Discovery of management endpoints

[hernancerm]

Solves #5006

Created the endpoint /management to reveal mangament routes in a HATEOAS format. This is the format that Spring Boot's /actuator uses. Example output:

{
  "_links": {
    "self": {
      "href": "http://localhost:8080/management",
      "templated": false
    },
    "threaddump": {
      "href": "http://localhost:8080/threaddump",
      "templated": false
    },
    "loggers": [
      {
        "href": "http://localhost:8080/loggers/{name}",
        "templated": true
      },
      {
        "href": "http://localhost:8080/loggers",
        "templated": false
      }
    ]
}

Considerations:

• Duplicate route paths are not shown because the output does not provide HTTP method information to differentiate them. For example, if a route accepts GET and HEAD, a single path is shown (not one per method).
• Regardless of the HTTP method of the route, it is shown if it is a management endpoint. This means that to use some links it is not enough to click on them. I allowed this to keep the design similar to Spring Boot Actuator, since at /actuator it can show /actuator/shutdown which expects a POST, not a GET.
• The implementation also shows custom endpoints defined by the user.

Work that I think is pending

• [x] Implement tests for ManagementController

[jameskleeh]

Thinking about this more it seems like it would be better done with a controller if the goal is to discover the HTTP links

[hernancerm]

Thinking about this more it seems like it would be better done with a controller if the goal is to discover the HTTP links

@jameskleeh By using a controller, would an EmbeddedServer injected in the controller return the correct scheme, host and port to create the links? I think that having clickable links as the author of the issue mentions would be helpful for navigation

[jameskleeh]

Thinking about this more it seems like it would be better done with a controller if the goal is to discover the HTTP links

@jameskleeh By using a controller, would an EmbeddedServer injected in the controller return the correct scheme, host and port to create the links? I think that having clickable links as the author of the issue mentions would be helpful for navigation

No you would have to inject the HttpHostResolver

[hernancerm]

@jameskleeh I've addressed your suggestions, now I'm also targeting branch 3.0.x

[hernancerm]

@jameskleeh I've implemented the tests for the management controller.

Locally ./gradlew check passes all tests

[hernancerm]

Hi @jameskleeh, are there additional changes that I should make?

[jameskleeh]

@HerCerM Overall it looks OK however we are hard at work getting the next milestone of 3.0 out so we'll get this merged afterwards

[hernancerm]

Hi @graemerocher, thanks for the review and sorry for the delay. I expect to address the changes during the next week, since currently I have other things at hand

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}