Starting a service inside of a Dockerfile - apache

Question

I'm building a Docker container and in this container I am downloading the Apache service. Is it possible to automatically start the Apache service at some point? Systemctl start httpd does not work inside of the Dockerfile.
Basically, I want the apache service to be started when the docker container is started.
FROM centos:7
MAINTAINER me <me#me.com>
RUN yum update -y && yum install -y httpd php
RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done); \
rm -f /lib/systemd/system/multi-user.target.wants/*;\
rm -f /etc/systemd/system/*.wants/*;\
rm -f /lib/systemd/system/local-fs.target.wants/*; \
rm -f /lib/systemd/system/sockets.target.wants/*udev*; \
rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
rm -f /lib/systemd/system/basic.target.wants/*;\
rm -f /lib/systemd/system/anaconda.target.wants/*;
VOLUME [ "/sys/fs/cgroup" ]
EXPOSE 80
EXPOSE 443
CMD ["/usr/sbin/init"]

Answer 1

Try using CMD ["/usr/sbin/httpd", "-DFOREGROUND"].
You also can run :
docker run -d <image name> /usr/sbin/httpd -DFOREGROUND

Answer 2

According to the Docker reference (Entrypoint reference), in the scenario you describe, you would use ENTRYPOINT, as you want your web server to "immutably" start. CMD is for commands or command line options that you are likely change/be overwritten:
Command line arguments to docker run will be appended after all elements in an exec form ENTRYPOINT, and will override all elements specified using CMD. This allows arguments to be passed to the entry point, i.e., docker run -d will pass the -d argument to the entry point.
If you must override an ENTRYPOINT, e.g. for testing/diagnostics, use the specific --entrypoint option.
Further:
You can use the exec form of ENTRYPOINT to set fairly stable default commands and arguments and then use either form of CMD to set additional defaults that are more likely to be changed.
So, ENTRYPOINT for the fixed services/application part, CMD for overrideable commands or options.
Using both ENTRYPOINT and CMD allows you to set a "fixed" commands part (including options) and a "variable" part. Like so:
FROM ubuntu
ENTRYPOINT ["top", "-b"]
CMD ["-c"]
Which means, in your case you may consider to have:
ENTRYPOINT ["/usr/sbin/httpd"]
CMD ["-DFOREGROUND"]
Which allows you do:
docker run -d <image name>
when you want to run your web server in the foreground, but
docker run -d <image name> -DBACKGROUND
if you want that same server to run with the -DBACKGROUND option overriding only the -DFOREGROUND part.