Alien::Build(3p)

NAME
Alien::Build - Build external dependencies for use in CPAN

VERSION
version 2.84

SYNOPSIS
 my $build = Alien::Build->load('./alienfile');
 $build->load_requires('configure');
 $build->set_prefix('/usr/local');
 $build->set_stage('/foo/mystage');  # needs to be absolute
 $build->load_requires($build->install_type);
 $build->download;
 $build->build;
 # files are now in /foo/mystage, it is your job (or
 # ExtUtils::MakeMaker, Module::Build, etc) to copy
 # those files into /usr/local

DESCRIPTION
This module provides tools for building external (non-CPAN) dependencies for CPAN. It is mainly designed to be used at install time of a CPAN client, and work closely with Alien::Base which is used at runtime.

This is the detailed documentation for the Alien::Build class. If you are starting out you probably want to do so from one of these documents:

Alien::Build::Manual::Alien
    A broad overview of "Alien-Build" and its ecosystem.

Alien::Build::Manual::AlienUser
    For users of an "Alien::libfoo" that is implemented using Alien::Base. (The developer of "Alien::libfoo" should provide the documentation necessary, but if not, this is the place to start).

Alien::Build::Manual::AlienAuthor
    If you are writing your own Alien based on Alien::Build and Alien::Base.

Alien::Build::Manual::FAQ
    If you have a common question that has already been answered, like "How do I use alienfile with some build system".

Alien::Build::Manual::PluginAuthor
    This is for the brave souls who want to write plugins that will work with Alien::Build + alienfile.

Alien::Build::Manual::Security
    If you are concerned that Aliens might be downloading tarballs off the internet, then this is the place for you. This will discuss some of the risks of downloading (really any) software off the internet and will give you some tools to remediate these risks.

Note that you will not usually create a Alien::Build instance directly, but rather be using a thin installer layer, such as Alien::Build::MM (for use with ExtUtils::MakeMaker) or Alien::Build::MB (for use with Module::Build). One of the goals of this project is to remain installer agnostic.

CONSTRUCTORS

  new
 my $build = Alien::Build->new;

This creates a new empty instance of Alien::Build. Normally you will want to use "load" below to create an instance of Alien::Build from an alienfile recipe.

  load
 my $build = Alien::Build->load($alienfile);

This creates an Alien::Build instance with the given alienfile recipe.

  resume
 my $build = Alien::Build->resume($alienfile, $root);

Load a checkpointed Alien::Build instance. You will need the original alienfile and the build root (usually "_alien"), and a build that had been properly checkpointed using the "checkpoint" method below.

PROPERTIES
There are three main properties for Alien::Build. There are a number of properties documented here with a specific usage. Note that these properties may need to be serialized into something primitive like JSON that does not support: regular expressions, code references of blessed objects.

If you are writing a plugin (Alien::Build::Plugin) you should use a prefix like "plugin_name" (where name is the name of your plugin) so that it does not interfere with other plugin or future versions of Alien::Build. For example, if you were writing "Alien::Build::Plugin::Fetch::NewProtocol", please use the prefix "plugin_fetch_newprotocol":

 sub init
 {
   my($self, $meta) = @_;

   $meta->prop( plugin_fetch_newprotocol_foo => 'some value' );

   $meta->register_hook(
     some_hook => sub {
       my($build) = @_;
       $build->install_prop->{plugin_fetch_newprotocol_bar} = 'some other value';
       $build->runtime_prop->{plugin_fetch_newprotocol_baz} = 'and another value';
     }
   );
 }

If you are writing a alienfile recipe please use the prefix "my_":

 use alienfile;

 meta_prop->{my_foo} = 'some value';

 probe sub {
   my($build) = @_;
   $build->install_prop->{my_bar} = 'some other value';
   $build->install_prop->{my_baz} = 'and another value';
 };

Any property may be used from a command:

 probe [ 'some command %{.meta.plugin_fetch_newprotocol_foo}' ];
 probe [ 'some command %{.install.plugin_fetch_newprotocol_bar}' ];
 probe [ 'some command %{.runtime.plugin_fetch_newprotocol_baz}' ];
 probe [ 'some command %{.meta.my_foo}' ];
 probe [ 'some command %{.install.my_bar}' ];
 probe [ 'some command %{.runtime.my_baz}' ];

  meta_prop
 my $href = $build->meta_prop;
 my $href = Alien::Build->meta_prop;

