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Use Linux diagnostic extension 3.0 to monitor metrics and logs

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Caution

This article references CentOS, a Linux distribution that is End Of Life (EOL) status. Please consider your use and plan accordingly. For more information, see the CentOS End Of Life guidance.

This document describes version 3.0 and newer of the Linux diagnostic extension (LAD).

Important

For information about version 2.3 and earlier, see Monitor the performance and diagnostic data of a Linux VM.

Introduction

The Linux diagnostic extension helps a user monitor the health of a Linux VM that runs on Microsoft Azure. It has the following capabilities:

  • Collects system performance metrics from the VM and stores them in a specific table in a designated storage account.
  • Retrieves log events from syslog and stores them in a specific table in the designated storage account.
  • Enables users to customize the data metrics that are collected and uploaded.
  • Enables users to customize the syslog facilities and severity levels of events that are collected and uploaded.
  • Enables users to upload specified log files to a designated storage table.
  • Supports sending metrics and log events to arbitrary Azure Event Hubs endpoints and JSON-formatted blobs in the designated storage account.

This extension works with both Azure deployment models.

Install the extension on a VM

You can enable the extension by using Azure PowerShell cmdlets, Azure CLI scripts, Azure Resource Monitor templates (ARM templates), or the Azure portal. For more information, see Extensions features.

Note

Some components of the LAD VM extension are also shipped in the Log Analytics VM extension. Because of this architecture, conflicts can arise if both extensions are instantiated in the same ARM template.

To avoid install-time conflicts, use the dependsOn directive to ensure the extensions are installed sequentially. The extensions can be installed in either order.

These installation instructions and a downloadable sample configuration to configure LAD 3.0 to:

  • Capture and store the same metrics as in LAD 2.3.
  • Capture a useful set of file system metrics. This functionality is new in LAD 3.0.
  • Capture the default syslog collection that LAD 2.3 enabled.
  • Enable the Azure portal experience for charting and alerting on VM metrics.

The downloadable configuration is just an example. Modify it to suit your needs.

Prerequisites

  • Azure Linux Agent version 2.2.0 or later. Most Azure VM Linux gallery images include version 2.2.7 or later. Run /usr/sbin/waagent -version to confirm the version installed on the VM. If the VM is running an older version, Update the guest agent.
  • The Azure CLI. If necessary, set up the Azure CLI environment on your machine.
  • The wget command. If you don't already have it, install it using the corresponding package manager.
  • An existing Azure subscription.
  • An existing general purpose storage account to store the data. General purpose storage accounts must support table storage. A blob storage account won't work.
  • Python 2.

Python requirement

The Linux diagnostic extension requires Python 2. If your virtual machine uses a distribution that doesn't include Python 2 by default, you must install it. The following sample commands install Python 2 on various distributions:

  • Red Hat, CentOS, Oracle: yum install -y python2
  • Ubuntu, Debian: apt-get install -y python2
  • SUSE: zypper install -y python2

The python2 executable file must be aliased to python. Here's one method to set this alias:

  1. Run the following command to remove any existing aliases.

    sudo update-alternatives --remove-all python

  2. Run the following command to create the alias.

    sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 1

Sample installation

The sample configuration downloaded in the following examples collects a set of standard data and sends it to table storage. The URL for the sample configuration and its contents can change.

In most cases, you should download a copy of the portal settings JSON file and customize it for your needs. Then use templates or your own automation to use a customized version of the configuration file rather than downloading from the URL each time.

Note

For the following samples, fill in the correct values for the variables in the first section before you run the code.

Azure CLI sample

# Set your Azure VM diagnostic variables.
my_resource_group=<your_azure_resource_group_name_containing_your_azure_linux_vm>
my_linux_vm=<your_azure_linux_vm_name>
my_diagnostic_storage_account=<your_azure_storage_account_for_storing_vm_diagnostic_data>

# Login to Azure before you do anything else.
az login

# Select the subscription that contains the storage account.
az account set --subscription <your_azure_subscription_id>

# Download the sample public settings. (You could also use curl or any web browser.)
wget https://raw.githubusercontent.com/Azure/azure-linux-extensions/master/Diagnostic/tests/lad_2_3_compatible_portal_pub_settings.json -O portal_public_settings.json

# Build the VM resource ID. Replace the storage account name and resource ID in the public settings.
my_vm_resource_id=$(az vm show -g $my_resource_group -n $my_linux_vm --query "id" -o tsv)
sed -i "s#__DIAGNOSTIC_STORAGE_ACCOUNT__#$my_diagnostic_storage_account#g" portal_public_settings.json
sed -i "s#__VM_RESOURCE_ID__#$my_vm_resource_id#g" portal_public_settings.json

