How to fetch size details from storage account in Azure?

I am trying to fetch the size details or Used Capacity using Azure Monitoring API but it's returning me blank json.

import requests
from datetime import datetime, timedelta
from azure.identity import ClientSecretCredential

#start_time = (datetime.utcnow() - timedelta(hours=1)).replace(microsecond=0).isoformat() + "Z"
#end_time = datetime.utcnow().replace(microsecond=0).isoformat() + "Z"

start_time = (datetime.utcnow() - timedelta(hours=23)).replace(microsecond=0).isoformat() + "Z"
end_time = (datetime.utcnow() - timedelta(hours=22)).replace(microsecond=0).isoformat() + "Z"



#print("Start_Time:",start_time)
#print("End_Time:",end_time)

subscription_id = ""
resource_group = ""
storage_account_name = ""
metric_name = "UsedCapacity" 
time_range = f"{start_time}/{end_time}"  
api_version = "2021-05-01"

tenant_id = dbutils.secrets.get(scope="scope",key="tenant-id")
client_id = dbutils.secrets.get(scope="scope", key="clientid")
client_secret = dbutils.secrets.get(scope="sn_scope", key="secret")

token_endpoint = f"https://login.microsoftonline.com/{tenant_id}/oauth2/token" 

data = {
  "grant_type": "client_credentials",
  "client_id": f"{client_id}",  
  "client_secret": f"{client_secret}",  
  "resource": "https://management.azure.com/"
}

response = requests.post(token_endpoint, data=data)

if response.status_code == 200:
  post_response = response.text
  print("POST_Response:",post_response)
  access_token = response.json()["access_token"]
  #print("Access Token:", access_token)
else:
  print("Error generating access token:", response.status_code)


headers = {
  "Authorization": f"Bearer {access_token}",
  "Content-Type" : "application/json"
}


api_url = f"https://management.azure.com/subscriptions/{subscription_id}/resourceGroups/{resource_group}/providers/Microsoft.Storage/storageAccounts/{storage_account_name}/providers/microsoft.insights/metrics?timespan={time_range}&metricnames={metric_name}&api-version={api_version}"


print("API:",api_url)

response = requests.get(api_url,headers=headers)

if response.status_code == 200:
  data = response.text
  print("GET_Response:",data)
else:
  print("Error retrieving metrics data:", response.status_code)
  print("Error Message:",response.text)

Response I am getting from this API is 200 but the json file only returns { "value" :[] }
Is there any other API to fetch the size of storage account?

> How to fetch size details from storage account in Azure using Python.

I tried in my environment and got the below results:

Initially, I created App to get the Client-id,tenant-id and Client-secret.

Assigned contributor role to the appvenkat under subscription level.

I tried with the same code with minimal modification and I can able to fetch the used capacity of the storage account using Python.

Code:

    import requests
    from datetime import datetime, timedelta
    
    start_time = (datetime.utcnow() - timedelta(hours=23)).replace(microsecond=0).isoformat() + "Z"
    end_time = (datetime.utcnow() - timedelta(hours=22)).replace(microsecond=0).isoformat() + "Z"
    
    
    subscription_id = "your subscription id"
    resource_group = "your resourcegroup name"
    storage_account_name = "your storage account name"
    metric_name = "UsedCapacity" 
    time_range = f"{start_time}/{end_time}"  
    api_version = "2021-05-01"
    
    tenant_id = "your tenant id"
    client_id = "your client id"
    client_secret = "your client secret
    
    token_endpoint = f"https://login.microsoftonline.com/{tenant_id}/oauth2/token" 
    
    data = {
      "grant_type": "client_credentials",
      "client_id": f"{client_id}",  
      "client_secret": f"{client_secret}",  
      "resource": "https://management.azure.com/"
    }
    
    response = requests.post(token_endpoint, data=data)
    
    if response.status_code == 200:
      post_response = response.text
      #print("POST_Response:",post_response)
      access_token = response.json()["access_token"]
    #   print("Access Token:", access_token)
    else:
      print("Error generating access token:", response.status_code)
    
    
    headers = {
      "Authorization": f"Bearer {access_token}",
      "Content-Type" : "application/json"
    }
    
    
    api_url = f"https://management.azure.com/subscriptions/{subscription_id}/resourceGroups/{resource_group}/providers/Microsoft.Storage/storageAccounts/{storage_account_name}/providers/microsoft.insights/metrics?timespan={time_range}&metricnames={metric_name}&api-version={api_version}"
    
    
    print("API:",api_url)
    
    response = requests.get(api_url,headers=headers)
    print(response)
    print (response.headers)
    print(response.text)

Output:

API: https://management.azure.com/subscriptions/xxxxx/resourceGroups/xxx/providers/Microsoft.Storage/storageAccounts/venkat123/providers/microsoft.insights/metrics?timespan=2023-06-15T08:11:21Z/2023-06-15T09:11:21Z&metricnames=UsedCapacity&api-version=2021-05-01
<Response [200]>
{'Cache-Control': 'no-cache', 'Pragma': 'no-cache', 'Transfer-Encoding': 'chunked', 'Content-Type': 'application/json; charset=utf-8', 'Content-Encoding': 'gzip', 'Expires': '-1', 'Vary': 'Accept-Encoding', 'x-ms-correlation-request-id': 'ad9c6052-xxx2', 'x-ms-ratelimit-remaining-subscription-reads': '11974', 'Request-Context': 'appId=cid-v1:b0xxxx', 'x-ms-request-id': '{ad9c6xxxxx2}', 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains', 'Access-Control-Allow-Origin': '*', 'x-ms-routing-request-id': 'xxxxZ:ad9c605xxxxx2', 'X-Content-Type-Options': 'nosniff', 'Date': 'Fri, 16 Jun 2023 07:11:22 GMT'}
Used capacity of Storage account:
{"cost":59,"timespan":"2023-06-15T08:11:21Z/2023-06-15T09:11:21Z","interval":"PT1H","value":[{"id":"/subscriptions/xxxxx/resourceGroups/xxx/providers/Microsoft.Storage/storageAccounts/venkat123/providers/Microsoft.Insights/metrics/UsedCapacity","type":"Microsoft.Insights/metrics","name":{"value":"UsedCapacity","localizedValue":"Used capacity"},"displayDescription":"The amount of storage used by the storage account. For standard storage accounts, it's the sum of capacity used by blob, table, file, and queue. For premium storage accounts and Blob storage accounts, it is the same as BlobCapacity or FileCapacity.","unit":"Bytes","timeseries":[{"metadatavalues":[],"data":[{"timeStamp":"2023-06-15T08:11:00Z","average":2160775175}]}],"errorCode":"Success"}],"namespace":"Microsoft.Storage/storageAccounts","resourceregion":"eastus"}