How to set up alerts for performance problems in Azure Monitor for containers

  • Article

Azure Monitor for containers monitors the performance of container workloads that are deployed to Azure Container Instances or to managed Kubernetes clusters that are hosted on Azure Kubernetes Service (AKS).

This article describes how to enable alerts for the following situations:

  • When CPU or memory utilization on cluster nodes exceeds a threshold
  • When CPU or memory utilization on any container within a controller exceeds a threshold as compared to a limit that's set on the corresponding resource
  • NotReady status node counts
  • Failed, Pending, Unknown, Running, or Succeeded pod-phase counts
  • When free disk space on cluster nodes exceeds a threshold

To alert for high CPU or memory utilization, or low free disk space on cluster nodes, use the queries that are provided to create a metric alert or a metric measurement alert. Metric alerts have lower latency than log alerts. But log alerts provide advanced querying and greater sophistication. Log alerts queries compare a datetime to the present by using the now operator and going back one hour. (Azure Monitor for containers stores all dates in Coordinated Universal Time (UTC) format.)

If you're not familiar with Azure Monitor alerts, see Overview of alerts in Microsoft Azure before you start. To learn more about alerts that use log queries, see Log alerts in Azure Monitor. For more about metric alerts, see Metric alerts in Azure Monitor.

Resource utilization log search queries

The queries in this section support each alerting scenario. They're used in step 7 of the create alert section of this article.

The following query calculates average CPU utilization as an average of member nodes' CPU utilization every minute.

let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
let capacityCounterName = 'cpuCapacityNanoCores';
let usageCounterName = 'cpuUsageNanoCores';
KubeNodeInventory
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
// cluster filter would go here if multiple clusters are reporting to the same Log Analytics workspace
| distinct ClusterName, Computer
| join hint.strategy=shuffle (
  Perf
  | where TimeGenerated < endDateTime
  | where TimeGenerated >= startDateTime
  | where ObjectName == 'K8SNode'
  | where CounterName == capacityCounterName
  | summarize LimitValue = max(CounterValue) by Computer, CounterName, bin(TimeGenerated, trendBinSize)
  | project Computer, CapacityStartTime = TimeGenerated, CapacityEndTime = TimeGenerated + trendBinSize, LimitValue
) on Computer
| join kind=inner hint.strategy=shuffle (
  Perf
  | where TimeGenerated < endDateTime + trendBinSize
  | where TimeGenerated >= startDateTime - trendBinSize
  | where ObjectName == 'K8SNode'
  | where CounterName == usageCounterName
  | project Computer, UsageValue = CounterValue, TimeGenerated
) on Computer
| where TimeGenerated >= CapacityStartTime and TimeGenerated < CapacityEndTime
| project ClusterName, Computer, TimeGenerated, UsagePercent = UsageValue * 100.0 / LimitValue
| summarize AggregatedValue = avg(UsagePercent) by bin(TimeGenerated, trendBinSize), ClusterName

The following query calculates average memory utilization as an average of member nodes' memory utilization every minute.

let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
let capacityCounterName = 'memoryCapacityBytes';
let usageCounterName = 'memoryRssBytes';
KubeNodeInventory
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
// cluster filter would go here if multiple clusters are reporting to the same Log Analytics workspace
| distinct ClusterName, Computer
| join hint.strategy=shuffle (
  Perf
  | where TimeGenerated < endDateTime
  | where TimeGenerated >= startDateTime
  | where ObjectName == 'K8SNode'
  | where CounterName == capacityCounterName
  | summarize LimitValue = max(CounterValue) by Computer, CounterName, bin(TimeGenerated, trendBinSize)
  | project Computer, CapacityStartTime = TimeGenerated, CapacityEndTime = TimeGenerated + trendBinSize, LimitValue
) on Computer
| join kind=inner hint.strategy=shuffle (
  Perf
  | where TimeGenerated < endDateTime + trendBinSize
  | where TimeGenerated >= startDateTime - trendBinSize
  | where ObjectName == 'K8SNode'
  | where CounterName == usageCounterName
  | project Computer, UsageValue = CounterValue, TimeGenerated
) on Computer
| where TimeGenerated >= CapacityStartTime and TimeGenerated < CapacityEndTime
| project ClusterName, Computer, TimeGenerated, UsagePercent = UsageValue * 100.0 / LimitValue
| summarize AggregatedValue = avg(UsagePercent) by bin(TimeGenerated, trendBinSize), ClusterName

Important

The following queries use the placeholder values <your-cluster-name> and <your-controller-name> to represent your cluster and controller. Replace them with values specific to your environment when you set up alerts.