Meta properties have to do with the recipe itself, and not any particular instance that probes or builds that recipe. Meta properties can be changed from within an alienfile using the "meta_prop" directive, or from a plugin from its "init" method (though should NOT be modified from any hooks registered within that "init" method). This is not strictly enforced, but if you do not follow this rule your recipe will likely be broken.

arch
    This is a hint to an installer like Alien::Build::MM or Alien::Build::MB, that the library or tool contains architecture dependent files and so should be stored in an architecture dependent location. If not specified by your alienfile then it will be set to true.

check_digest
    True if cryptographic digest should be checked when files are fetched or downloaded. This is set by Digest negotiator plugin.

destdir
    Some plugins (Alien::Build::Plugin::Build::Autoconf for example) support installing via "DESTDIR". They will set this property to true if they plan on doing such an install. This helps Alien::Build find the staged install files and how to locate them.

    If available, "DESTDIR" is used to stage install files in a sub directory before copying the files into "blib". This is generally preferred method if available.

destdir_filter
    Regular expression for the files that should be copied from the "DESTDIR" into the stage directory. If not defined, then all files will be copied.

destdir_ffi_filter
    Same as "destdir_filter" except applies to "build_ffi" instead of "build".

digest
    This properties contains the cryptographic digests (if any) that should be used when verifying any fetched and downloaded files. It is a hash reference where the key is the filename and the value is an array reference containing a pair of values, the first being the algorithm ('SHA256' is recommended) and the second is the actual digest. The special filename "*" may be specified to indicate that any downloaded file should match that digest. If there are both real filenames and the "*" placeholder, the real filenames will be used for filenames that match and any other files will use the placeholder. Example:

     $build->meta_prop->{digest} = {
       'foo-1.00.tar.gz' => [ SHA256 => '9feac593aa49a44eb837de52513a57736457f1ea70078346c60f0bfc5f24f2c1' ],
       'foo-1.01.tar.gz' => [ SHA256 => '6bbde6a7f10ae5924cf74afc26ff5b7bc4b4f9dfd85c6b534c51bd254697b9e7' ],
       '*'               => [ SHA256 => '33a20aae3df6ecfbe812b48082926d55391be4a57d858d35753ab1334b9fddb3' ],
     };

    Cryptographic signatures will only be checked if the check_digest meta property is set and if the Digest negotiator plugin is loaded. (The Digest negotiator can be used directly, but is also loaded automatically if you use the digest directive is used by the alienfile).

env Environment variables to override during the build stage.

env_interpolate
    Environment variable values will be interpolated with helpers. Example:

     meta->prop->{env_interpolate} = 1;
     meta->prop->{env}->{PERL} = '%{perl}';

local_source
    Set to true if source code package is available locally. (that is not fetched over the internet). This is computed by default based on the "start_url" property. Can be set by an alienfile or plugin.

platform
    Hash reference. Contains information about the platform beyond just $^O.

    platform.compiler_type
        Refers to the type of flags that the compiler accepts. May be expanded in the future, but for now, will be one of:

        microsoft
            On Windows when using Microsoft Visual C++

        unix
            Virtually everything else, including gcc on windows.

        The main difference is that with Visual C++ "-LIBPATH" should be used instead of "-L", and static libraries should have the ".LIB" suffix instead of ".a".

    platform.system_type
        $^O is frequently good enough to make platform specific logic in your alienfile, this handles the case when $^O can cover platforms that provide multiple environments that Perl might run under. The main example is windows, but others may be added in the future.

        unix
        vms
        windows-activestate
        windows-microsoft
        windows-mingw
        windows-strawberry
        windows-unknown

        Note that "cygwin" and "msys" are considered "unix" even though they run on windows!

    platform.cpu.count
        Contains a non-negative integer of available (possibly virtual) CPUs on the system. This can be used by build plugins to build in parallel. The environment variable "ALIEN_CPU_COUNT" can be set to override the CPU count.

    platform.cpu.arch.name
        Contains a normalized name for the architecture of the current Perl. This can be used by fetch plugins to determine which binary packages to download. The value may be one of the following, but this list will be expanded as needed.

