public virtual void failover()
{
try
{
// Modify the autoscaling group to remove the AZ affected which is the AZ passed in the input
// Find the autoscaling group that this is deployed into
// Note: This changes the asynchronous call to a synchronous one
DescribeAutoScalingGroupsResponse autoScalingGroupsResponse = AUTO_SCALING_CLIENT.DescribeAutoScalingGroupsAsync().GetAwaiter().GetResult();
if (autoScalingGroupsResponse != null && autoScalingGroupsResponse.AutoScalingGroups.Count > 0)
{
// Note: This assumes an Auto Scaling group exists; no error checking for readability
AutoScalingGroup autoScalingGroup = autoScalingGroupsResponse.AutoScalingGroups[0];
string autoScalingGroupName = autoScalingGroup.AutoScalingGroupName;
// Find all subnets in the availability zone passed in the input
DescribeSubnetsResponse subnetsResult
= EC2_CLIENT.DescribeSubnetsAsync(new DescribeSubnetsRequest()
{
Filters = new List <Amazon.EC2.Model.Filter> {
new Amazon.EC2.Model.Filter {
Name = "vpc-id",
Values = new List <string> {
vpcId
}
}
}
}).GetAwaiter().GetResult();
IList <string> desiredSubnetsForASG = new List <string>();
foreach (Amazon.EC2.Model.Subnet subnet in subnetsResult.Subnets)
{
if (!string.Equals(subnet.AvailabilityZone, azId, StringComparison.OrdinalIgnoreCase))
{
desiredSubnetsForASG.Add(subnet.SubnetId);
}
}
List <string> desiredSubnets = new List <String>(autoScalingGroup.VPCZoneIdentifier.Split(new[] { ',' }, StringSplitOptions.None));
var tempList = new List <String>(desiredSubnets);
foreach (var subnet in desiredSubnets)
{
if (!desiredSubnetsForASG.Contains(subnet))
{
tempList.Remove(subnet);
}
}
desiredSubnets = tempList;
Console.WriteLine("Updating the auto scaling group " + autoScalingGroupName + " to remove the subnet in the AZ");
// Note: This turns the asynchronous call into a synchronous one
UpdateAutoScalingGroupResponse updateAutoScalingGroupResponse
= AUTO_SCALING_CLIENT.UpdateAutoScalingGroupAsync(new UpdateAutoScalingGroupRequest
{
AutoScalingGroupName = autoScalingGroupName,
VPCZoneIdentifier = string.Join(",", desiredSubnets)
}).GetAwaiter().GetResult();
}
// Find all subnets in the availability zone passed in the input
// Note: This turns the asynchronous call into a synchronous one
DescribeSubnetsResponse describeSubnetsResult
= EC2_CLIENT.DescribeSubnetsAsync(new DescribeSubnetsRequest
{
Filters = new List <Amazon.EC2.Model.Filter> {
new Amazon.EC2.Model.Filter {
Name = "vpc-id",
Values = new List <string> {
vpcId
}
},
new Amazon.EC2.Model.Filter {
Name = "availabilityZone",
Values = new List <string> {
azId
}
}
}
}).GetAwaiter().GetResult();
IList <string> desiredSubnetsForAddingNewNacl = new List <string>();
foreach (Amazon.EC2.Model.Subnet subnet in describeSubnetsResult.Subnets)
{
desiredSubnetsForAddingNewNacl.Add(subnet.SubnetId);
}
//Find all the network acl associations matching the subnets identified above
// Note: This turns the asynchronous call into a synchronous one
DescribeNetworkAclsResponse describeNetworkAclsResult
= EC2_CLIENT.DescribeNetworkAclsAsync(new DescribeNetworkAclsRequest()
{
Filters = new List <Amazon.EC2.Model.Filter> {
new Amazon.EC2.Model.Filter {
Name = "association.subnet-id",
Values = (List <string>)desiredSubnetsForAddingNewNacl
}
}
}).GetAwaiter().GetResult();
IList <NetworkAclAssociation> desiredAclAssociations = new List <NetworkAclAssociation>();
// Note: This assumes a Network ACL is present for readability
IList <NetworkAclAssociation> networkAclsAssociatedWithSubnet = describeNetworkAclsResult.NetworkAcls[0].Associations;
foreach (string subnetId in desiredSubnetsForAddingNewNacl)
{
foreach (NetworkAclAssociation networkAcl in networkAclsAssociatedWithSubnet)
{
if (string.Equals(networkAcl.SubnetId, subnetId, StringComparison.OrdinalIgnoreCase))
{
desiredAclAssociations.Add(networkAcl);
}
}
}
//create new network acl association with both ingress and egress denying to all the traffic
CreateNetworkAclRequest createNetworkAclRequest = new CreateNetworkAclRequest();
createNetworkAclRequest.VpcId = vpcId;
// Note: This turns the asynchronous call into a synchronous one
CreateNetworkAclResponse createNetworkAclResponse = EC2_CLIENT.CreateNetworkAclAsync(createNetworkAclRequest).GetAwaiter().GetResult();
string networkAclId = createNetworkAclResponse.NetworkAcl.NetworkAclId;
createNetworkAclEntry(networkAclId, 100, "0.0.0.0/0", true, "-1", createPortRange(0, 65535), RuleAction.Deny);
createNetworkAclEntry(networkAclId, 101, "0.0.0.0/0", false, "-1", createPortRange(0, 65535), RuleAction.Deny);
// replace all the network acl associations identified for the above subnets with the new network
// acl association which will deny all traffic for those subnets in that AZ
Console.WriteLine("Creating new network ACL associations");
replaceNetworkAclAssociations(desiredAclAssociations, networkAclId);
//fail over rds which is in the same AZ
// Note: This turns the asynchronous call into a synchronous one
DescribeDBInstancesResponse describeDBInstancesResult = RDS_CLIENT.DescribeDBInstancesAsync().GetAwaiter().GetResult();
IList <DBInstance> dbInstances = describeDBInstancesResult.DBInstances;
string dbInstancedId = null;
foreach (DBInstance dbInstance in dbInstances)
{
if (string.Equals(dbInstance.DBSubnetGroup.VpcId, vpcId, StringComparison.OrdinalIgnoreCase) &&
(string.Equals(dbInstance.AvailabilityZone, azId, StringComparison.OrdinalIgnoreCase)) &&
dbInstance.MultiAZ && dbInstance.StatusInfos.Count == 0)
{
dbInstancedId = dbInstance.DBInstanceIdentifier;
}
}
// we want to fail over rds if rds is present in the same az where it is affected
if (!string.IsNullOrEmpty(dbInstancedId))
{
RebootDBInstanceRequest rebootDBInstanceRequest = new RebootDBInstanceRequest();
rebootDBInstanceRequest.DBInstanceIdentifier = dbInstancedId;
rebootDBInstanceRequest.ForceFailover = true;
Console.WriteLine("Rebooting dbInstanceId to secondary AZ " + dbInstancedId);
// Note: This turns the asynchronous call into a synchronous one
RDS_CLIENT.RebootDBInstanceAsync(rebootDBInstanceRequest).GetAwaiter().GetResult();
}
}
catch (Exception exception)
{
Console.WriteLine("Unkown exception occured " + exception.Message);
}
}