Docker_Error_Python_Couchdb sh: 1: docker: not found

Question

I tried to run docker image but have this problem. All the files are saved in the directory "my_new_docker_build". This is the Dockerfile:

FROM python:2.7.14
RUN mkdir /my_new_docker_build
WORKDIR /my_new_docker_build
ADD . /my_new_docker_build/
EXPOSE 5984
CMD ["python", "/my_new_docker_build/py_couchdb.py"]

And this is is my Python code cadded "py_couchdb.py":

from os import system

# Launch volume docker couchdb from command line
system("docker run --name my-couchdb -v /my/custom-config-dir:/opt/couchdb/etc/local.d -d couchdb")

# Coudchdb visible in open world
system("docker run -p 5984:5984 -d couchdb")