callback-logger

A small Kotlin and Micronaut service that receives callbacks, for testing APIs locally that send them. Point the API at port 7071 and every request it sends is recorded, whatever its path, method or content type. Then watch them arrive in the web UI on port 7070.

Features

• Records callbacks to any path with any HTTP method, using an embedded WireMock server
• A live inbox in the browser, with a Copy as curl button on every callback
• Configurable response status code, payload and content type
• Keeps the newest 1000 callbacks in memory by default, or as many as you choose
• Works offline: every asset the web UI needs is served by the app itself

Requirements

• Java 25 or later (callback-logger runs on the JVM only; a GraalVM native image is not supported)

Install

There are no releases yet, so build and run it from source:

git clone https://github.com/leeturner/callback-logger.git
cd callback-logger
./gradlew build run

Usage

Callbacks are received by an embedded WireMock server on its own port, 7071, while the web interface stays on 7070. Point the API you are testing at any path on the callback port, with any HTTP method, for example http://localhost:7071/callback or http://localhost:7071/orders/42/status. Every request is recorded, whatever its path, method or content type. You can send a callback manually using the following curl request:

curl -X POST --location "http://localhost:7071/callback" \
    -H "Content-Type: application/json" \
    -d "{\"hello\": \"world\"}"

or

curl -X PATCH --location "http://localhost:7071/orders/42/status" \
    -H "Content-Type: application/xml" \
    -d "<hello>world</hello>" 

More examples, including form posts, query strings and custom methods such as PROPFIND, are in src/test/resources/http/callbacks.http.

Each callback in the inbox has a Copy as curl button that copies a curl command to send it to the callback logger again.

Paths under /__admin are reserved by WireMock. Its admin API is locked, so those requests are refused with a 401 and are not recorded as callbacks.

Change the callback port

The callback port is set in the application.conf file:

callback-logger {
  wiremock {
    port = 7071
  }
}

Set the HTTP response code

By default, callback-logger returns a 200 response code for all callbacks. If you need to return a different response code then you can define the response code in the application.conf file. For example:

callback-logger {
  callback-response-status-code = 201
}

The application will fail to start if the response code is not a valid http response code.

Set the HTTP response payload

By default, callback-logger returns an empty string as the response payload for all callbacks, with a Content-Type: application/json header. If you need to return a different response payload then you can change that in the application.conf file. For example:

callback-logger {
  callback-response-payload = "{\"status\": \"OK\", \"message\": \"Callback received\"}"
}

Set the HTTP response content type

By default, callback-logger returns a Content-Type: application/json header with every response, including when the setting is missing or blank. If your payload is in a different format then set the content type to match. For example, to return XML:

callback-logger {
  callback-response-payload = "<status>OK</status>"
  callback-response-content-type = "application/xml"
}

The application will fail to start if the content type is not a valid media type, such as xml instead of application/xml.

Limit how many callbacks are kept

Callbacks are kept in memory, and by default only the newest 1000 are kept: once there are more, the oldest are dropped. To keep a different number, set it in the application.conf file. For example:

callback-logger {
  max-callbacks = 5000
}

The application will fail to start if the number is not greater than zero.

Web UI

The web interface shows the callbacks you have received. Open http://localhost:7070/callback-logger in your browser.

New callbacks appear in the inbox as they arrive, and clearing or deleting them updates every open tab. Press Refresh to reload the inbox on demand, Clear All to empty it, or the bin button on a callback to delete just that one. All of them update the page in place using Datastar, without a full page reload. The page is styled with Bulma, and Bulma, Datastar and highlight.js are all served by the app itself, so the inbox works with no internet connection.

Building

Run the tests with:

./gradlew test

Bug reports and ideas are welcome in issues.

Licence

Apache License 2.0. See LICENSE.