add devcontainer configs and docker network orchestration

devcontainer-api/initdb/notify-db-entrypoint.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -ex
+
+###################################################################
+# This script will get executed *once* the Docker container has 
+# been built. Commands that need to be executed with all available
+# tools and the filesystem mount enabled should be located here. 
+#
+# The PostgreSQL Docker image has an extension mechanism that does 
+# not necessitate to override the entrypoint or main command. One
+# simply has to copy a shell script into the 
+# /docker-entrypoint-initdb.d/ initialization folder. 
+###################################################################
+
+# Notify database setup.
+createdb --user=postgres notification_api
+
+wall "The db container entrypoint setup is complete!"