Evaluate environment from host before creating containers

Question

Evaluate environment from host before creating containers

Jeffrey K 171

Im trying to create a deployment in IoTHub with the environment variable from the host set to the container environment variable. Is there a way to evaluate the environment variables from the host before setting the options for the container?

When I try to set the the container options Env say: [ "DISPLAY=$DISPLAY" ], the container running at the edge considers the env value $DISPLAY as string but does not evaluate them.

When I docker run the image manually I can see the value being evaluated before being set. eg: docker run -e DISPLAY=$DISPLAY hello-world

Any advice to achieve this through IoTEdge deployments?

QuantumCache 20,681 Reputation points Moderator

2022-04-01T18:33:30.367+00:00

Hello @Jeffrey K

createOptions follows Docker's spec,

One tip for writing create options is to use the docker inspect command. As part of your development process, run the module locally using docker run <container name>. Once you have the module working the way you want it, run docker inspect <container name>. This command outputs the module details in JSON format. Find the parameters that you configured, and copy the JSON.

For more information, see this document: Format create options

I hope this helps with your initial query!
Jeffrey K 171 Reputation points

2022-04-01T18:38:56.853+00:00

The problem is the environment variable $DISPLAY is not the same for all the edge devices, we need this value computed at the time the containers are being created by IoTedge instead of hardcoding them. :(

Any suggestion?
QuantumCache 20,681 Reputation points Moderator

2022-04-01T18:52:29.887+00:00

Did you check this article? Set environment variables (-e, --env, --env-file)
Looks like you have already tried that command/
Jeffrey K 171 Reputation points

2022-04-01T21:33:10.933+00:00

Correct that works when I used docker run (as part of my question earlier) but since IotEdge agent uses docker create container we are unable to get the environment variable evaluated before setting the value to it
QuantumCache 20,681 Reputation points Moderator

2022-04-02T01:30:41.513+00:00

Hello @Jeffrey K

We have a response from the product team!

Unfortunately, parameterized settings are not available in the Edge deployment manifest.

I will leave this thread to the community for any workarounds or suggestions on this topic!
Jeffrey K 171 Reputation points

2022-04-02T15:42:58.727+00:00

Sure, if any workaround for this issue is very much appreciated