Wait for postgres to be up and running via an entrypoint

[refs #787cfcc66d1c]

Author: jfahrer

developing/webapp/Dockerfile

@@ -13,4 +13,5 @@ RUN bundle install
 WORKDIR /app
 COPY . .
 
+ENTRYPOINT ["/app/docker-entrypoint.sh"]
 CMD ["ruby", "app.rb"]

developing/webapp/docker-compose.yml

@@ -10,8 +10,11 @@ services:
       - POSTGRES_PASSWORD=secret
       - POSTGRES_DB=demo
       - POSTGRES_HOST=pg
+      - WAIT_FOR_POSTGRES=true
     volumes:
       - .:/app
+    depends_on:
+      - pg
 
   pg:
     image: postgres:9.6-alpine

developing/webapp/docker-entrypoint.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+if [ ! -z $WAIT_FOR_POSTGRES ]
+then
+  echo Waiting for postgres to start...
+  while ! pg_isready -h $POSTGRES_HOST > /dev/null; do
+    sleep 0.5
+  done
+  echo '... done'
+fi
+"$@"