Scala

1. Prerequisites#

• Middleware Host Agent running on the same machine (or reachable). In containers, point apps to the agent with MW_AGENT_SERVICE: Docker 172.17.0.1, Kubernetes mw-service.mw-agent-ns.svc.cluster.local.
• Scala/SBT project (Scala 2.11.6+ is fine) and JDK 8+. Check using:

  scala --version
  java --version

  

// build.sbt
ThisBuild / scalaVersion := "2.13.14"

// ensure SBT forks for run so javaOptions apply
(run / fork) := true

(run / javaOptions) ++= Seq(
  // point to where you stored the agent jar
  "-javaagent:middleware-javaagent-1.6.0.jar",
  // logical service name shown in Middleware APM
  "-Dotel.service.name={APM-SERVICE-NAME}"
)

MW_API_KEY="<API-key>" sbt run

// build.sbt (add one more property)
(run / javaOptions) ++= Seq(
  "-Dotel.exporter.otlp.endpoint=https://ruplp.middleware.io" // serverless ingest URL
)

(Optional) Custom logs from your Scala code#

If you want to emit custom logs (INFO/WARN/DEBUG/ERROR) that correlate with traces, add the agent-apm-java library to your build and use its Logger:

• Add dependency (SBT):

  // build.sbt
  libraryDependencies += "io.github.middleware-labs" % "agent-apm-java" % "0.0.18"

• Use the logger (Scala/Java interop):

  // anywhere in your app code
  import io.github.middlewarelabs.agentapmjava.Logger
  
  Logger.info("info message")
  Logger.debug("debug message")
  Logger.warn("warn message")
  Logger.error("error message")

• Record stack errors Call recordError from a catch block to attach stack traces to the active span:

  try {
    // ...
  } catch {
    case e: Exception =>
      io.github.middlewarelabs.agentapmjava.Logger.recordError(e)
      throw e
  }

View your data#

After you start the app, wait 3–5 minutes, then open Traces, Logs, and Profiling in Middleware to verify data is flowing. (This mirrors your Scala page’s flow.)

SBT notes & tips#

• Forking is required for javaOptions (like -javaagent) to apply to sbt run. Configure (run / fork) := true.
• If you package with sbt-native-packager, you can also push Java options into start scripts via Universal / javaOptions or add extra defines to scripts.
• When sending data without a local collector, otel.exporter.otlp.endpoint is the standard knob; OTLP exporters also support header-based auth via otel.exporter.otlp.headers if you ever need it.

Environment variables#

Troubleshooting#

• No telemetry appears → Confirm (run / fork) := true and the -javaagent: path is correct. SBT only applies javaOptions to a forked run.
• Still no data on serverless → Ensure the endpoint property is set (otel.exporter.otlp.endpoint) and that your key is present. OTLP HTTP exporters derive /v1/{signal} paths automatically when you set a base endpoint.
• Packaging instead of sbt run → Use sbt-native-packager’s Universal / javaOptions or script defines so the agent flags end up in the generated start scripts.