Camunda behind Spring Cloud Gateway not returning CSS files for cockpit - camunda

Question

I have a Camunda instance embedded within a Spring Boot app (called service-workflow) that starts on a dynamic port, registered with Spring Cloud via Eureka.
The main class for the Camunda service is simply:
#EnableDiscoveryClient
#SpringBootApplication
#EnableConfigurationProperties(ServiceContextConfig.class)
public class WorkflowServiceApplication {
public static void main(String[] args) {
SpringApplication.run(WorkflowServiceApplication.class, args);
}
}
And the configuration properties:
server.port=0
eureka.client.healthcheck.enabled=true
The services sit behind a local Spring Cloud Gateway running on port that uses Eureka to register the host - and is accessible and routing via http://localhost:8080
The code for the gateway is:
#SpringBootApplication
#EnableDiscoveryClient
public class GatewayServiceApplication {
public static void main(String[] args) {
SpringApplication.run(GatewayServiceApplication.class, args);
}
}
And the configuration properties:
server.port=8080
spring.cloud.gateway.discovery.locator.enabled=true
spring.cloud.gateway.discovery.locator.lowerCaseServiceId=true
There are no routes defined - it relies purely on Eureka to find the routes. This works without issues for the REST connectivity.
Any client using the runtimeService, can start a workflow using feign with the URL:
feign.client.config.remoteRuntimeService.url=service-workflow/rest/
Therefore, the workflow service is reachable via the gateway URL for REST APIs.
When the Camunda service starts, and gets assigned port x, I can view the cockpit by http://localhost:x/app/cockpit/default/
However, if I try through the gateway i.e., http://localhost:8080/service-workflow/app/cockpit/default/ it fails to return any CSS files - the gateway log shows:
2020-09-25 16:46:00,454 DEBUG [reactor-http-nio-2] reactor.netty.http.server.HttpServer (Loggers.java:254) - [id: 0xe08516d1, L:/0:0:0:0:0:0:0:1:8080 - R:/0:0:0:0:0:0:0:1:61018] Handler is being applied: org.springframework.http.server.reactive.ReactorHttpHandlerAdapter#74cedfb5
2020-09-25 16:46:00,453 DEBUG [reactor-http-nio-8] org.springframework.web.server.adapter.HttpWebHandlerAdapter (LogFormatUtils.java:91) - [9407161c-27] HTTP GET "/app/cockpit/styles/styles.css?bust=7.12.0"
2020-09-25 16:46:00,456 DEBUG [reactor-http-nio-2] org.springframework.web.server.adapter.HttpWebHandlerAdapter (LogFormatUtils.java:91) - [e08516d1-28] HTTP GET "/app/cockpit/styles/user-styles.css?bust=7.12.0"
2020-09-25 16:46:00,455 DEBUG [reactor-http-nio-7] reactor.netty.http.server.HttpServer (Loggers.java:254) - [id: 0x125a09dc, L:/0:0:0:0:0:0:0:1:8080 - R:/0:0:0:0:0:0:0:1:61253] Handler is being applied: org.springframework.http.server.reactive.ReactorHttpHandlerAdapter#74cedfb5
2020-09-25 16:46:00,458 DEBUG [reactor-http-nio-8] org.springframework.web.reactive.handler.SimpleUrlHandlerMapping (AbstractHandlerMapping.java:183) - [9407161c-27] Mapped to ResourceWebHandler ["classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"]
2020-09-25 16:46:00,460 DEBUG [reactor-http-nio-7] org.springframework.web.server.adapter.HttpWebHandlerAdapter (LogFormatUtils.java:91) - [125a09dc-29] HTTP GET "/app/cockpit/styles/styles-components.css?bust=7.12.0"
2020-09-25 16:46:00,460 DEBUG [reactor-http-nio-2] org.springframework.web.reactive.handler.SimpleUrlHandlerMapping (AbstractHandlerMapping.java:183) - [e08516d1-28] Mapped to ResourceWebHandler ["classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"]
2020-09-25 16:46:00,463 DEBUG [reactor-http-nio-8] org.springframework.web.reactive.resource.ResourceWebHandler (ResourceWebHandler.java:324) - [9407161c-27] Resource not found
2020-09-25 16:46:00,464 DEBUG [reactor-http-nio-7] org.springframework.web.reactive.handler.SimpleUrlHandlerMapping (AbstractHandlerMapping.java:183) - [125a09dc-29] Mapped to ResourceWebHandler ["classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"]
2020-09-25 16:46:00,465 DEBUG [reactor-http-nio-2] org.springframework.web.reactive.resource.ResourceWebHandler (ResourceWebHandler.java:324) - [e08516d1-28] Resource not found
2020-09-25 16:46:00,466 DEBUG [reactor-http-nio-7] org.springframework.web.reactive.resource.ResourceWebHandler (ResourceWebHandler.java:324) - [125a09dc-29] Resource not found
2020-09-25 16:46:00,469 DEBUG [reactor-http-nio-2] org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler (CompositeLog.java:147) - [e08516d1-28] Resolved [ResponseStatusException: 404 NOT_FOUND] for HTTP GET /app/cockpit/styles/user-styles.css
2020-09-25 16:46:00,468 DEBUG [reactor-http-nio-8] org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler (CompositeLog.java:147) - [9407161c-27] Resolved [ResponseStatusException: 404 NOT_FOUND] for HTTP GET /app/cockpit/styles/styles.css
2020-09-25 16:46:00,476 DEBUG [reactor-http-nio-2] org.springframework.core.codec.CharSequenceEncoder (CompositeLog.java:147) - [e08516d1-28] Writing "<html><body><h1>Whitelabel Error Page</h1><p>This application has no configured error view, so you (truncated)...
2020-09-25 16:46:00,479 DEBUG [reactor-http-nio-7] org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler (CompositeLog.java:147) - [125a09dc-29] Resolved [ResponseStatusException: 404 NOT_FOUND] for HTTP GET /app/cockpit/styles/styles-components.css
2020-09-25 16:46:00,477 DEBUG [reactor-http-nio-8] org.springframework.core.codec.CharSequenceEncoder (CompositeLog.java:147) - [9407161c-27] Writing "<html><body><h1>Whitelabel Error Page</h1><p>This application has no configured error view, so you (truncated)...
2020-09-25 16:46:00,480 DEBUG [reactor-http-nio-7] org.springframework.core.codec.CharSequenceEncoder (CompositeLog.java:147) - [125a09dc-29] Writing "<html><body><h1>Whitelabel Error Page</h1><p>This application has no configured error view, so you (truncated)...
2020-09-25 16:46:00,480 DEBUG [reactor-http-nio-2] reactor.netty.http.server.HttpServerOperations (Loggers.java:254) - [id: 0xe08516d1, L:/0:0:0:0:0:0:0:1:8080 - R:/0:0:0:0:0:0:0:1:61018] Decreasing pending responses, now 0

Answer 1

The way I eventually solved this was to add a custom route in the gateway:
.route("camunda", r -> r.path("/camunda/**")
//.filters(f -> f.rewritePath("/report/(?<segment>.*)", "/${segment}"))
.uri("lb://my-camunda-service"))