Diagnostic settings in autoscale

Article
05/06/2024

Autoscale has two log categories and a set of metrics that can be enabled via the Diagnostics settings tab on the Autoscale setting page.

The two categories are:

Autoscale Evaluations contain log data relating to rule evaluation.
Autoscale Scale Actions log data relating to each scale event.

For more information about autoscale metrics, see the Supported metrics document.

You can send logs and metrics to various destinations:

Log Analytics workspaces
Storage accounts
Event hubs
Partner solutions

For more information on diagnostics, see Diagnostic settings in Azure Monitor.

Run history

View the history of your autoscale activity on the Run history tab. The Run history tab includes a chart of resource instance counts over time and the resource activity log entries for autoscale.

Resource log schemas

The following examples are the general formats for autoscale resource logs with example data included. Not all the examples are properly formed JSON because they might include a valid list for a given field.

Use these logs to troubleshoot issues in autoscale. For more information, see Troubleshooting autoscale problems.

Note

Although the logs may refer to "scale up" and "scale down" actions, the actual action taken is scale in or scale out.

Autoscale evaluations log

The following schemas appear in the autoscale evaluations log.

Profile evaluation

Logged when autoscale first looks at an autoscale profile:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": ["FixedDateProfileEvaluation", "RecurrentProfileEvaluation", "DefaultProfileEvaluation"],
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "profile": "defaultProfile",
    "profileSelected": [true, false]
  }
}

Profile cool-down evaluation

Logged when autoscale evaluates if it shouldn't scale because of a cool-down period:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "ScaleRuleCooldownEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "selectedProfile": "defaultProfile",
    "scaleDirection": ["Increase", "Decrease"]
    "lastScaleActionTime": "2018-09-10 18:08:00.6132593",
    "cooldown": "00:30:00",
    "evaluationTime": "2018-09-10 18:11:00.6132593",
    "skipRuleEvaluationForCooldown": true
  }
}

Rule evaluation

Logged when autoscale first starts evaluating a particular scale rule:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "ScaleRuleEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "metricName": "Percentage CPU",
    "metricNamespace": "",
    "timeGrain": "00:01:00",
    "timeGrainStatistic": "Average",
    "timeWindow": "00:10:00",
    "timeAggregationType": "Average",
    "operator": "GreaterThan",
    "threshold": 70,
    "observedValue": 25,
    "estimateScaleResult": ["Triggered", "NotTriggered", "Unknown"]
  }
}

Metric evaluation

Logged when autoscale evaluates the metric being used to trigger a scale action:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "MetricEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "metricName": "Percentage CPU",
    "metricNamespace": "",
    "timeGrain": "00:01:00",
    "timeGrainStatistic": "Average",
    "startTime": "2018-09-10 18:00:00.43833793",
    "endTime": "2018-09-10 18:10:00.43833793",
    "data": [0.33333333333333331,0.16666666666666666,1.0,0.33333333333333331,2.0,0.16666666666666666,9.5]
  }
}

Instance count evaluation

Logged when autoscale evaluates the number of instances already running in preparation for deciding if it should start more, shut down some, or do nothing:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "InstanceCountEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "currentInstanceCount": 20,
    "minimumInstanceCount": 15,
    "maximumInstanceCount": 30,
    "defaultInstanceCount": 20
  }
}

Scale action evaluation

Logged when autoscale starts evaluation if a scale action should take place:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "ScaleActionOperationEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "lastScaleActionOperationId": "378ejr-7yye-892d-17dd-92ndijfe1738",
    "lastScaleActionOperationStatus": ["InProgress", "Timeout"]
	"skipCurrentAutoscaleEvaluation": [true, false]
  }
}

Instance update evaluation

Logged when autoscale updates the number of compute instances running, either up or down:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "InstanceUpdateEvaluation",
  "category": "AutoscaleEvaluations",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "currentInstanceCount": 20,
    "newInstanceCount": 21,
    "shouldUpdateInstance": [true, false],
    "reason": ["Scale down action triggered", "Scale up to default instance count", ...]
  }
}

Autoscale scale actions log

The following schemas appear in the autoscale evaluations log.

Scale action

Logged when autoscale initiates a scale action, either up or down:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "InstanceScaleAction",
  "category": "AutoscaleScaleActions",
  "resultType": ["Succeeded", "InProgress", "Failed"],
  "resultDescription": ["Create async operation job failed", ...]
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "currentInstanceCount": 20,
    "newInstanceCount": 21,
    "scaleDirection": ["Increase", "Decrease"],
    ["createdAsyncScaleActionJob": [true, false],]
    ["createdAsyncScaleActionJobId": "378ejr-7yye-892d-17dd-92ndijfe1738",]
  }
}

Scale action tracking

Logged at different intervals of an instance scale action:

