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Last pushed: 19 days ago
Short Description
centos 7 base (forked from https://github.com/xeor/docker-base)
Full Description

Info

  • The official centos image is the parent.

Usage

Use FROM xeor/base on top of your Dockerfile to use this base-image.

Environment variables

  • DOCKER_DEBUG: Sets docker-startup scripts in debugger mode (set -x and so on), and print some extra information regarding startup.
  • DEPENDING_ENVIRONMENT_VARS: We wont start before we got all variables listed here (space separated list). We will also give an error listing the missing variables.
  • SUPERVISORD_LOGLEVEL: Supervisord loglevel, defaults to error.
  • DUID: The UID of the already existing docker user.
  • DGID: The GID of the already existing docker group.
  • SETUP: This command will get ran just after the entrypoint-pre / setup script. We will run this command using eval, so you are free to do whatever you want here. Example usage is to use rm or find to cleanup old .pid files if container was not shut down cleanly. Use this variable as a temporary solution, or special solution; cleanups like that should be in the entrypoint-pre script.

User

There is a user created as default called docker belonging to a group called docker, both with GID and GID of 950.
We are not using it for anything as default, it is ment for in your supervisord.ini files, CMD, etc. You can change the UID and GID of this user when you start the container with setting the environment variables DUID and/or DGID to the ID you want the docker user/group to have.

Note that setting USER to docker in a Dockerfile, then setting DUID and/or DGID on startup, wont work. It's our entrypoint file that sets the correct ID's on the docker-user, and if you start docker with another user, we wont have access. We will start, but you will get a warning.

Daemon-mode

If we find 1 or more *.ini files in /etc/supervisord.d we will use supervisord as a loader. A simple COPY supervisord.d/ /etc/supervisord.d/ in your Dockerfile does the trick.
A simple nginx.ini might look like this (documentation is @ http://supervisord.org/configuration.html#program-x-section-settings):

[program:nginx]
command=/usr/sbin/nginx
autostart=true
autorestart=true

# Redirect output so we can see it using "docker logs"
stdout_logfile=/dev/stdout
stdout_logfile_maxbytes=0
stderr_logfile=/dev/stderr
stderr_logfile_maxbytes=0

Inotify

inotify-tools are installed, so you can use inotify without installing anything extra.
Example, if you want to restart nginx when a file is changed. You can add a supervisord with a command parameter as something like this; command=/bin/bash -c 'while inotifywait -e move -e create -e delete -r /etc/nginx/vhosts; do /usr/bin/supervisorctl restart nginx; done'.

Hooks

There are different hooks that is ran when we startup. This is done to make it easier to implement containers that looks the same, but example runs different supervisord configs based on an environment variable (remember to have auto_start to false).

If you want your hook to be debuggable, look for the DOCKER_DEBUG variable. A simple [[ ${DOCKER_DEBUG} ]] && set -x on top of your shell script is probably good enough.

We are setting executable bit on the hooks if it is not sat! If you want to temporary disable it, rename it to eg. .disabled instead.

  • /hooks/entrypoint-pre: Early in the entrypoint. Before we do anything.
  • /hooks/entrypoint-run: Runs if CMD is not overridden. (ie, we are doing daemon-mode or spawns a default bash shell).
  • /hooks/entrypoint-exec: Runs only if CMD is overridden. Runs just before we execute CMD.
  • /hooks/supervisord-pre: Just before we fire up supervisord.
  • /hooks/supervisord-ready: Runned after we know that supervisord is ready. This hook is triggered from supervisord itself, when it fires the SUPERVISOR_STATE_CHANGE_RUNNING event.

  • /init/setup: Runs right after entrypoint-pre, are there for backwards compatibility and because its easy to remember.

Other files / folders

Versions / tags / changelog

Each tag in this repository is getting build as it's corresponding docker-tag. The tagname 7.1-2 means that we use centos7 base, updated to 7.1, and it's our 2nd build.

  • latest is bound to the master branch. Careful using this :)

  • Changelog

    • 2015-12-20 - :7.2-1: CentOS 7.2, SETUP environment variable, and default inotify-tools.
    • 2015-11-23 - :7.1-6: Installing correct python ssl libs to get rid of ssl insecure warning.
    • 2015-11-22 - :7.1-5: A much better, more reliable way of triggering a hook when supervisord is ready.
    • 2015-11-21 - :7.1-4: Fixing supervisorctl, it didnt work. Added sane default ENV's. docker-user with configurable UID/GID.
    • 2015-11-20 - :7.1-3: Adding /init/setup compatibility.
    • 2015-11-19 - :7.1-2: First "kinda-working" version, lots of ideas implemented and tested.
    • 2015-11-18 - :7.1-1: Intitial version
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jameseckersall
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