SqlAGDatabase Fix for issue #1492 (#1642)

- SqlAGDatabase - Added AutomaticSeeding for this resource. In Set-TargetResource added logic that looks at all replicas of an availability group. When automatic seeding is found, it will use that (issue #1492). - Lots of extra tests to check AutomaticSeeding. - The parameter `BackupPath` is still needed just in case a database never has been backuped
dsccommunity · Dec 13, 2020 · 0731bc9 · 0731bc9
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- SqlAGDatabase
+  - Fix for issue ([issue #1492](https://github.com/dsccommunity/SqlServerDsc/issues/1492))
+    added AutomaticSeeding for this resource. In Set-TargetResource added logic that looks 
+    at all replicas of an availability group. When automatic seedig is found, it will use that.
+  - Lots of extra tests to check AutomaticSeeding.
+  - The parameter `BackupPath` is still needed just in case a database never has been backuped before.
 - SqlMaxDop
   - Fixes ([issue #396](https://github.com/dsccommunity/SqlServerDsc/issues/396)).
     Added three return values in Get-Target resource.

diff --git a/source/DSCResources/DSC_SqlAGDatabase/DSC_SqlAGDatabase.psm1 b/source/DSCResources/DSC_SqlAGDatabase/DSC_SqlAGDatabase.psm1
@@ -234,7 +234,7 @@ function Set-TargetResource
     # Create a hash table to store the databases that failed to be added to the Availability Group
     $databasesToAddFailures = @{}
 
-    # Create a hash table to store the databases that failed to be added to the Availability Group
+    # Create a hash table to store the databases that failed to be removed from the Availability Group
     $databasesToRemoveFailures = @{}
 
     if ( $databasesToAddToAvailabilityGroup.Count -gt 0 )
@@ -422,57 +422,89 @@ function Set-TargetResource
                 }
             }
 
-            if ( $prerequisiteCheckFailures.Count -eq 0 )
-            {
-                $databaseFullBackupFile = Join-Path -Path $BackupPath -ChildPath "$($databaseObject.Name)_Full_$(Get-Date -Format 'yyyyMMddhhmmss').bak"
-                $databaseLogBackupFile = Join-Path -Path $BackupPath -ChildPath "$($databaseObject.Name)_Log_$(Get-Date -Format 'yyyyMMddhhmmss').trn"
-
-                # Build the backup parameters. If no backup was previously taken, a standard full will be taken. Otherwise a CopyOnly backup will be taken.
-                $backupSqlDatabaseParameters = @{
-                    DatabaseObject = $databaseObject
-                    BackupAction   = 'Database'
-                    BackupFile     = $databaseFullBackupFile
-                    ErrorAction    = 'Stop'
-                }
+            <#
+                Determine whether SEEDING_MODE = for all replicas is Automatic or Manual. If all replicas are Automatic, a restore is not needed.
+                When the database is fresh, and never backuped before, a backup is still needed.
+            #>
+            $backupNeeded = $false
+            $restoreNeeded = $false
 
-                # If database object last backup data not equal to 0 then backup with CopyOnly.
-                if ( $databaseObject.LastBackupDate -ne 0 )
+            foreach ( $availabilityGroupReplica in $secondaryReplicas )
+            {
+                if ( $availabilityGroupReplica.SeedingMode -eq 'Manual')
                 {
-                    $backupSqlDatabaseParameters.Add('CopyOnly', $true)
+                    $backupNeeded = $true
+                    $restoreNeeded = $true
                 }
+            }
 
