By default, the embedded tomcat port number for a Spring Boot application is
8080. If you are like me and run multiple machines while developing locally, you have no doubt encountered a situation where port 8080 is already in use or where you will need 8080 for something else.
There are three ways to set the port number for your application: Command Line, application.properties file, application.yml file.
For those of you who are unfamiliar with the application.properties file, it can be renamed to applicaton.yml to use the popular YAML format. These are the same file but follow a different format.
Set Spring Boot Tomcat Port From Command Line
To set the Spring Boot port from the command line, you passing an option with the -D operator. My build tool of choice for working with spring boot applications is gradle, so here is an example of passing in the port number using an embedded gradle distribution:
./gradlew clean bootRun -Dserver.port=9000
Setting Spring Boot Port from Config files
I am not going to get into profile configuration here but if you are looking to set the port for your application to always run on a specific port or perhaps on a different port for multiple environments, you will no doubt opt to set the port from your application.properties or application.yml file.
See the following examples for setting the Spring Boot embedded tomcat port number with the application config file.
Set Spring Boot Port from application.properties file
Set Spring Boot Port from application.yml file
As always, please comment with kudos, questions, etc…