* Set error message for certain template variable combinations
- Make use of setError method from query editor
- Update Azure Monitor error type
- Add test for case 2 from https://github.com/grafana/grafana/pull/51331
* Update template variable docs
* Fix lint issues
* Update docs/sources/datasources/azuremonitor/template-variables.md
Co-authored-by: Garrett Guillotte <100453168+gguillotte-grafana@users.noreply.github.com>
* PR comment updates
Co-authored-by: Garrett Guillotte <100453168+gguillotte-grafana@users.noreply.github.com>
| summarize avg(CounterValue) by bin(TimeGenerated, $__interval), Computer
| order by TimeGenerated asc
```
## Limitations
As of Grafana 9.0, a resource URI is constructed to identify resources using the resource picker. On dashboards created prior to Grafana 9.0, Grafana automatically migrates any queries using the prior resource-picking mechanism to use this method.
Some resource types use nested namespaces and resource names, such as `Microsoft.Storage/storageAccounts/tableServices` and `storageAccount/default`, or `Microsoft.Sql/servers/databases` and `serverName/databaseName`. Such template variables cannot be used because the result could be a malformed resource URI.
### Supported cases
#### Standard namespaces and resource names
```kusto
metricDefinition = $ns
$ns = Microsoft.Compute/virtualMachines
resourceName = $rs
$rs = testvirtualmachine
```
#### Namespaces with a non-templated sub-namespace
```kusto
metricDefinition = $ns/tableServices
$ns = Microsoft.Storage/storageAccounts
resourceName = $rs/default
$rs = storageaccount
```
#### Storage namespaces missing the `default` keyword
```kusto
metricDefinition = $ns/tableServices
$ns = Microsoft.Storage/storageAccounts
resourceName = $rs
$rs = storageaccount
```
#### Namespaces with a templated sub-namespace
```kusto
metricDefinition = $ns/$sns
$ns = Microsoft.Storage/storageAccounts
$sns = tableServices
resourceName = $rs
$rs = storageaccount
```
### Unsupported case
If a dashboard uses this unsupported case, migrate it to one of the [supported cases](#supported-cases).
If a namespace or resource name template variable contains multiple segments, Grafana will construct the resource URI incorrectly because the template variable cannot be appropriately split.
This would result in an incorrect resource URI containing `Microsoft.Storage/storageAccounts/tableServices/storageaccount/default`. However, the correct URI would have the format `Microsoft.Storage/storageAccounts/storageaccount/tableServices/default`.
An appropriate fix would be to update the template variable that does not match a supported case. If the namespace variable `$ns` is of the form `Microsoft.Storage/storageAccounts/tableServices` this could be split into two variables: `$ns1 = Microsoft.Storage/storageAccounts` and `$ns2 = tableServices`. The metric definition would then take the form `$ns1/$ns2` which leads to a correctly formatted URI.