-                try
+            if ( $backupNeeded -eq $false)
+            {
+                <#
+                    Because an availability group can only be made when the database has at least one backup,
+                    if there is no backup, create one. This backup is not needed for restore, only the initial setup
+                    of the LSN in the database is needed
+                #>
+                if ( $primaryServerObject.Databases[$databaseToAddToAvailabilityGroup].CreateDate -gt $primaryServerObject.Databases[$databaseToAddToAvailabilityGroup].LastBackupDate)
                 {
-                    Backup-SqlDatabase @backupSqlDatabaseParameters
+                    $needsBackup = $true
                 }
-                catch
+            }
+
+            if ( $prerequisiteCheckFailures.Count -eq 0 )
+            {
+                if ( $backupNeeded)
                 {
-                    # Log the failure
-                    $databasesToAddFailures.Add($databaseToAddToAvailabilityGroup, $_.Exception)
+                    $databaseFullBackupFile = Join-Path -Path $BackupPath -ChildPath "$($databaseObject.Name)_Full_$(Get-Date -Format 'yyyyMMddhhmmss').bak"
+                    $databaseLogBackupFile = Join-Path -Path $BackupPath -ChildPath "$($databaseObject.Name)_Log_$(Get-Date -Format 'yyyyMMddhhmmss').trn"
+
+                    # Build the backup parameters. If no backup was previously taken, a standard full will be taken. Otherwise a CopyOnly backup will be taken.
+                    $backupSqlDatabaseParameters = @{
+                        DatabaseObject = $databaseObject
+                        BackupAction   = 'Database'
+                        BackupFile     = $databaseFullBackupFile
+                        ErrorAction    = 'Stop'
+                    }
 
-                    # Move on to the next database
-                    continue
-                }
+                    # If database object last backup data not equal to 0 then backup with CopyOnly.
+                    if ( $databaseObject.LastBackupDate -ne 0 )
+                    {
+                        $backupSqlDatabaseParameters.Add('CopyOnly', $true)
+                    }
 
-                # Create the parameters to perform a transaction log backup
-                $backupSqlDatabaseLogParams = @{
-                    DatabaseObject = $databaseObject
-                    BackupAction   = 'Log'
-                    BackupFile     = $databaseLogBackupFile
-                    ErrorAction    = 'Stop'
-                }
+                    try
+                    {
+                        Backup-SqlDatabase @backupSqlDatabaseParameters
+                    }
+                    catch
+                    {
+                        # Log the failure
+                        $databasesToAddFailures.Add($databaseToAddToAvailabilityGroup, $_.Exception)
 
-                try
-                {
-                    Backup-SqlDatabase @backupSqlDatabaseLogParams
-                }
-                catch
-                {
-                    # Log the failure
-                    $databasesToAddFailures.Add($databaseToAddToAvailabilityGroup, $_.Exception)
+                        # Move on to the next database
+                        continue
+                    }
 
-                    # Move on to the next database
-                    continue
+                    # Create the parameters to perform a transaction log backup
+                    $backupSqlDatabaseLogParams = @{
+                        DatabaseObject = $databaseObject
+                        BackupAction   = 'Log'
+                        BackupFile     = $databaseLogBackupFile
+                        ErrorAction    = 'Stop'
+                    }
+
+                    try
+                    {
+                        Backup-SqlDatabase @backupSqlDatabaseLogParams
+                    }
+                    catch
+                    {
+                        # Log the failure
+                        $databasesToAddFailures.Add($databaseToAddToAvailabilityGroup, $_.Exception)
+
+                        # Move on to the next database
+                        continue
+                    }
                 }
 
                 # Add the database to the availability group on the primary instance
@@ -489,62 +521,65 @@ function Set-TargetResource
                     continue
                 }
 
-                # Need to restore the database with a query in order to impersonate the correct login
-                $restoreDatabaseQueryStringBuilder = New-Object -TypeName System.Text.StringBuilder
-
-                if ( $MatchDatabaseOwner )
+                if ( $restoreNeeded)
                 {
-                    $restoreDatabaseQueryStringBuilder.Append('EXECUTE AS LOGIN = ''') | Out-Null
-                    $restoreDatabaseQueryStringBuilder.Append($databaseObject.Owner) | Out-Null
+                    # Need to restore the database with a query in order to impersonate the correct login
+                    $restoreDatabaseQueryStringBuilder = New-Object -TypeName System.Text.StringBuilder
+
+                    if ( $MatchDatabaseOwner )
+                    {
+                        $restoreDatabaseQueryStringBuilder.Append('EXECUTE AS LOGIN = ''') | Out-Null
+                        $restoreDatabaseQueryStringBuilder.Append($databaseObject.Owner) | Out-Null
+                        $restoreDatabaseQueryStringBuilder.AppendLine('''') | Out-Null
+                    }
+
+                    $restoreDatabaseQueryStringBuilder.Append('RESTORE DATABASE [') | Out-Null
+                    $restoreDatabaseQueryStringBuilder.Append($databaseToAddToAvailabilityGroup) | Out-Null
+                    $restoreDatabaseQueryStringBuilder.AppendLine(']') | Out-Null
+                    $restoreDatabaseQueryStringBuilder.Append('FROM DISK = ''') | Out-Null
+                    $restoreDatabaseQueryStringBuilder.Append($databaseFullBackupFile) | Out-Null
                     $restoreDatabaseQueryStringBuilder.AppendLine('''') | Out-Null
-                }
+                    $restoreDatabaseQueryStringBuilder.Append('WITH NORECOVERY') | Out-Null
 
