[ IoT Edge Azure ] How can containers resolve hostnames on different hosts without DNS server in LAN in nested architecture ?

Galgani, Stefano 205

Hi all,

I have an industry scenario at the edge side based on Azure IoT edge nested architecture with 2 tiers with parent and child hosts where inside them are working edge runtime and module containers.
I have a LAN without DNS server to resolve host name.

When I try to connect to the Edge container on the leaf, trying to ping parent hostname is not able to reach the parent container, instead when I try with the IP address the container is reached.

My questions are:

How can setup the mapping parent hostname to ip address in the leaf container ?

Where can I setup the mapping to allow to leaf containers to reach the parent container ? (As usual we have done inside file /etc/hosts)

Thanks

LeelaRajeshSayana-MSFT 13,871 Reputation points

2023-09-22T20:28:44.5533333+00:00

Hi @Galgani, Stefano Greetings! Thank you for posting the question here. Have you reviewed the documentation on Connect Azure IoT Edge devices to create a hierarchy. The section Update downstream configuration file points to modify the /etc/aziot/config.toml file where you can find the parameter parent_hostname. The parent_hostname parameter accepts the FQDN or IP address of the parent device. You can provide the IP address here and see if the mapping succeeds. Kindly refer the documentation for more details. Please let us know if you have any additional questions on this or need further assistance.
Galgani, Stefano 205 Reputation points

2023-09-23T14:27:38.9166667+00:00
Hi @LeelaRajeshSayana-MSFT , I found parent_hostname in /etc/aziot/config.toml , when I put parent IP address, the child is able to reach the parent instead when I put parent FQDN the child is not able to reach the parent and it said the host is not resolved.

if I don't have a DNS server in LAN,
where can I put the mapping ( IP address - Host Name) to allow to the child to reach the parent with FQDN as well ?

in other cases when a host doesn't have DNS to resolve a FQDN it uses the hosts file.

mapping example:

3.0.0.143 ubuntuparent.xxx.xxxxx.com

If you it helps you maybe I found at this link an hint about my issue

look in the followed image highlighted in yellow:

Could you provide me some details about adding a host file entry ?

Thanks
LeelaRajeshSayana-MSFT 13,871 Reputation points

2023-09-27T21:28:38.03+00:00

Hi @Galgani, Stefano Thank you for providing additional details on the issue you are facing. As far as I Know, we would still make the mappings as usual in the /etc/hosts file. And the approach is still the same as you pointed out in the example. You would provide the IP address followed by the FQDN of the parent device in the hosts file. This should help with resolving the mapping issue.

Please let us know if you experience any connectivity issues after setting the mappings on the hosts file. We would be happy to assist you further.
Galgani, Stefano 205 Reputation points

2023-09-29T06:26:15.43+00:00

Hi @LeelaRajeshSayana-MSFT thanks for the reply.
My case is using BRIDGE docker network type and by default this type doesn't see /etc/hosts file.
Could you provide me an example where I can setup my property ?
LeelaRajeshSayana-MSFT 13,871 Reputation points

2023-10-02T21:54:38.69+00:00

Hi @Galgani, Stefano For a deeper investigation and assistance on this issue, please file a support request @ https://aka.ms/azsupt? If you do not have access to a support plan, could you please send an email to azcommunity@microsoft.com with the below details, so that we can work closely on this matter.

Thread URL: Link to this thread.

Azure Subscription ID:

Email Subject : Attn Leela

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[ IoT Edge Azure ] How can containers resolve hostnames on different hosts without DNS server in LAN in nested architecture ?