The following query calculates the average CPU utilization of all containers in a controller as an average of CPU utilization of every container instance in a controller every minute. The measurement is a percentage of the limit set up for a container.

let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
let capacityCounterName = 'cpuLimitNanoCores';
let usageCounterName = 'cpuUsageNanoCores';
let clusterName = '<your-cluster-name>';
let controllerName = '<your-controller-name>';
KubePodInventory
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
| where ClusterName == clusterName
| where ControllerName == controllerName
| extend InstanceName = strcat(ClusterId, '/', ContainerName),
         ContainerName = strcat(controllerName, '/', tostring(split(ContainerName, '/')[1]))
| distinct Computer, InstanceName, ContainerName
| join hint.strategy=shuffle (
    Perf
    | where TimeGenerated < endDateTime
    | where TimeGenerated >= startDateTime
    | where ObjectName == 'K8SContainer'
    | where CounterName == capacityCounterName
    | summarize LimitValue = max(CounterValue) by Computer, InstanceName, bin(TimeGenerated, trendBinSize)
    | project Computer, InstanceName, LimitStartTime = TimeGenerated, LimitEndTime = TimeGenerated + trendBinSize, LimitValue
) on Computer, InstanceName
| join kind=inner hint.strategy=shuffle (
    Perf
    | where TimeGenerated < endDateTime + trendBinSize
    | where TimeGenerated >= startDateTime - trendBinSize
    | where ObjectName == 'K8SContainer'
    | where CounterName == usageCounterName
    | project Computer, InstanceName, UsageValue = CounterValue, TimeGenerated
) on Computer, InstanceName
| where TimeGenerated >= LimitStartTime and TimeGenerated < LimitEndTime
| project Computer, ContainerName, TimeGenerated, UsagePercent = UsageValue * 100.0 / LimitValue
| summarize AggregatedValue = avg(UsagePercent) by bin(TimeGenerated, trendBinSize) , ContainerName

The following query calculates the average memory utilization of all containers in a controller as an average of memory utilization of every container instance in a controller every minute. The measurement is a percentage of the limit set up for a container.

let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
let capacityCounterName = 'memoryLimitBytes';
let usageCounterName = 'memoryRssBytes';
let clusterName = '<your-cluster-name>';
let controllerName = '<your-controller-name>';
KubePodInventory
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
| where ClusterName == clusterName
| where ControllerName == controllerName
| extend InstanceName = strcat(ClusterId, '/', ContainerName),
         ContainerName = strcat(controllerName, '/', tostring(split(ContainerName, '/')[1]))
| distinct Computer, InstanceName, ContainerName
| join hint.strategy=shuffle (
    Perf
    | where TimeGenerated < endDateTime
    | where TimeGenerated >= startDateTime
    | where ObjectName == 'K8SContainer'
    | where CounterName == capacityCounterName
    | summarize LimitValue = max(CounterValue) by Computer, InstanceName, bin(TimeGenerated, trendBinSize)
    | project Computer, InstanceName, LimitStartTime = TimeGenerated, LimitEndTime = TimeGenerated + trendBinSize, LimitValue
) on Computer, InstanceName
| join kind=inner hint.strategy=shuffle (
    Perf
    | where TimeGenerated < endDateTime + trendBinSize
    | where TimeGenerated >= startDateTime - trendBinSize
    | where ObjectName == 'K8SContainer'
    | where CounterName == usageCounterName
    | project Computer, InstanceName, UsageValue = CounterValue, TimeGenerated
) on Computer, InstanceName
| where TimeGenerated >= LimitStartTime and TimeGenerated < LimitEndTime
| project Computer, ContainerName, TimeGenerated, UsagePercent = UsageValue * 100.0 / LimitValue
| summarize AggregatedValue = avg(UsagePercent) by bin(TimeGenerated, trendBinSize) , ContainerName

The following query returns all nodes and counts that have a status of Ready and NotReady.

let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
let clusterName = '<your-cluster-name>';
KubeNodeInventory
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
| distinct ClusterName, Computer, TimeGenerated
| summarize ClusterSnapshotCount = count() by bin(TimeGenerated, trendBinSize), ClusterName, Computer
| join hint.strategy=broadcast kind=inner (
    KubeNodeInventory
    | where TimeGenerated < endDateTime
    | where TimeGenerated >= startDateTime
    | summarize TotalCount = count(), ReadyCount = sumif(1, Status contains ('Ready'))
                by ClusterName, Computer,  bin(TimeGenerated, trendBinSize)
    | extend NotReadyCount = TotalCount - ReadyCount
) on ClusterName, Computer, TimeGenerated
| project   TimeGenerated,
            ClusterName,
            Computer,
            ReadyCount = todouble(ReadyCount) / ClusterSnapshotCount,
            NotReadyCount = todouble(NotReadyCount) / ClusterSnapshotCount
| order by ClusterName asc, Computer asc, TimeGenerated desc

The following query returns pod phase counts based on all phases: Failed, Pending, Unknown, Running, or Succeeded.

