Docker pull can authenticate but run cannot - amazon-web-services

Question

I built, tagged & published my first (ever) Docker image to Quay:
docker build -t myapp .
docker tag <imageId> quay.io/myorg/myapp:1.0.0-SNAPSHOT
docker login quay.io
docker push quay.io/myorg/myapp:1.0.0-SNAPSHOT
I then logged into Quay.io to confirm the tagged image was successfully pushed, and it was. So then I SSHed into a brand-spanking-new AWS EC2 instance and followed their instructions to install Docker:
sudo yum update -y
sudo yum install -y docker
sudo service docker start
sudo usermod -a -G docker ec2-user
sudo docker info
Interestingly enough the sudo usermod -a -G docker ec2-user command doesn't seem to work as advertised as I still need to append sudo to all my commands...
So I try to pull my tagged image:
sudo docker pull quay.io/myorg/myapp:1.0.0-SNAPSHOT
Please login prior to pull:
Username: myorguser
Password: <password entered>
1.0.0-SNAPSHOT: Pulling from myorg/myapp
<hashNum1>: Pull complete
<hashNum2>: Pull complete
<hashNum3>: Pull complete
<hashNum4>: Pull complete
<hashNum5>: Pull complete
<hashNum6>: Pull complete
Digest: sha256:<longHashNum>
Status: Downloaded newer image for quay.io/myorg/myapp:1.0.0-SNAPSHOT
So far, so good (I guess!). Let's see what images my local Docker engine knows about:
sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
Hmmm...that doesn't seem right. Oh well, let' try running a container for my (successfully?) pulled image:
sudo docker run -it -p 8080:80 -d --name myapp:1.0.0-SNAPSHOT myapp:1.0.0-SNAPSHOT
Unable to find image 'myapp:1.0.0-SNAPSHOT' locally
docker: Error response from daemon: repository myapp not found: does not exist or no pull access.
See 'docker run --help'.
Any idea where I'm going awry?

Answer 1

To list images, you need to use: docker images
When you pull, the image has the same tag. So if you wish to run, you will need to use:
sudo docker run -it -p 8080:80 -d --name myapp:1.0.0-SNAPSHOT quay.io/myorg/myapp:1.0.0-SNAPSHOT
If you wish to use a short name, you need to retag it after the docker pull:
sudo docker tag quay.io/myorg/myapp:1.0.0-SNAPSHOT myapp:1.0.0-SNAPSHOT
After that, your docker run command will work. Note that docker ps is for containers that are running (or have exited in the recent past if used with -a)