Log coloring lost in recent image due to single-character `detected_level` values

[shin19991207]

Hi team,

I’ve noticed that recent versions of the image are emitting log entries where the detected_level field contains only a single character (I, W, E, etc.) instead of the full word (info, warn, etc.). As a result, Grafana’s Explore UI no longer applies color coding to log levels—everything shows as grey.

Older version (log coloring works as expected):

Newer version (logs are grey, detected_level is a single letter):

I verified this using the same application and OpenTelemetry source, but with different versions of the docker-otel-lgtm image.

• Older versions of the image output full text values for detected_level, and Grafana colored the logs as expected.
• With the latest image, only a single character is emitted, and log coloring is lost.

Is this change intentional, or a regression? Will full-word detected_level support (for colored logs) return in a future release? Or is there a recommended workaround for log coloring in Grafana?

Color-coded logs are much more useful for observability.

Thanks in advanced!

[zeitlinger]

@cyrille-leclerc can you help out?

[cyrille-leclerc]

@shin19991207 can you please capture details of the other log metadata on both log entries, particularly severity_text , telemetry_sdk_name , and telemetry_sdk_version.

[shin19991207]

Hi @cyrille-leclerc

Here's the details:

A log from an older image (e.g. 0.9.3):

Full JSON:

{"line":"Received response with status: 200","timestamp":"1752068726022000000","fields":{"trace_id":"b3dace6f9eb7290436aa154881cc9745","detected_level":"info","flags":"1","host_arch":"aarch64","host_name":"Mac","io_openliberty_ext_app_name":"guide-microprofile-telemetry-inventory","io_openliberty_module":"io.openliberty.guides.inventory.client.SystemClient","io_openliberty_sequence":"1752068726022_000000000004D","io_openliberty_type":"liberty_message","observed_timestamp":"1752068726023000000","os_description":"Mac OS X 15.5","os_type":"darwin","process_command_line":"/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/bin/java -Xoptionsfile=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/options.default -Xlockword:mode=default,noLockword=java/lang/String,noLockword=java/util/MapEntry,noLockword=java/util/HashMap$Entry,noLockword=org/apache/harmony/luni/util/ModifiedMap$Entry,noLockword=java/util/Hashtable$Entry,noLockword=java/lang/invoke/MethodType,noLockword=java/lang/invoke/MethodHandle,noLockword=java/lang/invoke/CollectHandle,noLockword=java/lang/invoke/ConstructorHandle,noLockword=java/lang/invoke/ConvertHandle,noLockword=java/lang/invoke/ArgumentConversionHandle,noLockword=java/lang/invoke/AsTypeHandle,noLockword=java/lang/invoke/ExplicitCastHandle,noLockword=java/lang/invoke/FilterReturnHandle,noLockword=java/lang/invoke/DirectHandle,noLockword=java/lang/invoke/ReceiverBoundHandle,noLockword=java/lang/invoke/DynamicInvokerHandle,noLockword=java/lang/invoke/FieldHandle,noLockword=java/lang/invoke/FieldGetterHandle,noLockword=java/lang/invoke/FieldSetterHandle,noLockword=java/lang/invoke/StaticFieldGetterHandle,noLockword=java/lang/invoke/StaticFieldSetterHandle,noLockword=java/lang/invoke/IndirectHandle,noLockword=java/lang/invoke/InterfaceHandle,noLockword=java/lang/invoke/VirtualHandle,noLockword=java/lang/invoke/PrimitiveHandle,noLockword=java/lang/invoke/InvokeExactHandle,noLockword=java/lang/invoke/InvokeGenericHandle,noLockword=java/lang/invoke/VarargsCollectorHandle,noLockword=java/lang/invoke/ThunkTuple -XX:+EnsureHashed:java/lang/Class,java/lang/Thread -Xjcl:jclse29 -Dcom.ibm.oti.vm.bootstrap.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib -Dsun.boot.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib -Djava.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib:/usr/lib -Djava.home=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home -Duser.dir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/defaultServer -Xverbosegclog:/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/defaultServer/logs/verbosegc.%seq.log,10,1024 -Djdk.nativePBKDF2=true -Xshareclasses:name=liberty-%u,nonfatal,cacheDir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/.classCache,cacheDirPerm=1000 -XX:ShareClassesEnableBCI -Xscmx130m -Djdk.nativePBKDF2=true -Xshareclasses:name=liberty-%u,nonfatal,cacheDir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/.classCache,cacheDirPerm=1000 -XX:ShareClassesEnableBCI -Xscmx130m -javaagent:/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-javaagent.jar -Djava.awt.headless=true -Djdk.attach.allowAttachSelf=true --add-exports=java.base/sun.security.action=ALL-UNNAMED --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-exports=java.naming/com.sun.jndi.url.ldap=ALL-UNNAMED --add-exports=jdk.naming.dns/com.sun.jndi.dns=ALL-UNNAMED --add-exports=jdk.naming.dns/com.sun.jndi.url.dns=ALL-UNNAMED --add-exports=java.security.jgss/sun.security.krb5.internal=ALL-UNNAMED --add-exports=jdk.attach/sun.tools.attach=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.naming/javax.naming.spi=ALL-UNNAMED --add-opens=java.naming/com.sun.naming.internal=ALL-UNNAMED --add-opens=jdk.naming.rmi/com.sun.jndi.url.rmi=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED --add-opens=java.rmi/java.rmi=ALL-UNNAMED --add-opens=java.sql/java.sql=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.desktop/java.awt.image=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.text=ALL-UNNAMED --add-opens=java.base/sun.net.www.protocol.https=ALL-UNNAMED --add-exports=jdk.management.agent/jdk.internal.agent=ALL-UNNAMED --add-exports=java.base/jdk.internal.vm=ALL-UNNAMED -Dwas.debug.mode=true -Dsun.reflect.noInflation=true -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=7777 -Djava.class.path=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-server.jar -Dsun.java.command=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-server.jar defaultServer -Dsun.java.launcher=SUN_STANDARD /Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-server.jar defaultServer","process_executable_path":"/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/bin/java","process_pid":"27612","process_runtime_description":"Eclipse OpenJ9 Eclipse OpenJ9 VM openj9-0.48.0","process_runtime_name":"IBM Semeru Runtime Open Edition","process_runtime_version":"17.0.13+11","scope_name":"io.openliberty.microprofile.telemetry","service_instance_id":"76dee002-7b8f-4af6-a9ec-b8cd62bfb6c5","service_name":"inventory","severity_number":"9","severity_text":"I","span_id":"f22be0f57c8e03c4","telemetry_sdk_language":"java","telemetry_sdk_name":"opentelemetry","telemetry_sdk_version":"1.39.0","thread_id":"56","thread_name":"Default Executor-thread-2"}}

