESOURCE__CACHE_SIZE=5678

Concepts

Conceptual information

https://docs.wildfly.org/26/Admin_Guide.html#overridden-attribute-value

Procedures

Administrative tasks (if required)

N/A

Concepts

Procedures

Expected Outcome

With this procedure, the user can deploy an EAP application and adapt its configuration to the target platform without having to directly modify the standalone configuration.

This allows to specify target specific information (host, port, credentials) that are not know in advance (before the application is deployed on OpenShift for example).