generator-jhipster: Tomcat: Broken Metrics page in 5.8.1

Overview of the issue

Metrics page display nothing.

Motivation for or Use Case

Because it can be interesting to have metrics.

Reproduce the error

generate the app, change nothing. Launch it by eclipse or just in a tomcat http://localhost:8080/#/admin/jhi-metrics

We see a stack in console: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?) (through reference chain: java.util.HashMap[“cache”]->java.util.HashMap[“null”]) at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:294) at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:102) at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:272) at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:180) at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:119) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:891) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) … at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748) Caused by: com.fasterxml.jackson.databind.JsonMappingException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?) (through reference chain: java.util.HashMap[“cache”]->java.util.HashMap[“null”]) at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:285) at com.fasterxml.jackson.databind.SerializerProvider.mappingException(SerializerProvider.java:1251) … at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913) at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:285) … 101 common frames omitted

Related issues

No see, it’s since jhipster migrate to micrometer

Suggest a Fix

the metric tomcat.cache.hit have no key because it have no tag name but have a name So i suggest to change JHipsterMetricsEndpoint.cacheMetrics() from: String name = counter.getId().getTag("name"); to

String name = counter.getId().getTag("name");
if(name ==null) {
name = counter.getId().getName(); //maybe we can substring before the first dot found
}

JHipster Version(s)

5.8.1

JHipster configuration

See above

JHipster Version(s)

reqhub@0.0.0 H:\git\mcp\com.trululu.mcp.requirement.product.server\plugins\com.trululu.mcp.server\com.trululu.metax.requirement.server.webapp
`-- generator-jhipster@5.8.1

JHipster configuration, a .yo-rc.json file generated in the root folder

{
    "generator-jhipster": {
        "promptValues": {
            "packageName": "com.trululu.metax.requirement.server.webapp",
            "nativeLanguage": "en"
        },
        "jhipsterVersion": "5.8.1",
        "applicationType": "monolith",
        "baseName": "reqhub",
        "packageName": "com.trululu.metax.requirement.server.webapp",
        "packageFolder": "com/trululu/metax/requirement/server/webapp",
        "serverPort": "8080",
        "authenticationType": "session",
        "cacheProvider": "ehcache",
        "enableHibernateCache": true,
        "websocket": false,
        "databaseType": "sql",
        "devDatabaseType": "h2Disk",
        "prodDatabaseType": "mariadb",
        "searchEngine": false,
        "messageBroker": false,
        "serviceDiscoveryType": false,
        "buildTool": "maven",
        "enableSwaggerCodegen": false,
        "rememberMeKey": "YourJWTSecretKeyWasReplacedByThisMeaninglessTextByTheJHipsterInfoCommandForObviousSecurityReasons",
        "clientFramework": "angularX",
        "useSass": false,
        "clientPackageManager": "npm",
        "testFrameworks": ["gatling", "protractor"],
        "jhiPrefix": "jhi",
        "otherModules": [],
        "enableTranslation": true,
        "nativeLanguage": "en",
        "languages": ["en"],
        "entitySuffix": "",
        "dtoSuffix": "DTO"
    }
}

JDL for the Entity configuration(s) entityName.json files generated in the .jhipster directory

Environment and Tools

java version “1.8.0_181” Java™ SE Runtime Environment (build 1.8.0_181-b13) Java HotSpot™ 64-Bit Server VM (build 25.181-b13, mixed mode)

git version 2.19.0.windows.1

node: v8.12.0

npm: 6.7.0

yeoman: 2.0.5

INFO! Congratulations, JHipster execution is complete!

Entity configuration(s) entityName.json files generated in the .jhipster directory

no entity

Browsers and Operating System

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