        "armel"
            32-bit ARM soft-float

        "armhf"
            32-bit ARM hard-float

        "aarch64"
            64-bit ARM

        "ppc"
            32-bit PowerPC (big-endian)

        "ppc64"
            64-bit PowerPC (big-endian)

        "x86"
            32-bit Intel (i386, i486, i686)

        "x86_64"
            64-bit Intel (AMD64)

        "unknown"
            Unable to detect architecture. Please report this if needed.

out_of_source
    Build in a different directory from the where the source code is stored. In autoconf this is referred to as a "VPATH" build. Everyone else calls this an "out-of-source" build. When this property is true, instead of extracting to the source build root, the downloaded source will be extracted to an source extraction directory and the source build root will be empty. You can use the "extract" install property to get the location of the extracted source.

network
    True if a network fetch is available. This should NOT be set by an alienfile or plugin. This is computed based on the "ALIEN_INSTALL_NETWORK" environment variables.

start_url
    The default or start URL used by fetch plugins.

  install_prop
 my $href = $build->install_prop;

Install properties are used during the install phase (either under "share" or "system" install). They are remembered for the entire install phase, but not kept around during the runtime phase. Thus they cannot be accessed from your Alien::Base based module.

autoconf_prefix
    The prefix as understood by autoconf. This is only different on Windows Where MSYS is used and paths like "C:/foo" are represented as "/C/foo" which are understood by the MSYS tools, but not by Perl. You should only use this if you are using Alien::Build::Plugin::Build::Autoconf in your alienfile. This is set during before the build hook is run.

download
    The location of the downloaded archive (tar.gz, or similar) or directory. This will be undefined until the archive is actually downloaded.

download_detail
    This property contains optional details about a downloaded file. This property is populated by Alien::Build core. This property is a hash reference. The key is the path to the file that has been downloaded and the value is a hash reference with additional detail. All fields are optional.

    download_detail.digest
        This, if available, with the cryptographic signature that was successfully matched against the downloaded file. It is an array reference with a pair of values, the algorithm (typically something like "SHA256") and the digest.

    download_detail.protocol
        This, if available, will be the URL protocol used to fetch the downloaded file.

env Environment variables to override during the build stage. Plugins are free to set additional overrides using this hash.

extract
    The location of the last source extraction. For a "out-of-source" build (see the "out_of_source" meta property above), this will only be set once. For other types of builds, the source code may be extracted multiple times, and thus this property may change.

old [deprecated]

    Hash containing information on a previously installed Alien of the same name, if available. This may be useful in cases where you want to reuse the previous install if it is still sufficient.

    old.prefix
        [deprecated]

        The prefix for the previous install. Versions prior to 1.42 unfortunately had this in typo form of "preifx".

    old.runtime
        [deprecated]

        The runtime properties from the previous install.

patch
    Directory with patches, if available. This will be "undef" if there are no patches. When initially installing an alien this will usually be a sibling of the "alienfile", a directory called "patch". Once installed this will be in the share directory called "_alien/patch". The former is useful for rebuilding an alienized package using af.

prefix
    The install time prefix. Under a "destdir" install this is the same as the runtime or final install location. Under a non-"destdir" install this is the "stage" directory (usually the appropriate share directory under "blib").

root
    The build root directory. This will be an absolute path. It is the absolute form of "./_alien" by default.

stage
    The stage directory where files will be copied. This is usually the root of the blib share directory.

system_probe_class
    After the probe step this property may contain the plugin class that performed the system probe. It shouldn't be filled in directly by the plugin (instead if should use the hook property "probe_class", see below). This is optional, and not all probe plugins will provide this information.

system_probe_instance_id
    After the probe step this property may contain the plugin instance id that performed the system probe. It shouldn't be filled in directly by the plugin (instead if should use the hook property "probe_instance_id", see below). This is optional, and not all probe plugins will provide this information.

  plugin_instance_prop
 my $href = $build->plugin_instance_prop($plugin);

This returns the private plugin instance properties for a given plugin. This method should usually only be called internally by plugins themselves to keep track of internal state. Because the content can be used arbitrarily by the owning plugin because it is private to the plugin, and thus is not part of the Alien::Build spec.

  runtime_prop
 my $href = $build->runtime_prop;

Runtime properties are used during the install and runtime phases (either under "share" or "system" install). This should include anything that you will need to know to use the library or tool during runtime, and shouldn't include anything that is no longer relevant once the install process is complete.

alien_build_version
    The version of Alien::Build used to install the library or tool.

