Tutorial Monitor a Java Application - Feedback on some problems encountered

[daverick]

Hi,

I have followed the Monitor a Java Application tutorial This is a great tutorial!

but I have found some problems along the way and some solutions too. I am not a Java Developper so they might not be the best ones ;-)

• in the Step 1.10, I need to add a dependencies in the build.gradle to be able to execute the application (openJDK 15)

implementation 'org.slf4j:slf4j-simple:1.7.30

• in the steps 4, Write logs as JSON I had to change the log4j2 settings to:

<Loggers>
    <Logger name="de.spinscale.javalin.App" level="INFO"/>
    <Root level="ERROR">
      <AppenderRef ref="Console" />
      <AppenderRef ref="JavalinAppLogRolling" />
    </Root>
  </Loggers>

• on step 7, customer transactions I had to add in App.java

import co.elastic.apm.api.ElasticApm;

• on step 7, method tracing via agent configuration, the new logger class is not working correctly and generate messages and before the Step 2- Log requests ;-(

And in the Step 4, ingest nodes, step 3 I would rather put the pipeline configuration at the input level instead of the output. It's the same result but imo it is better placed at that level as it should only be used for this log.

filebeat.inputs:
- type: log
  paths:
    - /tmp/javalin/*.log
  multiline.pattern: ^20
  multiline.negate: true
  multiline.match: after
  processors:
  - add_host_metadata: ~
  pipeline: javalin_pipeline

[spinscale]

hey, thanks for the comments, I'll work on a PR for all of those.

One question regarding Step 2 - what happens if you do not include that example? No logging at all? As this uses log4j2 (the successer to log4j) I am wondering how the above dependency helps.

Just for reference, you can always check the final app at https://github.com/spinscale/observability-using-the-elastic-stack-java

[spinscale]

can you also explain the step 7 (tracing via agent configuration) issue? I don't fully understand that one by just reading it -I might be missing a detail here.

[daverick]

One question regarding Step 2 - what happens if you do not include that example? No logging at all? As this uses log4j2 (the successor to log4j) I am wondering how the above dependency helps.
My note were incorrect. It is in Step 1.10 when starting for the first time the new Java application. I have updated the issue.
My complete error log:

docker run --rm --name my-app \
            -v "$(PWD)"/build:/build \
            -v "$(PWD)"/logs:/tmp/ \
            -p 7000:7000 \
            openjdk:15 java -jar /build/libs/javalin-app-all.jar
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
-------------------------------------------------------------------

-------------------------------------------------------------------
Missing dependency 'Slf4j simple'. Add the dependency.

pom.xml:
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>1.7.30</version>
</dependency>

build.gradle:
compile "org.slf4j:slf4j-simple:1.7.30"

Find the latest version here:
https://search.maven.org/search?q=g%3Aorg.slf4j+AND+a%3Aslf4j-simple
-------------------------------------------------------------------
-------------------------------------------------------------------
OR
-------------------------------------------------------------------

-------------------------------------------------------------------
Missing dependency 'Slf4j simple with Provider'. Add the dependency.

pom.xml:
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.8.0-beta4</version>
</dependency>

build.gradle:
compile "org.slf4j:slf4j-api:1.8.0-beta4"

Find the latest version here:
https://search.maven.org/search?q=g%3Aorg.slf4j+AND+a%3Aslf4j-api
------------------------------------------------------------------- and

-------------------------------------------------------------------
Missing dependency 'Slf4j simple with Provider'. Add the dependency.

pom.xml:
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>1.8.0-beta4</version>
</dependency>

build.gradle:
compile "org.slf4j:slf4j-simple:1.8.0-beta4"

Find the latest version here:
https://search.maven.org/search?q=g%3Aorg.slf4j+AND+a%3Aslf4j-simple
-------------------------------------------------------------------
-------------------------------------------------------------------
Visit https://javalin.io/documentation#logging if you need more help

[daverick]

can you also explain the step 7 (tracing via agent configuration) issue? I don't fully understand that one by just reading it -I might be missing a detail here.

The instructions for showing Method tracing via agent configuration in the Step 7 give a code for a new logger class so that it could be easily configure with the elastic.apm.trace_methods. But the code for this logger is not working as expected: no logs like GET / 200 172.17.0.1 "curl/7.64.1" 0 are generated anymore.

[spinscale]

can you share that repo with your code in a github repo? I just tried running via docker locally and it logs as expected, so I suppose something is different between our setups or repos. I also suspect those issues of not logging might be linked to each other...

[daverick]

https://github.com/daverick/observability-tutorial-java

[bmorelli25]

👋 Are these updates still required?

[dedemorton]

I'm going to assign this to myself because I'm making updates to the tutorial. I'll take your feedback into consideration. Thanks!