generate.pl: Support building for multiple Debian releases

This adds generating Dockerfiles for each Perl version on multiple
Debian releases, such as for the current 5.30.x to support both Debian
10 (buster) and 9 (stretch).  We also change the directory structure to
better indicate which Debian release it provides for.

Author: zakame

generate.pl

@@ -139,58 +139,60 @@ sub die_with_sample {
   }
 
   for my $build (keys %builds) {
-    $release->{url} = $url;
+    $release->{url}             = $url;
     $release->{"cpanm_dist_$_"} = $cpanm{$_} for keys %cpanm;
 
     $release->{extra_flags}    ||= '';
-    $release->{debian_release} ||= 'stretch';
+    $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";
-    }
+    $release->{image} = $build =~ /main/ ? 'buildpack-deps' : 'debian';
 
-    my $output = $template;
-    $output =~ s/\{\{$_\}\}/$release->{$_}/mg
-      for (qw(version pause extra_flags sha256 type url image tag cpanm_dist_name cpanm_dist_url cpanm_dist_sha256));
-    $output =~ s/\{\{args\}\}/$builds{$build}/mg;
-
-    if ($build =~ /slim/) {
-      $output =~ s/\{\{docker_slim_run_install\}\}/$docker_slim_run_install/mg;
-      $output =~ s/\{\{docker_slim_run_purge\}\}/$docker_slim_run_purge/mg;
-    }
-    else {
-      $output =~ s/\{\{docker_slim_run_install\}\}/true/mg;
-      $output =~ s/\{\{docker_slim_run_purge\}\}/true/mg;
+    if (ref $release->{debian_release} ne 'ARRAY') {
+      $release->{debian_release} = [$release->{debian_release}];
     }
 
-    my $dir = sprintf "%i.%03i.%03i-%s", ($release->{version} =~ /(\d+)\.(\d+)\.(\d+)/), $build;
-
-    mkdir $dir unless -d $dir;
-
-    # Set up the generated DevelPatchPerl.patch
-    {
-      open my $fh, ">", "$dir/DevelPatchPerl.patch";
-      print $fh $patch;
+    for my $debian_release (@{$release->{debian_release}}) {
+
+      my $output = $template;
+      $output =~ s/\{\{$_\}\}/$release->{$_}/mg
+        for (qw(version pause extra_flags sha256 type url image cpanm_dist_name cpanm_dist_url cpanm_dist_sha256));
+      $output =~ s/\{\{args\}\}/$builds{$build}/mg;
+
+      if ($build =~ /slim/) {
+        $output =~ s/\{\{docker_slim_run_install\}\}/$docker_slim_run_install/mg;
+        $output =~ s/\{\{docker_slim_run_purge\}\}/$docker_slim_run_purge/mg;
+        $output =~ s/\{\{tag\}\}/$debian_release-slim/mg;
+      }
+      else {
+        $output =~ s/\{\{docker_slim_run_install\}\}/true/mg;
+        $output =~ s/\{\{docker_slim_run_purge\}\}/true/mg;
+        $output =~ s/\{\{tag\}\}/$debian_release/mg;
+      }
+
+      my $dir = sprintf "%i.%03i.%03i-%s-%s", ($release->{version} =~ /(\d+)\.(\d+)\.(\d+)/), $build, $debian_release;
+
+      mkdir $dir unless -d $dir;
+
+      # Set up the generated DevelPatchPerl.patch
+      {
+        open my $fh, ">", "$dir/DevelPatchPerl.patch";
+        print $fh $patch;
+      }
+
+      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") {
+        $output =~ s/\{\{test\}\}/TEST_JOBS=\$(nproc) make test_harness/;
+      }
+      else {
+        die "test_parallel was provided for $release->{version} but is invalid; should be 'yes' or 'no'\n";
+      }
+
+      open my $dockerfile, ">", "$dir/Dockerfile" or die "Couldn't open $dir/Dockerfile for writing";
+      print $dockerfile $output;
+      close $dockerfile;
     }
-
-    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") {
-      $output =~ s/\{\{test\}\}/TEST_JOBS=\$(nproc) make test_harness/;
-    }
-    else {
-      die "test_parallel was provided for $release->{version} but is invalid; should be 'yes' or 'no'\n";
-    }
-
-    open my $dockerfile, ">", "$dir/Dockerfile" or die "Couldn't open $dir/Dockerfile for writing";
-    print $dockerfile $output;
-    close $dockerfile;
   }
 }
 
@@ -237,6 +239,15 @@ =head1 DESCRIPTION
 L<https://hub.docker.com/_/buildpack-deps|buildpack-deps> and
 L<https://hub.docker.com/_/debian|debian> Docker images.
 
+This can be a single tag, or a list of tags to generate multiple
+Dockerfiles for different Debian versions:
+
+    - version: 5.30.0
+      type:    xz
+      debian_release:
+        - stretch
+        - buster
+
 Defaults: C<stretch> for C<main> builds, C<stretch-slim> for C<slim>
 builds.