A log from the latest image:

Full JSON:

{"line":"Received response with status: 200","timestamp":"1752066771482000000","date":"2025-07-09T13:12:51.482Z","fields":{"trace_id":"701cdb4b68f6d9cb4ae9d3ea96ad14bb","detected_level":"I","flags":"1","host_arch":"aarch64","host_name":"Mac","io_openliberty_ext_app_name":"guide-microprofile-telemetry-inventory","io_openliberty_module":"io.openliberty.guides.inventory.client.SystemClient","io_openliberty_sequence":"1752066771482_0000000000022","io_openliberty_type":"liberty_message","observed_timestamp":"1752066771483000000","os_description":"Mac OS X 15.5","os_type":"darwin","process_command_line":"/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/bin/java -Xoptionsfile=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/options.default -Xlockword:mode=default,noLockword=java/lang/String,noLockword=java/util/MapEntry,noLockword=java/util/HashMap$Entry,noLockword=org/apache/harmony/luni/util/ModifiedMap$Entry,noLockword=java/util/Hashtable$Entry,noLockword=java/lang/invoke/MethodType,noLockword=java/lang/invoke/MethodHandle,noLockword=java/lang/invoke/CollectHandle,noLockword=java/lang/invoke/ConstructorHandle,noLockword=java/lang/invoke/ConvertHandle,noLockword=java/lang/invoke/ArgumentConversionHandle,noLockword=java/lang/invoke/AsTypeHandle,noLockword=java/lang/invoke/ExplicitCastHandle,noLockword=java/lang/invoke/FilterReturnHandle,noLockword=java/lang/invoke/DirectHandle,noLockword=java/lang/invoke/ReceiverBoundHandle,noLockword=java/lang/invoke/DynamicInvokerHandle,noLockword=java/lang/invoke/FieldHandle,noLockword=java/lang/invoke/FieldGetterHandle,noLockword=java/lang/invoke/FieldSetterHandle,noLockword=java/lang/invoke/StaticFieldGetterHandle,noLockword=java/lang/invoke/StaticFieldSetterHandle,noLockword=java/lang/invoke/IndirectHandle,noLockword=java/lang/invoke/InterfaceHandle,noLockword=java/lang/invoke/VirtualHandle,noLockword=java/lang/invoke/PrimitiveHandle,noLockword=java/lang/invoke/InvokeExactHandle,noLockword=java/lang/invoke/InvokeGenericHandle,noLockword=java/lang/invoke/VarargsCollectorHandle,noLockword=java/lang/invoke/ThunkTuple -XX:+EnsureHashed:java/lang/Class,java/lang/Thread -Xjcl:jclse29 -Dcom.ibm.oti.vm.bootstrap.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib -Dsun.boot.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib -Djava.library.path=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib/default:/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home/lib:/usr/lib -Djava.home=/Library/Java/JavaVirtualMachines/ibm-semeru-open-17.jdk/Contents/Home -Duser.dir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/defaultServer -Xverbosegclog:/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/defaultServer/logs/verbosegc.%seq.log,10,1024 -Djdk.nativePBKDF2=true -Xshareclasses:name=liberty-%u,nonfatal,cacheDir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/.classCache,cacheDirPerm=1000 -XX:ShareClassesEnableBCI -Xscmx130m -Djdk.nativePBKDF2=true -Xshareclasses:name=liberty-%u,nonfatal,cacheDir=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/usr/servers/.classCache,cacheDirPerm=1000 -XX:ShareClassesEnableBCI -Xscmx130m -javaagent:/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-javaagent.jar -Djava.awt.headless=true -Djdk.attach.allowAttachSelf=true --add-exports=java.base/sun.security.action=ALL-UNNAMED --add-exports=java.naming/com.sun.jndi.ldap=ALL-UNNAMED --add-exports=java.naming/com.sun.jndi.url.ldap=ALL-UNNAMED --add-exports=jdk.naming.dns/com.sun.jndi.dns=ALL-UNNAMED --add-exports=jdk.naming.dns/com.sun.jndi.url.dns=ALL-UNNAMED --add-exports=java.security.jgss/sun.security.krb5.internal=ALL-UNNAMED --add-exports=jdk.attach/sun.tools.attach=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.nio=ALL-UNNAMED --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.naming/javax.naming.spi=ALL-UNNAMED --add-opens=java.naming/com.sun.naming.internal=ALL-UNNAMED --add-opens=jdk.naming.rmi/com.sun.jndi.url.rmi=ALL-UNNAMED --add-opens=java.naming/javax.naming=ALL-UNNAMED --add-opens=java.rmi/java.rmi=ALL-UNNAMED --add-opens=java.sql/java.sql=ALL-UNNAMED --add-opens=java.management/javax.management=ALL-UNNAMED --add-opens=java.base/java.lang.reflect=ALL-UNNAMED --add-opens=java.desktop/java.awt.image=ALL-UNNAMED --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.text=ALL-UNNAMED --add-opens=java.base/sun.net.www.protocol.https=ALL-UNNAMED --add-exports=jdk.management.agent/jdk.internal.agent=ALL-UNNAMED --add-exports=java.base/jdk.internal.vm=ALL-UNNAMED -Dwas.debug.mode=true -Dsun.reflect.noInflation=true -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=61145 -Djava.class.path=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-server.jar -Dsun.java.command=/Users/morganchang/Desktop/draft-guide-microprofile-telemetry-automatic/finish/inventory/target/liberty/wlp/bin/tools/ws-server.jar defaultServer -Dsun.java.launcher=SUN_STANDARD 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[cyrille-leclerc]

The newer Grafana version seems to be more strict on how to interpret the log severity.

You instrumentation passes severity_text: I , severity_number: 9 and the version of Grafana in otel-lgtm:0.9.3 did interpret I as the INFO log level when latest versions of Grafana seem to be stricter and fail to interpret.

What is the OpenTelemetry logs bridge used ?
I think it should evolve to produce severity nmes matching https://opentelemetry.io/docs/specs/otel/logs/data-model/#displaying-severity

[shin19991207]

Thanks for the quick response. I'm using the Open Liberty mpTelemetry feature as the bridge, and I've asked the SME to investigate this issue further.

[fmhwong]

Can Grafana use severity_number to determine the detected_level? The serverity_number is just a number between 1-24 so it will be a lot easier than comparing strings with severity_text.

[shantanualsi]

Hello @fmhwong, Loki already uses severity_number to determine detected_level - https://github.com/grafana/loki/blob/main/pkg/distributor/field_detection.go#L156

Detected level is computed in Loki on a best effort basis - it first scans attributes for familiar fields such as level, severity_text, etc. If not found, then looks for severity_number.

In your case, severity_text is just I which loki reads and uses it as detected_level.

[Yas-Franco]

@shantanualsi Severity_text is an optional field and should be set to what the log level is known as at the source. Therefore I don't think it should take priority over the severity_number