docker-devbox

Docker-Devbox (DDB) is a set of utilities that allow easy setup, login and teardown of Docker containers, much in the vein of Vagrant. In addition, it provides per-user container customization, systemd and shares the invoking user's account and home directory into the containers for a consistent user experience.

Important Caveats

DDB is intended for use in expendable development systems. It is not for use in production.

DDB will run Docker as the invoking user if that user is the superuser or is in the docker group. Otherwise, it will attempt to escalate to the superuser using sudo(8). If you have containers and images built as the superuser with older versions of DDB, it can be forced into the old behavior by setting the environment variable DDB_FORCE_ROOT to any non-empty value.

Containers being run as the superuser are accessible to any other user with the same rights. The separation between users provided is for convenience, not security.

Installation and Setup

Prerequisites

DDB has been tested on several distributions of Linux and macOS but should work on any operating system that can provide the following:

• A POSIX-compliant shell and standard utilities, including m4.

• functioning instance of Docker or Podman with the latter configured to behave like Docker (i.e., it responds to docker commands).

• An account that is the superuser or can become the superuser via sudo(8). For low-friction operation, it is recommended that sudo be configured to allow repeated use after providing a password or invocation of Docker (usually /bin/docker) without requiring a password.

Installation

Clone this repository into a convenient place, such as /opt/docker-devbox, which will be used in subsequent examples.

In your shell's rc (note that only Bourne-like, POSIX shells are supported), add the following:

eval $(/opt/docker-devbox/setup)

To add convenience aliases (described below):

eval $(/opt/docker-devbox/setup --aliases)

Quick Start

# Set up Docker DevBox
you@host$ eval $(/opt/docker-devbox/setup --aliases)

# Build a customized-for-you image of EL9 plus Unibuild
you@host$ ddb build el9u

# Start that image in a container
you@host$ ddb boot tester el9u
Starting tester as el9u
f245ebc74207b5485a80602e4b676bd98443cdba2bb11cb8310ac7331eba555a

# Log into the container and do your business
you@host$ ddb login tester

you@tester$ ...do things...
you@tester$ exit

# Destroy the container
you@host$ ddb halt tester

Commands

build BASE - Build a container image

The process of using DDB begins with creating a container from an existing Docker image such as almalinux:8 or debian:10. Any container that Docker can pull can be used.

The BASE parameter names one of the base containers listed in /opt/docker-devbox/etc/bases to be used as the basis for the DBB-customized container. The contents of that file may be customized as needed. Note that DDB is built to support most currently-supported variants of Red Hat and Debian Linux; running containers with other distributions will require customization.

DDB will build a new image from the base, apply its own customizations and then run the script found in ~/.ddb/prep.m4 if it exists. The file is processed using M4 with the following macros made available for making decisions about what to do:

Macro	Description	Example
__OS	Operating system as reported by uname(1)	Linux
__DISTRO	Operating system distribution, empty of not applicable	CentOS
__FAMILY	Operating system family, empty where not applicable	RedHat
__RELEASE	Operating system release	7.9.2009
__CODENAME	Codename of operating system release	Core
__MAJOR	Major version of RELEASE, empty if not present	7
__MINOR	Minor version of RELEASE, empty if not present	9
__PATCH	Patch version of RELEASE, empty if not present	2009
__PACKAGING	Type of packaging used by this system (Currently deb or rpm)	rpm
__ARCH	Machine architecture as reported by uname(1)	x86_64

A sample of this file can be found in /opt/docker-devbox/etc/prep-example.m4.

Example:

[yourlogin@host ~]$ ddb build el8

... (Much Output Deleted) ...

Complete!
COMMIT ddb__yourlogin__el8
--> 65bce79d0be
Successfully tagged localhost/ddb__yourlogin__el8:latest
65bce79d0be3049a6f955e31c4b12fefebfe64606998c4be5af0cdcf5b4f0d90

[yourlogin@host ~]$

NOTE: The actual name of the image within Docker will be ddb__USERNAME__BASE, where USERNAME is the invoking user's login and BASE is the shorthand for the base image provided when build was invoked (e.g., ddb__steveb__el8). This allows for multiple users on the same system to have their own customized containers.

User-Supplied Macros

Additional macros may be supplied to the build process two ways:

On the command line, one or more instances of --define MACRO=VALUE may be used when invoking build, e.g.:

ddb build --define FOO=bar --define BAZ=quux

In the bases file (etc/bases), macros can be defined after the name of the base image, e.g.:

nine-plus almalinux:9 FOO=bar BAZ=quux

Note: All user-defined macros are, like those provided by Unibuild, prefixed with a double underscore to prevent them from colliding with useful words (e.g., FOO will become __FOO).

boot NAME IMAGE - Start a container

Once an image has been built, it can be instantiated as a container by booting it.

Example:

[yourlogin@host ~]$ ddb boot devel el8

[yourlogin@host ~]$

Aliases:

• ddbb = ddb boot
• ddbbl = ddb boot --login

NOTE: The actual name of the Docker container will be ddb__USERNAME__NAME, where USERNAME is the invoking user's login and NAME is the NAME parameter provided when boot was invoked (e.g., ddb__steveb__devel). This allows for multiple users on the same system to have their own same-named containers.

NOTE: The container is started in privileged mode. This will change in the near future.

login NAME - Log into a container

This command starts a login shell in the container using your account.

Example:

[yourlogin@host ~]$ ddb login devel

[yourlogin@devel ~]$

... Do some things ...

[yourlogin@devel ~]$ exit

[yourlogin@host ~]$

Aliases:

• ddbl = ddb login

ps - Show a list of running containers.

This command lists the containers running on your behalf.

[yourlogin@host ~]$ ddb ps
devel
test
issue-1234

[yourlogin@host ~]$

quick IMAGE - Run an itinerant container

This command boots a container based on IMAGE, logs into it and then destroys it once the login session has exited.

Example:

[yourlogin@host ~]$ ddb ps
(No output)
[yourlogin@host ~]$ ddb quick el9u
Starting quick-GQTXmh6T from image el9u
b6067fd9d973c17b83c1ced2a8519d6ea40140eb15a438145c35be46f9707fc1
[yourlogin@quick-GQTXmh6T]$
[yourlogin@quick-GQTXmh6T]$ exit
logout
[yourlogin@host ~]$ ddb ps
(No output)
[yourlogin@host ~]$

Aliases:

• ddbq = ddb quick

halt [ --all ] NAME [ NAME ... ] - Stop and destroy a container

This command halts and destroys running containers.

If given the --all switch, all containers being run on the invoking user's behalf will be destroyed.

Example:

[yourlogin@host ~]$ ddb halt devel
Powering off.

[yourlogin@host ~]$

Aliases:

• ddbh = ddb halt

drain - Remove all DDB images and containers

This command will remove all DDB-created images and containers and will prune all dangling Docker resources if the --prune switch is present. Note that pruning may remove non-DDB resources.

Everything Else

Some of the ideas for docker-devbox came from Akihiro Suda's containerized systemd.