# Build the protected settings (storage account SAS token).
my_diagnostic_storage_account_sastoken=$(az storage account generate-sas --account-name $my_diagnostic_storage_account --expiry 2037-12-31T23:59:00Z --permissions wlacu --resource-types co --services bt -o tsv)
my_lad_protected_settings="{'storageAccountName': '$my_diagnostic_storage_account', 'storageAccountSasToken': '$my_diagnostic_storage_account_sastoken'}"

# Finally, tell Azure to install and enable the extension.
az vm extension set --publisher Microsoft.Azure.Diagnostics --name LinuxDiagnostic --version 3.0 --resource-group $my_resource_group --vm-name $my_linux_vm --protected-settings "${my_lad_protected_settings}" --settings portal_public_settings.json

Azure CLI sample to install LAD 3.0 on the virtual machine scale set instance

#Set your Azure Virtual Machine Scale Sets diagnostic variables.
$my_resource_group=<your_azure_resource_group_name_containing_your_azure_linux_vm>
$my_linux_vmss=<your_azure_linux_vmss_name>
$my_diagnostic_storage_account=<your_azure_storage_account_for_storing_vm_diagnostic_data>

# Login to Azure before you do anything else.
az login

# Select the subscription that contains the storage account.
az account set --subscription <your_azure_subscription_id>

# Download the sample public settings. (You could also use curl or any web browser.)
wget https://raw.githubusercontent.com/Azure/azure-linux-extensions/master/Diagnostic/tests/lad_2_3_compatible_portal_pub_settings.json -O portal_public_settings.json

# Build the virtual machine scale set resource ID. Replace the storage account name and resource ID in the public settings.
$my_vmss_resource_id=$(az vmss show -g $my_resource_group -n $my_linux_vmss --query "id" -o tsv)
sed -i "s#__DIAGNOSTIC_STORAGE_ACCOUNT__#$my_diagnostic_storage_account#g" portal_public_settings.json
sed -i "s#__VM_RESOURCE_ID__#$my_vmss_resource_id#g" portal_public_settings.json

# Build the protected settings (storage account SAS token).
$my_diagnostic_storage_account_sastoken=$(az storage account generate-sas --account-name $my_diagnostic_storage_account --expiry 2037-12-31T23:59:00Z --permissions wlacu --resource-types co --services bt -o tsv)
$my_lad_protected_settings="{'storageAccountName': '$my_diagnostic_storage_account', 'storageAccountSasToken': '$my_diagnostic_storage_account_sastoken'}"

# Finally, tell Azure to install and enable the extension.
az vmss extension set --publisher Microsoft.Azure.Diagnostics --name LinuxDiagnostic --version 3.0 --resource-group $my_resource_group --vmss-name $my_linux_vmss --protected-settings "${my_lad_protected_settings}" --settings portal_public_settings.json

PowerShell sample

$storageAccountName = "yourStorageAccountName"
$storageAccountResourceGroup = "yourStorageAccountResourceGroupName"
$vmName = "yourVMName"
$VMresourceGroup = "yourVMResourceGroupName"

# Get the VM object
$vm = Get-AzVM -Name $vmName -ResourceGroupName $VMresourceGroup

# Get the public settings template from GitHub and update the templated values for storage account and resource ID
$publicSettings = (Invoke-WebRequest -Uri https://raw.githubusercontent.com/Azure/azure-linux-extensions/master/Diagnostic/tests/lad_2_3_compatible_portal_pub_settings.json).Content
$publicSettings = $publicSettings.Replace('__DIAGNOSTIC_STORAGE_ACCOUNT__', $storageAccountName)
$publicSettings = $publicSettings.Replace('__VM_RESOURCE_ID__', $vm.Id)

# If you have customized public settings, you can inline those rather than using the preceding template: $publicSettings = '{"ladCfg":  { ... },}'

# Generate a SAS token for the agent to use to authenticate with the storage account
$sasToken = New-AzStorageAccountSASToken -Service Blob,Table -ResourceType Service,Container,Object -Permission "racwdlup" -Context (Get-AzStorageAccount -ResourceGroupName $storageAccountResourceGroup -AccountName $storageAccountName).Context -ExpiryTime $([System.DateTime]::Now.AddYears(10))

# Build the protected settings (storage account SAS token)
$protectedSettings="{'storageAccountName': '$storageAccountName', 'storageAccountSasToken': '$sasToken'}"

# Finally, install the extension with the settings you built
Set-AzVMExtension -ResourceGroupName $VMresourceGroup -VMName $vmName -Location $vm.Location -ExtensionType LinuxDiagnostic -Publisher Microsoft.Azure.Diagnostics -Name LinuxDiagnostic -SettingString $publicSettings -ProtectedSettingString $protectedSettings -TypeHandlerVersion 3.0

Update the extension settings

After you change your protected or public settings, deploy them to the VM by running the same command. If the settings changed, the updates are sent to the extension. LAD reloads the configuration and restarts itself.