-                $restoreDatabaseQueryStringBuilder.Append('RESTORE DATABASE [') | Out-Null
-                $restoreDatabaseQueryStringBuilder.Append($databaseToAddToAvailabilityGroup) | Out-Null
-                $restoreDatabaseQueryStringBuilder.AppendLine(']') | Out-Null
-                $restoreDatabaseQueryStringBuilder.Append('FROM DISK = ''') | Out-Null
-                $restoreDatabaseQueryStringBuilder.Append($databaseFullBackupFile) | Out-Null
-                $restoreDatabaseQueryStringBuilder.AppendLine('''') | Out-Null
-                $restoreDatabaseQueryStringBuilder.Append('WITH NORECOVERY') | Out-Null
+                    if ( $ReplaceExisting )
+                    {
+                        $restoreDatabaseQueryStringBuilder.Append(',REPLACE') | Out-Null
+                    }
 
-                if ( $ReplaceExisting )
-                {
-                    $restoreDatabaseQueryStringBuilder.Append(',REPLACE') | Out-Null
-                }
+                    if ( $MatchDatabaseOwner )
+                    {
+                        $restoreDatabaseQueryStringBuilder.AppendLine() | Out-Null
+                        $restoreDatabaseQueryStringBuilder.Append('REVERT') | Out-Null
+                    }
+                    $restoreDatabaseQueryString = $restoreDatabaseQueryStringBuilder.ToString()
 
-                if ( $MatchDatabaseOwner )
-                {
-                    $restoreDatabaseQueryStringBuilder.AppendLine() | Out-Null
-                    $restoreDatabaseQueryStringBuilder.Append('REVERT') | Out-Null
-                }
-                $restoreDatabaseQueryString = $restoreDatabaseQueryStringBuilder.ToString()
+                    # Need to restore the database with a query in order to impersonate the correct login
+                    $restoreLogQueryStringBuilder = New-Object -TypeName System.Text.StringBuilder
 
-                # Need to restore the database with a query in order to impersonate the correct login
-                $restoreLogQueryStringBuilder = New-Object -TypeName System.Text.StringBuilder
+                    if ( $MatchDatabaseOwner )
+                    {
+                        $restoreLogQueryStringBuilder.Append('EXECUTE AS LOGIN = ''') | Out-Null
+                        $restoreLogQueryStringBuilder.Append($databaseObject.Owner) | Out-Null
+                        $restoreLogQueryStringBuilder.AppendLine('''') | Out-Null
+                    }
 
-                if ( $MatchDatabaseOwner )
-                {
-                    $restoreLogQueryStringBuilder.Append('EXECUTE AS LOGIN = ''') | Out-Null
-                    $restoreLogQueryStringBuilder.Append($databaseObject.Owner) | Out-Null
+                    $restoreLogQueryStringBuilder.Append('RESTORE DATABASE [') | Out-Null
+                    $restoreLogQueryStringBuilder.Append($databaseToAddToAvailabilityGroup) | Out-Null
+                    $restoreLogQueryStringBuilder.AppendLine(']') | Out-Null
+                    $restoreLogQueryStringBuilder.Append('FROM DISK = ''') | Out-Null
+                    $restoreLogQueryStringBuilder.Append($databaseLogBackupFile) | Out-Null
                     $restoreLogQueryStringBuilder.AppendLine('''') | Out-Null
-                }
+                    $restoreLogQueryStringBuilder.Append('WITH NORECOVERY') | Out-Null
 
