Telemetry traces for Functions Optimized Container apps are duplicated in Application Insights transaction logs.

Question

Telemetry traces for Functions Optimized Container apps are duplicated in Application Insights transaction logs.

Shigeru Nakagaki 120

hi

i read this article and i setup open telemetry logs for container apps.

it worked. but ah, trace logs in transaction search of application insights are duplicated.

The level of Log is Information in host.json. (if set None level, there is no logs in log analytics.)

The telemetryMode in host.json is "OpenTelemetry". (if set telemetryMode nothing, there is no trace logs in application insights but only user logs.)

the log setting of host.json is below.


  "logging": {
      "fileLoggingMode": "debugOnly",
      "logLevel": {
          "default": "Warning",
          "Host.Aggregator": "Warning",
          "Host.Results": "Warning",
          "Function": "Warning",
          "Function.HealthCheck": "Warning",
          "Function.HealthCheck.User": "Information"
      },
      "console": {
          "isEnabled": false,
          "DisableColors": true
      },
      "applicationInsights": {
          "samplingSettings": {
              "isEnabled": false
          },
          "enableLiveMetricsFilters": true
      }
  },
  "telemetryMode": "OpenTelemetry"

Diagnostic settings for the container app environment are configured.

The Container Apps Environment properties are below.

        "appLogsConfiguration": {
            "destination": "azure-monitor",
            "logAnalyticsConfiguration": null
        },
        "openTelemetryConfiguration": {
            "destinationsConfiguration": null,
            "tracesConfiguration": {
                "includeDapr": false,
                "destinations": [
                    "appInsights"
                ]
            },
            "logsConfiguration": {
                "destinations": [
                    "appInsights"
                ]
            },
            "metricsConfiguration": null
        },

What should I do?

thanks

Shigeru Nakagaki 120 Reputation points

2025-08-04T05:25:14.25+00:00

Here is a screenshot of duplicated logs.
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-04T06:59:38.8033333+00:00

Hello @Shigeru Nakagaki

Have you recently made any changes to the telemetry settings that might contribute to this issue?

Can you confirm if you have both OpenTelemetry and Application Insights SDKs configured in your application at the same time?

Shigeru Nakagaki 120

Hi, Sai

I deleted OpenTelemetry settings from Azure Container Apps Environment.

Now, it's only host.json of Azure Functions in Azure Container Apps.

  "logging": {
      "fileLoggingMode": "debugOnly",
      "logLevel": {
          "default": "None",
          "Host.Aggregator": "Warning",
          "Host.Results": "Warning",
          "Function": "Warning",
          "Function.HealthCheck": "Warning",
          "Function.HealthCheck.User": "Information"
      },
      "console": {
          "isEnabled": false,
          "DisableColors": true
      },
      "applicationInsights": {
          "samplingSettings": {
              "isEnabled": true,
              "maxTelemetryItemsPerSecond": 20,
              "excludedTypes": "Request;Exception"
          },
          "enableLiveMetricsFilters": true
      }
  },
  "telemetryMode": "OpenTelemetry"

There is no setting in source code of python.

Still there are duplicated logs.

thanks

Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-04T09:57:04.7466667+00:00

Hello @Shigeru Nakagaki

It looks like you're running into duplicate transaction logs in Application Insights for your Azure Functions or Container Apps. This is a known issue and usually happens when multiple telemetry paths are active.

Here are a few quick things to check:

Telemetry Overlap If both OpenTelemetry and the built-in Application Insights SDK are enabled (via host.json or environment-level settings), this can cause duplicate entries. Try removing "telemetryMode": "OpenTelemetry" from host.json temporarily to test.

Diagnostic Settings Ensure you're not sending telemetry from multiple services (Functions, Container Apps, etc.) to the same Log Analytics workspace. This was a root cause in similar cases: https://learn.microsoft.com/en-us/answers/questions/1178793/ https://learn.microsoft.com/en-us/answers/questions/2284965/

Sampling and Log Levels Set "samplingSettings": { "isEnabled": false } and adjust the log level to "default": "Information" during testing. This can help you see where the duplication is occurring.

Analyze with Kusto Use Kusto queries in Application Insights to group by operation_Id, timestamp, and message. This will help identify actual duplicates. Here's a guide on handling them: https://learn.microsoft.com/en-us/azure/data-explorer/dealing-with-duplicates

Extra Consideration If your environment uses built-in policies that enforce diagnostic settings, those may need to be reviewed or overridden.
Shigeru Nakagaki 120 Reputation points

2025-08-05T03:00:29.3066667+00:00

Hi, Sai

About diagnostic settings, we need to set diagnostic settings because of saving logs in log analytics.

The resources hold logs only for 90 days, right?

