Virtual Private Cloud:Dhcp options sets and dns hostnames

Console

Go to the VPC console - DHCP Options Sets page and click Create DHCP Options Set. Configure the Domain Name and DNS Server IP parameters.

When you enable DNS hostnames for a VPC in a region for the first time, a default DHCP options set is automatically created and associated with the VPC. The default DHCP options set cannot be modified.

API

Call CreateDhcpOptionsSet to create a DHCP options set.

Terraform

# Specify the region of the VPC.
provider "alicloud" {
  region = "cn-hangzhou"
}

# Create a DHCP options set.
resource "alicloud_vpc_dhcp_options_set" "test_dhcp_options_set" {
  dhcp_options_set_name = "test_dhcp_options_set_name"
  domain_name           = "example.com"                 # Specify the domain name.
  domain_name_servers   = "100.100.2.136,100.100.2.138" # Specify the DNS server IP addresses.
}

Resources: alicloud_vpc_dhcp_options_set

Console

Manage the association between a VPC and a DHCP options set from two places:

• On the VPC details page, in the DHCP Options Set section: create, change, or remove the association.

• On the DHCP options set details page or in the Actions column: select Associate VPC.

After an association changes, new ECS instances automatically use the updated configuration. For existing ECS instances, restart the DHCP process to apply the change:

sudo dhclient -r eth0 && sudo dhclient eth0

If an association is removed, Alibaba Cloud configures the default DNS servers for the ECS instances through DHCP. To ensure the new configuration takes effect on existing instances without affecting your services, you can restart the instances or their network services.

If the VPC has the shared VPC feature enabled, the DHCP options set also applies to ECS instances within the shared VPC.

API

• AttachDhcpOptionsSetToVpc — attach a DHCP options set to a VPC

• DetachDhcpOptionsSetFromVpc — detach a DHCP options set from a VPC

• ReplaceVpcDhcpOptionsSet — change the DHCP options set associated with a VPC

Terraform

# Associate the DHCP options set with a VPC.
resource "alicloud_vpc_dhcp_options_set_attachment" "test_attachment_vpc" {
  vpc_id              = "vpc-8vbg******"                                       # Specify the ID of the VPC to associate.
  dhcp_options_set_id = alicloud_vpc_dhcp_options_set.test_dhcp_options_set.id # Specify the ID of the DHCP options set to associate.
}

Resources: alicloud_vpc_dhcp_options_set_attachment

Console

On the DHCP options set details page or in the Actions column, click Edit.

API

Call UpdateDhcpOptionsSetAttribute to modify the configuration.

Console

1. Go to Private Zone and click Add Zone. Configure a custom domain name and set the Effective Scope to the target VPC. On the zone details page, go to the ECS Hostname tab and click Add ECS Hostname. The system automatically adds DNS records for the hostnames and IP addresses of ECS instances in the selected region.

   DNS records are not automatically updated when a hostname changes. Enable Auto Sync to have the system add and synchronize DNS records every minute. To add a custom domain prefix, go to the DNS Records tab and add a Host Record.

2. Go to the VPC console - DHCP Options Sets page and click Create DHCP Options Set. Set Domain Name to the private zone domain name.

3. In the Actions column of the new DHCP options set, select Associate VPC. ECS instances with DNS records can then be reached by hostname or host record from other instances in the associated VPC.

API

1. Call AddZone to add a private zone.

2. Call the API to add a DNS record, or call UpdateSyncEcsHostTask to configure hostname synchronization.

3. Call CreateDhcpOptionsSet to create a DHCP options set.

4. Call AttachDhcpOptionsSetToVpc to associate the DHCP options set with the VPC.

Terraform

Automatic addition of ECS hostname records is not supported. Add custom DNS records one by one.

# Specify the region of the target VPC.
provider "alicloud" {
  region = "cn-hangzhou"
}

# Configure a private zone.
resource "alicloud_pvtz_zone" "test_pvtz_zone" {
  zone_name = "example.com"
}

# Set the scope of the domain name.
resource "alicloud_pvtz_zone_attachment" "test_pvtz_zone_attachment" {
  zone_id = alicloud_pvtz_zone.test_pvtz_zone.id
  vpc_ids = ["vpc-8vba******"] # Specify the ID of the VPC where the domain name takes effect.
}

# Add a DNS record.
resource "alicloud_pvtz_zone_record" "test_pvtz_zone_record" {
  zone_id = alicloud_pvtz_zone.test_pvtz_zone.id
  rr      = "abc"         # Specify the host record.
  type    = "A"           # Specify the DNS record type.
  value   = "192.168.0.4" # Specify the DNS record value.
}

# Create a DHCP options set.
resource "alicloud_vpc_dhcp_options_set" "test_dhcp_options_set" {
  dhcp_options_set_name = "test_dhcp_options_set_name"
  domain_name           = "example.com"                 # Specify the domain name.
  domain_name_servers   = "100.100.2.136,100.100.2.138" # Specify the Alibaba Cloud default DNS server IP addresses.
}

# Associate the DHCP options set with a VPC.
resource "alicloud_vpc_dhcp_options_set_attachment" "test_attachment_vpc" {
  vpc_id              = "vpc-8vba******"                                       # Specify the ID of the VPC to associate.
  dhcp_options_set_id = alicloud_vpc_dhcp_options_set.test_dhcp_options_set.id # Specify the ID of the DHCP options set to associate.
}

Resources: alicloud_pvtz_zone, alicloud_pvtz_zone_attachment, alicloud_pvtz_zone_record, alicloud_vpc_dhcp_options_set, alicloud_vpc_dhcp_options_set_attachment

Console

1. Go to the VPC console - DHCP Options Sets page and click Create DHCP Options Set. Set Domain Name to your custom domain name, click Custom Server IP, and place the self-managed DNS server IP address first in the list.

2. In the Actions column, select Associate VPC. ECS instances with configured DNS records can then be reached by hostname from other instances in the associated VPC.

API

1. Call CreateDhcpOptionsSet to create a custom DHCP options set with the domain name and self-managed DNS server IP address.

2. Call AttachDhcpOptionsSetToVpc to associate the DHCP options set with the VPC.

Terraform

# Specify the region of the VPC.
provider "alicloud" {
  region = "cn-hangzhou"
}

# Create a DHCP options set with a self-managed DNS server.
resource "alicloud_vpc_dhcp_options_set" "test_dhcp_options_set" {
  dhcp_options_set_name = "test_dhcp_options_set_name"
  domain_name           = "example.com"                              # Specify the domain name.
  domain_name_servers   = "192.168.0.10,100.100.2.136,100.100.2.138" # Place the self-managed DNS server IP first.
}

# Associate the DHCP options set with a VPC.
resource "alicloud_vpc_dhcp_options_set_attachment" "test_attachment_vpc" {
  vpc_id              = "vpc-8vbg******"                                       # Specify the ID of the VPC to associate.
  dhcp_options_set_id = alicloud_vpc_dhcp_options_set.test_dhcp_options_set.id # Specify the ID of the DHCP options set to associate.
}

Resources: alicloud_vpc_dhcp_options_set, alicloud_vpc_dhcp_options_set_attachment