[Serverless Mini Agent] Run in Azure Spring Apps

[duncanpharvey]

What does this PR do?

Updates Serverless Mini Agent to run in Azure Spring Apps.

Motivation

• https://datadoghq.atlassian.net/browse/SVLS-4435
• https://datadoghq.atlassian.net/browse/SVLS-5081
• https://datadoghq.atlassian.net/browse/SVLS-5158

Additional Notes

• Use ASCSVCRT_SPRING__APPLICATION__NAME environment variable to determine if mini agent is running in an Azure Spring Apps environment
• Update info endpoint so Datadog Java Tracer knows where to send trace metrics when DD_TRACE_TRACER_METRICS_ENABLED is true
  • Add config.statsd_port
• Update /v0.4/traces endpoint to work with Datadog Java Tracer
  • Change response status code from 202 - Accepted to 200 - OK
  • Change response body from message to {"rate_by_service":{"service:,env:":1}. This is just a placeholder to satisfy the response requirement by the Datadog Java Tracer but will need to be updated in a future PR to properly set the trace sampling priority
    • Helpful explanation of rate_by_service here: question: what is rate_by_service? datadog-agent#3031 (comment)

Error from Datadog Java Tracer when Mini Agent trace endpoint returns 200 - OK status code

[dd.trace 2024-07-19 18:36:30:140 +0000] [dd-trace-processor] DEBUG datadog.trace.agent.common.writer.ddagent.DDAgentApi - {"message":"Successfully buffered traces to be flushed."} while sending 1 (size=1KB) traces. Total: 1, Received: 1, Sent: 0, Failed: 1. Status: 202, Response: Accepted, Body: {"message":"Successfully buffered traces to be flushed."}
[dd.trace 2024-07-19 18:36:30:140 +0000] [dd-trace-processor] DEBUG datadog.trace.agent.common.writer.PayloadDispatcherImpl - Failed to send 1 traces of size 1276 bytes to the API

Error from Datadog Java Tracer when Mini Agent trace endpoint returns json with message instead of json with rate_by_service

[dd.trace 2024-07-19 19:56:40:234 +0000] [dd-trace-processor] ERROR datadog.trace.agent.common.writer.TraceProcessingWorker$DaemonTraceSerializingHandler - Uncaught exception com.squareup.moshi.JsonDataException: Expected BEGIN_OBJECT but was STRING at path $.message in dd-trace-processor
com.squareup.moshi.JsonDataException: Expected BEGIN_OBJECT but was STRING at path $.message

How to test the change?

• Build an Azure Spring App with persistent storage
• ssh into the Azure Spring App instance and upload the Datadog Java Tracer and Serverless Mini Agent
• Add -javaagent:/persistent/dd-java-agent.jar to the JVM options
• Set DD_TRACE_TRACER_METRICS_ENABLED to true
• Start the Serverless Mini Agent

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 66.66667% with 6 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@f148c87). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #547   +/-   ##
=======================================
  Coverage        ?   70.44%           
=======================================
  Files           ?      213           
  Lines           ?    28455           
  Branches        ?        0           
=======================================
  Hits            ?    20044           
  Misses          ?     8411           
  Partials        ?        0           

Components	Coverage Δ
crashtracker	25.21% <ø> (?)
datadog-alloc	98.73% <ø> (?)
data-pipeline	50.00% <ø> (?)
data-pipeline-ffi	0.00% <ø> (?)
ddcommon	86.23% <ø> (?)
ddcommon-ffi	74.58% <ø> (?)
ddtelemetry	58.95% <ø> (?)
ipc	84.18% <ø> (?)
profiling	78.09% <ø> (?)
profiling-ffi	56.76% <ø> (?)
serverless	0.00% <ø> (?)
sidecar	35.42% <ø> (?)
sidecar-ffi	0.00% <ø> (?)
spawn-worker	54.98% <ø> (?)
trace-mini-agent	70.88% <71.42%> (?)
trace-normalization	98.24% <ø> (?)
trace-obfuscation	95.73% <ø> (?)
trace-protobuf	77.16% <ø> (?)
trace-utils	90.90% <50.00%> (?)

[pr-commenter]

Benchmarks

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[jcstorms1]

This looks good!