Without diagnostic settings, how can we save logs to log analytics for one year?

thanks
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-05T07:36:12.4166667+00:00
Hello @Shigeru Nakagaki

To save logs in Log Analytics for more than 90 days, you need to configure diagnostic settings. By setting up diagnostic settings, you can export telemetry data, including logs, to a Log Analytics workspace. This allows you to retain logs for a longer period, as the default retention period for logs in Log Analytics can be configured up to two years, depending on your needs.

Without diagnostic settings, the logs generated by Azure Functions Optimized Container apps will not be retained beyond the default retention period of 90 days. Therefore, it is essential to set up diagnostic settings to ensure that your logs are stored in Log Analytics for the desired duration.

References:

Diagnostic settings in Azure Monitor

Create and configure Application Insights resources
Shigeru Nakagaki 120 Reputation points

2025-08-05T07:56:48.9266667+00:00
Is my understanding correct?

The following architecture causes duplicated logs in Transaction search of Application Insights?

Application Insights A connects to Log Analytics Workspace A.

Container Apps A send telemetry to Application Insights A.

Container Apps Environment A outputs logs to Log Analytics Workspace A through Azure Monitor by Diagnostic Settings of Container Apps Environment A.
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-06T07:52:40.9966667+00:00
Hello @Shigeru Nakagaki

Yes, your understanding is correct - this setup can lead to duplicate logs showing up in the Transaction Search in Application Insights.

The reason is that telemetry is being sent via two paths:

Your Function app within the Container App sends logs directly to Application Insights using "telemetryMode": "OpenTelemetry" in the host.json file.

Meanwhile, the Container Apps Environment forwards logs to the same Log Analytics workspace using diagnostic settings, which is also linked to Application Insights.

As a result, Application Insights receives the same telemetry twice.

Since you need diagnostic settings to keep logs in Log Analytics for over 90 days, the best way to prevent duplication is to remove the "telemetryMode": "OpenTelemetry" setting from host.json.

This ensures telemetry flows only through diagnostic settings, giving you all the logs you need without duplicates.
Shigeru Nakagaki 120 Reputation points

2025-08-06T10:19:09.5966667+00:00
removing "telemetryMode": "OpenTelemetry" does not solve this problem. It still produces duplicated logs.

to solve this problem,

creating new log analytics workspace

creating new application insights which connects "1."

Container Apps connects "2."

thanks
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-07T05:58:00.13+00:00

@Shigeru Nakagaki

Thanks for the update, please let us know if the duplication issue gets resolved with this new setup.
Shigeru Nakagaki 120 Reputation points

2025-08-07T06:16:45.5333333+00:00

I finally figured it out.

The problem is diagnostics setting of Application Insights.

The diagnostics setting of Application Insights exports telemetry logs to Log Analytics Workspace.

Also Container Apps Environment has a diagnostics setting and it exports logs to same Log Analytics Workspace as above.

So, these logs are duplicated.

We can not remove diagnostics settings for each resources because we have to save logs for each resources for long term.

Therefore, removing diagnostics setting of Application Insights solves duplicated logs.

thanks

Accepted answer

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Shigeru Nakagaki 120 Reputation points

2025-08-04T05:25:14.25+00:00

Here is a screenshot of duplicated logs.
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-04T06:59:38.8033333+00:00

Hello @Shigeru Nakagaki

Have you recently made any changes to the telemetry settings that might contribute to this issue?

Can you confirm if you have both OpenTelemetry and Application Insights SDKs configured in your application at the same time?
Shigeru Nakagaki 120 Reputation points

2025-08-04T07:24:06.46+00:00

Hi, Sai

I deleted OpenTelemetry settings from Azure Container Apps Environment.

Now, it's only host.json of Azure Functions in Azure Container Apps.

"logging": { "fileLoggingMode": "debugOnly", "logLevel": { "default": "None", "Host.Aggregator": "Warning", "Host.Results": "Warning", "Function": "Warning", "Function.HealthCheck": "Warning", "Function.HealthCheck.User": "Information" }, "console": { "isEnabled": false, "DisableColors": true }, "applicationInsights": { "samplingSettings": { "isEnabled": true, "maxTelemetryItemsPerSecond": 20, "excludedTypes": "Request;Exception" }, "enableLiveMetricsFilters": true } }, "telemetryMode": "OpenTelemetry"

There is no setting in source code of python.

Still there are duplicated logs.

thanks
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-04T09:57:04.7466667+00:00

Hello @Shigeru Nakagaki

It looks like you're running into duplicate transaction logs in Application Insights for your Azure Functions or Container Apps. This is a known issue and usually happens when multiple telemetry paths are active.

Here are a few quick things to check:

Telemetry Overlap If both OpenTelemetry and the built-in Application Insights SDK are enabled (via host.json or environment-level settings), this can cause duplicate entries. Try removing "telemetryMode": "OpenTelemetry" from host.json temporarily to test.

