generate.pl: overhaul to support building slim images

Do a long-needed overhaul of this script allow building of `slim`
variants:

- Make the base image configurable through a new `builds` setting.
- Rename the `64bit` image to `main`, as bit-ness no longer applies as
  we already build on multiple architectures.
- Rename `Releases.yaml` to the more general `config.yml`, allowing it
  to contain the supported image variants and Configure options.
- Run through perltidy 💄

The `slim` variants installs the minimum build-deps needed to build
Perl, and removes them after (save for make and netbase, to retain being
able to install CPAN modules through cpanm.)

config.yml

@@ -1,39 +1,48 @@
+---
+builds:
+  - main
+  - slim
+
+options:
+  common: "-Duseshrplib -Dvendorprefix=/usr/local"
+  threaded: "-Dusethreads"
+
 releases:
   - version: 5.8.9
     sha256:  1097fbcd48ceccb2bc735d119c9db399a02a8ab9f7dc53e29e47e6a8d0d72e79
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.10.1
     sha256:  9385f2c8c2ca8b1dc4a7c31903f1f8dc8f2ba867dc2a9e5c93012ed6b564e826
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.12.5
     sha256:  10749417fd3010aae320a34181ad4cd6a4855c1fc63403b87fa4d630b18e966c
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.14.4
     sha256:  eece8c2b0d491bf6f746bd1f4f1bb7ce26f6b98e91c54690c617d7af38964745
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.16.3
     sha256:  bb7bc735e6813b177dcfccd480defcde7eddefa173b5967eac11babd1bfa98e8
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.18.4
     sha256:  1fb4d27b75cd244e849f253320260efe1750641aaff4a18ce0d67556ff1b96a5
     extra_flags: "-A ccflags=-fwrapv"
     test_parallel: no
-    buildpack_deps: jessie
+    debian_release: jessie
 
   - version: 5.20.3
     sha256:  1b40068166c242e34a536836286e70b78410602a80615143301e52aa2901493b

generate.pl

@@ -9,23 +9,68 @@ use LWP::Simple;
 sub die_with_sample {
   die <<EOF;
 
-The Releases.yaml file must look roughly like:
+The config.yml file must look roughly like:
+
+    ---
+    builds:
+      - main
+      - slim
+
+    options:
+      common: "-Duseshrplib -Dvendorprefix=/usr/local"
+      threaded: "-Dusethreads"
 
     releases:
       - version: 5.20.0
         sha256:  asdasdadas
 
-Where version is the version number of Perl and sha256 is the SHA256 of
+Where "version" is the version number of Perl and "sha256" is the SHA256
-the tar.bz2 file.
+of the Perl distribution tarball.
 
 If needed or desired, extra_flags: can be added, which will be passed
 verbatim to Configure.
 
+Run "perldoc ./generate.pl" to read the complete documentation.
+
 EOF
 }
 
-my $yaml = do {
+my $docker_slim_run_install = <<'EOF';
-  open my $fh, "<", "Releases.yaml" or die "Couldn't open releases";
+apt-get update \
+    && apt-get install -y --no-install-recommends \
+       bzip2 \
+       ca-certificates \
+       # cpio \
+       curl \
+       dpkg-dev \
+       # file \
+       gcc \
+       # g++ \
+       # libbz2-dev \
+       # libdb-dev \
+       libc6-dev \
+       # libgdbm-dev \
+       # liblzma-dev \
+       make \
+       netbase \
+       patch \
+       # procps \
+       # zlib1g-dev \
+       xz-utils
+EOF
+chomp $docker_slim_run_install;
+
+my $docker_slim_run_purge = <<'EOF';
+savedPackages="make netbase" \
+    && apt-mark auto '.*' > /dev/null \
+    && apt-mark manual $savedPackages \
+    && apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+    && rm -fr /var/cache/apt/* /var/lib/apt/lists/*
+EOF
+chomp $docker_slim_run_purge;
+
+my $config = do {
+  open my $fh, '<', 'config.yml' or die "Couldn't open config";
   local $/;
   Load <$fh>;
 };
@@ -35,15 +80,7 @@ my $template = do {
   <DATA>;
 };
 
-my $common = join " ", qw{
+my %builds;
--Duseshrplib
--Dvendorprefix=/usr/local
-};
-
-my %builds = (
-  "64bit"          => "$common",
-  "64bit,threaded" => "-Dusethreads $common",
-);
 
