[FIXED] How to run Docker with python and Java?

Issue

I need both java and python in my docker container to run some code.

This is my dockerfile: It works perpectly if I don't add the FROM openjdk:slim

#get python
FROM python:3.6-slim

RUN pip install --trusted-host pypi.python.org flask

#get openjdk

FROM openjdk:slim


COPY . /targetdir
WORKDIR /targetdir

# Make port 81 available to the world outside this container
EXPOSE 81

CMD ["python", "test.py"]

And the test.py app is in the same directory:

from flask import Flask

import os
app = Flask(__name__)


@app.route("/")

def hello():
    html = "<h3>Test:{test}</h3>"
    test = os.environ['JAVA_HOME']

    return html.format(test = test)


if __name__ == '__main__':
    app.run(debug=True,host='0.0.0.0',port=81)

I'm getting this error:

D:\MyApps\Docker Toolbox\Docker Toolbox\docker.exe: Error response from daemon: OCI runtime create failed: container_linux.go:348: starting container process caused "exec: \"python\": executable file not found in $PATH": unknown.

What exactly am I doing wrong here? I'm new to docker, perhaps I'm missing a step.

Additional details

My goal

I have to run a python program that runs a Java file. The python library I'm using requires the path to JAVA_HOME.

My issues:

• I do not know Java, so I cannot run the file properly.

• My entire code is in Python, except this Java bit

• The Python wrapper runs the file in a way I need it to run.

Solution

OK it took me a little while to figure it out. And my thanks go to this answer.

I think my approach didn't work because I did not have a basic version of Linux.

So it goes like this:

1. Get Linux (I'm using Alpine because it's barebones)
2. Get Java via the package manager
3. Get Python, PIP

OPTIONAL: find and set JAVA_HOME

4. Find the path to JAVA_HOME. Perhaps there is a better way to do this, but I did this running the running the container, then I looked inside the container using docker exec -it [COINTAINER ID] bin/bash and found it.
5. Set JAVA_HOME in dockerfile and build + run it all again

Here is the final Dockerfile ( it should work with the python code in the question) :

### 1. Get Linux
FROM alpine:3.7

### 2. Get Java via the package manager
RUN apk update \
&& apk upgrade \
&& apk add --no-cache bash \
&& apk add --no-cache --virtual=build-dependencies unzip \
&& apk add --no-cache curl \
&& apk add --no-cache openjdk8-jre

### 3. Get Python, PIP

RUN apk add --no-cache python3 \
&& python3 -m ensurepip \
&& pip3 install --upgrade pip setuptools \
&& rm -r /usr/lib/python*/ensurepip && \
if [ ! -e /usr/bin/pip ]; then ln -s pip3 /usr/bin/pip ; fi && \
if [[ ! -e /usr/bin/python ]]; then ln -sf /usr/bin/python3 /usr/bin/python; fi && \
rm -r /root/.cache

### Get Flask for the app
RUN pip install --trusted-host pypi.python.org flask

####
#### OPTIONAL : 4. SET JAVA_HOME environment variable, uncomment the line below if you need it

#ENV JAVA_HOME="/usr/lib/jvm/java-1.8-openjdk"

####

EXPOSE 81    
ADD test.py /
CMD ["python", "test.py"]

I'm new to Docker, so this may not be the best possible solution. I'm open to suggestions.

UPDATE: COMMON ISUUES

• Difficulty using python packages

As Joabe Lucena pointed out here, Alpine can have issues certain python packages. I recommend that you use a Linux distro that works best for you, e.g. centos.

Answered By - pajamas
Answer Checked By - Robin (JavaFixing Admin)