How to properly use the resources: [] element?

[matthiasguentert]

Currently I am referencing dependents via its name, which works just fine.

resource psql 'Microsoft.DBForPostgreSQL/servers@2017-12-01' = {
  // ... 
}

resource db 'Microsoft.DBForPostgreSQL/servers/databases@2017-12-01' = {
  name: '${psql.name}/mydb'
  dependsOn: [
    psql
  ]
  
  // ...
} 

However, when looking at the ARM reference/documentation, e.g. for Postgres server the template contains a property called resources of type array.

resource symbolicname 'Microsoft.DBforPostgreSQL/servers@2017-12-01' = {
  // ...
  resources: []
}

The documentation further says it can take values of e.g. securityAlertPolicies, configurations, databases, virtualNetworkRules and firewallRules . However all variations below produce:

The property "resources" is not allowed on objects of type "Microsoft.DBForPostgreSQL/servers". Permissible properties inclued "dependsOn", "identity", "tags". bicep(BCP0367)

Is this a bug? What am I doing wrong here? Thanks in advance!

Resource reference

resource psql 'Microsoft.DBForPostgreSQL/servers@2017-12-01' = {
  // ...
  
  resources: [ 
    db1
  ]
}

resource db1 'Microsoft.DBForPostgreSQL/servers/databases@2017-12-01' = {
  name: '${name}/mydatabase'
  properties: {
    charset: 'UTF8'
    collation: 'English_United States.1252'
  }
}

Empty array

resource psql 'Microsoft.DBForPostgreSQL/servers@2017-12-01' = {
  // ...
  
  resources: [   
  ]
}

ARM/JSON Style

resource psql 'Microsoft.DBForPostgreSQL/servers@2017-12-01' = {
  // ...
  
  resources: [
    {
      name: 'mydatabase'
      type: 'Microsoft.DBforPostgreSQL/servers/databases'
      apiVersion: '2017-12-01'
      properties: {
        charset: 'UTF8'
        collation: 'English_United States.1252'
      }
    }
  ]
}

[alex-frankel]

We have a slightly different syntax for expressing child resources, which is what the resources property is for in ARM JSON. Instead of using this property, you declare the resource just like a top level resource. In this case:

resource psql 'Microsoft.DBForPostgreSQL/servers@2017-12-01' = {
  // ...
  
  resources db 'databases' = {
      name: 'mydatabase'
      properties: {
        charset: 'UTF8'
        collation: 'English_United States.1252'
      }
    }
}

Notice we inherit the parent type and apiVersion. You can override the apiVersion if you need to (i.e. 'databases@2021-01-01')

More info here: https://github.com/Azure/bicep/blob/main/docs/spec/resources.md#resource-nesting