add heroku files and instructions

Procfile

@@ -0,0 +1 @@
+web: java -jar target/twelve-factor-demo.jar

README.md

@@ -1,13 +1,13 @@
 # 12 Factor Demo Deployment guide
 
-## Java
+## Java fat jar
 
 Download the jar from the [releases](/releases) page.
 
 Create a configuration file (`config/application.properties`) with the following content
 
 ```
-SERVER_PORT=8080
+PORT=8080
 CUSTOM_MESSAGE="Hello World From Configs"
 
 # use the endpoint if you are using minio
@@ -31,6 +31,21 @@ Run the application
 java -jar 12-factor-app.jar
 ```
 
+## Heroku
+
+```
+heroku create
+
+git push heroku master
+
+heroku config:set CUSTOM_MESSAGE="Hello World From Heroku"
+heroku config:set AWS_REGION="eu-south-1"
+heroku config:set AWS_ACCESS_KEY=""
+heroku config:set AWS_SECRET_KEY=""
+heroku config:set AWS_BUCKET="twelve-factor-demo"
+```
+
+
 ## Docker Compose
 
 Run the entire app using docker compose

src/main/docker/12-factor.yml

@@ -3,7 +3,7 @@ services:
   12-factor-demo:
     image: intesys/twelve-factor-app:latest
     environment:
-      - SERVER_PORT=8080
+      - PORT=8080
       - CUSTOM_MESSAGE=Hello World From Docker
       - AWS_ENDPOINT=http://minio:9000
       - AWS_ACCESS_KEY=myuser

src/main/java/it/intesys/academy/twelvefactordemo/TwelveFactorApp.java

@@ -34,7 +34,7 @@ public static void main(String[] args) {
         }
 
         // start web server
-        var serverPort = Configs.getIntegerProperty("SERVER_PORT");
+        var serverPort = Configs.getIntegerProperty("PORT");
         Javalin app = Javalin.create()
                 .start(serverPort);
 

src/main/resources/application.properties

@@ -1,4 +1,4 @@
-SERVER_PORT=8080
+PORT=8080
 CUSTOM_MESSAGE="Hello World From Configs"
 
 # use the endpoint if you are using minio

system.properties

@@ -0,0 +1 @@
+java.runtime.version=17