spring-boot-starter-actuator needs a newer version of micrometer-core

[SingingBush]

Due to changes in micrometer-core, spring-boot-starter-actuator was updated in issue #27688 to handle the fact that micrometer have changed the package that DiskSpaceMetrics is in (it's now in io.micrometer.core.instrument.binder.system.DiskSpaceMetrics).

The problem is that micrometer-core did that change in the 1.8.* versions but spring-boot-starter-actuator (2.6.1) is pulling in the older 1.7.3 version of micrometer-core which has that class in the old package.

This results in a java.lang.NoClassDefFoundError when initialising the SimpleMetricsExportAutoConfiguration bean.

I was able to work around this problem locally by adding an explicit dependency to micrometer-core 1.8.1 in my pom:

    <dependency>
        <groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>io.micrometer</groupId>
        <artifactId>micrometer-core</artifactId>
        <version>1.8.1</version>
    </dependency>

[wilkinsona]

Spring Boot 2.6 should use Micrometer 1.8 by default. Can you please provide a minimal example that shows 1.7.3 being used?

[antti-markus-cko]

Spring Boot 2.6.1 uses Micrometer 1.8.0 by default - https://github.com/antti-markus-cko/issuedemo

./gradlew dependencyinsight --dependency micrometer
gives

> Task :dependencyInsight
io.micrometer:micrometer-core:1.8.0 (selected by rule)
   variant "compile" [
      org.gradle.status              = release (not requested)
      org.gradle.usage               = java-api
      org.gradle.libraryelements     = jar (compatible with: classes)
      org.gradle.category            = library

      Requested attributes not found in the selected variant:
         org.gradle.dependency.bundling = external
         org.gradle.jvm.environment     = standard-jvm
         org.gradle.jvm.version         = 17
   ]

io.micrometer:micrometer-core:1.8.0
\--- org.springframework.boot:spring-boot-starter-actuator:2.6.1
     \--- compileClasspath (requested org.springframework.boot:spring-boot-starter-actuator)

[SingingBush]

that's weird, when I do mvn dependency:tree the only dependency pulling in micrometer-core is spring-boot-starter-actuator and the version is 1.7.3:

[INFO] +- org.springframework.boot:spring-boot-starter-actuator:jar:2.6.1:compile
[INFO] |  +- org.springframework.boot:spring-boot-actuator-autoconfigure:jar:2.6.1:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-actuator:jar:2.6.1:compile
[INFO] |  |  \- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.12.5:compile
[INFO] |  \- io.micrometer:micrometer-core:jar:1.7.3:compile
[INFO] |     +- org.hdrhistogram:HdrHistogram:jar:2.1.12:compile
[INFO] |     \- org.latencyutils:LatencyUtils:jar:2.0.3:runtime

[snicoll]

@SingingBush That doesn't mean anything if the version was forced by some dependency management in your project. As Andy requested, please share a small sample we can run ourselves that reproduces this.

[spring-projects-issues]

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