`az monitor metrics list` returns null for future times

[ElvenSpellmaker]

Hi there,

~~~I've noticed that the command used to extract this data seems to return null for any recent time (randomly, it was working early yesterday evening until a certain point, but then has stopped again).~~~

~~~Commands such as:~~~
```bash
az monitor metrics list --resource /subscriptions/<id>/resourceGroups/POC-JACK-BS-METRICS/providers/Microsoft.Compute/virtualMachines/poc-jack-bs-metrics --metric 'CPU Credits Consumed,CPU Credits Remaining' --interval PT1M --start-time 2018-04-23T21:01:02Z --end-time 2018-04-23T21:02:02Z
```
~~~work absolutely fine (but didn't last night when the time was recent), whereas:~~~
```bash
az monitor metrics list --resource /subscriptions/<id>/resourceGroups/POC-JACK-BS-METRICS/providers/Microsoft.Compute/virtualMachines/poc-jack-bs-metrics --metric 'CPU Credits Consumed,CPU Credits Remaining' --interval PT1M --start-time 2018-04-24T07:14:02Z --end-time 2018-04-24T07:15:02Z
```
~~~doesn't work and returns:~~~
```json
{
  "additionalProperties": {},
  "cost": 0.0,
  "interval": "0:01:00",
  "namespace": "Microsoft.Compute/virtualMachines",
  "resourceregion": "westeurope",
  "timespan": "2018-04-24T07:14:02Z/2018-04-24T07:15:02Z",
  "value": [
    {
      "additionalProperties": {},
      "id": "/subscriptions/<id>/resourceGroups/POC-JACK-BS-METRICS/providers/Microsoft.Compute/virtualMachines/poc-jack-bs-metrics/providers/Microsoft.Insights/metrics/CPU Credits Consumed",
      "name": {
        "additionalProperties": {},
        "localizedValue": "CPU Credits Consumed",
        "value": "CPU Credits Consumed"
      },
      "resourceGroup": "POC-JACK-BS-METRICS",
      "timeseries": [
        {
          "additionalProperties": {},
          "data": [
            {
              "additionalProperties": {},
              "average": null,
              "count": null,
              "maximum": null,
              "minimum": null,
              "timeStamp": "2018-04-24T07:14:00+00:00",
              "total": null
            }
          ],
          "metadatavalues": []
        }
      ],
      "type": "Microsoft.Insights/metrics",
      "unit": "Count"
    },
    {
      "additionalProperties": {},
      "id": "/subscriptions/<id>/resourceGroups/POC-JACK-BS-METRICS/providers/Microsoft.Compute/virtualMachines/poc-jack-bs-metrics/providers/Microsoft.Insights/metrics/CPU Credits Remaining",
      "name": {
        "additionalProperties": {},
        "localizedValue": "CPU Credits Remaining",
        "value": "CPU Credits Remaining"
      },
      "resourceGroup": "POC-JACK-BS-METRICS",
      "timeseries": [
        {
          "additionalProperties": {},
          "data": [
            {
              "additionalProperties": {},
              "average": null,
              "count": null,
              "maximum": null,
              "minimum": null,
              "timeStamp": "2018-04-24T07:14:00+00:00",
              "total": null
            }
          ],
          "metadatavalues": []
        }
      ],
      "type": "Microsoft.Insights/metrics",
      "unit": "Count"
    }
  ]
}
```

If I run a similar query for the whole last day, I get a point of crossover:
```json
            {
              "additionalProperties": {},
              "average": 636.0,
              "count": null,
              "maximum": null,
              "minimum": null,
              "timeStamp": "2018-04-24T06:47:00+00:00",
              "total": null
            },
            {
              "additionalProperties": {},
              "average": null,
              "count": null,
              "maximum": null,
              "minimum": null,
              "timeStamp": "2018-04-24T06:48:00+00:00",
              "total": null
            },
```

~~~The portal seems to have all this information:~~~
![image](https://user-images.githubusercontent.com/2286713/39170611-17e85e22-4794-11e8-846b-de029c54f72d.png)

~~~I'm puzzled as to what the problem is here and any help would be great thanks.~~~ 🤔

[ElvenSpellmaker]

What I'm most puzzled about is that if I use date then it seems to work:
Running a command like:

az monitor metrics list --resource /subscriptions/<id>/resourceGroups/POC-JACK-BS-METRICS/providers/Microsoft.Compute/virtualMachines/poc-jack-bs-metrics --metric 'CPU Credits Consumed,CPU Credits Remaining' --interval PT1M --start-time $(date -u +"%Y-%m-%dT%H:%M:%SZ" --date='2 minutes ago') --end-time $(date -u +"%Y-%m-%dT%H:%M:%SZ" --date='1 minute ago')

seems to work. 🤔

[ElvenSpellmaker]

Just worked it out, it's timezone related, the Ruby script I'm using isn't taking the timezone into account, date in bash does and so I'm querying times an hour into the future.

To be honest the output from this command should probably error if times in the future are queried?

[tjprescott]

It is arguable whether this should fail if a future time is given. We will help the user diagnose issues by showing the OData filter supplied when the user supplied --verbose.

[ElvenSpellmaker]

Out of interest, what's the argument for it not returning an error for a future time?

It seems pretty logical to me to throw an error to the user if they're querying metrics for something that hasn't happened yet (as opposed to a time that's happened but has no metrics).