Fix new Hadolint warning DL3045

[tschaffter]

This new warning makes the lint job of most of our repositories fail. The warning is described here.

[tschaffter]

Example of the current code from the Date Annotator Example. This code should meet the best practice defined by DL3045 (APP_DIR an absolute path). My guess is that the linter fails because I used a variable while it's looking for a string that starts with /....

ENV APP_DIR=/opt/app

COPY openapi_server ${APP_DIR}/openapi_server
COPY requirements.txt uwsgi.ini ${APP_DIR}/
COPY docker-entrypoint.sh /
RUN chmod +x /docker-entrypoint.sh

Mu current preferred solution is:

ENV APP_DIR=/opt/app

WORKDIR ${APP_DIR}
COPY openapi_server openapi_server/
COPY requirements.txt prod-requirements.txt uwsgi.ini ./
RUN pip install --no-cache-dir \
    -r requirements.txt -r prod-requirements.txt

WORKDIR /
COPY docker-entrypoint.sh .
RUN chmod +x docker-entrypoint.sh

Notes:

• I could get rid of the APP_DIR variable (removes two lines). However, I'm think to keep the APP_DIR as a kind of standard in all our images to know where the application directory is (may not longer be needed if we always place the app in /opt/app). I also like to have this variable at the top of the Dockerfile as it quickly indicates the location of the app dir, for example if someone want to troubleshoot the official Docker image and is looking to important directories.
• I like to set the working directory where the entrypoint is located (here in /). The Dockerfile would be one line shorter without it.

[thomasyu888]

+1 for your current preferred solution. I didn't reallize you could do pip install requirements.txt without the -r

[tschaffter]

I didn't reallize you could do pip install requirements.txt without the -r

It's actually a typo. I updated the proposed solution to reflect this typo.

[tschaffter]

I updated the Dockerfiles of the NLP Sandbox and ROCC.