解决Azure PowerShell中Get-AzMetric获取App Service指标的类型转换错误

问题原因 #

你遇到的错误源于两个核心问题：

1. 脚本使用了错误的参数名：-Aggregation，而Get-AzMetric的正确参数名为-AggregationType
2. -AggregationType参数仅支持传入单个AggregationType枚举值，无法直接接受数组类型的多个聚合值，PowerShell无法将数组转换为参数要求的可空枚举类型，因此抛出转换错误。

另外，你的脚本未切换到指定订阅，需添加订阅切换命令确保后续操作在目标订阅下执行。

解决方案 #

要获取多个聚合类型的指标，需要为每个聚合类型单独调用Get-AzMetric，或者合并不同聚合类型的结果。以下是两种可行的修改方案：

方案1：按聚合类型分别输出指标 #

该方案循环遍历指定的聚合类型，分别获取并输出每个类型的指标数据：

# Connect to Azure account
Connect-AzAccount -UseDeviceAuthentication

# Specify the subscription ID
$subscriptionId = "<subscription-id>"

# Switch to the target subscription
Set-AzContext -Subscription $subscriptionId

# Get all App Services in the subscription
$appServices = Get-AzWebApp

# Specify the time range for metrics retrieval
$startTime = (Get-Date).AddDays(-90) 
$endTime = Get-Date  

# Define aggregation types to retrieve
$aggregations = @("Maximum", "Minimum", "Average")

# Iterate through each App Service and retrieve metrics
foreach ($appService in $appServices) {
    $appServiceName = $appService.Name
    $resourceGroup = $appService.ResourceGroup

    Write-Host "`nRetrieving metrics for App Service: $appServiceName"

    # Retrieve CPU metrics for each aggregation type
    Write-Host "`nCPU Metrics:"
    foreach ($agg in $aggregations) {
        $cpuMetrics = Get-AzMetric -ResourceId $appService.Id `
                                  -StartTime $startTime `
                                  -EndTime $endTime `
                                  -MetricNames "CpuPercentage" `
                                  -AggregationType $agg
        
        $cpuMetrics.Data | Select-Object Timestamp, @{Name=$agg; Expression={$_.$agg}}
    }

    # Retrieve memory metrics for each aggregation type
    Write-Host "`nMemory Metrics:"
    foreach ($agg in $aggregations) {
        $memoryMetrics = Get-AzMetric -ResourceId $appService.Id `
                                     -StartTime $startTime `
                                     -EndTime $endTime `
                                     -MetricNames "MemoryPercentage" `
                                     -AggregationType $agg
        
        $memoryMetrics.Data | Select-Object Timestamp, @{Name=$agg; Expression={$_.$agg}}
    }
}

方案2：合并同一时间戳的多聚合值 #

该方案将同一时间戳的最大、最小、平均值合并到同一对象中输出，更贴近你原本的预期格式：

# Connect to Azure account
Connect-AzAccount -UseDeviceAuthentication

# Specify the subscription ID
$subscriptionId = "<subscription-id>"

# Switch to the target subscription
Set-AzContext -Subscription $subscriptionId

# Get all App Services in the subscription
$appServices = Get-AzWebApp

# Specify the time range for metrics retrieval
$startTime = (Get-Date).AddDays(-90) 
$endTime = Get-Date  

# Iterate through each App Service and retrieve metrics
foreach ($appService in $appServices) {
    $appServiceName = $appService.Name
    $resourceGroup = $appService.ResourceGroup

    Write-Host "`nRetrieving metrics for App Service: $appServiceName"

    # Retrieve CPU metrics with all aggregations
    $cpuMax = Get-AzMetric -ResourceId $appService.Id `
                          -StartTime $startTime `
                          -EndTime $endTime `
                          -MetricNames "CpuPercentage" `
                          -AggregationType Maximum
    $cpuMin = Get-AzMetric -ResourceId $appService.Id `
                          -StartTime $startTime `
                          -EndTime $endTime `
                          -MetricNames "CpuPercentage" `
                          -AggregationType Minimum
    $cpuAvg = Get-AzMetric -ResourceId $appService.Id `
                          -StartTime $startTime `
                          -EndTime $endTime `
                          -MetricNames "CpuPercentage" `
                          -AggregationType Average

    # Combine CPU metrics into single objects
    $combinedCpuMetrics = for ($i=0; $i -lt $cpuMax.Data.Count; $i++) {
        [PSCustomObject]@{
            Timestamp = $cpuMax.Data[$i].Timestamp
            Maximum   = $cpuMax.Data[$i].Maximum
            Minimum   = $cpuMin.Data[$i].Minimum
            Average   = $cpuAvg.Data[$i].Average
        }
    }

    Write-Host "`nCPU Metrics:"
    $combinedCpuMetrics

    # Retrieve and combine Memory metrics
    $memoryMax = Get-AzMetric -ResourceId $appService.Id `
                             -StartTime $startTime `
                             -EndTime $endTime `
                             -MetricNames "MemoryPercentage" `
                             -AggregationType Maximum
    $memoryMin = Get-AzMetric -ResourceId $appService.Id `
                             -StartTime $startTime `
                             -EndTime $endTime `
                             -MetricNames "MemoryPercentage" `
                             -AggregationType Minimum
    $memoryAvg = Get-AzMetric -ResourceId $appService.Id `
                             -StartTime $startTime `
                             -EndTime $endTime `
                             -MetricNames "MemoryPercentage" `
                             -AggregationType Average

    $combinedMemoryMetrics = for ($i=0; $i -lt $memoryMax.Data.Count; $i++) {
        [PSCustomObject]@{
            Timestamp = $memoryMax.Data[$i].Timestamp
            Maximum   = $memoryMax.Data[$i].Maximum
            Minimum   = $memoryMin.Data[$i].Minimum
            Average   = $memoryAvg.Data[$i].Average
        }
    }

    Write-Host "`nMemory Metrics:"
    $combinedMemoryMetrics
}

额外注意事项 #

• 确保安装最新版本的Az.Monitor模块，执行Update-Module -Name Az.Monitor完成更新
• 部分App Service可能无有效指标数据，脚本会输出空结果，属于正常情况

内容的提问来源于stack exchange，提问作者mo taar