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Configure Event Hubs for VM watch

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VM watch can send signal data to a preconfigured Event Hub.

This article provides instructions on configuring Event Hubs to access signals collected by VM watch

Prerequisites

This article assumes that you're familiar with:

Enable Event Hubs Output

1: Prepare Event Hubs for VM watch

Important

VM watch supports managed identity, SAS token, and connection string as authentication methods. When multiple authentication methods are provided, managed identity is prioritized as the highest, while the connection string is assigned the lowest priority.

2: Enable Event Hubs output for VM watch

For each Event Hub authentication method, you need to combine both the common and authentication specific parameter settings. Instructions are given for each authentication scenario. For virtual machines and virtual machine scale sets, specify the following settings within vmWatchSettings in the JSON configurations. See Configure VM watch for instructions on how to access vmWatchSettings using ARM template, Azure CLI, or PowerShell.

Common parameters for Event Hubs output

For all authentication methods, the following parameter set applies:

Parameter Is required Description
EVENT_HUB_OUTPUT_NAMESPACE Yes Event hub name space name, without the domain name ".servicebus.windows.net"
EVENT_HUB_OUTPUT_NAME Yes Event hub name within the given namespace
EVENT_HUB_OUTPUT_DOMAIN_NAME No Event hub domain name. Default value "servicebus.windows.net"
EVENT_HUB_OUTPUT_CLOSE_TIMEOUT No Client close time-out. Default is 30s
EVENT_HUB_OUTPUT_PARTITION_ID No Metric tag or field name to use for the event partition key. Default is null
EVENT_HUB_OUTPUT_MAX_MESSAGE_SIZE No The maximum batch message size in bytes. Setting this parameter to 0 means using the default size from the Azure Event Hubs Client library (1,000,000 bytes). Default is 0
SEND_INTERNAL_TELEMETRY_TO_EVENT_HUB No To receive VM watch internal metrics (startup and heartbeat events), set this value to "true." Default is "false"
Authentication specific parameters for Event Hubs output
Parameter Is required Description
EVENT_HUB_OUTPUT_USE_MANAGED_IDENTITY No Set this value to "true." Default is "false"
EVENT_HUB_OUTPUT_MANAGED_IDENTITY_CLIENT_ID No If you're using a specific managed identity to authenticate, specify this value

For example, the following VM watch JSON configuration sets the environment variables EVENT_HUB_OUTPUT_NAMESPACE, EVENT_HUB_OUTPUT_NAME, and EVENT_HUB_OUTPUT_USE_MANAGED_IDENTITY. This allows Event Hubs to use managed identity as the authentication method without needing to specify a managed identity client ID.

{
  "vmWatchSettings": {
    "enabled": true,
    "parameterOverrides": {
      "EVENT_HUB_OUTPUT_NAMESPACE": "<example event hub namespace>",
      "EVENT_HUB_OUTPUT_NAME": "<example event hub name>",
      "EVENT_HUB_OUTPUT_USE_MANAGED_IDENTITY": "true"
    }
  }
}

3: Examine events in Event Hubs

Once VM watch settings are successfully configured to use Event Hubs as the output, VM watch restarts. Events start flowing into Event Hubs within a few minutes. You can use the Azure portal to observe the incoming messages.

The following screenshot shows data flowing into the Event Hub

Screenshot that shows VM watch data flowing into Event Hubs.

Also, you can use the Event Hubs Data Explorer feature to view incoming event and content.

The following screenshot shows Event Hubs Data Explorer

Screenshot that shows Event Hubs data explorer.

Event Hubs Events schema

Each Event Hub event has the following schema:

Field Name Data Type Description
DateTime time The time the signal was emitted
SignalType string The type of the signal, which can be either "StartUp," "Heartbeat," "Check," "Metric," or "EventLog"
SignalName string The name of the signal
SubscriptionId string The VM subscription ID
ResourceGroup string The VM resource group name
ResourceId string The Azure resource URI of the VM
VmId string The unique ID of the VM queried from IMDS endpoint within the VM
Vmss string The virtual machine scale set name, if applicable
Offer string The Azure VM offer
VmSize string The VM size
MeasurementTarget string The target that the signal is measuring at. Name field and MeasurementTarget are used together for raw signal aggregation
SignalValue json The value of this signal, where the schema depends on the SignalType
Version string The version of the Event Hub output event schema

Debug Event Hubs connection issues

If there are no events in Event Hubs after several minutes, check the VM watch logs in the following directories on the virtual machine or virtual machine scale set to diagnose the issue:

/var/log/azure/Microsoft.ManagedServices.ApplicationHealthLinux/vmwatch.log

Next steps