So I forgot to update the blog since version 2.3x.x -  This means had to upgrade ghost to the latest version of 2.38.3 before leap frogging to version 4.x. according to upgrade guide from ghost blog official site

List docker containers to get an idea of the environment

sudo docker ps

List docker images to check which version  of ghost we have running

sudo docker images

Download ghost version 2.38.2 

sudo docker pull ghost:2.38.2-alpine

Remove the old docker container

sudo docker rm -f <container ID of old ghost blog>

Remove the old docker image

sudo docker rmi <image ID>

Restart docker container with the newer ghost blog version

sudo docker run --restart=always -d -e 'ROOT_URL=https://<blog URL>' -e 'VIRTUAL_HOST=<blog URL>' -e 'NODE_ENV=production' -e 'url=https://<blog URL>' --expose 2368 -v /home/Blog:/var/lib/ghost/content:rw ghost:2.38.2-alpine

Check if the container restarted with the correct image

sudo docker ps

If you want to track the restart process by viewing logs, use the command

 sudo docker logs -f <container ID>

After the ghost blog comes back online successfully, we can move on to download the desired ghost version 4.9.4

sudo docker pull ghost:4.9.4-alpine

After the download is complete, list the current running docker containers

sudo docker ps -a

Remove the old container running the older version of ghost using this command. 

sudo docker rm -f <container ID of old ghost blog>

The command below will force docker to spin up a new container which will use the latest version of ghost.

sudo docker run --restart=always -d -e 'ROOT_URL=https://<blog URL>' -e 'VIRTUAL_HOST=<blog URL>' -e 'NODE_ENV=production' -e 'url=https://<blog URL>' --expose 2368 -v /home/Blog:/var/lib/ghost/content:rw ghost:4.9.4-alpine

Run the command below one more time to confirm that the ghost blog is online and running the correct version

sudo docker ps -a