Enable cron

README.md

@@ -26,9 +26,12 @@ Why use baseimage-docker instead of doing everything yourself in Dockerfile?
 | Fixes APT incompatibilities with Docker | See https://github.com/dotcloud/docker/issues/1024. |
 | syslog-ng | A syslog daemon is necessary so that many services - including the kernel itself - can correctly log to /var/log/syslog. If no syslog daemon is running, a lot of important messages are silently swallowed. <br><br>Only listens locally. |
 | ssh server | Allows you to easily login to your container to inspect or administer things. <br><br>Password and challenge-response authentication are disabled by default. Only key authentication is allowed.<br>It allows an predefined key by default to make debugging easy. You should replace this ASAP. See instructions. |
+| cron | The cron daemon must be running for cron jobs to work. |
 | [runit](http://smarden.org/runit/) | For service supervision and management. Much easier to use than SysV init and supports restarting daemons when they crash. Much easier to use and more lightweight than Upstart. |
 | `setuser` | A tool for running a command as another user. Easier to use than `su`, has a smaller attack vector than `sudo`, and unlike `chpst` this tool sets `$HOME` correctly. Available as `/sbin/setuser`. |
 
+Baseimage-docker is very lightweight: it only consumes 4 MB of memory.
+
 ## Using baseimage-docker as base image
 
 The image is called `phusion/baseimage`, and is available on the Docker registry.
@@ -41,6 +44,9 @@ By default, it allows SSH access for the key in `image/insecure_key`. This makes
     # a list of version numbers.
     FROM phusion/baseimage:<VERSION>
     
+    # Set correct environment variables.
+    ENV HOME /root
+
     # Remove authentication rights for insecure_key.
     RUN rm -f /root/.ssh/authorized_keys /home/*/.ssh/authorized_keys
     

image/buildconfig

@@ -1,2 +1,3 @@
 export LC_ALL=C
 export DEBIAN_FRONTEND=noninteractive
+minimal_apt_get_install='apt-get install -y --no-install-recommends'

image/prepare.sh

@@ -9,7 +9,7 @@ echo deb http://archive.ubuntu.com/ubuntu precise-updates main universe >> /etc/
 apt-get update
 
 ## Install HTTPS support for APT.
-apt-get install -y apt-transport-https
+$minimal_apt_get_install apt-transport-https
 
 ## Fix some issues with APT packages.
 ## See https://github.com/dotcloud/docker/issues/1024
@@ -18,8 +18,8 @@ ln -s /bin/true /sbin/initctl
 
 ## Upgrade all packages.
 echo "initscripts hold" | dpkg --set-selections
-apt-get upgrade -y
+apt-get upgrade -y --no-install-recommends
 
 ## Fix locale.
-apt-get install -y language-pack-en
+$minimal_apt_get_install language-pack-en
 locale-gen en_US

image/runit/cron

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec /usr/sbin/cron -f

image/system_services.sh

@@ -7,15 +7,15 @@ set -x
 cp /build/my_init /sbin/
 
 ## Install runit.
-apt-get install -y runit
+$minimal_apt_get_install runit
 
 ## Install a syslog daemon.
-apt-get install -y syslog-ng
+$minimal_apt_get_install syslog-ng-core
 mkdir /etc/service/syslog-ng
 cp /build/runit/syslog-ng /etc/service/syslog-ng/run
 
 ## Install the SSH server.
-apt-get install -y openssh-server
+$minimal_apt_get_install openssh-server
 mkdir /var/run/sshd
 mkdir /etc/service/sshd
 cp /build/runit/sshd /etc/service/sshd/run
@@ -26,3 +26,8 @@ mkdir -p /root/.ssh
 chmod 700 /root/.ssh
 chown root:root /root/.ssh
 cat /build/insecure_key.pub > /root/.ssh/authorized_keys
+
+## Install cron daemon.
+$minimal_apt_get_install cron
+mkdir /etc/service/cron
+cp /build/runit/cron /etc/service/cron/run

image/utilities.sh

@@ -4,7 +4,7 @@ source /build/buildconfig
 set -x
 
 ## Often used tools.
-apt-get install -y curl less nano vim psmisc
+$minimal_apt_get_install curl less nano vim psmisc
 
 ## This tool runs a command as another user and sets $HOME.
 cp /build/setuser /sbin/setuser