{
  "time": "2018-09-10 18:12:00.6132593",
  "resourceId": "/SUBSCRIPTIONS/BA13C41D-C957-4774-8A37-092D62ACFC85/RESOURCEGROUPS/AUTOSCALETRACKING12042017/PROVIDERS/MICROSOFT.INSIGHTS/AUTOSCALESETTINGS/DEFAULTSETTING",
  "operationName": "InstanceScaleAction",
  "category": "AutoscaleScaleActions",
  "correlationId": "e8f67045-f381-445d-bc2d-eeff81ec0d77",
  "property": {
    "targetResourceId": "/subscriptions/d45c994a-809b-4cb3-a952-e75f8c488d23/resourceGroups/RingAhoy/providers/Microsoft.Web/serverfarms/ringahoy",
    "scaleActionOperationId": "378ejr-7yye-892d-17dd-92ndijfe1738",
    "scaleActionOperationStatus": ["InProgress", "Timeout", "Canceled", ...],
    "scaleActionMessage": ["Scale action is inprogress", ...]
  }
}

Activity logs

The following events are logged to the activity log with a CategoryValue of Autoscale:

Autoscale scale-up initiated
Autoscale scale-up completed
Autoscale scale-down initiated
Autoscale scale-down completed
Predictive autoscale scale-up initiated
Predictive autoscale scale-up completed
Metric failure
Metric recovery
Predictive metric failure
Flapping

An extract of each log event name, showing the relevant parts of the Properties element, are shown next.

Autoscale action

Logged when autoscale attempts to scale in or out:

{
   "eventCategory": "Autoscale",
    "eventName": "AutoscaleAction",
    ...
    "eventProperties": "{
        "Description": "The autoscale engine attempting to scale resource '/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan' from 2 instances count to 1 instancescount.",
        "ResourceName": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
        "OldInstancesCount": 2,
        "NewInstancesCount": 1,
        "ActiveAutoscaleProfile": {
            "Name": "Default scale condition",
            "Capacity": {
                "Minimum": "1",
                "Maximum": "5",
                "Default": "1"
            },
            "Rules": [
                {
                    "MetricTrigger": {
                        "Name": "CpuPercentage",
                        "Namespace": "microsoft.web/serverfarms",
                        "Resource": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
                        "ResourceLocation": "China North",
                        "TimeGrain": "PT1M",
                        "Statistic": "Average",
                        "TimeWindow": "PT2M",
                        "TimeAggregation": "Average",
                        "Operator": "GreaterThan",
                        "Threshold": 40.0,
                        "Source": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
                        "MetricType": "MDM",
                        "Dimensions": [],
                        "DividePerInstance": false
                    },
                    "ScaleAction": {
                        "Direction": "Increase",
                        "Type": "ChangeCount",
                        "Value": "1",
                        "Cooldown": "PT3M"
                    }
                },
                {
                    "MetricTrigger": {
                        "Name": "CpuPercentage",
                        "Namespace": "microsoft.web/serverfarms",
                        "Resource": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
                        "ResourceLocation": "China North",
                        "TimeGrain": "PT1M",
                        "Statistic": "Average",
                        "TimeWindow": "PT5M",
                        "TimeAggregation": "Average",
                        "Operator": "LessThanOrEqual",
                        "Threshold": 30.0,
                        "Source": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/ed-rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
                        "MetricType": "MDM",
                        "Dimensions": [],
                        "DividePerInstance": false
                    },
                    "ScaleAction": {
                        "Direction": "Decrease",
                        "Type": "ExactCount",
                        "Value": "1",
                        "Cooldown": "PT5M"
                    }
                }
            ]
                },
    "LastScaleActionTime": "Thu, 26 Jan 2023 12:57:14 GMT"
    }",
    ...
   "activityStatusValue": "Succeeded"
}

Get operation status result

Logged following a scale event:


"Properties":{
    "eventCategory": "Autoscale",
    "eventName": "GetOperationStatusResult",
    ...
    "eventProperties": "{"OldInstancesCount":3,"NewInstancesCount":2}",
    ...
    "activityStatusValue": "Succeeded"
}

Metric failure

Logged when autoscale can't determine the value of the metric used in the scale rule:

"Properties":{
    "eventCategory": "Autoscale",
    "eventName": "MetricFailure",
    ...
    "eventProperties": "{
        "Notes":"To ensure service availability, Autoscale will scale out the resource to the default capacity if it is greater than the current capacity}",
    ...
    "activityStatusValue": "Failed"
}

Metric recovery

Logged when autoscale can once again determine the value of the metric used in the scale rule after a MetricFailure event:

"Properties":{
    "eventCategory": "Autoscale",
    "eventName": "MetricRecovery",
    ...
    "eventProperties": "{}",
    ...
    "activityStatusValue": "Succeeded"
}

Predictive metric failure

Logged when autoscale can't calculate predicted scale events because the metric is unavailable:

"Properties": {
    "eventCategory": "Autoscale",
    "eventName": "PredictiveMetricFailure",
    ...
    "eventProperties": "{
        "Notes": "To ensure service availability, Autoscale will scale out the resource to the default capacity if it is greater than the current capacity"
    }",
   ...
    "activityStatusValue": "Failed"
}

Flapping occurred

Logged when autoscale detects flapping could occur and scales differently to avoid it:

