Run a CLI inside a GreenGrass docker image

Question

I have a few greengrass (docker) components that listen to IPC local topics.
I now want to test to see if they are actually responding to messages on the local topics so i've written a `greengrass_pub` application (similar to `mosquitto_pub`) so i can call:
`greengrass_pub --topic "local/topic" --payload "{ \"do_some\" : \"stuff\" } " `

to check if the other components pick this up.

I have also installed this greengrass_pub application in the docker image, so i should be able to start up another docker image.

Can i startup a docker image to run under the greengrass credentials so I have access to IPC in an interactive way **AND** have a command prompt where I can try different calls ?

How could I start this up ? ( like a docker interactive (-it) session ? )

note: this is only for development as a tool to check.(i have the greengrass cli installed)

Accepted Answer

Run your docker container as a docker component in Greengrass following the instructions in [Use interprocess communication in Docker container components](https://docs.aws.amazon.com/greengrass/v2/developerguide/run-docker-container.html#docker-container-ipc).

Then, from the shell on the host where Greengrass is running, find the container name or id via `docker ps` and run `docker exec -it  /bin/sh`

Now you can run `greengrass_pub --topic "local/topic" --payload "{ \"do_some\" : \"stuff\" } "`

Is your command open source? Could you share the repo?

Answer

Thank you for that suggestion Massimiliano,

I have followed the instructions to start the docker that runs the program that listens to ipc  already and the container can happily listen to IoT-Core topics  so i think the permissions are alright. I've also added the accessControl to allow access to local topics.

```
{
  "Run": "docker run --name=abcd --cap-add=SYS_PTRACE --runtime=nvidia -e DISPLAY=$DISPLAY --privileged --volume /tmp/.X11-unix:/tmp/.X11-unix --net=host -e NVIDIA_VISIBLE_DEVICES=all -v $HOME/.Xauthority:/root/.Xauthority -v /run/udev/control:/run/udev/control -v /greengrass/v2:/greengrass/v2 -e SVCUID -e AWS_GG_NUCLEUS_DOMAIN_SOCKET_FILEPATH_FOR_COMPONENT -v /dev:/dev -v /sys/firmware/devicetree/base/serial-number:/sys/firmware/devicetree/base/serial-number -v /data:/data -e NVIDIA_DRIVER_CAPABILITIES=compute,utility,graphics   xxxxxxxxxx.dkr.ecr.ap-southeast-2.amazonaws.com/smartdvr:dev3 runscript.sh"
}
```

runscript.sh looks like:

```
#!/bin/sh
ret=0
while [ $ret -eq 0 ]; do
	exec /usr/sbin/my_application_that_listens_to_ipc
	ret=$?
	sleep 30
done

```

when i run 
`docker exec -it abcd /bin/sh`

it shows a command prompt ( `#` ) but as soon as i try to use the command prompt it hangs..

i think that is because it only runs my_application_that_listens_to_ipc .. and i'm not sure that exec can start another 'session' ?

Run a CLI inside a GreenGrass docker image

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