Use a secrets file for the postgres password

[refs %60f29fdc993a]

Author: jfahrer

swarm/swarm-demo-frontend/Dockerfile

@@ -1,6 +1,6 @@
 FROM ruby:2.4.3-alpine
 
-RUN apk --no-cache add build-base postgresql-dev
+RUN apk --no-cache add bash build-base postgresql-dev
 
 WORKDIR /tmp
 COPY Gemfile* ./
@@ -11,4 +11,5 @@ COPY . .
 
 EXPOSE 8080
 
+ENTRYPOINT ["/app/docker-entrypoint.sh"]
 CMD ["/usr/local/bin/bundle", "exec", "ruby", "app.rb"]

swarm/swarm-demo-frontend/app.rb

@@ -5,8 +5,6 @@
 set :bind, '0.0.0.0'
 set :port, 8080
 
-raise "Simulating an error"
-
 AppState = {}
 AppState[:total_requests] = 0
 

swarm/swarm-demo-frontend/docker-compose.yml

@@ -2,22 +2,25 @@ version: "3.3"
 
 services:
   frontend:
-    image: jfahrer/swarm-demo-frontend:v7
+    image: jfahrer/swarm-demo-frontend:v8
     build:
       context: .
     ports:
       - 8080:8080
     volumes:
       - .:/app
+      - ./pg_secret:/var/run/pg_secret
     environment:
       - POSTGRES_USER=demo
-      - POSTGRES_PASSWORD=secret
       - POSTGRES_DB=demo
       - POSTGRES_HOST=db
+      - POSTGRES_PASSWORD_FILE=/var/run/pg_secret
 
   db:
     image: jfahrer/swarm-demo-db:v1
     environment:
       - POSTGRES_USER=demo
-      - POSTGRES_PASSWORD=secret
       - POSTGRES_DB=demo
+      - POSTGRES_PASSWORD_FILE=/var/run/pg_secret
+    volumes:
+      - ./pg_secret:/var/run/pg_secret

swarm/swarm-demo-frontend/docker-entrypoint.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+set +e
+
+if [ ! -z "$POSTGRES_PASSWORD_FILE" ]; then
+  echo "Reading password from $POSTGRES_PASSWORD_FILE"
+  export POSTGRES_PASSWORD="$(< "${POSTGRES_PASSWORD_FILE}")"
+fi
+
+exec "$@"

swarm/swarm-demo-frontend/pg_secret

@@ -0,0 +1 @@
+foobar