Add: psql support to entrypoint.sh

scripts/entrypoint.sh

@@ -1,6 +1,104 @@
 #!/usr/bin/env sh
 
-python manage.py migrate --no-input
-python manage.py collectstatic --no-input
 
-gunicorn logs_collector.wsgi:application
+# set global variables:
+_DB_URL="${DB_URL}"
+
+
+# parses the database connection url and sets global variables:
+#
+# _DBMS: {psql, sqlite} default dbms used
+# _DB_HOST {domain,ip_address} for connections
+# _DB_PORT {5432,3306,etc} for connections
+# _DB_USER {root,admin,etc} db username
+# _DB_PASSWORD {super_secret} db user password
+parse_db_url() {
+	local db_url=$1
+	echo "-------- Check used DBMS --------"
+	if [ -n "${db_url}" ]; then
+		# ! PARSING:
+		# -- -- --
+		# extract the protocol
+		local proto="$(echo "${db_url}" | grep '://' | sed -e's,^\(.*://\).*,\1,g')"
+		local dbms=${proto%:*}
+		# if dpms is "sqlite" we do not need parse url args
+		if [ "${dbms}" = "psql" ]; then
+			# remove the protocol (clean url)
+			local url=$(echo "${db_url}" | sed -e s,"${proto}",,g)
+			# extract the user and password (if any)
+			local userpass="$(echo "${url}" | grep @ | cut -d@ -f1)"
+			local password=$(echo "${userpass}" | grep : | cut -d: -f2)
+			# extract the host and port connection
+			local hostport=$(echo "${url}" | sed -e s,$userpass@,,g | cut -d/ -f1)
+			local port=$(echo "${hostport}" | grep : | cut -d: -f2)
+			# ! SET VARIABLES:
+			# -- -- -- -- --
+			# _DB_HOST or/and _DB_PORT for test db connection
+			if [ -n "${port}" ]; then
+					_DB_HOST=$(echo "${hostport}" | grep : | cut -d: -f1)
+					_DB_PORT="${port}"
+			else
+					_DB_HOST="${hostport}"
+			fi
+			# _DB_USER or/and _DB_PASSWORD for future features
+			if [ -n "${password}" ]; then
+					_DB_USER=$(echo "${userpass}" | grep : | cut -d: -f1)
+					_DB_PASSWORD="${password}"
+			else
+					_DB_USER="${userpass}"
+			fi
+		fi
+	# _DBMS (sqlite or psql)
+	_DBMS="${dbms}"
+	echo "${_DBMS} is set as the default DBMS"
+	else
+		# _DBMS (sqlite)
+		_DBMS="sqlite"
+		echo "${_DBMS} is set as the default DBMS"
+	fi
+}
+
+
+# waits until the database becomes available for connection
+wait_db() {
+	local dbms=$1
+	local db_host=$2
+	local db_port=$3
+	if [ "${dbms}" = "psql" ];then
+		echo "------- Waiting for database start -------"
+		while ! nc -z $db_host $db_port; do
+			sleep 0.1
+		done
+		echo "PostgreSQL started"
+	fi
+}
+
+
+# app config performs database migration, collects static files
+app_config() {
+	echo "-------- Apply migration --------"
+	python manage.py migrate --no-input
+	echo "----- Collect static files ------"
+	python manage.py collectstatic --no-input
+}
+
+
+# run app wsgi web server
+app_run() {
+	echo "--------- Run gunicorn ----------"
+	gunicorn logs_collector.wsgi:application
+}
+
+
+# app entrypoint
+main() {
+	parse_db_url $_DB_URL
+	wait_db $_DBMS $_DB_HOST $_DB_PORT
+	app_config
+	app_run
+}
+
+# RUN
+main
+
+exec "$@"