jekyll_docker/data/entrypoint.sh

#!/bin/bash
source /opt/jekyll/.env
export AUTHOR_EMAIL=$AUTHOR_EMAIL
export BLOG_NAME=$BLOG_NAME
export BASE_URL=$BASE_URL
export GEM_HOME="/usr/local/bundle"
export GITHUB_USERNAME=$GITHUB_USERNAME
export HOST_URL=$HOST_URL
export LIVERELOAD_PORT=$LIVERELOAD_PORT
export PATH="$GEM_HOME/bin:$GEM_HOME/gems/bin:$PATH"
export SITE_PATH="/app/jekyll/$BLOG_NAME"
export SITE_TITLE=$SITE_TITLE
export THEME=$THEME
export TWITTER_USERNAME=$TWITTER_USERNAME
export WWW_PORT=$WWW_PORT
export URL=$URL

update_config() {
	for ENV_VAR in 'AUTHOR_EMAIL' 'BASE_URL' 'GITHUB_USERNAME' \
		'SITE_TITLE' 'THEME' 'TWITTER_USERNAME' 'URL'; do
		case $ENV_VAR in
		"AUTHOR_EMAIL") param="email" ;;
		"BASE_URL") param="baseurl" ;;
		"GITHUB_USERNAME") param="github_username" ;;
		"SITE_TITLE") param="title" ;;
		"THEME") param="theme" ;;
		"TWITTER_USERNAME") param="twitter_username" ;;
		"URL") param="url" ;;
		esac
		initial_config=$(grep -E "^${param}: " ${SITE_PATH}/_config.yml)
		[[ "$initial_config" != "$param: ${!ENV_VAR}" && ! -z ${!ENV_VAR} ]] && {
			echo "Config change detected on $param: updating _config.yml"
			echo "New $param: ${!ENV_VAR}"
			[[ $ENV_VAR == "BASE_URL" || $ENV_VAR == "URL" ]] && {
				sed -i "s/\(${param}: \).*/\1\"${!ENV_VAR}\"/g" ${SITE_PATH}/_config.yml
			} || {
				sed -i "s/\(${param}: \).*/\1${!ENV_VAR}/g" ${SITE_PATH}/_config.yml
			}
		} || {
			echo "No change or empty variable for $param, continuing..."
		}
	done
}

update_description() {
	initial_description=$(sed -n '/^description/,/^baseurl/p' ${SITE_PATH}/_config.yml | sed '/^description/d' |
		sed '/^baseurl: ""/d' | sed 's/^[[:space:]]*//' | sed '/^description:/,/^baseurl:/ { /^description:/n; /^baseurl:/! { /^$/d; } }')
	current_description=$(sed 's/^[[:space:]]*//' /opt/jekyll/${BLOG_NAME}_description.txt)
	[[ "$initial_description" != "$current_description" && ! -z $current_description ]] && {
		echo "Config change detected on site description: updating _config.yml"
		sed -i "/^description/,/^baseurl:/!b;//!d;/^description/r /opt/jekyll/${BLOG_NAME}_description.txt" ${SITE_PATH}/_config.yml
		sed -i '/^description:/,/^baseurl:/ { /^description:/n; /^baseurl:/! s/^[^[:space:]]/  &/; }' ${SITE_PATH}/_config.yml
	} || {
		echo "No change or empty variable for site $BLOG_NAME description, continuing..."
		sed -i '/^description:/,/^baseurl:/ { /^description:/n; /^baseurl:/! s/^[^[:space:]]/  &/; }' ${SITE_PATH}/_config.yml
		sed '/^description:/,/^baseurl:/ { /^description:/n; /^baseurl:/! { /^$/d; } }'
	}
}

cd /app/jekyll &&
	gem install jekyll jekyll-docs jekyll-compose bundler webrick

[[ -f ${SITE_PATH}/_config.yml ]] &&
	{
		cd $SITE_PATH
		bundle install
		update_config
		update_description
		bundle exec jekyll serve --host $HOST_URL
	} || {
	jekyll new $SITE_PATH
	cd $SITE_PATH
	bundle install
	update_config
	update_description
	bundle exec jekyll serve --host $HOST_URL
}