Spring Boot - How to get the running port

Question

I have a spring boot application  using embedded tomcat 7   and I ve set server port   0 in my application properties so I can have a random port   After the server is booted up and running on a port  I need to be able to get the port that that was chosen   I cannot use  Value   server port   because it s zero   This is a seemingly simple piece of information  so why can t I access it from my java code   How can I access it

User · Answer

Spring s Environment holds this information for you    Autowired Environment environment   String port   environment getProperty  local server port      On the surface this looks identical to injecting a field annotated  Value    local server port     or  LocalServerPort  which is identical   whereby an autowiring failure is thrown at startup as the value isn t available until the context is fully initialised  The difference here is that this call is implicitly being made in runtime business logic rather than invoked at application startup  and hence the  lazy-fetch  of the port resolves ok

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You can get the port that is being used by an embedded Tomcat instance during tests by injecting the local server port value as such      Inject which port we were assigned  Value    local server port    int port

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You can get the server port from the HttpServletRequest   Autowired private HttpServletRequest request    GetMapping value    quot  port quot   public Object getServerPort        System out println  quot I am from  quot    request getServerPort        return  quot I am from   quot    request getServerPort

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I solved it with a kind of proxy bean  The client gets initialized when it is needed  by then the port should be available   Component public class GraphQLClient        private ApolloClient apolloClient      private final Environment environment       public GraphQLClient Environment environment            this environment   environment             public ApolloClient getApolloClient             if  apolloClient    null                String port   environment getProperty  quot local server port quot                initApolloClient port                     return apolloClient             public synchronized void initApolloClient String port            this apolloClient   ApolloClient builder                    serverUrl  quot http   localhost  quot    port    quot  graphql quot                    build               public  lt D extends Operation Data  T  V extends Operation Variables gt  GraphQLCallback lt T gt  graphql Operation lt D  T  V gt  operation            GraphQLCallback lt T gt  graphQLCallback   new GraphQLCallback lt  gt             if  operation instanceof Query                Query lt D  T  V gt  query    Query lt D  T  V gt   operation              getApolloClient                        query query                       enqueue graphQLCallback             else               Mutation lt D  T  V gt  mutation    Mutation lt D  T  V gt   operation              getApolloClient                        mutate mutation                       enqueue graphQLCallback                      return graphQLCallback

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Thanks to  Dirk Lachowski for pointing me in the right direction   The solution isn t as elegant as I would have liked  but I got it working   Reading the spring docs  I can listen on the EmbeddedServletContainerInitializedEvent and get the port once the server is up and running   Here s what it looks like -   import org springframework boot context embedded EmbeddedServletContainerInitializedEvent  import org springframework context ApplicationListener  import org springframework stereotype Component           Component     public class MyListener implements ApplicationListener lt EmbeddedServletContainerInitializedEvent gt            Override       public void onApplicationEvent final EmbeddedServletContainerInitializedEvent event              int thePort   event getEmbeddedServletContainer   getPort

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After Spring Boot 2  a lot has changed  The above given answers work prior to Spring Boot 2  Now if you are running your application with runtime arguments for the server port  then you will only get the static value with  Value  quot   server port  quot    that is mentioned in the application properties file  Now to get the actual port in which the server is running  use the following method       Autowired     private ServletWebServerApplicationContext server        GetMapping  quot  server-port quot       public String serverPort              return  quot  quot    server getWebServer   getPort           Also  if you are using your applications as Eureka Discovery Clients with load balanced RestTemplate or WebClient  the above method will return the exact port number

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Just so others who have configured their apps like mine benefit from what I went through     None of the above solutions worked for me because I have a   config directory just under my project base with 2 files  application properties application-dev properties In application properties I have   spring profiles active   dev    set my default profile to  dev    In application-dev properties I have   server host   localhost server port   8080   This is so when I run my fat jar from the CLI the   properties files will be read from the   config dir and all is good   Well  it turns out that these properties files completely override the webEnvironment   SpringBootTest WebEnvironment RANDOM PORT setting in   SpringBootTest in my Spock specs  No matter what I tried  even with webEnvironment set to RANDOM PORT Spring would always startup the embedded Tomcat container on port 8080  or whatever value I d set in my   config   properties files    The ONLY way I was able to overcome this was by adding an explicit properties    server port 0  to the  SpringBootTest annotation in my Spock integration specs    SpringBootTest  webEnvironment   SpringBootTest WebEnvironment RANDOM PORT  properties    server port 0     Then  and only then did Spring finally start to spin up Tomcat on a random port  IMHO this is a Spring testing framework bug  but I m sure they ll have their own opinion on this   Hope this helped someone

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Is it also possible to access the management port in a similar way  e g       SpringBootTest classes    Application class   webEnvironment   WebEnvironment RANDOM PORT    public class MyTest         LocalServerPort     int randomServerPort        LocalManagementPort     int randomManagementPort

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None of these solutions worked for me  I needed to know the server port while constructing a Swagger configuration bean  Using ServerProperties worked for me   import javax annotation PostConstruct  import javax inject Inject  import javax ws rs ApplicationPath   import io swagger jaxrs config BeanConfig  import io swagger jaxrs listing ApiListingResource  import io swagger jaxrs listing SwaggerSerializers   import org glassfish jersey server ResourceConfig  import org springframework stereotype Component    Component  ApplicationPath  api   public class JerseyConfig extends ResourceConfig         Inject     private org springframework boot autoconfigure web ServerProperties serverProperties       public JerseyConfig                  property org glassfish jersey server ServerProperties BV SEND ERROR IN RESPONSE  true               PostConstruct     protected void postConstruct                    register application endpoints         registerAndConfigureSwaggerUi               private void registerAndConfigureSwaggerUi                 register ApiListingResource class           register SwaggerSerializers class            final BeanConfig config   new BeanConfig               set other properties         config setHost  localhost     serverProperties getPort        gets server port from application properties file                    This example uses Spring Boot auto configuration and JAX-RS  not Spring MVC

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Starting with Spring Boot 1 4 0 you can use this in your test   import org springframework boot context embedded LocalServerPort    SpringBootTest classes    Application class   webEnvironment   WebEnvironment RANDOM PORT  public class MyTest       LocalServerPort   int randomPort

User · Answer

Please make sure you have imported the correct package  import org springframework core env Environment    and then use the Environment object    Autowired private Environment env        Environment Object containts the port number    GetMapping   status     public String status            return  it is runing on   env getProperty  local server port

[spring] Spring Boot - How to get the running port

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