Greengrass/Docker local volume permissions

I have a greengrass component that runs a docker container, I am struggling to understand how the permissions of folders and file are set when this is run by greengrass.

A snippet of my recipe looks like this:

"Install": {
          "Skipif": {
            "exists": "/home/ggc_user/data/package.json"
          },
          "Script": "mkdir -m 777 /home/ggc_user/data"
        },
        "Run": {
          "Script": "docker run --restart always -v /home/ggc_user/onwatch-data:/home/node/.signalk --log-opt max-size=10m --log-opt max-file=5  --network host --name testContainter testContainer"
        }

When I look at the permissions of /home/ggc_user/ using ls -l after the component is installed the file permissions look like:

drwxrwxrwx 4 ggc_user ggc_group 4096 Oct 6 15:38 data

I then go into the 'data' directory and look at the permissions of the files created inside from the docker container and the files are owned by admin which is my standard user.

-rw-r--r-- 1 admin admin   186 Oct  6 15:33 package.json
drwxr-xr-x 2 admin admin  4096 Oct  6 15:33 plugin-config-data

I would have thought it would create these with ggc_user as the owner. I have issues getting the container to run unless I set the permissions to 777.

What am I doing wrong?