 # sha256 taken from http://www.cpan.org/authors/id/M/MI/MIYAGAWA/CHECKSUMS
 my %cpanm = (
@@ -52,15 +89,21 @@ my %cpanm = (
   sha256 => "9b60767fe40752ef7a9d3f13f19060a63389a5c23acc3e9827e19b75500f81f3",
 );
 
-die_with_sample unless defined $yaml->{releases};
+die_with_sample unless defined $config->{releases};
-die_with_sample unless ref $yaml->{releases} eq "ARRAY";
+die_with_sample unless ref $config->{releases} eq "ARRAY";
 
 if (!-d "downloads") {
   mkdir "downloads" or die "Couldn't create a downloads directory";
 }
 
-for my $release (@{$yaml->{releases}}) {
+for my $build (@{$config->{builds}}) {
-  do { die_with_sample unless $release->{$_}} for (qw(version sha256));
+  $builds{$build} = $config->{options}{common};
+  $builds{"$build,threaded"} = "@{$config->{options}}{qw/threaded common/}";
+}
+
+for my $release (@{$config->{releases}}) {
+  do { die_with_sample unless $release->{$_} }
+    for (qw(version sha256));
 
   die "Bad version: $release->{version}" unless $release->{version} =~ /\A5\.\d+\.\d+\Z/;
 
@@ -68,10 +111,10 @@ for my $release (@{$yaml->{releases}}) {
   $release->{type} ||= 'bz2';
   my $file = "perl-$release->{version}.tar.$release->{type}";
   my $url  = "https://www.cpan.org/src/5.0/$file";
-  if (-f "downloads/$file" &&
+  if (-f "downloads/$file" && `sha256sum downloads/$file` =~ /^\Q$release->{sha256}\E\s+\Qdownloads\/$file\E/) {
-    `sha256sum downloads/$file` =~ /^\Q$release->{sha256}\E\s+\Qdownloads\/$file\E/) {
     print "Skipping download of $file, already current\n";
-  } else {
+  }
+  else {
     print "Downloading $url\n";
     getstore($url, "downloads/$file");
   }
@@ -95,20 +138,37 @@ for my $release (@{$yaml->{releases}}) {
     die "Couldn't create a Devel::PatchPerl patch for $release->{version}" if $? != 0;
   }
 
+  for my $build (keys %builds) {
     $release->{url} = $url;
-  $release->{extra_flags} = "" unless defined $release->{extra_flags};
-  $release->{_tag} = $release->{buildpack_deps} || "stretch";
     $release->{"cpanm_dist_$_"} = $cpanm{$_} for keys %cpanm;
 
-  for my $config (keys %builds) {
+    $release->{extra_flags}    ||= '';
+    $release->{debian_release} ||= 'stretch';
+
+    if ($build =~ /main/) {
+      $release->{image} = 'buildpack-deps';
+      $release->{tag}   = $release->{debian_release};
+    }
+    else {
+      $release->{image} = 'debian';
+      $release->{tag}   = "@{[ $release->{debian_release} ]}-slim";
+    }
+
     my $output = $template;
     $output =~ s/\{\{$_\}\}/$release->{$_}/mg
-        for (qw(version pause extra_flags sha256 type url _tag cpanm_dist_name cpanm_dist_url cpanm_dist_sha256));
+      for (qw(version pause extra_flags sha256 type url image tag cpanm_dist_name cpanm_dist_url cpanm_dist_sha256));
-    $output =~ s/\{\{args\}\}/$builds{$config}/mg;
+    $output =~ s/\{\{args\}\}/$builds{$build}/mg;
 
-    my $dir = sprintf "%i.%03i.%03i-%s",
+    if ($build =~ /slim/) {
-                      ($release->{version} =~ /(\d+)\.(\d+)\.(\d+)/),
+      $output =~ s/\{\{docker_slim_run_install\}\}/$docker_slim_run_install/mg;
-                      $config;
+      $output =~ s/\{\{docker_slim_run_purge\}\}/$docker_slim_run_purge/mg;
+    }
+    else {
+      $output =~ s/\{\{docker_slim_run_install\}\}/true/mg;
+      $output =~ s/\{\{docker_slim_run_purge\}\}/true/mg;
+    }
+
+    my $dir = sprintf "%i.%03i.%03i-%s", ($release->{version} =~ /(\d+)\.(\d+)\.(\d+)/), $build;
 
     mkdir $dir unless -d $dir;
 
