Azure device update agent unable to connect from device

Question

Azure device update agent unable to connect from device

Simran Singh 61

Hello,

I'm trying to add the device update agent on my ubuntu 18.04 VM, following the provided reference (https://learn.microsoft.com/en-us/azure/iot-hub-device-update/device-update-ubuntu-agent#manually-prepare-a-device).

I got everything to the point where I need to start the daemon. The device update agent is unable to start on device with the error; Cannot read configuration file: /etc/adu/du-config.json

File(/etc/adu/du-config.json) looks like this:

<Connection String> is obviously the primary connection String from my IoT Hub Device.

Here are the error logs from device update agent service on my ubuntu VM device when I am starting the device update agent service:-

*Please note,
--> My device is already connected to IOT Hub as an edge device.
--> Device optimization service is up and running on my system.
--> Connection string is replaced in file.
--> The edgeAgent and edgeHub are in running state.

Please let me know the possible solutions. Also if any other information needed.

Bas Pruijn 956 Reputation points

2022-10-10T09:15:01.253+00:00

Based on your description it could be that the /etc/adu/du-config.json file is created by a root user and is not accessible for other users. You could verify by going to the /etc/adu directory (cd /etc/adu) and then perform a ls -la du-config.json. You will see the owner (probably root), the group (probably also root) and the access rights (probably -rw-------).

If this is the issue, you can allow all users on the system to read the file by executing chmod 644 du-config.json

This URL (https://www.guru99.com/file-permissions.html) describes the way linux rights work
chbeier 1,871 Reputation points

2022-10-10T12:12:05.943+00:00

@Bas Pruijn this is not good practice as in most cases people forget to reapply a secure setting. Although the default installation of the Debian package sets the right user and group ("adu").

@Simran Singh please check validity of you adjusted du-config.json file as mentioned in my previous comment.
Bas Pruijn 956 Reputation points

2022-10-11T10:35:57.52+00:00

I agree @chbeier that my suggestion was not to solve the issue, but to investigate the root cause of the issue. Thanks for pointing that one out. I still believe that extending the access to the file might give you insight in the root cause. If extending access does not solve the issue, the issue is related to the contents of the file.

The error message "cannot read config file" can be caused by either.

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Bas Pruijn 956 Reputation points

2022-10-10T09:15:01.253+00:00

Based on your description it could be that the /etc/adu/du-config.json file is created by a root user and is not accessible for other users. You could verify by going to the /etc/adu directory (cd /etc/adu) and then perform a ls -la du-config.json. You will see the owner (probably root), the group (probably also root) and the access rights (probably -rw-------).

If this is the issue, you can allow all users on the system to read the file by executing chmod 644 du-config.json

This URL (https://www.guru99.com/file-permissions.html) describes the way linux rights work
chbeier 1,871 Reputation points

2022-10-10T12:12:05.943+00:00

@Bas Pruijn this is not good practice as in most cases people forget to reapply a secure setting. Although the default installation of the Debian package sets the right user and group ("adu").

@Simran Singh please check validity of you adjusted du-config.json file as mentioned in my previous comment.
Bas Pruijn 956 Reputation points

2022-10-11T10:35:57.52+00:00

I agree @chbeier that my suggestion was not to solve the issue, but to investigate the root cause of the issue. Thanks for pointing that one out. I still believe that extending the access to the file might give you insight in the root cause. If extending access does not solve the issue, the issue is related to the contents of the file.

The error message "cannot read config file" can be caused by either.

Answer 1

chbeier 1,871

Good morning @Simran Singh ,

You mentioned that you replaced the connection string in the config. Did you also set manufacturer, model, and name to get a valid /etc/adu/du-config.json? You might load the resulting JSON config to vs code to check the syntax. Unfortunately, in my eyes the documentation is not perfectly accurate in step 3.

Simran Singh 61 Reputation points

2022-10-10T18:07:08.157+00:00

@Bas Pruijn , to me it looks like the default permission on /etc/adu/du-config.json are correct as mentioned by @chbeier

Sharing the default permissions set on file
QuantumCache 20,676 Reputation points Moderator

2022-10-10T19:45:14.277+00:00

Converting this to an Answer, so that other readers get benefit from this discussion.
QuantumCache 20,676 Reputation points Moderator

2022-10-10T19:46:43.317+00:00

Hello @Simran Singh Just checking on this.

Were you able to start the device update agent?//
Simran Singh 61 Reputation points

2022-10-13T06:20:37.98+00:00

Hello @QuantumCache , yes I am able to start the agent. Its working fine now.
Thanks
Simran Singh 61 Reputation points

2022-10-13T06:21:52.303+00:00

Thanks @chbeier for the approach. It helped in starting the device update agent.
QuantumCache 20,676 Reputation points Moderator

2022-10-13T07:10:12.027+00:00

Hello @Simran Singh If the response is helpful, please click "Accept Answer" and upvote it. So that we can close this thread and is helpful to other readers on the community.

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Azure device update agent unable to connect from device

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