A java.lang.instrument agent providing a clojure repl that is spring aware. The intent is to allow any spring based service or app to be started with this agent and provide useful clojurey things to java-based software. Even if you don't care about spring, this agent can still be useful to create an nrepl server in an existing application without modifying any code or dependencies of the application.
Create the agent jar via:
lein uberjar
Add this option to your java application's startup args:
-javaagent:/your/path/to/target/spring-repl-1.0.0-standalone.jar
At startup, this agent will create an nrepl server on port 8000. You can then use any nrepl client to connect. In addition to starting an nrepl server, the agent detects the creation of a Spring ApplicationContext, and maintains a clojure var referring to it. This allows clojure code to access any beans in the application context. However, even if your application/service is not using spring, the repl has full access to anything on the classpath of the JVM you are running.
For example
lein repl :connect localhost:8000
Execute the following to list spring-related functions available:
(dir spring-repl.context)
For convenience, you might want to require the namespace and give it a shorter alias:
(require '[spring-repl.context :as ctx])
In the future I will likely make this require automatic.
Keep in mind that you can also import any java classes available on the classpath and invoke instances via clojure's java interop. This tool has utility beyond spring environments.
Add this to your build.gradle for running in your IDE:
bootRun {
jvmArgs = ["-javaagent:/your/path/to/target/spring-repl-1.0.0-standalone.jar"]
}
If you are running a spring boot app outside an IDE, you should not need any special config other than the -javaagent JVM option.
The first couple of verisions of this agent included dependencies which could cause all manner of chaos at runtime. These dependencies have been removed. I included them for my own experiments in using the agent as a vehicle to inject new dependencies into a running JVM for running tests in an unorthodox manner.
The spring-specific functions provided are minimal at the moment. I will likely add more over time. I have exclusively been using this agent as a vehicle for injecting clojure code into crufty legacy java code for testing purposes. Specifically, I have used this to experiment with writing integration tests for java code which will never be refactored for testability due to resource constraints. Having a repl which can access all java packages and spring beans in a full running application has been interesting and useful.
Copyright © 2017 Todd Stout Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.