let endDateTime = now();
    let startDateTime = ago(1h);
    let trendBinSize = 1m;
    let clusterName = '<your-cluster-name>';
    KubePodInventory
    | where TimeGenerated < endDateTime
    | where TimeGenerated >= startDateTime
    | where ClusterName == clusterName
    | distinct ClusterName, TimeGenerated
    | summarize ClusterSnapshotCount = count() by bin(TimeGenerated, trendBinSize), ClusterName
    | join hint.strategy=broadcast (
        KubePodInventory
        | where TimeGenerated < endDateTime
        | where TimeGenerated >= startDateTime
        | distinct ClusterName, Computer, PodUid, TimeGenerated, PodStatus
        | summarize TotalCount = count(),
                    PendingCount = sumif(1, PodStatus =~ 'Pending'),
                    RunningCount = sumif(1, PodStatus =~ 'Running'),
                    SucceededCount = sumif(1, PodStatus =~ 'Succeeded'),
                    FailedCount = sumif(1, PodStatus =~ 'Failed')
                 by ClusterName, bin(TimeGenerated, trendBinSize)
    ) on ClusterName, TimeGenerated
    | extend UnknownCount = TotalCount - PendingCount - RunningCount - SucceededCount - FailedCount
    | project TimeGenerated,
              TotalCount = todouble(TotalCount) / ClusterSnapshotCount,
              PendingCount = todouble(PendingCount) / ClusterSnapshotCount,
              RunningCount = todouble(RunningCount) / ClusterSnapshotCount,
              SucceededCount = todouble(SucceededCount) / ClusterSnapshotCount,
              FailedCount = todouble(FailedCount) / ClusterSnapshotCount,
              UnknownCount = todouble(UnknownCount) / ClusterSnapshotCount
| summarize AggregatedValue = avg(PendingCount) by bin(TimeGenerated, trendBinSize)

Note

To alert on certain pod phases, such as Pending, Failed, or Unknown, modify the last line of the query. For example, to alert on FailedCount use:
| summarize AggregatedValue = avg(FailedCount) by bin(TimeGenerated, trendBinSize)

The following query returns cluster nodes disks which exceed 90% free space used. To get the cluster ID, first run the following query and copy the value from the ClusterId property:

InsightsMetrics
| extend Tags = todynamic(Tags)            
| project ClusterId = Tags['container.azm.ms/clusterId']   
| distinct tostring(ClusterId)   

let clusterId = '<cluster-id>';
let endDateTime = now();
let startDateTime = ago(1h);
let trendBinSize = 1m;
InsightsMetrics
| where TimeGenerated < endDateTime
| where TimeGenerated >= startDateTime
| where Origin == 'container.azm.ms/telegraf'            
| where Namespace == 'container.azm.ms/disk'            
| extend Tags = todynamic(Tags)            
| project TimeGenerated, ClusterId = Tags['container.azm.ms/clusterId'], Computer = tostring(Tags.hostName), Device = tostring(Tags.device), Path = tostring(Tags.path), DiskMetricName = Name, DiskMetricValue = Val   
| where ClusterId =~ clusterId       
| where DiskMetricName == 'used_percent'
| summarize AggregatedValue = max(DiskMetricValue) by bin(TimeGenerated, trendBinSize)
| where AggregatedValue >= 90

Create an alert rule

Follow these steps to create a log alert in Azure Monitor by using one of the log search rules that was provided earlier.

  1. Sign in to the Azure portal.

  2. Select Monitor from the pane on the left side. Under Insights, select Containers.

  3. On the Monitored Clusters tab, select a cluster from the list.

  4. In the pane on the left side under Monitoring, select Logs to open the Azure Monitor logs page. You use this page to write and execute Azure Log Analytics queries.

  5. On the Logs page, select +New alert rule.

  6. In the Condition section, select the Whenever the Custom log search is <logic undefined> pre-defined custom log condition. The custom log search signal type is automatically selected because we're creating an alert rule directly from the Azure Monitor logs page.

  7. Paste one of the queries provided earlier into the Search query field.

  8. Configure the alert as follows:

    1. From the Based on drop-down list, select Metric measurement. A metric measurement creates an alert for each object in the query that has a value above our specified threshold.
    2. For Condition, select Greater than, and enter 75 as an initial baseline Threshold for the CPU and memory utilization alerts. For the low disk space alert, enter 90. Or enter a different value that meets your criteria.
    3. In the Trigger Alert Based On section, select Consecutive breaches. From the drop-down list, select Greater than, and enter 2.
    4. To configure an alert for container CPU or memory utilization, under Aggregate on, select ContainerName. To configure for cluster node low disk alert, select ClusterId.
    5. In the Evaluated based on section, set the Period value to 60 minutes. The rule will run every 5 minutes and return records that were created within the last hour from the current time. Setting the time period to a wide window accounts for potential data latency. It also ensures that the query returns data to avoid a false negative in which the alert never fires.

  9. Select Done to complete the alert rule.

  10. Enter a name in the Alert rule name field. Specify a Description that provides details about the alert. And select an appropriate severity level from the options provided.

  11. To immediately activate the alert rule, accept the default value for Enable rule upon creation.

  12. Select an existing Action Group or create a new group. This step ensures that the same actions are taken every time that an alert is triggered. Configure based on how your IT or DevOps operations team manages incidents.

  13. Select Create alert rule to complete the alert rule. It starts running immediately.

Next steps

  • View log query examples to see pre-defined queries and examples to evaluate or customize for alerting, visualizing, or analyzing your clusters.
  • To learn more about Azure Monitor and how to monitor other aspects of your AKS cluster, see View Azure Kubernetes Service health.