Support launching processes with inherited IO

[fbricon]

Create and unzip the simplest quarkus app possible. When running mvn quarkus:dev, the server logs are displayed following the maven traces:

❯ mvn quarkus:dev
executing mvnw instead of mvn
[INFO] Scanning for projects...
[INFO]
[INFO] -----------------------< org.acme:mvnd-quarkus >------------------------
[INFO] Building mvnd-quarkus 1.0.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- quarkus-maven-plugin:1.9.2.Final:dev (default-cli) @ mvnd-quarkus ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Nothing to compile - all classes are up to date
Listening for transport dt_socket at address: 5005

---

--/ __ / / / / _ | / _ / /// / / / __/
-/ // / // / __ |/ , / ,< / // /\
--___// |//|//||_//
2020-11-27 17:25:40,822 INFO [io.quarkus] (Quarkus Main Thread) mvnd-quarkus 1.0.0-SNAPSHOT on JVM (powered by Quarkus 1.9.2.Final) started in 0.559s.
2020-11-27 17:25:40,841 INFO [io.quarkus] (Quarkus Main Thread) Profile dev activated. Live Coding activated.
2020-11-27 17:25:40,841 INFO [io.quarkus] (Quarkus Main Thread) Installed features: [cdi]
hello commando
2020-11-27 17:25:40,874 INFO [io.quarkus] (Quarkus Main Thread) mvnd-quarkus stopped in 0.022s
Quarkus application exited with code 0
Press Enter to restart or Ctrl + C to quit
^C%

Now, using mvnd 0.1.1, with mvnd quarkus:dev -Dmvnd.noBuffering=true, the application logs are not shown (which is an issue for vscode-quarkus, since it can't detect the debugger is available):

❯ mvnd quarkus:dev -Dmvnd.noBuffering=true
[INFO] Scanning for projects...
[mvnd-quarkus] [INFO] BuildTimeEventSpy is registered.
[mvnd-quarkus] [INFO]
[mvnd-quarkus] [INFO] Using the SmartBuilder implementation with a thread count of 11
[mvnd-quarkus] [INFO] Task segments : [quarkus:dev]
[mvnd-quarkus] [INFO] Build maximum degree of concurrency is 11
[mvnd-quarkus] [INFO] Total number of projects is 1
[mvnd-quarkus] [INFO]
[mvnd-quarkus] [INFO] -----------------------< org.acme:mvnd-quarkus >------------------------
[mvnd-quarkus] [INFO] Building mvnd-quarkus 1.0.0-SNAPSHOT
[mvnd-quarkus] [INFO] --------------------------------[ jar ]---------------------------------
[mvnd-quarkus] [INFO]
[mvnd-quarkus] [INFO] --- quarkus-maven-plugin:1.9.2.Final:dev (default-cli) @ mvnd-quarkus ---
[mvnd-quarkus] [INFO] Using 'UTF-8' encoding to copy filtered resources.
[mvnd-quarkus] [INFO] Copying 1 resource
[mvnd-quarkus] [INFO] Nothing to compile - all classes are up to date

at that point, the server is actually running, but there's no clue from the output.

I suspect this will be a similar issue with other microservices or processes spawned from maven plugins

[gnodet]

Yes, this is caused by the quarkus maven plugin spawning a process. It does use the inheritIO() on the ProcessBuilder, but mvnd does set specific system streams using System.setOut/Err(). Those can't be reused by spawned processes. I need to investigate if mvnd can go a bit deeper.

[gnodet]

I see 2 solutions:

• find a way to use dup2 using JNI so that the stream can be inherited, that does not seem really easy to do
• change the maven quarkus plugin to not inherit the system output, but poll the output and print it to System.out instead

[gnodet]

The first solution can't be done easily, so a change to quarkus maven plugin is the best solution imho.