Migrate from previous versions of the extension

The latest version of the extension is 4.0.

Important

This extension introduces breaking changes to the configuration. One such change improved the security of the extension, so backward compatibility with 2.x couldn't be maintained. Also, the extension publisher for this extension differs from the publisher for the 2.x versions.

To migrate from 2.x to the new version, first uninstall the old extension (under the old publisher name). Then install version 3.

Recommendations:

  • Install the extension with automatic minor version upgrade enabled.
    • On classic deployment model VMs, specify version 3.* if you're installing the extension through the Azure XPLAT CLI or PowerShell.
    • On Azure Resource Manager deployment model VMs, include "autoUpgradeMinorVersion": true in the VM deployment template.
  • Use a new or different storage account for LAD 3.0. LAD 2.3 and LAD 3.0 have several small incompatibilities that make sharing an account troublesome:
    • LAD 3.0 stores syslog events in a table that has a different name.
    • The counterSpecifier strings for builtin metrics differ in LAD 3.0.

Protected settings

This set of configuration information contains sensitive information that should be protected from public view. It contains, for example, storage credentials. These settings are transmitted to and stored by the extension in encrypted form.

{
    "storageAccountName" : "the storage account to receive data",
    "storageAccountEndPoint": "the hostname suffix for the cloud for this account",
    "storageAccountSasToken": "SAS access token",
    "mdsdHttpProxy": "HTTP proxy settings",
    "sinksConfig": { ... }
}
Name Value
storageAccountName The name of the storage account in which data is written by the extension.
storageAccountEndPoint (Optional) The endpoint that identifies the cloud in which the storage account exists. If this setting is absent, the LAD default is the Azure public cloud, https://core.windows.net. To use a storage account in Azure Germany, Azure Government, or Microsoft Azure operated by 21Vianet, set this value as required.
storageAccountSasToken An Account SAS token for blob and table services (ss='bt'). It applies to containers and objects (srt='co'). It grants add, create, list, update, and write permissions (sp='acluw'). Do not include the leading question-mark (?).
mdsdHttpProxy (Optional) HTTP proxy information that the extension needs to connect to the specified storage account and endpoint.
sinksConfig (Optional) Details of alternative destinations to which metrics and events can be delivered. The following sections address details about each data sink supported by the extension.

To get a SAS token within an ARM template, use the listAccountSas function. For an example template, see List function example.

You can construct the required SAS token through the Azure portal:

  1. Select the general-purpose storage account to which you want the extension to write.
  2. In the menu on the left, under Settings, select Shared access signature.
  3. Make the selections as previously described.
  4. Select Generate SAS.

Screenshot shows the Shared access signature page with the Generate S A S button.

Copy the generated SAS into the storageAccountSasToken field. Remove the leading question mark (?).

sinksConfig

"sinksConfig": {
    "sink": [
        {
            "name": "sinkname",
            "type": "sinktype",
            ...
        },
        ...
    ]
},

The sinksConfig optional section defines more destinations to which the extension sends the information it collects. The sink array contains an object for each additional data sink. The type attribute determines the other attributes in the object.

Element Value
name A string that refers to this sink elsewhere in the extension configuration.
type The type of sink being defined. Determines the other values (if any) in instances of this type.

LAD version 3.0 supports two sink types: EventHub and JsonBlob.

EventHub sink

"sink": [
    {
        "name": "sinkname",
        "type": "EventHub",
        "sasURL": "https SAS URL"
    },
    ...
]

The "sasURL" entry contains the full URL, including the SAS token, for the event hub to which data should be published. LAD requires a SAS to name a policy that enables the send claim.

For example:

  • Create an Azure Event Hubs namespace called contosohub.
  • Create an event hub in the namespace called syslogmsgs.
  • Create a shared access policy on the event hub that enables the send claim. Name the policy writer.

If your SAS is good until midnight UTC on January 1, 2018, the sasURL value might be like this example:

https://contosohub.servicebus.windows.net/syslogmsgs?sr=contosohub.servicebus.windows.net%2fsyslogmsgs&sig=xxxxxxxxxxxxxxxxxxxxxxxxx&se=1514764800&skn=writer

For more information about generating and retrieving information on SAS tokens for Event Hubs, see Generate a SAS token.

