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Java Deploying to Heroku

Rebekah Smith
Rebekah Smith
7,263 Points
Posted by Rebekah Smith
Rebekah Smith
7,263 Points

Heroku does not support H2 as a datasource, only PostGreSQL. Why does Chris's weather demo work with Heroku?

On Windows the Heroku deployment was slow and painful, and only to discover afterwards that Heroku does not support H2.

My error after deploy:

2017-06-21T21:58:25.639583+00:00 app[web.1]: 2017-06-21 21:58:25.639  WARN 4 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [com/rebekahperkins/website/config/DataConfig.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory

Here Heroku serves up Chris's weather demo even though the datasource is configured for H2: https://teamtreehouse.com/library/deploying-to-heroku

3 Answers

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

Quite often the database server and the app server are separate. This is almost always true with Heroku. The database is an add-on and you have to supply the database server's URL through config variables. The "almost always" part is where Chris pulled a little trick to sneak in H2. H2 is written in Java and runs on the JVM. What Chris does is install and run H2 through the same JVM as the Spring Boot app so they are running together on the same app server.

J Tan
J Tan
11,847 Points
J Tan
J Tan
11,847 Points

How do I deploy H2 on the same JVM as Spring Boot? The workshop is not clear how thats done. Or is the fact that the properties file has localhost automatically handles deploying H2 on the same JVM?

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

It's a runtime dependency in the build.gradle file.

J Tan
J Tan
11,847 Points
J Tan
J Tan
11,847 Points

Seth Kroger I think this is the build.gradle file you're referring to: https://github.com/treehouse-projects/spring-unit-test-weather/blob/master/build.gradle

runtime 'com.h2database:h2'