I’m using the Docker default one-click-install from DO. If I restart my droplet, There are 5 docker processes running. My pstree looks something like this.

~# pstree -p
init(1)─┬─acpid(971)
        ├─atd(973)
        ├─cron(972)
        ├─dbus-daemon(741)
        ├─docker(1709)─┬─{docker}(1715)
        │              ├─{docker}(1717)
        │              ├─{docker}(1718)
        │              ├─{docker}(1719)
        │              └─{docker}(1720)
        ├─getty(931)
        ├─getty(934)
        ├─getty(939)
        ├─getty(940)
        ├─getty(942)
        ├─getty(1565)
        ├─nginx(1021)───nginx(1022)
        ├─rsyslogd(850)─┬─{rsyslogd}(851)
        │               ├─{rsyslogd}(852)
        │               └─{rsyslogd}(853)
        ├─sendmail-mta(1491)
        ├─sshd(966)───sshd(1348)───bash(1406)───pstree(1748)
        ├─systemd-logind(843)
        ├─systemd-udevd(385)
        ├─upstart-file-br(878)
        ├─upstart-socket-(680)
        └─upstart-udev-br(371)

The problem is that if I have multiple containers running, they will also run 5x times and create a lot of unnecessary processes. Because of that, I’m have to use a 10gb droplet that runs out of memory very quickly, despite getting almost no traffic.

This is how my pstree looks like after building and running a container.

~# pstree -p
init(1)─┬─acpid(971)
        ├─atd(973)
        ├─cron(972)
        ├─dbus-daemon(741)
        ├─docker(1709)─┬─docker(1985)─┬─{docker}(1986)
        │              │              ├─{docker}(1987)
        │              │              ├─{docker}(1988)
        │              │              ├─{docker}(1989)
        │              │              └─{docker}(1990)
        │              ├─ghost-start(1991)───su(2022)───bash(2023)───npm(2024)─┬─sh(2030)───node(2031)─┬─{node}(2032)
        │              │                                                       │                       ├─{node}(2033)
        │              │                                                       │                       ├─{node}(2034)
        │              │                                                       │                       ├─{node}(2035)
        │              │                                                       │                       └─{node}(2036)
        │              │                                                       ├─{npm}(2025)
        │              │                                                       ├─{npm}(2026)
        │              │                                                       ├─{npm}(2027)
        │              │                                                       ├─{npm}(2028)
        │              │                                                       └─{npm}(2029)
        │              ├─{docker}(1715)
        │              ├─{docker}(1717)
        │              ├─{docker}(1718)
        │              ├─{docker}(1719)
        │              ├─{docker}(1720)
        │              ├─{docker}(1910)
        │              ├─{docker}(1911)
        │              ├─{docker}(1912)
        │              ├─{docker}(2013)
        │              └─{docker}(2016)
        ├─getty(931)
        ├─getty(934)
        ├─getty(939)
        ├─getty(940)
        ├─getty(942)
        ├─getty(1565)
        ├─nginx(1021)───nginx(1022)
        ├─rsyslogd(850)─┬─{rsyslogd}(851)
        │               ├─{rsyslogd}(852)
        │               └─{rsyslogd}(853)
        ├─sendmail-mta(1491)
        ├─sshd(966)───sshd(2037)───bash(2085)───pstree(2100)
        ├─systemd-logind(843)
        ├─systemd-udevd(385)
        ├─upstart-file-br(878)
        ├─upstart-socket-(680)
        └─upstart-udev-br(371)

Docker version:

~# docker -v
Docker version 1.6.0, build 4749651

I’m using fig 1.0.0 (Should probably switch to docker-compose).

Question

What’s the best way to reduce the number of processes to just one? Why are there 5 docker processes running? Is there a reason this was setup this way in the first place?