JsonBlob sink

"sink": [
    {
        "name": "sinkname",
        "type": "JsonBlob"
    },
    ...
]

Data directed to a JsonBlob sink is stored in blobs in Azure Storage. Each instance of LAD creates a blob every hour for each sink name. Each blob always contains a syntactically valid JSON array of objects. New entries are atomically added to the array.

Blobs are stored in a container that has the same name as the sink. The Azure Storage rules for blob container names apply to the names of JsonBlob sinks. The name must have between 3 and 63 lowercase alphanumeric ASCII characters or dashes.

Public settings

The public settings structure contains various blocks of settings that control the information the extension collects. Each setting is optional. If you specify ladCfg, you must also specify StorageAccount.

{
    "ladCfg":  { ... },
    "perfCfg": { ... },
    "fileLogs": { ... },
    "StorageAccount": "the storage account to receive data",
    "mdsdHttpProxy" : ""
}
Element Value
StorageAccount The name of the storage account in which data is written by the extension. It must be the name specified in the protected settings.
mdsdHttpProxy (Optional) Same as in the protected settings. The public value is overridden by the private value, if it's set. Place proxy settings that contain a secret, such as a password, in the protected settings.

The following sections provide details for the remaining elements.

ladCfg

"ladCfg": {
    "diagnosticMonitorConfiguration": {
        "eventVolume": "Medium",
        "metrics": { ... },
        "performanceCounters": { ... },
        "syslogEvents": { ... }
    },
    "sampleRateInSeconds": 15
}

The ladCfg structure is optional. It controls the gathering of metrics and logs that are delivered to the Azure Monitor Metrics service and to other data sinks. You must specify:

  • Either performanceCounters or syslogEvents or both.
  • The metrics structure.
Element Value
eventVolume (Optional) Controls the number of partitions created within the storage table. It must be "Large", "Medium", or "Small". If a value isn't specified, the default is "Medium".
sampleRateInSeconds (Optional) The default interval between the collection of raw (unaggregated) metrics. The smallest supported sample rate is 15 seconds. If the value isn't specified, the default is 15.

metrics

"metrics": {
    "resourceId": "/subscriptions/...",
    "metricAggregation" : [
        { "scheduledTransferPeriod" : "PT1H" },
        { "scheduledTransferPeriod" : "PT5M" }
    ]
}
Element Value
resourceId The Azure Resource Manager resource ID of the VM or of the scale set to which the VM belongs. This setting must be also specified if any JsonBlob sink is used in the configuration.
scheduledTransferPeriod The frequency at which aggregate metrics are computed and transferred to Azure Monitor Metrics. The frequency is expressed as an IS 8601 time interval. The smallest transfer period is 60 seconds, that is, PT1M. Specify at least one scheduledTransferPeriod.

Samples of the metrics specified in the performanceCounters section are collected every 15 seconds or at the sample rate explicitly defined for the counter. If multiple scheduledTransferPeriod frequencies appear, as in the example, each aggregation is computed independently.

performanceCounters

"performanceCounters": {
    "sinks": "",
    "performanceCounterConfiguration": [
        {
            "type": "builtin",
            "class": "Processor",
            "counter": "PercentIdleTime",
            "counterSpecifier": "/builtin/Processor/PercentIdleTime",
            "condition": "IsAggregate=TRUE",
            "sampleRate": "PT15S",
            "unit": "Percent",
            "annotation": [
                {
                    "displayName" : "Aggregate CPU %idle time",
                    "locale" : "en-us"
                }
            ]
        }
    ]
}

The performanceCounters optional section controls the collection of metrics. Raw samples are aggregated for each scheduledTransferPeriod to produce these values:

  • Mean
  • Minimum
  • Maximum
  • Last-collected value
  • Count of raw samples used to compute the aggregate
Element Value
sinks (Optional) A comma-separated list of names of sinks to which LAD sends aggregated metric results. All aggregated metrics are published to each listed sink. Example: "EHsink1, myjsonsink". For more information, see sinksConfig.
type Identifies the actual provider of the metric.
class Together with "counter", identifies the specific metric within the provider's namespace.
counter Together with "class", identifies the specific metric within the provider's namespace.
counterSpecifier Identifies the specific metric within the Azure Monitor Metrics namespace.
condition (Optional) Selects a specific instance of the object to which the metric applies. Or it selects the aggregation across all instances of that object.
sampleRate The IS 8601 interval that sets the rate at which raw samples for this metric are collected. If the value isn't set, the collection interval is set by the value of sampleRateInSeconds. The shortest supported sample rate is 15 seconds (PT15S).
unit Defines the unit for the metric. Should be one of these strings: "Count", "Bytes", "Seconds", "Percent", "CountPerSecond", "BytesPerSecond", "Millisecond". Consumers of the collected data expect the collected data values to match this unit. LAD ignores this field.
displayName The label to be attached to the data in Azure Monitor Metrics. This label is in the language specified by the associated locale setting. LAD ignores this field.

