Alpine baseimage

UPDATE 2018-10-07 - Possible breakage! I have decided to switch back to using tagged repositories. This means you may have to add @repotag to packages not in the main repositories. repo-tags are: @edge, @edgecommunity and @testing

UPDATE 2018-11-23 - fcron has been removed. If you need a cron daemon, install it.

UPDATE 2020-06-12 - Versions 3.7 and 3.8 removed

A baseimage based on Alpine 3.x with Skarnet's s6 process supervision installed from Just Container's s6 Overlay.

Bits and pieces have been sourced from other fine Docker images

Tags

Use ajoergensen/baseimage-alpine:3.X where X is either 9, 10, 11 or 12

Environment

• PUID - Changes the uid of the app user, default 911
• PGID - Changes the gid of the app group, default 911
• DISABLE_CRON - Do not run cron. Default is TRUE
• DISABLE_SYSLOG - If set to TRUE, do not run rsyslog inside the container. Default is FALSE
• REMOTE_SYSLOG_HOST - If you want to log to a remote syslog server, set this variable to the IP or DNS name of the server. Remote logging is off by default.
• REMOTE_SYSLOG_PORT - Port used by the remote syslog server. Default is 514
• REMOTE_SYSLOG_PROTO - Protocol to use for the remote syslog server. Possible values are tcp or udp, default is tcp.
• SMTP_HOST - Change the SMTP relay server used by ssmtp (sendmail)
• SMTP_USER - Username for the SMTP relay server
• SMTP_PASS - Password for the SMTP relay server
• SMTP_PORT - Outgoing SMTP port, default 587
• SMTP_SECURE - Does the SMTP server requires a secure connection, default TRUE if SMTP_USER is set.
• SMTP_TLS - Use STARTTLS, default TRUE (if SMTP_TLS is FALSE and SMTP_SECURE is true, SMTP over SSL will be used)
• SMTP_MASQ - Masquerade outbound emails using this domain, default empty

Running applications

It is recommended to run applications as the unpriviledged user app.

To run the application, add a start-up script like this

#/usr/bin/with-contenv bash
exec s6-setuidgid app /path/to/application

One shortcoming is the fact s6-setuidgid does not set the $HOME variable. The work-around looks like this:

#/usr/bin/with-contenv bash
export HOME="~app"
exec s6-setuidgid app /path/to/application

I have looked at the possiblity of adding setuser from the phusion baseimage but doing requires installing Python 3 which add bloat.

If you want add setuser, create a Dockerfile like this:

FROM ajoergensen/baseimage-alpine
RUN \
        apk add --no-cache python3 && \
        wget https://raw.githubusercontent.com/phusion/baseimage-docker/master/image/bin/setuser -O /sbin/setuser && \
        chmod +x /sbin/setuser

Email

If you need to send mail and cannot use SMTP directly, ssmtp is installed to provide /usr/bin/sendmail and is configured using the SMTP_ variables.

If SMTP_USER is not set, unauthenticated SMTP will be used and SSL/TLS is disabled.

Persistent data

Generally I store configuration data in /config and store it in a volume. If an application does not permit changing the location of its configuration data, add a script to /etc/cont-init.d which changes the app user's $HOME