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Last pushed: 2 hours ago
Short Description
Base Image for Blacklabelops Images.
Full Description

Blacklabelops Docker Base Image

Alpine images are smaller than full distributions, e.g. CentOS. This is a base image with some tweaks based on the official alpine image on Dockerhub.

Image Features:

  • Includes repository updates
  • tini: Zombie Process Reaper
  • su-exec: Execute processes as different user
  • wait-for-it: Waiting for available server ports.
  • Feature Script: Runtime user definition with environment variables.

Build the Image

$ cd alpine && docker build -t blacklabelops/alpine .

Run the Image

$ docker run -it --rm blacklabelops/alpine bash

Blacklabelops Dockerwait Feature

The Blacklabelops Dockerwait Feature is a script for polling server ports. This is mandatory when you want to wait for other containers starting web servers or databases.

You can define a the waiting parameters with the enviromnemt variables:

  • DOCKER_WAIT_HOST: The host to poll. Mandatory!
  • DOCKER_WAIT_PORT: The port to poll Mandatory!
  • DOCKER_WAIT_TIMEOUT: The timeout in seconds. Optional! Default: 60
  • CURRENT_DOCKER_WAIT_INTERVAL: The polling interval in seconds. Optional! Default:5

Example waiting for a postgresql database:

First start the polling container:

$ docker network create testnetwork
$ docker run \
    --net testnetwork \
    -e "DOCKER_WAIT_HOST=postgres" \
    -e "DOCKER_WAIT_PORT=5432" \
    blacklabelops/alpine dockerwait

Waits at most 60 seconds for the database.

Secondly start the database:

$ docker run -d --name postgres \
    --net testnetwork --hostname postgres \
    -e 'POSTGRES_USER=postgres' \
    -e 'POSTGRES_PASSWORD=postgres' \
    postgres:9.4

Starts postgres database under hostname postgres in docker network testnetwork

You can integrate this feature inside your entrypoint:

#!/bin/bash

# Use The Feature Script
source /usr/bin/dockerwait
# Executing The Application
exec your_application_command_here

Simple entrypoint.sh script example.

Blacklabelops User Feature

The Blacklabelops User Feature is a script for specifiying the run user of your application with env variables.
The user will be created automatically and can be user inside your entrypoint to start your application using su-exec.

You can define a user for your application at startup with the environment variables:

  • DOCKER_USER: The user's name, should match a valid username on your host machine (Default: blacklabelops).
  • DOCKER_USER_ID: The user's id should match a valid id on your host machine (Default: 1000).
  • DOCKER_USERGROUP: The user's groupname, should match a valid groupname on your host machine (Default: blacklabelops).
  • DOCKER_USERGROUP_ID: The user's groupid, should match a valid goup id on your host machine (Default: 1000).

Example Use Case:

$ docker run \
    -e "DOCKER_USER=YourUser" \
    -e "DOCKER_USER_ID=2000" \
    -e "DOCKER_USERGROUP=YourGroup" \
    -e "DOCKER_USERGROUP_ID=2000" \
    blacklabelops/alpine ./var/blacklabelops/createuser.sh

In order to make this work you will have to hook this script in your individual entrypoint script:

#!/bin/bash

# Include The Feature Script
source /var/blacklabelops/dockeruser.sh
# Create The User
dockerUser
# Print User Information
printUserInfo
# Executing The Application
exec su-exec $CURRENT_DOCKER_USER your_application_command_here

Simple entrypoint.sh script example.

Using tini

Tini is used to wrap your images entrypoint!

More information: krallin/tini

Example:

ENTRYPOINT ["/sbin/tini","--","/yourpath/docker-entrypoint.sh"]

Will start your entrypoint under tini process management.

Using su-exec

Su-Exec C reimplementation of gosu! Simplified sudo to exec processes under different users.

More information: ncopa/su-exec

Use su-exec in your individual entrypoint script:

#!/bin/bash

# Executing The Application
exec su-exec your_user your_application_command_here

Simple entrypoint.sh script example.

Build the Image

$ docker build -t blacklabelops/alpine .

Run the Image

$ docker run -it --rm blacklabelops/alpine bash

Support

Leave a message and ask questions on Hipchat: blacklabelops/hipchat

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blacklabelops
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