ConnectionError when running Redis server inside Docker - docker

Question

I have the following Python script, example.py:
import redis
r = redis.Redis()
r.set('a','b')
and the following Dockerfile:
FROM ubuntu:18.04
# Install system-wide dependencies
RUN apt-get -yqq update
RUN apt-get -yqq install python3-dev python3-pip
RUN apt-get -yqq install redis-tools redis-server
RUN pip3 install redis
# Copy application code
ADD . /usr/local/example
WORKDIR /usr/local/example
# Start application
CMD /etc/init.d/redis-server restart \
&& python3 example.py
After I build the container (docker build -t redis-example .) and run it (docker run -P -it -d redis-example), the following stack trace is printed:
Stopping redis-server: redis-server.
Starting redis-server: redis-server.
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 484, in connect
sock = self._connect()
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 541, in _connect
raise err
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 529, in _connect
sock.connect(socket_address)
OSError: [Errno 99] Cannot assign requested address
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/redis/client.py", line 667, in execute_command
connection.send_command(*args)
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 610, in send_command
self.send_packed_command(self.pack_command(*args))
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 585, in send_packed_command
self.connect()
File "/usr/local/lib/python3.6/dist-packages/redis/connection.py", line 489, in connect
raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 99 connecting to localhost:6379. Cannot assign requested address.
I'm not sure why this very simple example is failing in Docker. I'd like to run an instance of a Redis server local to the Docker container.
It does not need to be reachable outside of the container and should be unique to the container.
How can I resolve this exception?