Step 3 of the Get Started guide giving me performance problems

General
1

Hi folks. I’m just trying to get started with Docker, and am following the Get Started guide. All is well on steps 1 and 2, and I get the sample page nice and fast.

As soon as I get to Step 3 though, where I start the containers up from a service with 5 replicas, the request to localhost takes 20 seconds. It does then return successfully, but always takes 20 seconds, plus a few ms.

I have tried with different numbers of replicas with the same result, and I even tried spinning up the service on labs.play-with-docker.com and I got the same problem.

This is my docker-compose.yml:

version: "3"
services:
  web:
    image: cylindric/get-started:part2
    deploy:
      replicas: 1
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "80:80"
    networks:
      - webnet
networks:
  webnet:

And the actual container Dockerfile is:

FROM python:2.7-slim
WORKDIR /app
ADD . /app
RUN pip install -r requirements.txt
EXPOSE 80
ENV NAME World
CMD ["python", "app.py"]

Obviously as I am just on step 3 off the first tutorial, I’m not really very well equipped to troubleshoot this problem.

2

I think this might be to do with the Redis part in the container, which is not used until later. When I removed that, the page seems to load even in a multi-replicate service.