The counterSpecifier is an arbitrary identifier. Consumers of metrics, like the Azure portal charting and alerting feature, use counterSpecifier as the "key" that identifies a metric or an instance of a metric.

For builtin metrics, we recommend counterSpecifier values that begin with /builtin/. If you're collecting a specific instance of a metric, we recommend you attach the identifier of the instance to the counterSpecifier value.

Here are some examples:

  • /builtin/Processor/PercentIdleTime - Idle time averaged across all vCPUs
  • /builtin/Disk/FreeSpace(/mnt) - Free space for the /mnt file system
  • /builtin/Disk/FreeSpace - Free space averaged across all mounted file systems

LAD and the Azure portal don't expect the counterSpecifier value to match any pattern. Be consistent in how you construct counterSpecifier values.

When you specify performanceCounters, LAD always writes data to a table in Azure Storage. The same data can be written to JSON blobs or Event Hubs or both. But you can't disable storing data to a table.

All instances of LAD that use the same storage account name and endpoint add their metrics and logs to the same table. If too many VMs write to the same table partition, Azure can throttle writes to that partition.

The eventVolume setting causes entries to be spread across 1 (small), 10 (medium), or 100 (large) partitions. Usually, medium partitions are sufficient to avoid traffic throttling.

The Azure Monitor Metrics feature of the Azure portal uses the data in this table to produce graphs or to trigger alerts. The table name is the concatenation of these strings:

  • WADMetrics
  • The "scheduledTransferPeriod" for the aggregated values stored in the table
  • P10DV2S
  • A date, in the form "YYYYMMDD", which changes every 10 days

Examples include WADMetricsPT1HP10DV2S20170410 and WADMetricsPT1MP10DV2S20170609.

syslogEvents

"syslogEvents": {
    "sinks": "",
    "syslogEventConfiguration": {
        "facilityName1": "minSeverity",
        "facilityName2": "minSeverity",
        ...
    }
}

The syslogEvents optional section controls the collection of log events from syslog. If the section is omitted, syslog events aren't captured at all.

The syslogEventConfiguration collection has one entry for each syslog facility of interest. If minSeverity is "NONE" for a particular facility, or if that facility doesn't appear in the element at all, no events from that facility are captured.

Element Value
sinks A comma-separated list of names of sinks to which individual log events are published. All log events that match the restrictions in syslogEventConfiguration are published to each listed sink. Example: "EHforsyslog"
facilityName A syslog facility name, such as "LOG_USER" or "LOG\LOCAL0". For more information, see the "Facility" section of the syslog man page.
minSeverity A syslog severity level, such as "LOG_ERR" or "LOG_INFO". For more information, see the "Level" section of the syslog man page. The extension captures events sent to the facility at or above the specified level.

When you specify syslogEvents, LAD always writes data to a table named LinuxSyslogVer2v0 in Azure Storage. The same data can be written to JSON blobs or Event Hubs or both. But you can't disable storing data to a table.

perfCfg

The perfCfg section is optional. It controls the running of arbitrary Open Management Infrastructure (OMI) queries.

"perfCfg": [
    {
        "namespace": "root/scx",
        "query": "SELECT PercentAvailableMemory, PercentUsedSwap FROM SCX_MemoryStatisticalInformation",
        "table": "LinuxOldMemory",
        "frequency": 300,
        "sinks": ""
    }
]
Element Value
namespace (Optional) The OMI namespace within which the query should be run. If unspecified, the default value is "root/scx". It's implemented by the System Center cross-platform providers.
query The OMI query to run.
table (Optional) The Azure Storage table, in the designated storage account. For more information, see Protected settings.
frequency (Optional) The number of seconds between query runs. The default value is 300 (5 minutes). The minimum value is 15 seconds.
sinks (Optional) A comma-separated list of names of more sinks to which raw sample metric results should be published. No aggregation of these raw samples is computed by the extension or by Azure Monitor Metrics.

Either "table" or "sinks" or both must be specified.

fileLogs

The fileLogs section controls the capture of log files. LAD captures new text lines as they're written to the file. It writes them to table rows and/or any specified sinks (JsonBlob or EventHub).

Note

The fileLogs are captured by a subcomponent of LAD called omsagent. To collect fileLogs, ensure that the omsagent user has read permissions on the files you specify. The user must also have execute permissions on all directories in the path to that file. After LAD is installed, you can check permissions by running sudo su omsagent -c 'cat /path/to/file'.