alt Alternate configurations. If the alienized package has multiple libraries this could be used to store the different compiler or linker flags for each library. Typically this will be set by a plugin in the gather stage (for either share or system installs).

cflags
    The compiler flags. This is typically set by a plugin in the gather stage (for either share or system installs).

cflags_static
    The static compiler flags. This is typically set by a plugin in the gather stage (for either share or system installs).

command
    The command name for tools where the name my differ from platform to platform. For example, the GNU version of make is usually "make" in Linux and "gmake" on FreeBSD. This is typically set by a plugin in the gather stage (for either share or system installs).

ffi_name
    The name DLL or shared object "name" to use when searching for dynamic libraries at runtime. This is passed into FFI::CheckLib, so if your library is something like "libarchive.so" or "archive.dll" you would set this to "archive". This may be a string or an array of strings. This is typically set by a plugin in the gather stage (for either share or system installs).

ffi_checklib
    This property contains two sub properties:

    ffi_checklib.share
         $build->runtime_prop->{ffi_checklib}->{share} = [ ... ];

        Array of additional FFI::CheckLib flags to pass in to "find_lib" for a "share" install.

    ffi_checklib.system
        Array of additional FFI::CheckLib flags to pass in to "find_lib" for a "system" install.

        Among other things, useful for specifying the "try_linker_script" flag:

         $build->runtime_prop->{ffi_checklib}->{system} = [ try_linker_script => 1 ];

    This is typically set by a plugin in the gather stage (for either share or system installs).

inline_auto_include
    [version 2.53]

    This property is an array reference of C code that will be passed into Inline::C to make sure that appropriate headers are automatically included. See "auto_include" in Inline::C for details.

install_type
    The install type. This is set by AB core after the probe hook is executed. Is one of:

    system
        For when the library or tool is provided by the operating system, can be detected by Alien::Build, and is considered satisfactory by the "alienfile" recipe.

    share
        For when a system install is not possible, the library source will be downloaded from the internet or retrieved in another appropriate fashion and built.

libs
    The library flags. This is typically set by a plugin in the gather stage (for either share or system installs).

libs_static
    The static library flags. This is typically set by a plugin in the gather stage (for either share or system installs).

perl_module_version
    The version of the Perl module used to install the alien (if available). For example if Alien::curl is installing "libcurl" this would be the version of Alien::curl used during the install step.

prefix
    The final install root. This is usually they share directory.

version
    The version of the library or tool. This is typically set by a plugin in the gather stage (for either share or system installs).

  hook_prop
 my $href = $build->hook_prop;

Hook properties are for the currently running (if any) hook. They are used only during the execution of each hook and are discarded after. If no hook is currently running then "hook_prop" will return "undef".

name
    The name of the currently running hook.

version (probe)
    Probe and PkgConfig plugins may set this property indicating the version of the alienized package. Not all plugins and configurations may be able to provide this.

probe_class (probe)
    Probe and PkgConfig plugins may set this property indicating the plugin class that made the probe. If the probe results in a system install this will be propagated to "system_probe_class" for later use.

probe_instance_id (probe)
    Probe and PkgConfig plugins may set this property indicating the plugin instance id that made the probe. If the probe results in a system install this will be propagated to "system_probe_instance_id" for later use.

METHODS

  checkpoint
 $build->checkpoint;

Save any install or runtime properties so that they can be reloaded on a subsequent run in a separate process. This is useful if your build needs to be done in multiple stages from a "Makefile", such as with ExtUtils::MakeMaker. Once checkpointed you can use the "resume" constructor (documented above) to resume the probe/build/install] process.

  root
 my $dir = $build->root;

This is just a shortcut for:

 my $root = $build->install_prop->{root};

Except that it will be created if it does not already exist.

  install_type
 my $type = $build->install_type;

This will return the install type. (See the like named install property above for details). This method will call "probe" if it has not already been called.

  is_system_install
 my $boolean = $build->is_system_install;

Returns true if the alien is a system install type.

  is_share_install
 my $boolean = $build->is_share_install;

Returns true if the alien is a share install type.

  download_rule
 my $rule = $build->download_rule;

This returns install rule as a string. This is determined by the environment and should be one of:

"warn"
    Warn only if fetching via non secure source (secure sources include "https", and bundled files, may include other encrypted protocols in the future).

