trident: Docker plugin fails to start after upgrade to 20.10+

Describe the bug After upgrading the docker netapp/trident-plugin to version 20.10, it fails to be re-enabled with an error of Error response from daemon: dial unix /run/docker/plugins/2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6/netapp.sock: connect: no such file or directory Upon following the troubleshooting steps in https://netapp-trident.readthedocs.io/en/stable-v20.10/docker/troubleshooting.html and checking the logs with journalctl, the following messages are logged:

Jan 14 10:59:35 hostname dockerd[14554]: time="2021-01-14T10:59:35-07:00" level=error msg="time=\"2021-01-14T17:59:35Z\" level=info msg=\"Running Trident storage orchestrator.\" binary=/netapp/trident build_time=\"Fri Jan  8 19:10:34 UTC 2021\" version=20.10.1" plugin=2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6
Jan 14 10:59:35 hostname dockerd[14554]: time="2021-01-14T10:59:35-07:00" level=error msg="time=\"2021-01-14T17:59:35Z\" level=fatal msg=\"Insufficient arguments provided for Trident to start.  Specify k8sAPIServer (for Kubernetes) or configPath (for Docker) or csiEndpoint (for CSI).\"" plugin=2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6
Jan 14 10:59:47 hostname dockerd[14554]: time="2021-01-14T10:59:47.360433094-07:00" level=error msg="Handler for POST /v1.40/plugins/netapp:latest/enable returned error: dial unix /run/docker/plugins/2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6/netapp.sock: connect: no such file or directory"

Environment Provide accurate information about the environment to help us reproduce the issue.

• Trident version: 20.10
• Trident installation flags used: docker plugin install --grant-all-permissions --alias netapp netapp/trident-plugin:19.10 config=/etc/netappdvp/config.json from the original install, though this is an upgrade
• Container runtime: Docker 19.03.14-CE
• Kubernetes version: N/A
• Kubernetes orchestrator: N/A
• Kubernetes enabled feature gates: N/A
• OS: Ubuntu 18.04.5 LTS
• NetApp backend types: ONTAP-NAS
• Other: N/A

To Reproduce Steps to reproduce the behavior: With a previous version of the netapp/trident-plugin installed (I tested with 19.10, 20.04, and 20.07) run through the steps in https://netapp-trident.readthedocs.io/en/latest/docker/use/managing.html#updating-trident

1. Disable plugin

$ sudo docker plugin disable -f netapp:latest
netapp:latest

1. Upgrade plugin

$ sudo docker plugin upgrade --skip-remote-check --grant-all-permissions netapp:latest netapp/trident-plugin:20.10
Upgrading plugin netapp:latest from netapp/trident-plugin:20.07 to netapp/trident-plugin:20.10
20.10: Pulling from netapp/trident-plugin
09043c5b1668: Download complete
Digest: sha256:bb73c2da04224603ce60a88546143b5045b235234c937c07331b4d4a1236da59
Status: Downloaded newer image for netapp/trident-plugin:20.10
Upgraded plugin netapp:latest to netapp/trident-plugin:20.10

1. Enable plugin

$ sudo docker plugin enable netapp:latest
Error response from daemon: dial unix /run/docker/plugins/2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6/netapp.sock: connect: no such file or directory

Expected behavior Expected a response of

$ sudo docker plugin enable netapp:latest
netapp:latest

Additional context In researching the error that is reported I found the corresponding code at https://github.com/NetApp/trident/blob/stable/v20.10/main.go#L129-L132 suggesting that the configPath may not be set. When the docker plugin was installed with docker plugin install the following parameter was passed though config=/etc/netappdvp/config.json and I can confirm that it is set by running docker plugin inspect netapp and seeing the output for Config.Env.config Value: “config.json” as well as this section of the output:

        "Id": "2311ab6e7b3b1461539ddc3c783ac65ad9a179d44fffd76b53aff9dd844ae1c6",
        "Name": "netapp:latest",
        "PluginReference": "docker.io/netapp/trident-plugin:20.10",
        "Settings": {
            "Args": [],
            "Devices": [],
            "Env": [
                "debug=true",
                "rest=false",
                "config=/etc/netappdvp/config.json"
            ],

I was able to downgrade back to 20.07 which functions as expected.