Update DHCP nameserver using API

[Dan_s_97]

We have been trying to update the name server for VLANs using Python through the API but have been getting errors or issues 

We can update using the GUI without issue but the idea is to do this in mass (we cannot use templates) 

the setting is under Security & SD WAN  > Configure > DHCP

our first attempt looks like this 

import meraki

from getpass import getpass

TARGET_NETWORK_NAME = "INSET NAME HERE "

VLANS_TO_UPDATE = [10, 11]

NEW_DNS = "1.1.1.1,8.8.8.8"

def main():

    API_KEY = getpass("Enter your Meraki API Key: ").strip()

    dashboard = meraki.DashboardAPI(api_key=API_KEY, print_console=False)

    org_id = dashboard.organizations.getOrganizations()[0]["id"]

    networks = dashboard.organizations.getOrganizationNetworks(

        org_id, total_pages='all'

    )

    net = next((n for n in networks if n["name"] == TARGET_NETWORK_NAME), None)

    if not net:

        print("Network not found")

        return

    net_id = net["id"]

    for vlan_id in VLANS_TO_UPDATE:

        print(f"\nReading VLAN {vlan_id}...")

        vlan = dashboard.appliance.getNetworkApplianceVlan(net_id, vlan_id)

        print("Current DNS:", vlan.get("dnsNameservers"))

    confirm = input("\nProceed with DNS update? (yes/no): ").lower()

    if confirm not in ("yes", "y"):

        return

    for vlan_id in VLANS_TO_UPDATE:

        print(f"\nUpdating VLAN {vlan_id}...")

        # MUST include required fields

        vlan = dashboard.appliance.getNetworkApplianceVlan(net_id, vlan_id)

        payload = {

            "name": vlan["name"],

            "subnet": vlan["subnet"],

            "applianceIp": vlan["applianceIp"],

            "dhcpHandling": vlan["dhcpHandling"],

            "dhcpLeaseTime": vlan["dhcpLeaseTime"],

            "dhcpBootOptionsEnabled": vlan["dhcpBootOptionsEnabled"],

            "dhcpOptions": vlan["dhcpOptions"],

            "dnsNameservers": NEW_DNS,  # legacy format uses this field

        }

        print("Payload:", payload)

        try:

            dashboard.appliance.updateNetworkApplianceVlan(

                net_id,

                vlan_id,

                **payload

            )

            print(f"Updated VLAN {vlan_id}")

        except Exception as e:

            print(f"Update failed for VLAN {vlan_id}: {e}")

if __name__ == "__main__":

    main()

but results in 

Enter your Meraki API Key:

Reading VLAN 10...
Current DNS: HIDDEN
HIDDEN

Reading VLAN 11...
Current DNS: HIDDEN
HIDDEN

Proceed with DNS update? (yes/no): yes

Updating VLAN 10...
Payload: {'name': 'POS-PCI', 'subnet': 'HIDDEN', 'applianceIp': 'HIDDEN', 'dhcpHandling': 'Run a DHCP server', 'dhcpLeaseTime': '1 day', 'dhcpBootOptionsEnabled': False, 'dhcpOptions': [], 'dnsNameservers': '8.8.8.8,1.1.1.1'}

Update failed for VLAN 10: appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ['The Custom nameservers list contains one or more invalid entries (should be IP addresses or domain names).']}

[alemabrahao]

I believe the problem is the comma; try updating only one IP address to see the result.

[PhilipDAth]

What I would do is setup a network how you want to be, and then use getNetworkApplianceVlan() to see how the data comes back for DNS.  Then you use that exact data format when calling updateNetworkApplianceVlan().

I don't know the answer, but my guess is it will need to be an array.

NEW_DNS = ["1.1.1.1","8.8.8.8"]

[RaphaelL]

Correct ! 

    "dhcpRelayServerIps": [
      "10.1.1.1",
      "10.2.2.2",
      "10.3.3.3",
      "10.4.4.4"
    ]

[Dan_s_97]

unfortunately the same issue still 

VLAN 10: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ['The Custom nameservers list contains one or more invalid entries (should be IP addresses or domain names).']}
VLAN 11: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ['The Custom nameservers list contains one or more invalid entries (should be IP addresses or domain names).']}
VLAN 900: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ['The Custom nameservers list contains one or more invalid entries (should be IP addresses or domain names).']}

i tried the other way around 

Applying DNS updates...
VLAN 10: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ["'dnsNameservers' must be a string"]}
VLAN 11: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ["'dnsNameservers' must be a string"]}
VLAN 900: ERROR → appliance, updateNetworkApplianceVlan - 400 Bad Request, {'errors': ["'dnsNameservers' must be a string"]}

[alemabrahao · Accepted solution]

You sent a list (["8.8.8.8", "1.1.1.1"]). The endpoint schema expects a single string value.

You also sent a comma-separated string. While the user interface allows commas, the API parser is more demanding; try using a newline (\n) between the inputs.

[Dan_s_97]

Thank you all 

final working code for anyone trying to do the same in future 

import meraki

from getpass import getpass

TARGET_NETWORK_NAME = "REDACTED_NETWORK_NAME"

VLANS_TO_UPDATE = [REDACTED_VLAN_ID_1, REDACTED_VLAN_ID_2]

NEW_DNS = "REDACTED_DNS_1\nREDACTED_DNS_2"

def main():

    API_KEY = getpass("Enter your Meraki API Key: ").strip()

    dashboard = meraki.DashboardAPI(api_key=API_KEY, print_console=False)

    org_id = dashboard.organizations.getOrganizations()[0]["id"]

    networks = dashboard.organizations.getOrganizationNetworks(

        org_id, total_pages='all'

    )

    net = next((n for n in networks if n["name"] == TARGET_NETWORK_NAME), None)

    if not net:

        print("Network not found")

        return

    net_id = net["id"]

    for vlan_id in VLANS_TO_UPDATE:

        print(f"\nReading VLAN {vlan_id}...")

        vlan = dashboard.appliance.getNetworkApplianceVlan(net_id, vlan_id)

        print("Current DNS:", vlan.get("dnsNameservers"))

    confirm = input("\nProceed with DNS update? (yes/no): ").lower()

    if confirm not in ("yes", "y"😞

        return

    for vlan_id in VLANS_TO_UPDATE:

        print(f"\nUpdating VLAN {vlan_id}...")

        vlan = dashboard.appliance.getNetworkApplianceVlan(net_id, vlan_id)

        payload = {

            "name": vlan["name"],

            "subnet": "REDACTED_SUBNET",

            "applianceIp": "REDACTED_APPLIANCE_IP",

            "dhcpHandling": vlan["dhcpHandling"],

            "dhcpLeaseTime": vlan["dhcpLeaseTime"],

            "dhcpBootOptionsEnabled": vlan["dhcpBootOptionsEnabled"],

            "dhcpOptions": vlan["dhcpOptions"],

            "dnsNameservers": NEW_DNS,

        }

        print("Payload:", payload)

        try:

            dashboard.appliance.updateNetworkApplianceVlan(

                net_id,

                vlan_id,

                **payload

            )

            print(f"Updated VLAN {vlan_id}")

        except Exception as e:

            print(f"Update failed for VLAN {vlan_id}: {e}")

if __name__ == "__main__":

    main()