hub.docker.com/tiredofit/alpine

Introduction

Dockerfile to build an alpine container image.

• Currently tracking 3.3, 3.4, 3.5, 3.6, 3.7 and edge
• s6 overlay enabled for PID 1 Init capabilities
• zabbix-agent based on 3.4.x compiled for individual container monitoring.
• Cron installed along with other tools (bash,curl, less, logrotate, nano, vim) for easier management.
• MSMTP enabled to send mail from container to external SMTP server.
• Ability to update User ID and Group ID Permissions for Development Purposes dyanmically.

Authors

• [Dave Conroy](dave at tiredofit dot ca) [https://github.com/tiredofit]

Table of Contents

• Introduction
• Prerequisites
• Installation
• Quick Start
• Configuration
  • Data Volumes
  • Environment Variables
  • Networking
• Maintenance
  • Shell Access
  • References

Prerequisites

No prequisites required

Installation

Automated builds of the image are available on Docker Hub and is the recommended method of installation.

docker pull tiredofit/alpine:(imagetag)

The following image tags are available:

• 3.3 - Alpine 3.3
• 3.4 - Alpine 3.4
• 3.5 - Alpine 3.5
• 3.6 - Alpine 3.6
• 3.7 - Alpine 3.7
• edge - Alpine edge
• latest - Alpine 3.7

Quick Start

Utilize this image as a base for further builds. By default it does not start the S6 Overlay system, but Bash. Please visit the s6 overlay repository for instructions on how to enable the S6 Init system when using this base or look at some of my other images which use this as a base.

Configuration

Data-Volumes

The following directories are used for configuration and can be mapped for persistent storage.

Directory	Description
/etc/zabbix/zabbix_agentd.conf.d/	Zabbix Agent Configuration Directory
/assets/cron-custom	Drop Custom Crontabs here

Environment Variables

Below is the complete list of available options that can be used to customize your installation.

Parameter	Description
DEBUG_MODE	Enable Debug Mode - Default: FALSE
DEBUG_SMTP	Setup Mail Catch all on port 1025 (SMTP) and 8025 (HTTP) - Default: FALSE
ENABLE_CRON	Enable Cron - Default: TRUE
ENABLE_SMTP	Enable SMTP services - Default: TRUE
ENABLE_ZABBIX	Enable Zabbix Agent - Default: TRUE
TIMEZONE	Set Timezone - Default: America/Vancouver

If you wish to have this send mail, set ENABLE_SMTP=TRUE and configure the following environment variables. See the MSMTP Configuration Options for further information on options to configure MSMTP

Parameter	Description
SMTP_HOST	Hostname of SMTP Server - Default: postfix-relay
SMTP_PORT	Port of SMTP Server - Default: 25
SMTP_DOMAIN	HELO Domain - Default: docker
SMTP_MAILDOMAIN	Mail Domain From - Default: example.org
SMTP_AUTHENTICATION	SMTP Authentication - Default: none
SMTP_USER	Enable SMTP services - Default: user
SMTP_PASS	Enable Zabbix Agent - Default: password
SMTP_TLS	Use TLS - Default: off
SMTP_STARTTLS	Start TLS from within Dession - Default: off
SMTP_TLSCERTCHECK	Check remote certificate - Default: off

See The Official Zabbix Agent Documentation for information about the following Zabbix values

Zabbix Parameters	Description
ZABBIX_LOGFILE	Logfile Location - Default: /var/log/zabbix/zabbix_agentd.log
ZABBIX_LOGFILESIZE	Logfile Size - Default: 1
ZABBIX_DEBUGLEVEL	Debug Level - Default: 1
ZABBIX_REMOTECOMMANDS	Enable Remote Commands (0/1) - Default: 1
ZABBIX_REMOTECOMMANDS_LOG	Enable Remote Commands Log (0/1)
ZABBIX_SERVER	Allow connections from Zabbix Server IP - Default: 0.0.0.0/0
ZABBIX_LISTEN_PORT	Zabbix Agent Listening Port - Default: 10050
ZABBIX_LISTEN_IP	Zabbix Agent Listening IP - Default: 0.0.0.0
ZABBIX_START_AGENTS	How many Zabbix Agents to Start - Default: `3
ZABBIX_SERVER_ACTIVE	Server for Active Checks - Default: zabbix-proxy
ZABBIX_HOSTNAME	Container hostname to report to server - Default: docker
ZABBIX_REFRESH_ACTIVE_CHECKS	Seconds to refresh Active Checks - Default: 120
ZABBIX_BUFFER_SEND	Buffer Send - Default: 5
ZABBIX_BUFFER_SIZE	Buffer Size - Default: 100
ZABBIX_MAXLINES_SECOND	Max Lines Per Second - Default: 20
ZABBIX_ALLOW_ROOT	Allow running as root - Default: 1
ZABBIX_USER	Zabbix user to start as - Default: zabbix

If you enable DEBUG_PERMISSIONS=TRUE all the users and groups have been modified in accordance with Environmental Variables will be displayed in output. e.g. If you add USER_NGINX=1000 it will reset the containers nginx user id from 82 to 1000 - Hint, also change the Group ID to your local development users UID & GID and avoid Docker permission issues when developing.

Parameter	Description
USER_<USERNAME>	The user's UID in /etc/passwd will be modified with new UID - Default N/A
GROUP_<GROUPNAME>	The group's GID in /etc/group and /etc/passwd will be modified with new GID - Default N/A
GROUP_ADD_<USERNAME>	The username will be added in /etc/group after the group name defined - Default N/A

Networking

The following ports are exposed.

Port	Description
1025	DEBUG_MODE & DEBUG_SMTP SMTP Catcher
8025	DEBUG_MODE & DEBUG_SMTP SMTP HTTP Viewer
10050	Zabbix Agent

Debug Mode

When using this as a base image, create statements in your startup scripts to check for existence of DEBUG_MODE=TRUE and set various parameters in your applications to output more detail, enable debugging modes, and so on. In this base image it does the following:

• Sets zabbix-agent to output logs in verbosity
• Enables MailHog mailcatcher, which replaces /usr/sbin/sendmail with it's own catchall executible. It also opens port 1025 for SMTP trapping, and you can view the messages it's trapped at port 8025

Maintenance

Shell Access

For debugging and maintenance purposes you may want access the containers shell.

docker exec -it (whatever your container name is e.g. alpine) bash

References

• https://www.alpinelinux.org