Docker container "training/webapp" is deprecated

[AstreaeLuna]

Issue:

Starting on page 251 (Chapter 7: Working with Multiple Providers: A Crash Course on Docker), an image called training/webapp created by the Docker team is referenced. Unfortunately, due to changes in the OCI Spec, the schema of the latest version of the image is incompatible with the latest versions of Docker (since Version 27.0.0).

How to reproduce:

This error results from attempting to run this container using the following command.

docker run training/webapp

docker: [DEPRECATION NOTICE] Docker Image Format v1 and Docker Image manifest version 2, schema 1 support is disabled by default and will > be removed in an upcoming release. Suggest the author of docker.io/training/webapp:latest to upgrade the image to the OCI Format or Docker > Image manifest v2, schema 2. More information at https://docs.docker.com/go/deprecated-image-specs/.

[brikis98]

Ah, thanks for the heads up. Looks like the Docker team hasn't updated the training/webapp image for a long time, and it now uses deprecated/disabled features.

Probably the quickest workaround for now is to do the following:

1. Check out the training/webapp repo onto your own computer.
2. Build the Docker image yourself with some new name, like webapp-local.
3. Now you can use webapp-local in all examples that previously had training/webapp.

git clone https://github.com/docker-training/webapp
cd webapp
docker build -t webapp-local .

[GammaBlaze]

docker build -t webapp-local .

 => ERROR [5/7] RUN pip install -qr /tmp/requirements.txt                                                                                           0.8s
------
 > [5/7] RUN pip install -qr /tmp/requirements.txt:
0.638   Cannot fetch index base URL https://pypi.python.org/simple/
0.788   Could not find any downloads that satisfy the requirement Flask (from -r /tmp/requirements.txt (line 1))
0.789 No distributions at all found for Flask (from -r /tmp/requirements.txt (line 1))
0.792 Storing debug log for failure in /root/.pip/pip.log

Couldn't get the above image to build locally as it would fall over at pip install, but weirdly it's perfectly happy to build and deploy into the AWS EKS cluster (version 1.32) built at the end of chapter 7:

Apply complete! Resources: 10 added, 0 changed, 0 destroyed.

Outputs:

service_endpoint = "http://a56dfa8a1ddd54aec8da086df7f0f2f9-1768005177.us-east-2.elb.amazonaws.com"
curl http://a56dfa8a1ddd54aec8da086df7f0f2f9-1768005177.us-east-2.elb.amazonaws.com
Hello Terraform!

So you can still do most of the Chapter 7 exercises successfully.