func (be *AwsVpcBackend) detectRouteTableID(instanceID string, ec2c *ec2.EC2) (string, error) {
instancesInput := &ec2.DescribeInstancesInput{
InstanceIds: []*string{&instanceID},
}
resp, err := ec2c.DescribeInstances(instancesInput)
if err != nil {
return "", fmt.Errorf("error getting instance info: %v", err)
}
if len(resp.Reservations) == 0 {
return "", fmt.Errorf("no reservations found")
}
if len(resp.Reservations[0].Instances) == 0 {
return "", fmt.Errorf("no matching instance found with id: %v", instanceID)
}
subnetID := resp.Reservations[0].Instances[0].SubnetId
vpcID := resp.Reservations[0].Instances[0].VpcId
log.Info("Subnet-ID: ", *subnetID)
log.Info("VPC-ID: ", *vpcID)
filter := newFilter()
filter.Add("association.subnet-id", *subnetID)
routeTablesInput := &ec2.DescribeRouteTablesInput{
Filters: filter,
}
res, err := ec2c.DescribeRouteTables(routeTablesInput)
if err != nil {
return "", fmt.Errorf("error describing routeTables for subnetID %s: %v", *subnetID, err)
}
if len(res.RouteTables) != 0 {
return *res.RouteTables[0].RouteTableId, nil
}
filter = newFilter()
filter.Add("association.main", "true")
filter.Add("vpc-id", *vpcID)
routeTablesInput = &ec2.DescribeRouteTablesInput{
Filters: filter,
}
res, err = ec2c.DescribeRouteTables(routeTablesInput)
if err != nil {
log.Info("error describing route tables: ", err)
}
if len(res.RouteTables) == 0 {
return "", fmt.Errorf("main route table not found")
}
return *res.RouteTables[0].RouteTableId, nil
}