"Properties":{
    "eventCategory": "Autoscale",
    "eventName": "FlappingOccurred",
    ...
    "eventProperties": 
        "{"Description":"Scale down will occur with updated instance count to avoid flapping. 
         Resource: '/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan'.
         Current instance count: '6', 
         Intended new instance count: '1'.
         Actual new instance count: '4'",
        "ResourceName":"/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/rg-001/providers/Microsoft.Web/serverFarms/ScaleableAppServicePlan",
        "OldInstancesCount":6,
        "NewInstancesCount":4,
        "ActiveAutoscaleProfile":{"Name":"Auto created scale condition",
        "Capacity":{"Minimum":"1","Maximum":"30","Default":"1"},
        "Rules":[{"MetricTrigger":{"Name":"Requests","Namespace":"microsoft.web/sites","Resource":"/subscriptions/    d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-001/providers/Microsoft.Web/sites/ScaleableWebApp1",    "ResourceLocation":"China North","TimeGrain":"PT1M","Statistic":"Average","TimeWindow":"PT1M","TimeAggregation":"Maximum",    "Operator":"GreaterThanOrEqual","Threshold":3.0,"Source":"/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/    rg-001/providers/Microsoft.Web/sites/ScaleableWebApp1","MetricType":"MDM","Dimensions":[],"DividePerInstance":true},    "ScaleAction":{"Direction":"Increase","Type":"ChangeCount","Value":"10","Cooldown":"PT1M"}},{"MetricTrigger":{"Name":"Requests",    "Namespace":"microsoft.web/sites","Resource":"/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-001/    providers/Microsoft.Web/sites/ScaleableWebApp1","ResourceLocation":"China North","TimeGrain":"PT1M","Statistic":"Max",    "TimeWindow":"PT1M","TimeAggregation":"Maximum","Operator":"LessThan","Threshold":3.0,"Source":"/subscriptions/    d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-001/providers/Microsoft.Web/sites/ScaleableWebApp1","MetricType":"MDM",    "Dimensions":[],"DividePerInstance":true},"ScaleAction":{"Direction":"Decrease","Type":"ChangeCount","Value":"5",    "Cooldown":"PT1M"}}]}}",
    ...
    "activityStatusValue": "Succeeded"
}

Flapping

Logged when autoscale detects flapping could occur and defers scaling in to avoid it:

"Properties": {
    "eventCategory": "Autoscale",
    "eventName": "Flapping",
    "Description": "{"Cannot scale down due to flapping observed. Resource: '/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/rg-001/providers/Microsoft.Compute/virtualMachineScaleSets/mac2'. Current instance count: '2', Intended new instance count '1'",
    "ResourceName": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourcegroups/rg-001/providers/Microsoft.Compute/virtualMachineScaleSets/mac2",
    "OldInstancesCount": "2",
    "NewInstancesCount": "2",
    "ActiveAutoscaleProfile": "ActiveAutoscaleProfile": {
        "Name": "Auto created default scale condition",
        "Capacity": {
            "Minimum": "1",
            "Maximum": "2",
            "Default": "1"
        },
        "Rules": [
            {
                "MetricTrigger": {
                    "Name": "StorageSuccesses",
                    "Namespace": "monitoringbackgroundjob",
                    "Resource": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-001/providers/microsoft.monitor/accounts/MACAzureInsightsPROD",
                    "ResourceLocation": "ChinaNorth2",
                    "TimeGrain": "PT1M",
                    "Statistic": "Average",
                    "TimeWindow": "PT10M",
                    "TimeAggregation": "Average",
                    "Operator": "LessThan",
                    "Threshold": 600.0,
                    "Source": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-001/providers/microsoft.monitor/accounts/MACAzureInsightsPROD",
                    "MetricType": "MDM",
                    "Dimensions": [],
                    "DividePerInstance": false
                },
                "ScaleAction": {
                    "Direction": "Decrease",
                    "Type": "ChangeCount",
                    "Value": "1",
                    "Cooldown": "PT5M"
                }
            },
            {
                "MetricTrigger": {
                    "Name": "TimeToStartupInMs",
                    "Namespace": "armrpclient",
                    "Resource": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-123/providers/microsoft.monitor/accounts/MACMetricsRP",
                    "ResourceLocation": "chinanorth2",
                    "TimeGrain": "PT1M",
                    "Statistic": "Percentile99th",
                    "TimeWindow": "PT10M",
                    "TimeAggregation": "Average",
                    "Operator": "GreaterThan",
                    "Threshold": 70.0,
                    "Source": "/subscriptions/d1234567-9876-a1b2-a2b1-123a567b9f8767/resourceGroups/rg-123/providers/microsoft.monitor/accounts/MACMetricsRP",
                    "MetricType": "MDM",
                    "Dimensions": [],
                    "DividePerInstance": false
                },
                "ScaleAction": {
                    "Direction": "Increase",
                    "Type": "ChangeCount",
                    "Value": "1",
                    "Cooldown": "PT5M"
                }
            }
        ]
    }"
}...