"fileLogs": [
    {
        "file": "/var/log/mydaemonlog",
        "table": "MyDaemonEvents",
        "sinks": ""
    }
]
Element Value
file The full path name of the log file to be watched and captured. The path name must name a single file. It can't name a directory or contain wildcard characters. The omsagent user account must have read access to the file path.
table (Optional) The Azure Storage table into which new lines from the "tail" of the file are written. The table must be in the designated storage account, as specified in the protected configuration.
sinks (Optional) A comma-separated list of names of more sinks to which log lines are sent.

Either "table" or "sinks", or both, must be specified.

Metrics supported by the builtin provider

The builtin metric provider is a source of metrics that are the most interesting to a broad set of users. These metrics fall into five broad classes:

  • Processor
  • Memory
  • Network
  • File system
  • Disk

builtin metrics for the Processor class

The Processor class of metrics provides information about processor usage in the VM. When percentages are aggregated, the result is the average across all CPUs.

In a two-vCPU VM, if one vCPU is 100 percent busy and the other is 100 percent idle, the reported PercentIdleTime is 50. If each vCPU is 50 percent busy for the same period, the reported result is also 50. In a four-vCPU VM, when one vCPU is 100 percent busy and the others are idle, the reported PercentIdleTime is 75.

Counter Meaning
PercentIdleTime Percentage of time during the aggregation window that processors ran the kernel idle loop
PercentProcessorTime Percentage of time running a non-idle thread
PercentIOWaitTime Percentage of time waiting for IO operations to finish
PercentInterruptTime Percentage of time running hardware or software interrupts and DPCs (deferred procedure calls)
PercentUserTime Of non-idle time during the aggregation window, the percentage of time spent in user mode at normal priority
PercentNiceTime Of non-idle time, the percentage spent at lowered (nice) priority
PercentPrivilegedTime Of non-idle time, the percentage spent in privileged (kernel) mode

The first four counters should sum to 100 percent. The last three counters also sum to 100 percent. These three counters subdivide the sum of PercentProcessorTime, PercentIOWaitTime, and PercentInterruptTime.

To aggregate a single metric across all processors, set "condition": "IsAggregate=TRUE". To obtain a metric for a specific processor, such as the second logical processor of a four-vCPU VM, set "condition": "Name=\\"1\\"". Logical processor numbers are in the range [0..n-1].

builtin metrics for the Memory class

The Memory class of metrics provides information about memory use, paging, and swapping.

Counter Meaning
AvailableMemory Available physical memory in MiB
PercentAvailableMemory Available physical memory as a percentage of total memory
UsedMemory In-use physical memory (MiB)
PercentUsedMemory In-use physical memory as a percentage of total memory
PagesPerSec Total paging (read/write)
PagesReadPerSec Pages read from the backing store, such as swap file, program file, and mapped file
PagesWrittenPerSec Pages written to the backing store, such as swap file and mapped file
AvailableSwap Unused swap space (MiB)
PercentAvailableSwap Unused swap space as a percentage of the total swap
UsedSwap In-use swap space (MiB)
PercentUsedSwap In-use swap space as a percentage of the total swap

This class of metrics has only one instance. The "condition" attribute has no useful settings and should be omitted.

builtin metrics for the Network class

The Network class of metrics provides information about network activity on an individual network interface since the startup.

LAD doesn't expose bandwidth metrics. You can get these metrics from host metrics.

Counter Meaning
BytesTransmitted Total bytes sent since startup
BytesReceived Total bytes received since startup
BytesTotal Total bytes sent or received since startup
PacketsTransmitted Total packets sent since startup
PacketsReceived Total packets received since startup
TotalRxErrors Number of receive errors since startup
TotalTxErrors Number of transmit errors since startup
TotalCollisions Number of collisions reported by the network ports since startup

Although the Network class is instanced, LAD doesn't support capturing Network metrics aggregated across all network devices. To obtain the metrics for a specific interface, such as eth0, set "condition": "InstanceID=\\"eth0\\"".

builtin metrics for the File system class

The File system class of metrics provides information about file system usage. Absolute and percentage values are reported as they would be displayed to an ordinary user (not root).