"digest"
    Require that any downloaded source package have a cryptographic signature in the alienfile and that signature matches what was downloaded.

"encrypt"
    Require that any downloaded source package is fetched via secure source.

"digest_or_encrypt"
    Require that any downloaded source package is either fetched via a secure source or has a cryptographic signature in the alienfile and that signature matches what was downloaded.

"digest_and_encrypt"
    Require that any downloaded source package is both fetched via a secure source and has a cryptographic signature in the alienfile and that signature matches what was downloaded.

The current default is "warn", but in the near future this will be upgraded to "digest_or_encrypt".

  set_prefix
 $build->set_prefix($prefix);

Set the final (unstaged) prefix. This is normally only called by Alien::Build::MM and similar modules. It is not intended for use from plugins or from an alienfile.

  set_stage
 $build->set_stage($dir);

Sets the stage directory. This is normally only called by Alien::Build::MM and similar modules. It is not intended for use from plugins or from an alienfile.

  requires
 my $hash = $build->requires($phase);

Returns a hash reference of the modules required for the given phase. Phases include:

configure
    These modules must already be available when the alienfile is read.

any These modules are used during either a "system" or "share" install.

share
    These modules are used during the build phase of a "share" install.

system
    These modules are used during the build phase of a "system" install.

  load_requires
 $build->load_requires($phase);

This loads the appropriate modules for the given phase (see "requires" above for a description of the phases).

  probe
 my $install_type = $build->probe;

Attempts to determine if the operating system has the library or tool already installed. If so, then the string "system" will be returned and a system install will be performed. If not, then the string "share" will be installed and the tool or library will be downloaded and built from source.

If the environment variable "ALIEN_INSTALL_TYPE" is set, then that will force a specific type of install. If the detection logic cannot accommodate the install type requested then it will fail with an exception.

  download
 $build->download;

Download the source, usually as a tarball, usually from the internet.

Under a "system" install this does not do anything.

  fetch
 my $res = $build->fetch;
 my $res = $build->fetch($url, %options);

Fetch a resource using the fetch hook. Returns the same hash structure described below in the fetch hook documentation.

[version 2.39]

As of Alien::Build 2.39, these options are supported:

http_headers
     my $res = $build->fetch($url, http_headers => [ $key1 => $value1, $key2 => $value 2, ... ]);

    Set the HTTP request headers on all outgoing HTTP requests. Note that not all protocols or fetch plugins support setting request headers, but the ones that do not should issue a warning if you try to set request headers and they are not supported.

  check_digest
[experimental]

 my $bool = $build->check_digest($path);

Checks any cryptographic signatures for the given file. The file is specified by $path which may be one of:

string
    Containing the path to the file to be checked.

Path::Tiny
    Containing the path to the file to be checked.

"HASH"
    A Hash reference containing information about a file. See the fetch hook for details on the format.

Returns true if the cryptographic signature matches, false if cryptographic signatures are disabled. Will throw an exception if the signature does not match, or if no plugin provides the correct algorithm for checking the signature.

  decode
 my $decoded_res = $build->decode($res);

Decode the HTML or file listing returned by "fetch". Returns the same hash structure described below in the decode hook documentation.

  prefer
 my $sorted_res = $build->prefer($res);

Filter and sort candidates. The preferred candidate will be returned first in the list. The worst candidate will be returned last. Returns the same hash structure described below in the prefer hook documentation.

  extract
 my $dir = $build->extract;
 my $dir = $build->extract($archive);

Extracts the given archive into a fresh directory. This is normally called internally to Alien::Build, and for normal usage is not needed from a plugin or alienfile.

  build
 $build->build;

Run the build step. It is expected that "probe" and "download" have already been performed. What it actually does depends on the type of install:

share
    The source is extracted, and built as determined by the alienfile recipe. If there is a "gather_share" that will be executed last.

system
    The gather_system hook will be executed.

  test
 $build->test;

Run the test phase

  clean_install
 $build->clean_install

Clean files from the final install location. The default implementation removes all files recursively except for the "_alien" directory. This is helpful when you have an old install with files that may break the new build.

For a non-share install this doesn't do anything.

  system
 $build->system($command);
 $build->system($command, @args);

Interpolates the command and arguments and run the results using the Perl "system" command.

  log
 $build->log($message);

Send a message to the log. By default this prints to "STDOUT".

  meta
 my $meta = Alien::Build->meta;
 my $meta = $build->meta;

Returns the meta object for your Alien::Build class or instance. The meta object is a way to manipulate the recipe, and so any changes to the meta object should be made before the "probe", "download" or "build" steps.

