From 0ed4f972f2a44f8ca02b6250c411c191746edfa3 Mon Sep 17 00:00:00 2001
From: Manoel Campos <manoelcampos@gmail.com>
Date: Wed, 14 Jul 2021 15:34:45 -0300
Subject: [PATCH] Close #21

---
 .github/workflows/asciidoctor-ghpages.yml | 1 +
 action.yml                                | 5 +++++
 entrypoint.sh                             | 7 +++++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/asciidoctor-ghpages.yml b/.github/workflows/asciidoctor-ghpages.yml
index 1a2eb5c..2b9ab2c 100644
--- a/.github/workflows/asciidoctor-ghpages.yml
+++ b/.github/workflows/asciidoctor-ghpages.yml
@@ -29,4 +29,5 @@ jobs:
         # adoc_file_ext: .ascii # default is .adoc
         # source_dir: docs/ # default is .
         # slides_build: true
+        # pre_build:
         # post_build:
diff --git a/action.yml b/action.yml
index 47be5cb..5aa3d0a 100644
--- a/action.yml
+++ b/action.yml
@@ -37,6 +37,10 @@ inputs:
     description: 'If slides are being generated using AsciiDoc Reveal.js, you may not want to build the regular html files using the asciidoctor command, but just using the asciidoctor-revealjs command. In order to generate only the slides.html instead of the regular html files, set this config to true.'
     default: 'false'
     required: false
+  pre_build:
+    description: 'Any arbitrary shell command to be executed before the asciidoc build is started. Optional.'
+    default: 'echo "No pre build command provided."'
+    required: false
   post_build:
     description: 'Any arbitrary shell command to be executed after the asciidoc build is complete and before committing changes on gh-pages branch. Optional.'
     default: 'echo "No post build command provided."'
@@ -54,4 +58,5 @@ runs:
     - ${{ inputs.slides_skip_asciidoctor_build }}
     - ${{ inputs.pdf_build }}
     - ${{ inputs.ebook_main_adoc_file }}
+    - ${{ inputs.pre_build }}
     - ${{ inputs.post_build }}
diff --git a/entrypoint.sh b/entrypoint.sh
index 41d828a..efb7a04 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -3,8 +3,6 @@
 # Exit if a command fails
 set -e
 
-sh -c "echo 'Input Parameters:' $*"
-
 OWNER="$(echo $GITHUB_REPOSITORY| cut -d'/' -f 1)"
 
 if [[ "$INPUT_ADOC_FILE_EXT" != .* ]]; then 
@@ -43,6 +41,11 @@ else
   git checkout "$COMMIT_HASH" -B gh-pages
 fi
 
+# Executes any arbitrary shell command (such as packages installation and environment setup)
+# before starting build.
+# If no command is provided, the default value is just an echo command.
+eval "$INPUT_PRE_BUILD"
+
 if [[ $INPUT_SLIDES_SKIP_ASCIIDOCTOR_BUILD == false ]]; then 
     echo "Converting AsciiDoc files to HTML"
     find . -name "*$INPUT_ADOC_FILE_EXT" | xargs asciidoctor -b html $INPUT_ASCIIDOCTOR_PARAMS