Counter Meaning
FreeSpace Available disk space in bytes
UsedSpace Used disk space in bytes
PercentFreeSpace Percentage free space
PercentUsedSpace Percentage used space
PercentFreeInodes Percentage of unused index nodes (inodes)
PercentUsedInodes Percentage of allocated (in use) inodes summed across all file systems
BytesReadPerSecond Bytes read per second
BytesWrittenPerSecond Bytes written per second
BytesPerSecond Bytes read or written per second
ReadsPerSecond Read operations per second
WritesPerSecond Write operations per second
TransfersPerSecond Read or write operations per second

You can get aggregated values across all file systems by setting "condition": "IsAggregate=True". Get values for a specific mounted file system, such as "/mnt", by setting "condition": 'Name="/mnt"'.

Note

If you're working in the Azure portal instead of JSON, the condition field form is Name='/mnt'.

builtin metrics for the Disk class

The Disk class of metrics provides information about disk device usage. These statistics apply to the entire drive.

When a device has multiple file systems, the counters for that device are, effectively, aggregated across all file systems.

Counter Meaning
ReadsPerSecond Read operations per second
WritesPerSecond Write operations per second
TransfersPerSecond Total operations per second
AverageReadTime Average seconds per read operation
AverageWriteTime Average seconds per write operation
AverageTransferTime Average seconds per operation
AverageDiskQueueLength Average number of queued disk operations
ReadBytesPerSecond Number of bytes read per second
WriteBytesPerSecond Number of bytes written per second
BytesPerSecond Number of bytes read or written per second

You can get aggregated values across all disks by setting "condition": "IsAggregate=True". To get information for a specific device (for example, /dev/sdf1), set "condition": "Name=\\"/dev/sdf1\\"".

Install and configure LAD 3.0

Azure CLI

If your protected settings are in the file ProtectedSettings.json and your public configuration information is in PublicSettings.json, run the following command.

az vm extension set --publisher Microsoft.Azure.Diagnostics --name LinuxDiagnostic --version 3.0 --resource-group <resource_group_name> --vm-name <vm_name> --protected-settings ProtectedSettings.json --settings PublicSettings.json

The command assumes you're using the Azure Resource Manager mode of the Azure CLI. To configure LAD for classic deployment model VMs, switch to "asm" mode (azure config mode asm) and omit the resource group name in the command.

For more information, see the cross-platform CLI documentation.

PowerShell

If your protected settings are in the $protectedSettings variable and your public configuration information is in the $publicSettings variable, run this command:

Set-AzVMExtension -ResourceGroupName <resource_group_name> -VMName <vm_name> -Location <vm_location> -ExtensionType LinuxDiagnostic -Publisher Microsoft.Azure.Diagnostics -Name LinuxDiagnostic -SettingString $publicSettings -ProtectedSettingString $protectedSettings -TypeHandlerVersion 3.0

Example LAD 3.0 configuration

Based on the preceding definitions, this section provides a sample LAD 3.0 extension configuration and some explanation. To apply this sample to your case, use your own storage account name, account SAS token, and Event Hubs SAS tokens.

Note

Depending on whether you use the Azure CLI or PowerShell to install LAD, the method for providing public and protected settings differs:

  • If you're using the Azure CLI, save the following settings to ProtectedSettings.json and PublicSettings.json to use the preceding sample command.
  • If you're using PowerShell, save the following settings to $protectedSettings and $publicSettings by running $protectedSettings = '{ ... }'.

Protected settings

The protected settings configure:

  • A storage account.
  • A matching account SAS token.
  • Several sinks (JsonBlob or EventHub with SAS tokens).
{
  "storageAccountName": "yourdiagstgacct",
  "storageAccountSasToken": "sv=xxxx-xx-xx&ss=bt&srt=co&sp=wlacu&st=yyyy-yy-yyT21%3A22%3A00Z&se=zzzz-zz-zzT21%3A22%3A00Z&sig=fake_signature",
  "sinksConfig": {
    "sink": [
      {
        "name": "SyslogJsonBlob",
        "type": "JsonBlob"
      },
      {
        "name": "FilelogJsonBlob",
        "type": "JsonBlob"
      },
      {
        "name": "LinuxCpuJsonBlob",
        "type": "JsonBlob"
      },
      {
        "name": "MyJsonMetricsBlob",
        "type": "JsonBlob"
      },
      {
        "name": "LinuxCpuEventHub",
        "type": "EventHub",
        "sasURL": "https://youreventhubnamespace.servicebus.windows.net/youreventhubpublisher?sr=https%3a%2f%2fyoureventhubnamespace.servicebus.windows.net%2fyoureventhubpublisher%2f&sig=fake_signature&se=1808096361&skn=yourehpolicy"
      },
      {
        "name": "MyMetricEventHub",
        "type": "EventHub",
        "sasURL": "https://youreventhubnamespace.servicebus.windows.net/youreventhubpublisher?sr=https%3a%2f%2fyoureventhubnamespace.servicebus.windows.net%2fyoureventhubpublisher%2f&sig=yourehpolicy&skn=yourehpolicy"
      },
      {
        "name": "LoggingEventHub",
        "type": "EventHub",
        "sasURL": "https://youreventhubnamespace.servicebus.windows.net/youreventhubpublisher?sr=https%3a%2f%2fyoureventhubnamespace.servicebus.windows.net%2fyoureventhubpublisher%2f&sig=yourehpolicy&se=1808096361&skn=yourehpolicy"
      }
    ]
  }
}