META METHODS

  prop
 my $href = $build->meta->prop;

Meta properties. This is the same as calling "meta_prop" on the class or Alien::Build instance.

  add_requires
 Alien::Build->meta->add_requires($phase, $module => $version, ...);

Add the requirement to the given phase. Phase should be one of:

configure
any
share
system

  interpolator
 my $interpolator = $build->meta->interpolator;
 my $interpolator = Alien::Build->interpolator;

Returns the Alien::Build::Interpolate instance for the Alien::Build class.

  has_hook
 my $bool = $build->meta->has_hook($name);
 my $bool = Alien::Build->has_hook($name);

Returns if there is a usable hook registered with the given name.

  register_hook
 $build->meta->register_hook($name, $instructions);
 Alien::Build->meta->register_hook($name, $instructions);

Register a hook with the given name. $instruction should be either a code reference, or a command sequence, which is an array reference.

  default_hook
 $build->meta->default_hook($name, $instructions);
 Alien::Build->meta->default_hook($name, $instructions);

Register a default hook, which will be used if the alienfile does not register its own hook with that name.

  around_hook
 $build->meta->around_hook($hook_name, $code);
 Alien::Build->meta->around_hook($hook_name, $code);

Wrap the given hook with a code reference. This is similar to a Moose method modifier, except that it wraps around the given hook instead of a method. For example, this will add a probe system requirement:

 $build->meta->around_hook(
   probe => sub {
     my $orig = shift;
     my $build = shift;
     my $type = $orig->($build, @_);
     return $type unless $type eq 'system';
     # also require a configuration file
     if(-f '/etc/foo.conf')
     {
       return 'system';
     }
     else
     {
       return 'share';
     }
   },
 );

  after_hook
 $build->meta->after_hook($hook_name, sub {
   my(@args) = @_;
   ...
 });

Execute the given code reference after the hook. The original arguments are passed into the code reference.

  before_hook
 $build->meta->before_hook($hook_name, sub {
   my(@args) = @_;
   ...
 });

Execute the given code reference before the hook. The original arguments are passed into the code reference.

  apply_plugin
 Alien::Build->meta->apply_plugin($name);
 Alien::Build->meta->apply_plugin($name, @args);

Apply the given plugin with the given arguments.

ENVIRONMENT
Alien::Build responds to these environment variables:

ALIEN_BUILD_LOG
    The default log class used. See Alien::Build::Log and Alien::Build::Log::Default.

ALIEN_BUILD_PKG_CONFIG
    Override the logic in Alien::Build::Plugin::PkgConfig::Negotiate which chooses the best "pkg-config" plugin.

ALIEN_BUILD_POSTLOAD
    semicolon separated list of plugins to automatically load after parsing your alienfile.

ALIEN_BUILD_PRELOAD
    semicolon separated list of plugins to automatically load before parsing your alienfile.

ALIEN_BUILD_RC
    Perl source file which can override some global defaults for Alien::Build, by, for example, setting preload and postload plugins.

ALIEN_DOWNLOAD_RULE
    This value determines the rules by which types of downloads are allowed. The legal values listed under "download_rule", plus "default" which will be the default for the current version of Alien::Build. For this version that default is "warn".

ALIEN_INSTALL_NETWORK
    If set to true (the default), then network fetch will be allowed. If set to false, then network fetch will not be allowed.

    What constitutes a local vs. network fetch is determined based on the "start_url" and "local_source" meta properties. An alienfile or plugin "could" override this detection (possibly inappropriately), so this variable is not a substitute for properly auditing of Perl modules for environments that require that.

ALIEN_INSTALL_TYPE
    If set to "share" or "system", it will override the system detection logic. If set to "default", it will use the default setting for the alienfile. The behavior of other values is undefined.

    Although the recommended way for a consumer to use an Alien::Base based Alien is to declare it as a static configure and build-time dependency, some consumers may prefer to fallback on using an Alien only when the consumer itself cannot detect the necessary package. In some cases the consumer may want the user to opt-in to using an Alien before requiring it.

