Spring boot known issues on Google Cloud Platform

Now a day, Spring boot is a powerful framework to build a RESTFul Web-services as well as Micro-services. However, I faced some issues when deploying on Google Appengine Standard.

Assume that we are using:

• Java 8
• Maven 3.5.x
• Spring-boot 1.5.x
• Google Appengine Standard

Setup Application Logging

By following this page Reading and Writing Application Logs, We can implement custom application logs easier. However, It does not works when we use this package “org.springframework.boot:spring-boot-starter-web” because Spring-boot’s default logging bridge conflicts with Jetty’s logging system (Appengine use Jetty).

To be able to capture the Spring-boot startup logs, you need to exclude “org.slf4j:jul-to-slf4j” dependency. The easiest way to do this is to set the dependency scope to provided, so that it won’t be included in the WAR file:

<!-- Exclude any jul-to-slf4j -->
<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>jul-to-slf4j</artifactId>
  <scope>provided</scope>
</dependency>

Sending Email with GAE Mail API

If you are going to use GAE Mail API, you should considering some following topics:

• Mail from: We can use any email address of the from anything@[APP_NAME].appspotmail.com
• Bounce notification: You need to implementing Bounce notification when mail is not delivered in case non-exist email address or exeeded 31.5 MB of message size
• You should remove SMTP configuration in Spring-boot applications.yaml file since Spring-boot will initial SMTP settings when starting up, so It may catch error
• You need to enabling GAE Client API dependence as following:

<dependency>
    <groupId>com.google.api-client</groupId>
    <artifactId>google-api-client-appengine</artifactId>
    <version>1.23.0</version>
</dependency>

For more detail, please read this document Mail API Overview