-                $restoreLogQueryStringBuilder.Append('RESTORE DATABASE [') | Out-Null
-                $restoreLogQueryStringBuilder.Append($databaseToAddToAvailabilityGroup) | Out-Null
-                $restoreLogQueryStringBuilder.AppendLine(']') | Out-Null
-                $restoreLogQueryStringBuilder.Append('FROM DISK = ''') | Out-Null
-                $restoreLogQueryStringBuilder.Append($databaseLogBackupFile) | Out-Null
-                $restoreLogQueryStringBuilder.AppendLine('''') | Out-Null
-                $restoreLogQueryStringBuilder.Append('WITH NORECOVERY') | Out-Null
+                    if ( $MatchDatabaseOwner )
+                    {
+                        $restoreLogQueryStringBuilder.AppendLine() | Out-Null
+                        $restoreLogQueryStringBuilder.Append('REVERT') | Out-Null
+                    }
 
-                if ( $MatchDatabaseOwner )
-                {
-                    $restoreLogQueryStringBuilder.AppendLine() | Out-Null
-                    $restoreLogQueryStringBuilder.Append('REVERT') | Out-Null
+                    $restoreLogQueryString = $restoreLogQueryStringBuilder.ToString()
                 }
 
-                $restoreLogQueryString = $restoreLogQueryStringBuilder.ToString()
-
                 try
                 {
                     foreach ( $availabilityGroupReplica in $secondaryReplicas )
@@ -554,9 +589,12 @@ function Set-TargetResource
                         $currentAvailabilityGroupReplicaServerObject = Connect-SQL @connectSqlParameters
                         $currentReplicaAvailabilityGroupObject = $currentAvailabilityGroupReplicaServerObject.AvailabilityGroups[$AvailabilityGroupName]
 
-                        # Restore the database
-                        Invoke-Query -ServerName $currentAvailabilityGroupReplicaServerObject.NetName -InstanceName $currentAvailabilityGroupReplicaServerObject.ServiceName -Database master -Query $restoreDatabaseQueryString -StatementTimeout 0
-                        Invoke-Query -ServerName $currentAvailabilityGroupReplicaServerObject.NetName -InstanceName $currentAvailabilityGroupReplicaServerObject.ServiceName -Database master -Query $restoreLogQueryString -StatementTimeout 0
+                        if ( $availabilityGroupReplica.SeedingMode -eq 'MANUAL')
+                        {
+                            # Restore the database
+                            Invoke-Query -ServerName $currentAvailabilityGroupReplicaServerObject.NetName -InstanceName $currentAvailabilityGroupReplicaServerObject.ServiceName -Database master -Query $restoreDatabaseQueryString -StatementTimeout 0
+                            Invoke-Query -ServerName $currentAvailabilityGroupReplicaServerObject.NetName -InstanceName $currentAvailabilityGroupReplicaServerObject.ServiceName -Database master -Query $restoreLogQueryString -StatementTimeout 0
+                        }
 
                         # Add the database to the Availability Group
                         Add-SqlAvailabilityDatabase -InputObject $currentReplicaAvailabilityGroupObject -Database $databaseToAddToAvailabilityGroup
@@ -572,8 +610,12 @@ function Set-TargetResource
                 }
                 finally
                 {
-                    # Clean up the backup files
-                    Remove-Item -Path $databaseFullBackupFile, $databaseLogBackupFile -Force -ErrorAction Continue
+                    # When a backup was made, it should be removed.
+                    if ( $backupNeeded)
+                    {
+                        # Clean up the backup files
+                        Remove-Item -Path $databaseFullBackupFile, $databaseLogBackupFile -Force -ErrorAction Continue
+                    }
                 }
             }
             else

diff --git a/source/DSCResources/DSC_SqlAGDatabase/README.md b/source/DSCResources/DSC_SqlAGDatabase/README.md
@@ -2,6 +2,8 @@
 
 The `SqlAGDatabase` DSC resource is used to add databases or remove
 databases from a specified availability group.
+When a replica has Automatic seeding on Automatic, no restore is use for that replica.
+When all replicas are on automatic seeding, no backup is made, unless the database has never been backuped.
 
 ## Requirements