Bug: Use of log.Fatalf in resourcemanager packages

[frodopwns]

Describe the bug
Some clients for azure resources are exiting due to log.Fatalf calls which runs os.Exit(1). This causes the service to exit and leads to unreachable code.

eg.
https://github.com/Azure/azure-service-operator/blob/master/pkg/resourcemanager/storages/storage.go#L73

To Reproduce
manually create a storage account, then create that same account using the operator
operator will exit with

2019/10/30 17:15:29 storage account not available: AlreadyExists
exit status 1
make: *** [run] Error 1

Expected behavior
Method returns error where it can be logged and the operator can decide to re-queue if necessary

Additional context
This happens in other files and all should probably be removed

10404 ± grep -r "log.Fatal" ./pkg/resourcemanager -l
./pkg/resourcemanager/storages/storage.go
./pkg/resourcemanager/resources/groups.go
./pkg/resourcemanager/resources/resources_test.go
./pkg/resourcemanager/resources/hybrid/groups.go
./pkg/resourcemanager/resourcegroups/resourcegroup.go
./pkg/resourcemanager/keyvaults/keyvault.go
./pkg/resourcemanager/rediscaches/rediscaches.go
./pkg/resourcemanager/cosmosdbs/cosmosdbs.go

[WilliamMortlMicrosoft]

leaving the log.fatal statements in test files... makes sense there

[frodopwns]

replace fatalfs in packages with errors that get returned instead

[buhongw7583c]

@frodopwns, cc @jananivMS , any thought to reproduce the issue on cosmosDB and appInsights?
I tried to create a cosmosDB manually then use the service operator to create another one with same name, no problem. Also tried to use wrong location name, modify the service principal to 'reader' permission, etc and couldn't run into the code 'log.Fatalf("failed to initialize authorizer: %v\n", err)'.

Any thought?

func getCosmosDBClient() documentdb.DatabaseAccountsClient {
cosmosDBClient := documentdb.NewDatabaseAccountsClientWithBaseURI(config.BaseURI(), config.SubscriptionID())
a, err := iam.GetResourceManagementAuthorizer()
if err != nil {
log.Fatalf("failed to initialize authorizer: %v\n", err)
}
cosmosDBClient.Authorizer = a
cosmosDBClient.AddToUserAgent(config.UserAgent())
return cosmosDBClient
}

[jananivMS]

@buhongw7583c I dont think we will be able to repro some of these errors to happen like in this case, we only fail here if getting an authorizer fails. You could follow the same pattern as we use for other clients.