Command Line Mode support (initial)

[paulrobinson]

Description

Having the ability to launch Quarkus as a short live, command line application. For example with Aesh or Picocli (the later is already GraalVM compatible and very popular)

Analysis

Discussion currently happening on the mailing list:

• Thoughts on Command Mode
• Command Mode
• Application startup redesign for command-based apps

Tasks

• Introduce command line argument based configuration binding (Introduce config-based command line argument binding #6497)
• Introduce and use exit request API with wait-for-exit method (Introduce an exit request API with wait-for-exit method #6498)
• Introduce ability to recognize and execute user main method(s) (with optional command line arguments, optionally returning an exit code) by annotation (Introduce ability to recognize and execute user main method(s) #6499)

[stalep]

Just a FYI, Æsh is GraalVM compatible as well (had it earlier than picocli :)

• not a popular as I have not had time to work on docs/webpage much and push it to projects, but AFAIK there are no features picocli has that's not in Æsh. - and Æsh have command mode with support for custom CommandInvocations so that it's very easy to add Quarkus specific capability when invoking the commands. Eg: look at Georgios POC for the first CLI attempt.

[maxandersen]

• Eg: look at Georgios POC for the first CLI attempt

where is that ? link ?

[bric3]

@maxandersen I think that's a typo, and @stalep refers to this PR : https://github.com/quarkusio/quarkus/pull/1301/files

[remkop]

Question about #6497 (configuring Quarkus from command line args): this is now listed as the first task in this epic, but is this a showstopper?

The Quarkus user community is very eager to get their hands on this Command Line Mode feature (and have been for over a year). Would it not make sense to focus on the minimum credible deliverable initially, and add features like #6497 later?

[maxandersen]

Yes @remkop, we just went through and triaged the work for this and a bunch of others. Don't get stuck on the sequence of bullet items in the epics. The important part is that we got agreement on how #6498 and #6499 will work. We are many eagerly waiting on this - have a little more patience :)

[remkop]

@maxandersen Understood, and thanks for providing insight into the process!

[lburgazzoli]

We need this also in camel-k to support delegating scheduling to the platform (k8s)

[remkop]

Quarkus team, would it be possible to provide a regular status update? From the outside it looks like there is nothing happening...

[maxandersen]

PR #7681 is on its way.

[maxandersen]

@remkop et.al. then fyi #7681 is. now working and looking for feedback/comments if you are interested in trying it out. Has docs and all included.