Document that application.* banner variables require a packaged jar or the use of Boot's launcher

[maciejwalkowiak]

With a following custom banner.txt file in src/main/resources:

Custom Banner

${application.title}: ${application.version}

When application is built to a native image, printed banner has placeholders resolved to empty strings:

Custom Banner

: 

Where the expected output is:

Custom Banner

spring-native-banner-test: 0.0.1-SNAPSHOT

[mhalbritter]

I can't reproduce this:

Custom Banner

the title: 1.0.0-SNAPSHOT

2022-12-08T10:16:53.797+01:00  INFO 131805 --- [           main] com.example.gh33489.Gh33489Application   : Starting AOT-processed Gh33489Application using Java 17.0.5 with PID 131805 (/home/moe/Downloads/issue-projects/gh-33489/build/native/nativeCompile/gh-33489 started by moe in /home/moe/Downloads/issue-projects/gh-33489)
2022-12-08T10:16:53.797+01:00  INFO 131805 --- [           main] com.example.gh33489.Gh33489Application   : No active profile set, falling back to 1 default profile: "default"
2022-12-08T10:16:53.802+01:00  INFO 131805 --- [           main] com.example.gh33489.Gh33489Application   : Started Gh33489Application in 0.016 seconds (process running for 0.025)

with application.properties containing:

application.title=the title
application.version=1.0.0-SNAPSHOT

Do you have a small sample application with which i can reproduce the problem?

[maciejwalkowiak]

With a regular executable JAR build there is no need to set these variables in application.properties. They are taken from somewhere else (perhaps manifest file?)

[mhalbritter]

Ah yes, you are right. They are read from the MANIFEST.MF, which doesn't work in native image.

[mhalbritter]

Hm, unfortunately it isn't as easy as first thought. The entries which are used in the banner are written by the bootJar task:

tasks.named("bootJar") {
	manifest {
		attributes(
				'Implementation-Title': 'myapp',
				'Implementation-Version': '1.0.0-SNAPSHOT'
		)
	}
}

When compiling the native image, we don't use the JAR, we provide the classpath to native-image. Therefore there is no Manifest which contains these entries which we could just register resource hints for.

Even at AOT processing time, the banner looks wrong:

> Task :processAot
Custom Banner, running Spring Boot 3.0.1

: 

2023-01-10T14:19:40.236+01:00  INFO 55412 --- [           main] com.example.gh33489.Gh33489Application   : Starting Gh33489Application using Java 17.0.5 with PID 55412 (/home/moe/Downloads/issue-projects/gh-33489/build/classes/java/main started by moe in /home/moe/Downloads/issue-projects/gh-33489)
2023-01-10T14:19:40.239+01:00  INFO 55412 --- [           main] com.example.gh33489.Gh33489Application   : No active profile set, falling back to 1 default profile: "default"

because the manifest is not yet written.

[wilkinsona]

I suspect the same problem exists with bootRun as well. In other words, this may not be AOT-specific and may also be a problem in 2.x.

[mhalbritter]

Yes, you're right Andy. gradle bootRun prints

Custom Banner, running Spring Boot 3.0.1

:

[wilkinsona]

The docs already have a note about this for application.version. I think the best we can do is to expand that note to cover application.title as well.