I'm experimenting with enabling systemd on the docker centos:7 image. Here's a simple example getting the centos7 systemd image set up, then building a docker image with nginx using that, and then running it.
Environment:
CentOS Linux release 7.3.1611 (Core)
Docker version 19.03.1, build 74b1e89
centos7-systemd.Dockerfile
# systemd is included with centos:7 but not enabled by default - START
# https://hub.docker.com/_/centos:
FROM centos:7
ENV container docker
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" ]
CMD ["/usr/sbin/init"]
# systemd is included with centos:7 but not enabled by default - ENDcentos7-systemd-nginx.Dockerfile
# This dockerfile is used when running cypress during a commit to the remote repo
FROM local/centos7-systemd
# install yum dependencies ansible
RUN yum install -y epel-release \
&& yum install -y nginx && systemctl enable nginx.service
EXPOSE 80
CMD ["/usr/sbin/init"]
Build images:
docker build --rm -t local/centos7-systemd -f centos7-systemd.Dockerfile .
docker build -t local/centos7-systemd-nginx -f centos7-systemd-nginx.Dockerfile .
Run container:
docker run -it --rm -d -v /sys/fs/cgroup:/sys/fs/cgroup:ro -v /run -p 80:80 --name web local/centos7-systemd-nginx
Test that nginx is running:
curl http://localhost/index.html
It returned an error HTML page, but I know nginx is running!
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>The page is not found</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<style type="text/css">
/*<![CDATA[*/
body {
background-color: #fff;
color: #000;
font-size: 0.9em;
font-family: sans-serif,helvetica;
margin: 0;
padding: 0;
}
:link {
color: #c00;
}
:visited {
color: #c00;
}
a:hover {
color: #f50;
}
h1 {
text-align: center;
margin: 0;
padding: 0.6em 2em 0.4em;
background-color: #294172;
color: #fff;
font-weight: normal;
font-size: 1.75em;
border-bottom: 2px solid #000;
}
h1 strong {
font-weight: bold;
font-size: 1.5em;
}
h2 {
text-align: center;
background-color: #3C6EB4;
font-size: 1.1em;
font-weight: bold;
color: #fff;
margin: 0;
padding: 0.5em;
border-bottom: 2px solid #294172;
}
h3 {
text-align: center;
background-color: #ff0000;
padding: 0.5em;
color: #fff;
}
hr {
display: none;
}
.content {
padding: 1em 5em;
}
.alert {
border: 2px solid #000;
}
img {
border: 2px solid #fff;
padding: 2px;
margin: 2px;
}
a:hover img {
border: 2px solid #294172;
}
.logos {
margin: 1em;
text-align: center;
}
/*]]>*/
</style>
</head>
<body>
<h1><strong>nginx error!</strong></h1>
<div class="content">
<h3>The page you are looking for is not found.</h3>
<div class="alert">
<h2>Website Administrator</h2>
<div class="content">
<p>Something has triggered missing webpage on your
website. This is the default 404 error page for
<strong>nginx</strong> that is distributed with
Fedora. It is located
<tt>/usr/share/nginx/html/404.html</tt></p>
<p>You should customize this error page for your own
site or edit the <tt>error_page</tt> directive in
the <strong>nginx</strong> configuration file
<tt>/etc/nginx/nginx.conf</tt>.</p>
</div>
</div>
<div class="logos">
<a href="http://nginx.net/"><img
src="/nginx-logo.png"
alt="[ Powered by nginx ]"
width="121" height="32" /></a>
<a href="http://fedoraproject.org/"><img
src="/poweredby.png"
alt="[ Powered by Fedora ]"
width="88" height="31" /></a>
</div>
</div>
</body>
</html>
These articles were helpful:
https://hub.docker.com/_/centos
https://stackoverflow.com/questions/36617368/docker-centos-7-with-systemctl-failed-to-mount-tmpfs-cgroup
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