Docker stack: Apache service will not start - apache

Question

Apache service in docker stack never starts (or, to be more accurate, keeps restarting). Any idea what's going on?
The containers are the ones in: https://github.com/adrianharabula/lampstack.git
My docker-compose.yml is:
version: '3'
services:
db:
image: mysql:5.7
volumes:
- ../db_files:/var/lib/mysql
restart: always
environment:
MYSQL_ROOT_PASSWORD: toor
#MYSQL_DATABASE: testdb
#MYSQL_USER: docky
#MYSQL_PASSWORD: docky
ports:
- 3306:3306
p71:
# depends_on:
# - db
image: php:7.1
build:
context: .
dockerfile: Dockerfile71
links:
- db
volumes:
- ../www:/var/www/html
- ./php.ini:/usr/local/etc/php/conf.d/php.ini
- ./virtualhost-php71.conf:/etc/apache2/sites-available/001-virtualhost-php71.conf
- ../logs/71_error.log:/var/www/71_error.log
- ../logs/71_access.log:/var/www/71_access.log
environment:
DB_HOST: db:3306
DB_PASSWORD: toor
ports:
- "81:80"
pma:
depends_on:
- db
image: phpmyadmin/phpmyadmin
And I start it with:
docker stack deploy -c docker-compose.yml webstack
db and pma services start correctly, but p71 service keeps restarting
docker service inspect webstack_p71
indicates:
"UpdateStatus": {
"State": "paused",
"StartedAt": "2018-01-19T16:28:17.090936496Z",
"CompletedAt": "1970-01-01T00:00:00Z",
"Message": "update paused due to failure or early termination of task 45ek431ssghuq2tnfpduk1jzp"
}
As you can see by the docker-composer.yml I already commented out the service dependency to avoid failures if dependencies are not met at first run.
$ docker service logs -f webstack_p71
$ docker service ps --no-trunc webstack_p71
What should I do to get that Apache/PHP (p71) service running?
All the containers work when run independently:
$ docker build -f Dockerfile71 -t php71 .
$ docker run -d -p 81:80 php71:latest

Answer 1

First of all, depends_on option doesn't work in swarm mode of version 3.(refer this issue)
In short...
depends_on is a no-op when used with docker stack deploy. Swarm mode
services are restarted when they fail, so there's no reason to delay
their startup. Even if they fail a few times, they will eventually
recover.
Of course, even though depends_on doesn't work, p71 should work properly since it would restart after the failure.
Thus, I think there is some error while running p71 service. that would be why the service keeps restarting. however, I am not sure what is happening inside the service only with the information you offer.
You could check the trace by checking log.
$ docker service logs -f webstack_p71
and error message
$ docker service ps --no-trunc webstack_p71 # check ERROR column