Azureのコスト管理入門｜Cost Managementと予算アラートでクラウド料金の想定外を防ぐ方法

この記事のポイント

・azure コスト管理はCost Management画面でサービス・リソースグループ別に可視化できる
・az costmanagement queryコマンドでCLIからコスト照会が可能
・予算（Budget）設定で月次コストが閾値を超えるとメールアラートが届く
・タグ（Tag）付けでリソースのコスト配分をプロジェクト別に集計できる

# サブスクリプションIDを確認
$ az account show --query "{name:name, id:id}" -o table
Name                             Id
-------------------------------  ------------------------------------
Visual Studio Enterprise         xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

# 今月のコストをリソースグループ別に照会
$ az costmanagement query \
  --type ActualCost \
  --timeframe MonthToDate \
  --scope "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" \
  --dataset-aggregation '{"totalCost":{"name":"PreTaxCost","function":"Sum"}}' \
  --dataset-grouping '[{"type":"Dimension","name":"ResourceGroupName"}]' \
  --query "properties.rows" \
  -o table
Column1     Column2                   Column3
----------  ------------------------  -------------------------
3218.45     rg-linux-practice         JPY
852.10      rg-monitoring             JPY
120.00      rg-storage-backup         JPY

# サービス種別でグループ化してコストを確認
$ az costmanagement query \
  --type ActualCost \
  --timeframe MonthToDate \
  --scope "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" \
  --dataset-aggregation '{"totalCost":{"name":"PreTaxCost","function":"Sum"}}' \
  --dataset-grouping '[{"type":"Dimension","name":"ServiceName"}]' \
  --query "properties.rows" \
  -o table
Column1     Column2                              Column3
----------  -----------------------------------  -------------------------
2540.30     Virtual Machines                     JPY
920.15      Storage                              JPY
480.00      Bandwidth                            JPY
250.10      Azure App Service                    JPY

# 直近7日間の使用コストを確認
$ az consumption usage list \
  --start-date 2026-07-12 \
  --end-date 2026-07-18 \
  --query "[].{Date:usageStart, Resource:instanceName, Cost:pretaxCost}" \
  -o table | head -15
Date                  Resource                     Cost
--------------------  ---------------------------  ------
2026-07-12T00:00:00Z  linuxvm-rhel94               182.40
2026-07-13T00:00:00Z  linuxvm-rhel94               182.40
2026-07-14T00:00:00Z  linuxvm-rhel94               182.40
2026-07-15T00:00:00Z  linuxvm-rhel94               182.40
2026-07-16T00:00:00Z  linuxvm-rhel94               182.40
2026-07-17T00:00:00Z  linuxvm-rhel94               182.40
2026-07-18T00:00:00Z  linuxvm-rhel94               182.40

# 月次予算5,000円 + 80%・100%アラートを作成
$ az consumption budget create \
  --budget-name "budget-learning-monthly" \
  --amount 5000 \
  --category Cost \
  --time-grain Monthly \
  --start-date 2026-07-01 \
  --end-date 2026-12-31 \
  --resource-group rg-linux-practice \
  --notifications '[
    {
      "enabled": true,
      "operator": "GreaterThan",
      "threshold": 80,
      "contactEmails": ["tomohiro@example.com"],
      "thresholdType": "Actual"
    },
    {
      "enabled": true,
      "operator": "GreaterThan",
      "threshold": 100,
      "contactEmails": ["tomohiro@example.com"],
      "thresholdType": "Actual"
    }
  ]'
{
  "amount": 5000.0,
  "category": "Cost",
  "currentSpend": {
    "amount": 4190.55,
    "unit": "JPY"
  },
  "name": "budget-learning-monthly",
  "timeGrain": "Monthly",
  "timePeriod": {
    "endDate": "2026-12-31T00:00:00+00:00",
    "startDate": "2026-07-01T00:00:00+00:00"
  }
}

# 作成した予算の一覧を確認
$ az consumption budget list \
  --resource-group rg-linux-practice \
  --query "[].{Name:name, Amount:amount, CurrentSpend:currentSpend.amount}" \
  -o table
Name                      Amount    CurrentSpend
------------------------  --------  --------------
budget-learning-monthly   5000.0    4190.55

# アラート履歴を確認（Cost Managementアラート）
$ az costmanagement alert list \
  --scope "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/rg-linux-practice" \
  --query "[].{Name:name, Type:properties.definition.type, Threshold:properties.definition.details.threshold}" \
  -o table
Name                   Type      Threshold
---------------------  --------  -----------
alert-80pct-triggered  Budget    80

# 実行中のVM一覧を確認
$ az vm list \
  --resource-group rg-linux-practice \
  --show-details \
  --query "[?powerState=='VM running'].{Name:name, Size:hardwareProfile.vmSize, State:powerState}" \
  -o table
Name              Size           State
----------------  -------------  ----------
linuxvm-rhel94    Standard_B2s   VM running
test-vm-dev       Standard_B4ms  VM running

# 使っていないVMを停止（割り当て解除）
$ az vm deallocate \
  --resource-group rg-linux-practice \
  --name test-vm-dev

# VMにタグを付ける
$ az vm update \
  --resource-group rg-linux-practice \
  --name linuxvm-rhel94 \
  --set tags.Project=linux-training tags.Owner=tomohiro

# タグが設定されているか確認
$ az vm show \
  --resource-group rg-linux-practice \
  --name linuxvm-rhel94 \
  --query tags \
  -o json
{
  "Owner": "tomohiro",
  "Project": "linux-training"
}

# Azure Advisorのコスト推奨事項を確認
$ az advisor recommendation list \
  --category Cost \
  --query "[].{Problem:shortDescription.problem, Impact:impact, Savings:extendedProperties.annualSavingsAmount}" \
  -o table
Problem                                          Impact   Savings
-----------------------------------------------  -------  -------
Shutdown or resize underutilized VMs             High     18200
Use reserved instances to save on VMs            Medium   12000
Delete unused managed disks                      Medium   3600

# 予算の詳細と現在の使用状況を確認
$ az consumption budget show \
  --budget-name "budget-learning-monthly" \
  --resource-group rg-linux-practice \
  --query "{Amount:amount, CurrentSpend:currentSpend.amount, Notifications:notifications}" \
  -o json
{
  "Amount": 5000.0,
  "CurrentSpend": 4190.55,
  "Notifications": {
    "Actual_GreaterThan_80_Percent": {
      "contactEmails": ["tomohiro@example.com"],
      "enabled": true,
      "operator": "GreaterThan",
      "threshold": 80.0
    }
  }
}