@@ -120,9 +180,11 @@ for my $release (@{$yaml->{releases}}) {
 
     if (defined $release->{test_parallel} && $release->{test_parallel} eq "no") {
       $output =~ s/\{\{test\}\}/make test_harness/;
-    } elsif (!defined $release->{test_parallel} || $release->{test_parallel} eq "yes") {
+    }
+    elsif (!defined $release->{test_parallel} || $release->{test_parallel} eq "yes") {
       $output =~ s/\{\{test\}\}/TEST_JOBS=\$(nproc) make test_harness/;
-    } else {
+    }
+    else {
       die "test_parallel was provided for $release->{version} but is invalid; should be 'yes' or 'no'\n";
     }
 
@@ -136,17 +198,18 @@ for my $release (@{$yaml->{releases}}) {
 
 =head1 NAME
 
-generate.pl
+generate.pl - generate Dockerfiles for Perl
 
 =head1 SYNOPSIS
 
-generate.pl is a little helper script to reinitalize the Dockerfiles from a YAML file.
+    cd /path/to/docker-perl
+    ./generate.pl
 
 =head1 DESCRIPTION
 
-generate.pl is meant to be run from the actual repo directory, with a Releases.yaml file
+generate.pl is meant to be run from the actual repo directory, with a
-correctly configured.  It starts with a 'releases' key, which contains a list of releases,
+config.yml file correctly configured.  It contains with a 'releases'
-each with the following keys:
+key, which contains a list of releases, each with the following keys:
 
 =over 4
 
@@ -160,23 +223,27 @@ The actual perl version, such as B<5.20.1>.
 
 =item sha256
 
-The SHA-256 of the C<.tar.bz2> file for that release.
+The SHA-256 of the tarball for that release.
+
+=back
 
 =item OPTIONAL
 
 =over 4
 
-=item buildpack_deps
+=item debian_release
 
-The Docker L<buildpack-deps|https://hub.docker.com/_/buildpack-deps>
+The Docker image tag which this Perl would build on, common to both the
-image tag which this Perl would build on.
+L<https://hub.docker.com/_/buildpack-deps|buildpack-deps> and
+L<https://hub.docker.com/_/debian|debian> Docker images.
 
-Defaults: C<stretch>
+Defaults: C<stretch> for C<main> builds, C<stretch-slim> for C<slim>
+builds.
 
 =item extra_flags
 
-Additional text to pass to C<Configure>.  At the moment, this is necessary for
+Additional text to pass to C<Configure>.  At the moment, this is
-5.18.x so that it can get the C<-fwrapv> flag.
+necessary for 5.18.x so that it can get the C<-fwrapv> flag.
 
 Default: C<"">
 
@@ -195,13 +262,14 @@ Default: C<yes>
 =cut
 
 __DATA__
-FROM buildpack-deps:{{_tag}}
+FROM {{image}}:{{tag}}
 LABEL maintainer="Peter Martini <PeterCMartini@GMail.com>, Zak B. Elep <zakame@cpan.org>"
 
 COPY *.patch /usr/src/perl/
 WORKDIR /usr/src/perl
 
-RUN curl -SL {{url}} -o perl-{{version}}.tar.{{type}} \
+RUN {{docker_slim_run_install}} \
+    && curl -SL {{url}} -o perl-{{version}}.tar.{{type}} \
     && echo '{{sha256}} *perl-{{version}}.tar.{{type}}' | sha256sum -c - \
     && tar --strip-components=1 -xaf perl-{{version}}.tar.{{type}} -C /usr/src/perl \
     && rm perl-{{version}}.tar.{{type}} \
@@ -217,6 +285,7 @@ RUN curl -SL {{url}} -o perl-{{version}}.tar.{{type}} \
     && curl -LO {{cpanm_dist_url}} \
     && echo '{{cpanm_dist_sha256}} *{{cpanm_dist_name}}.tar.gz' | sha256sum -c - \
     && tar -xzf {{cpanm_dist_name}}.tar.gz && cd {{cpanm_dist_name}} && perl bin/cpanm . && cd /root \
+    && {{docker_slim_run_purge}} \
     && rm -fr ./cpanm /root/.cpanm /usr/src/perl /usr/src/{{cpanm_dist_name}}* /tmp/*
 
 WORKDIR /root