    To keep the interface consistent among Aliens, the consumer of the fallback opt-in Alien may fallback on the Alien if the environment variable "ALIEN_INSTALL_TYPE" is set to any value. The rationale is that by setting this environment variable the user is aware that Alien modules may be installed and have indicated consent. The actual implementation of this, by its nature would have to be in the consuming CPAN module.

DESTDIR
    This environment variable will be manipulated during a destdir install.

PKG_CONFIG
    This environment variable can be used to override the program name for "pkg-config" when using the command line plugin: Alien::Build::Plugin::PkgConfig::CommandLine.

ftp_proxy, all_proxy
    If these environment variables are set, it may influence the Download negotiation plugin Alien::Build::Plugin::Download::Negotiate. Other proxy variables may be used by some Fetch plugins, if they support it.

SUPPORT
The intent of the "Alien-Build" team is to support the same versions of Perl that are supported by the Perl toolchain. As of this writing that means 5.16 and better.

Please feel encouraged to report issues that you encounter to the project GitHub Issue tracker:

<https://github.com/PerlAlien/Alien-Build/issues>

Better if you can fix the issue yourself, please feel encouraged to open pull-request on the project GitHub:

<https://github.com/PerlAlien/Alien-Build/pulls>

If you are confounded and have questions, join us on the "#native" channel on irc.perl.org. The "Alien-Build" developers frequent this channel and can probably help point you in the right direction. If you don't have an IRC client handy, you can use this web interface:

<https://chat.mibbit.com/?channel=%23native&server=irc.perl.org>

SEE ALSO
Alien::Build::Manual::AlienAuthor, Alien::Build::Manual::AlienUser, Alien::Build::Manual::Contributing, Alien::Build::Manual::FAQ, Alien::Build::Manual::PluginAuthor

alienfile, Alien::Build::MM, Alien::Build::Plugin, Alien::Base, Alien

THANKS
Alien::Base was originally written by Joel Berger, the rest of this project would not have been possible without him getting the project started. Thanks to his support I have been able to augment the original Alien::Base system with a reliable set of tools (Alien::Build, alienfile, Test::Alien), which make up this toolset.

The original Alien::Base is still copyright (c) 2012-2020 Joel Berger. It has the same license as the rest of the Alien::Build and related tools distributed as "Alien-Build". Joel Berger thanked a number of people who helped in in the development of Alien::Base, in the documentation for that module.

I would also like to acknowledge the other members of the PerlAlien github organization, Zakariyya Mughal (sivoais, ZMUGHAL) and mohawk (ETJ). Also important in the early development of Alien::Build were the early adopters Chase Whitener (genio, CAPOEIRAB, author of Alien::libuv), William N. Braswell, Jr (willthechill, WBRASWELL, author of Alien::JPCRE2 and Alien::PCRE2) and Ahmad Fatoum (a3f, ATHREEF, author of Alien::libudev and Alien::LibUSB).

The Alien ecosystem owes a debt to Dan Book, who goes by Grinnz on IRC, for answering question about how to use Alien::Build and friends.

AUTHOR
Author: Graham Ollis <plicease@cpan.org>

Contributors:

Diab Jerius (DJERIUS)

Roy Storey (KIWIROY)

Ilya Pavlov

David Mertens (run4flat)

Mark Nunberg (mordy, mnunberg)

Christian Walde (Mithaldu)

Brian Wightman (MidLifeXis)

Zaki Mughal (zmughal)

mohawk (mohawk2, ETJ)

Vikas N Kumar (vikasnkumar)

Flavio Poletti (polettix)

Salvador Fandiño (salva)

Gianni Ceccarelli (dakkar)

Pavel Shaydo (zwon, trinitum)

Kang-min Liu (劉康民, gugod)

Nicholas Shipp (nshp)

Juan Julián Merelo Guervós (JJ)

Joel Berger (JBERGER)

Petr Písař (ppisar)

Lance Wicks (LANCEW)

Ahmad Fatoum (a3f, ATHREEF)

José Joaquín Atria (JJATRIA)

Duke Leto (LETO)

Shoichi Kaji (SKAJI)

Shawn Laffan (SLAFFAN)

Paul Evans (leonerd, PEVANS)

Håkon Hægland (hakonhagland, HAKONH)

nick nauwelaerts (INPHOBIA)

Florian Weimer

COPYRIGHT AND LICENSE
This software is copyright (c) 2011-2022 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.