Docker container fails to initalize from docker-compose - docker

Question

I am new to Docker and in the process of learning Docker Compose, using CentOS 8 as the host system. All of these files are in the same directory and marked executable with mode 0755.
My main application is in webapp.py:
import time
import redis
from flask import Flask
app = Flask(__name__)
cache = redis.Redis(host='redis', port=6379)
def get_hit_count():
retries = 5
while True:
try:
return cache.incr('hits')
except redis.exceptions.ConnectionError as exc:
if retries == 0:
raise exc
retries -= 1
time.sleep(0.5)
#app.route('/')
def hello():
count = get_hit_count()
return 'Hello World! I have been seen {} times.\n'.format(count)
There is a matching requirements.txt file:
flask
redis
A Dockerfile:
FROM python:3.4-alpine
ADD . /code
WORKDIR /code
RUN pip install -r requirements.txt
CMD ["python", "webapp.py"]
And a docker-compose.yml file:
version: "3"
services:
web:
build: .
ports:
- "5000:5000"
stdin_open: true
tty: true
redis:
image: "redis:alpine"
However, when I run docker-compose up, it fails by exiting the web app. Compose outputs:
[root#localhost webappl]# docker-compose up
Starting webappl_redis_1 ... done
Starting webappl_web_1 ... done
Attaching to webappl_web_1, webappl_redis_1
redis_1 | 1:C 27 Dec 2021 09:03:35.861 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
redis_1 | 1:C 27 Dec 2021 09:03:35.861 # Redis version=6.2.6, bits=64, commit=00000000, modified=0, pid=1, just started
redis_1 | 1:C 27 Dec 2021 09:03:35.861 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
redis_1 | 1:M 27 Dec 2021 09:03:35.863 * monotonic clock: POSIX clock_gettime
redis_1 | 1:M 27 Dec 2021 09:03:35.864 * Running mode=standalone, port=6379.
redis_1 | 1:M 27 Dec 2021 09:03:35.864 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
redis_1 | 1:M 27 Dec 2021 09:03:35.864 # Server initialized
redis_1 | 1:M 27 Dec 2021 09:03:35.864 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
redis_1 | 1:M 27 Dec 2021 09:03:35.865 * Loading RDB produced by version 6.2.6
redis_1 | 1:M 27 Dec 2021 09:03:35.865 * RDB age 4147 seconds
redis_1 | 1:M 27 Dec 2021 09:03:35.865 * RDB memory usage when created 0.77 Mb
redis_1 | 1:M 27 Dec 2021 09:03:35.865 # Done loading RDB, keys loaded: 0, keys expired: 0.
redis_1 | 1:M 27 Dec 2021 09:03:35.865 * DB loaded from disk: 0.000 seconds
redis_1 | 1:M 27 Dec 2021 09:03:35.865 * Ready to accept connections
webappl_web_1 exited with code 0
Why does it exit?

Answer 1

can you trying adding following to your web: after ports:? if stdin_open doesn't work, try stdin
stdin_open: true
tty: true