Migration notes:

• Rate-limited sampling is now the default, if you haven't configured a fixed percentage previously. By default, it will capture at most around five requests per second, along with their dependencies, traces, and custom events. See fixed-percentage sampling if you want to revert to the previous behavior of capturing 100% of requests.

Enhancements:

• Standard metrics for HTTP requests and HTTP dependencies are now pre-aggregated inside of the Java agent, and so they are no longer affected by sampling (#2439).
• Rate-limited sampling has been introduced which can be used to tune ingestion costs (#2456), e.g.

  {
    "sampling": {
      "requestsPerSecond": 5
    }
  }
  

  Note: the requestsPerSecond can be a decimal value, including values less than 1.
• Exceptions are no longer captured directly on dependency records for these reasons:
  • in order to reduce ingestion cost
  • dependency exceptions which are uncaught, bubble up to the request-level where they are already captured
  • dependency exceptions which are caught, tend to be logged if they are important, where they are also already captured
    (#2423).
• New versions of the applicationinsights-core and applicationinsights-web 2.x SDK artifacts have been released, with a reduced API surface area to makes it clear which APIs interop with the 3.x Java agent (#2418). These new versions are no-ops when run without the Java agent. To update your dependencies:

  2.x dependency	Action	Remarks
  applicationinsights-core	Update the version to 3.4.0-BETA or later
  applicationinsights-web	Update the version to 3.4.0-BETA or later, and remove the Application Insights web filter your web.xml file.
  applicationinsights-web-auto	Replace with 3.4.0-BETA or later of applicationinsights-web
  applicationinsights-logging-log4j1_2	Remove the dependency and remove the Application Insights appender from your log4j configuration.	This is no longer needed since Log4j 1.2 is auto-instrumented in the 3.x Javaagent.
  applicationinsights-logging-log4j2	Remove the dependency and remove the Application Insights appender from your log4j configuration.	This is no longer needed since Log4j 2 is auto-instrumented in the 3.x Javaagent.
  applicationinsights-logging-log4j1_2	Remove the dependency and remove the Application Insights appender from your logback configuration.	This is no longer needed since Logback is auto-instrumented in the 3.x Javaagent.
  applicationinsights-spring-boot-starter	Replace with 3.4.0-BETA or later of applicationinsights-web	The cloud role name will no longer default to spring.application.name, see the 3.x configuration docs for configuring the cloud role name.

• ConnectionString overrides were introduced, and InstrumentationKey overrides were deprecated (#2471):

  {
    "preview": {
      "connectionStringOverrides": [
        {
          "httpPathPrefix": "/myapp1",
          "connectionString": "InstrumentationKey=12345678-0000-0000-0000-0FEEDDADBEEF;IngestionEndpoint=...;..."
        },
        {
          "httpPathPrefix": "/myapp2",
          "connectionString": "InstrumentationKey=87654321-0000-0000-0000-0FEEDDADBEEF;IngestionEndpoint=...;..."
        }
      ]
    }
  }
  

• Configuration to disable jdbc masking was introduced (#2453):

  {
    "instrumentation": {
      "jdbc": {
        "masking": {
          "enabled": false
        }
      }
    }
  }
  

• Sampling overrides can (and should) now be targeted to requests, dependencies, traces (logs) or exceptions (#2456), e.g.

  {
    "preview": {
      "sampling": {
        "overrides": [
          {
            "telemetryKind": "dependency",
            ...
            "percentage": 0
          }
        ]
      }
    }
  }
  

• Ingestion response codes 502 and 504 now trigger storing telemetry to disk and retrying (#2438).
• Metric namespaces are now supported via the new 3.x applicationinsights-core artifact (#2447).
• Ingestion sampling warnings are now suppressed since those are expected (#2473).
• Introduce a new preview feature: Java Profiler for Azure Monitor Application Insights
• Update OpenTelemetry to 1.18.0 #2509.
• Remove limit on filtering default metrics #2490.
• Add a new config to export logback code attributes #2518

Bug Fixes:

• Fix operation_Id and operation_parentID being captured as 00000000000000000000000000000000 for "standalone" log records (which occur outside of a request). These fields are now empty for "standalone" log records, to reflect that they are not part of an "operation" (i.e. request) #2432.