[Bug]: Seat Adjuster Dockerfile is not buildable "stand-alone"

[mikehaller]

What happened?

When trying to build the Seat Adjuster example using the provided Dockerfile, it fails due to a missing folder.
The folder ./app does not exist in the repository.

Operating System

Linux

What release version or branch did you use?

v0.9.0

Relevant log output

$ docker build https://github.com/eclipse-velocitas/vehicle-app-python-sdk.git#v0.9.0:examples/seat-adjuster
[+] Building 3.6s (6/16)                                                                                                                                                        
 => [internal] load git source https://github.com/eclipse-velocitas/vehicle-app-python-sdk.git#v0.9.0:examples/seat-adjuster                                               1.8s
 => [internal] load metadata for docker.io/library/python:3.10-slim-bullseye@sha256:1ee6094f44c67781fa9533a4215f44f80dd3f43a68751ad2c855712116c03b05                       1.7s 
 => [auth] library/python:pull token for registry-1.docker.io                                                                                                              0.0s 
 => [builder  1/10] FROM docker.io/library/python:3.10-slim-bullseye@sha256:1ee6094f44c67781fa9533a4215f44f80dd3f43a68751ad2c855712116c03b05                               0.2s 
 => => resolve docker.io/library/python:3.10-slim-bullseye@sha256:1ee6094f44c67781fa9533a4215f44f80dd3f43a68751ad2c855712116c03b05                                         0.2s 
 => CACHED [builder  2/10] RUN apt-get update && apt-get install -y binutils                                                                                               0.0s
 => ERROR [builder  3/10] COPY ./app /app                                                                                                                                  0.0s
------
 > [builder  3/10] COPY ./app /app:
------
Dockerfile:22
--------------------
  20 |     RUN apt-get update && apt-get install -y binutils
  21 |     
  22 | >>> COPY ./app /app
  23 |     
  24 |     # Remove this installation for Arm64 once staticx has a prebuilt wheel for Arm64
--------------------
ERROR: failed to solve: failed to compute cache key: failed to calculate checksum of ref moby::eqy6el1uiuv39ll6w2awkcg3g: "/app": not found

Code of Conduct

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[BjoernAtBosch]

#85 provides just a quick fix: It makes the Dockerfile buildable from devContainer of vehicle-app-python-template (and instances of it).
The final fix shall make the Dockerfile buildable "standalone", means it shall not rely on temporary artefacts created by prerequisite build steps outside the Dockerfile.

[BjoernAtBosch]

The Dockerfile of the seat-adjuster example contains a copy statement for the ./app folder and for the vehicle model to make it available in the created container.
This copy statement presumes a build step outside the Dockerfile, which is not (necessarily) done if the image build is just referring to the Dockerfile.

Dockerfiles shall be buildable "stand-alone", i.e. without requiring a devContainer where the container needs to be done.

This bug relates to eclipse-velocitas/vehicle-app-python-template#162