Diagnostic Settings Ensure you're not sending telemetry from multiple services (Functions, Container Apps, etc.) to the same Log Analytics workspace. This was a root cause in similar cases: https://learn.microsoft.com/en-us/answers/questions/1178793/ https://learn.microsoft.com/en-us/answers/questions/2284965/

Sampling and Log Levels Set "samplingSettings": { "isEnabled": false } and adjust the log level to "default": "Information" during testing. This can help you see where the duplication is occurring.

Analyze with Kusto Use Kusto queries in Application Insights to group by operation_Id, timestamp, and message. This will help identify actual duplicates. Here's a guide on handling them: https://learn.microsoft.com/en-us/azure/data-explorer/dealing-with-duplicates

Extra Consideration If your environment uses built-in policies that enforce diagnostic settings, those may need to be reviewed or overridden.
Shigeru Nakagaki 120 Reputation points

2025-08-05T03:00:29.3066667+00:00

Hi, Sai

About diagnostic settings, we need to set diagnostic settings because of saving logs in log analytics.

The resources hold logs only for 90 days, right?

Without diagnostic settings, how can we save logs to log analytics for one year?

thanks
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-05T07:36:12.4166667+00:00

Hello @Shigeru Nakagaki

To save logs in Log Analytics for more than 90 days, you need to configure diagnostic settings. By setting up diagnostic settings, you can export telemetry data, including logs, to a Log Analytics workspace. This allows you to retain logs for a longer period, as the default retention period for logs in Log Analytics can be configured up to two years, depending on your needs.

Without diagnostic settings, the logs generated by Azure Functions Optimized Container apps will not be retained beyond the default retention period of 90 days. Therefore, it is essential to set up diagnostic settings to ensure that your logs are stored in Log Analytics for the desired duration.

References:

Diagnostic settings in Azure Monitor

Create and configure Application Insights resources
Shigeru Nakagaki 120 Reputation points

2025-08-05T07:56:48.9266667+00:00

Is my understanding correct?

The following architecture causes duplicated logs in Transaction search of Application Insights?

Application Insights A connects to Log Analytics Workspace A.

Container Apps A send telemetry to Application Insights A.

Container Apps Environment A outputs logs to Log Analytics Workspace A through Azure Monitor by Diagnostic Settings of Container Apps Environment A.
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-06T07:52:40.9966667+00:00

Hello @Shigeru Nakagaki

Yes, your understanding is correct - this setup can lead to duplicate logs showing up in the Transaction Search in Application Insights.

The reason is that telemetry is being sent via two paths:

Your Function app within the Container App sends logs directly to Application Insights using "telemetryMode": "OpenTelemetry" in the host.json file.

Meanwhile, the Container Apps Environment forwards logs to the same Log Analytics workspace using diagnostic settings, which is also linked to Application Insights.

As a result, Application Insights receives the same telemetry twice.

Since you need diagnostic settings to keep logs in Log Analytics for over 90 days, the best way to prevent duplication is to remove the "telemetryMode": "OpenTelemetry" setting from host.json.

This ensures telemetry flows only through diagnostic settings, giving you all the logs you need without duplicates.
Shigeru Nakagaki 120 Reputation points

2025-08-06T10:19:09.5966667+00:00

removing "telemetryMode": "OpenTelemetry" does not solve this problem. It still produces duplicated logs.

to solve this problem,

creating new log analytics workspace

creating new application insights which connects "1."

Container Apps connects "2."

thanks
Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-08-07T05:58:00.13+00:00

@Shigeru Nakagaki

Thanks for the update, please let us know if the duplication issue gets resolved with this new setup.
Shigeru Nakagaki 120 Reputation points

2025-08-07T06:16:45.5333333+00:00

I finally figured it out.

The problem is diagnostics setting of Application Insights.

The diagnostics setting of Application Insights exports telemetry logs to Log Analytics Workspace.

Also Container Apps Environment has a diagnostics setting and it exports logs to same Log Analytics Workspace as above.

So, these logs are duplicated.

We can not remove diagnostics settings for each resources because we have to save logs for each resources for long term.

Therefore, removing diagnostics setting of Application Insights solves duplicated logs.

thanks

Answer 1

Glad to see you figured it out, @Shigeru Nakagaki .

To summarize the solution: The duplicate logs were caused by both Application Insights and the Container Apps Environment having diagnostic settings that exported telemetry to the same Log Analytics workspace, resulting in duplicated data.

Since diagnostic settings are required to retain logs long-term, and cannot be removed from all resources, you resolved the issue by removing the diagnostic settings specifically from Application Insights, while keeping them enabled for the Container Apps Environment. This ensures long-term log retention without duplication.

Thanks for sharing your findings—this will definitely help others facing a similar issue.

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Telemetry traces for Functions Optimized Container apps are duplicated in Application Insights transaction logs.

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