Public settings

The public settings cause LAD to:

  • Upload percent-processor-time metrics and used-disk-space metrics to the WADMetrics* table.
  • Upload messages from syslog facility "user" and severity "info" to the LinuxSyslog* table.
  • Upload raw OMI query results (PercentProcessorTime and PercentIdleTime) to the named LinuxCPU table.
  • Upload appended lines in file /var/log/myladtestlog to the MyLadTestLog table.

In each case, data is also uploaded to:

  • Azure Blob Storage. The container name is as defined in the JsonBlob sink.
  • The Event Hubs endpoint, as specified in the EventHub sink.
{
  "StorageAccount": "yourdiagstgacct",
  "ladCfg": {
    "sampleRateInSeconds": 15,
    "diagnosticMonitorConfiguration": {
      "performanceCounters": {
        "sinks": "MyMetricEventHub,MyJsonMetricsBlob",
        "performanceCounterConfiguration": [
          {
            "unit": "Percent",
            "type": "builtin",
            "counter": "PercentProcessorTime",
            "counterSpecifier": "/builtin/Processor/PercentProcessorTime",
            "annotation": [
              {
                "locale": "en-us",
                "displayName": "Aggregate CPU %utilization"
              }
            ],
            "condition": "IsAggregate=TRUE",
            "class": "Processor"
          },
          {
            "unit": "Bytes",
            "type": "builtin",
            "counter": "UsedSpace",
            "counterSpecifier": "/builtin/FileSystem/UsedSpace",
            "annotation": [
              {
                "locale": "en-us",
                "displayName": "Used disk space on /"
              }
            ],
            "condition": "Name=\"/\"",
            "class": "Filesystem"
          }
        ]
      },
      "metrics": {
        "metricAggregation": [
          {
            "scheduledTransferPeriod": "PT1H"
          },
          {
            "scheduledTransferPeriod": "PT1M"
          }
        ],
        "resourceId": "/subscriptions/your_azure_subscription_id/resourceGroups/your_resource_group_name/providers/Microsoft.Compute/virtualMachines/your_vm_name"
      },
      "eventVolume": "Large",
      "syslogEvents": {
        "sinks": "SyslogJsonBlob,LoggingEventHub",
        "syslogEventConfiguration": {
          "LOG_USER": "LOG_INFO"
        }
      }
    }
  },
  "perfCfg": [
    {
      "query": "SELECT PercentProcessorTime, PercentIdleTime FROM SCX_ProcessorStatisticalInformation WHERE Name='_TOTAL'",
      "table": "LinuxCpu",
      "frequency": 60,
      "sinks": "LinuxCpuJsonBlob,LinuxCpuEventHub"
    }
  ],
  "fileLogs": [
    {
      "file": "/var/log/myladtestlog",
      "table": "MyLadTestLog",
      "sinks": "FilelogJsonBlob,LoggingEventHub"
    }
  ]
}

The resourceId in the configuration must match that of the VM or the virtual machine scale set.

  • Azure platform metrics charting and alerting knows the resourceId of the VM you're working on. It expects to find the data for your VM by using the resourceId the lookup key.
  • If you use Azure Autoscale, the resourceId in the autoscale configuration must match the resourceId that LAD uses.
  • The resourceId is built in to the names of JSON blobs written by LAD.

View your data

Use the Azure portal to view performance data or to set alerts:

Screenshot shows the Azure portal. The Used disk space on metric is selected. The resulting chart is shown.

The performanceCounters data is always stored in an Azure Storage table. Azure Storage APIs are available for many languages and platforms.

Data sent to JsonBlob sinks is stored in blobs in the storage account named in the protected settings. You can consume the blob data by using any Azure Blob Storage APIs.

You also can use these UI tools to access the data in Azure Storage:

The following screenshot of an Azure Storage Explorer session shows the generated Azure Storage tables and containers from a correctly configured LAD 3.0 extension on a test VM. The image doesn't exactly match the sample LAD 3.0 configuration.

Screenshot shows Azure Storage Explorer.

For more information about how to consume messages published to an Event Hubs endpoint, see the relevant Event Hubs documentation.

Next steps