Specify spring expression language filter for KubernetesDiscoveryClient in Spring Boot Admin

Question

I've specified a spring expression language filter in my spring boot admin application:

filter: "'.*string.*'"

And I get this error:

org.springframework.expression.spel.SpelEvaluationException: EL1001E: Type conversion problem, cannot convert from java.lang.String to java.lang.Boolean
    at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:75) ~[spring-expression-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.expression.common.ExpressionUtils.convertTypedValue(ExpressionUtils.java:57) ~[spring-expression-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:377) ~[spring-expression-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.cloud.kubernetes.discovery.KubernetesDiscoveryClient.lambda$getServices$7(KubernetesDiscoveryClient.java:266) ~[spring-cloud-kubernetes-discovery-1.1.0.RELEASE.jar:1.1.0.RELEASE]
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:176) ~[na:na]
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
    at org.springframework.cloud.kubernetes.discovery.KubernetesDiscoveryClient.getServices(KubernetesDiscoveryClient.java:280) ~[spring-cloud-kubernetes-discovery-1.1.0.RELEASE.jar:1.1.0.RELEASE]
    at org.springframework.cloud.kubernetes.discovery.KubernetesDiscoveryClient.getServices(KubernetesDiscoveryClient.java:274) ~[spring-cloud-kubernetes-discovery-1.1.0.RELEASE.jar:1.1.0.RELEASE]
    at org.springframework.cloud.client.discovery.composite.CompositeDiscoveryClient.getServices(CompositeDiscoveryClient.java:67) ~[spring-cloud-commons-2.2.0.RELEASE.jar:2.2.0.RELEASE]
    at de.codecentric.boot.admin.server.cloud.discovery.InstanceDiscoveryListener.discover(InstanceDiscoveryListener.java:126) ~[spring-boot-admin-server-cloud-2.2.2.jar:2.2.2]
    at de.codecentric.boot.admin.server.cloud.discovery.InstanceDiscoveryListener.onApplicationReady(InstanceDiscoveryListener.java:100) ~[spring-boot-admin-server-cloud-2.2.2.jar:2.2.2]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.context.event.ApplicationListenerMethodAdapter.doInvoke(ApplicationListenerMethodAdapter.java:305) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.event.ApplicationListenerMethodAdapter.processEvent(ApplicationListenerMethodAdapter.java:190) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.event.ApplicationListenerMethodAdapter.onApplicationEvent(ApplicationListenerMethodAdapter.java:153) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:404) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:361) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.boot.context.event.EventPublishingRunListener.running(EventPublishingRunListener.java:103) ~[spring-boot-2.2.8.RELEASE.jar:2.2.8.RELEASE]
    at org.springframework.boot.SpringApplicationRunListeners.running(SpringApplicationRunListeners.java:77) ~[spring-boot-2.2.8.RELEASE.jar:2.2.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:330) ~[spring-boot-2.2.8.RELEASE.jar:2.2.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.8.RELEASE.jar:2.2.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.8.RELEASE.jar:2.2.8.RELEASE]
    at com.coremedia.blueprint.boot.admin.SpringBootAdminApp.main(SpringBootAdminApp.java:29) ~[classes/:na]
Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Boolean] for value '.*string.*'; nested exception is java.lang.IllegalArgumentException: Invalid boolean value '.*string.*'
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:47) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:191) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:70) ~[spring-expression-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    ... 33 common frames omitted
Caused by: java.lang.IllegalArgumentException: Invalid boolean value '.*string.*'
    at org.springframework.core.convert.support.StringToBooleanConverter.convert(StringToBooleanConverter.java:63) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.core.convert.support.StringToBooleanConverter.convert(StringToBooleanConverter.java:31) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.core.convert.support.GenericConversionService$ConverterAdapter.convert(GenericConversionService.java:385) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41) ~[spring-core-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    ... 35 common frames omitted

Why do I get this error?
How should I specify a filter in spring expression language here?

score 2 · Accepted Answer · answered Dec 20 '20 at 08:22

2

The el filter must return a boolean value. The discovered service, which should be filtered, is injected as #root in the expression. So #root.metadata.name retrieves the actual name of the kubernetes service.

This part of code of KubernetesDiscoveryClient does the filtering:

Expression filterExpr = this.parser.parseExpression(spelExpression);
filteredServices = (Service instance) -> {
    Boolean include = filterExpr.getValue(this.evalCtxt, instance, Boolean.class);
    ...
};

This is my full spring boot admin configuration:

spring:
    cloud:
        kubernetes:
            discovery:
                namespace: myname
                all-namespaces: true
                filter: "#root.metadata.name matches '.*string.*'"
                service-labels:
                    "[app.kubernetes.io/part-of]": myapp

answered Dec 20 '20 at 08:22

Matthias M

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do you know if #root.metadata.namespace is available? It's not printed on trace. – la00 Dec 20 '22 at 10:54
@la00 What do you mean by "It's not printed on trace"? In my case the syntax was just invalid. Otherwise the attributes of root depend on the object, which is passed as parameter. – Matthias M Dec 20 '22 at 13:59
I mean when I put TRACE level on logging. Anyway, I opened a ticket https://github.com/spring-cloud/spring-cloud-kubernetes/issues/1182 as it's still not fully working. – la00 Jan 04 '23 at 09:23

Specify spring expression language filter for KubernetesDiscoveryClient in Spring Boot Admin

1 Answers1