Container::Buildah Perl module for building OCI/Docker-compatible Linux containers
CPAN: https://metacpan.org/pod/Container::Buildah
Container::Buildah - wrapper around containers/buildah tool for multi-stage builds of OCI/Docker-compatible Linux containers
use <Container::Buildah>;
# configure container build stages
Container::Buildah::init_config(
basename => "swpkg",
base_image => 'docker://docker.io/alpine:[% alpine_version %]',
stages => {
build => {
from => "[% base_image %]",
func_exec => \&stage_build,
produces => [qw(/opt/swpkg-apk)],
},
runtime => {
from => "[% base_image %]",
consumes => [qw(build)],
func_exec => \&stage_runtime,
commit => ["[% basename %]:[% swpkg_version %]", "[% basename %]:latest"],
}
},
swpkg_version => "9.16.4",
);
# functions to run each stage inside their container namespaces
sub stage_build {
my $stage = shift;
# code to run inside the namespace of the build container
# set up build container and copy newly-built Alpine APK packages into /opt/swpkg-apk ...
# See Container::Buildah:Stage for the object passed to each stage function
}
sub stage_runtime {
my $stage = shift;
# code to run inside the namespace of the runtime container
# set up runtime container including installing Alpine APK packages from /opt/swpkg-apk ...
# See Container::Buildah:Stage for the object passed to each stage function
}
# Container::Buildah::main serves as script mainline including processing command-line arguments
Container::Buildah::main(); # run all the container stages
Container::Buildah allows Perl scripts to build OCI/Docker-compatible container images using the Open Source buildah command. Containers may be pipelined so the product of a build stage is consumed by one or more others.
The Container::Buildah module grew out of a wrapper script to run code inside the user namespace of a container under construction. That remains the core of its purpose. It simplifies rootless builds of containers.
Container::Buildah may be used to write a script to configure container build stages. The configuration of each build stage contains a reference to a callback function which will run inside the user namespace of the container in order to build it. The function is analagous to a Dockerfile, except that it's programmable with access to computation and the system.
The buildah command has subcommands equivalent to Dockerfile directives. For each stage of a container build, Container::Buildah creates a Container::Buildah::Stage object and passes it to the callback function for that stage. There are wrapper methods in Container::Buildah::Stage for subcommands of buildah which take a container name as a parameter.
The Container::Buildah module has one singleton instance per program. It contains configuration data for a container build process. The data is similar to what would be in a Dockerfile, except this module makes it scriptable.
prints a list of strings to STDERR, if debugging is set to level 1 or higher.
Prints a list of strings to STDERR, if debugging is at the specified level. If the first argument is a HASH reference, it is used for key/value parameters. The recognized parameters are =over =item "name" for the name of the caller function, defaults to the name from the Perl call stack =item "level" for the minimum debugging level to print the message =item "label" for an additional label string to enclose in brackets, such as a container name =back
Return integer value of debug level
Take an integer value parameter to set the debug level. A level of 0 means debugging is turned off. The default is 0.
Please report bugs via GitHub at https://github.com/ikluft/Container-Buildah/issues
Patches and enhancements may be submitted via a pull request at https://github.com/ikluft/Container-Buildah/pulls
Containers can only be run with a Linux kernel revision 2.8 or newer.
Ian Kluft <https://github.com/ikluft>
This software is Copyright (c) 2020 by Ian Kluft.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004