So I've got a multi-container application with a front-end, back-end API all sat behind an API gateway. At the moment all apps work fine when booted independently through their respective commands (Java spring apps and an Angular front-end). However, when I start the apps through docker-compose up
, none of the apps can communicate with each other (getting a connection refused).
The Gateway is just a basic spring-cloud-gateway starter app which routes requests through to the correct application. This is configured with the following code:
@Bean
public RouteLocator routeLocator(RouteLocatorBuilder builder) {
return builder.routes()
.route("api", route -> route.path("/api/**").uri("http://localhost:5001"))
.route("front-end", route -> route.path("/**").uri("http://localhost:4200"))
.build();
}
After sending a HTTP GET request to http://localhost:5000/api/categories
, this error message was produced in the gateway app.
api-gateway_1 | 2021-01-11 00:05:14.514 ERROR 1 --- [or-http-epoll-5] a.w.r.e.AbstractErrorWebExceptionHandler : [d29e1cbf-1] 500 Server Error for HTTP GET "/api/categories"
api-gateway_1 |
api-gateway_1 | io.netty.channel.AbstractChannel$AnnotatedConnectException: finishConnect(..) failed: Connection refused: localhost/127.0.0.1:5001
api-gateway_1 | Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
api-gateway_1 | Error has been observed at the following site(s):
api-gateway_1 | |_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
api-gateway_1 | |_ checkpoint ⇢ HTTP GET "/api/categories" [ExceptionHandlingWebHandler]
api-gateway_1 | Stack trace:
api-gateway_1 | Caused by: java.net.ConnectException: finishConnect(..) failed: Connection refused
api-gateway_1 | at io.netty.channel.unix.Errors.throwConnectException(Errors.java:124) ~[netty-transport-native-unix-common-4.1.55.Final.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.unix.Socket.finishConnect(Socket.java:251) ~[netty-transport-native-unix-common-4.1.55.Final.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.doFinishConnect(AbstractEpollChannel.java:673) ~[netty-transport-native-epoll-4.1.55.Final-linux-x86_64.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.finishConnect(AbstractEpollChannel.java:650) ~[netty-transport-native-epoll-4.1.55.Final-linux-x86_64.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe.epollOutReady(AbstractEpollChannel.java:530) ~[netty-transport-native-epoll-4.1.55.Final-linux-x86_64.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:470) ~[netty-transport-native-epoll-4.1.55.Final-linux-x86_64.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378) ~[netty-transport-native-epoll-4.1.55.Final-linux-x86_64.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.55.Final.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.55.Final.jar!/:4.1.55.Final]
api-gateway_1 | at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.55.Final.jar!/:4.1.55.Final]
api-gateway_1 | at java.base/java.lang.Thread.run(Unknown Source) ~[na:na]
I have tried defining my own network but this does not change anything so I have left the containers on the default network created upon running docker-compose up
.
I can hit each app independently via cURL
or through Postman and I can access the front-end through the browser.
version: "3"
services:
api:
build: ./api
ports:
- "5001:5001"
gateway:
build: ./gateway
ports:
- "5000:5000"
frontend:
build: ./frontend
ports:
- "4200:80"
FROM openjdk:11 as build
COPY . .
RUN ./gradlew build --parallel
FROM openjdk:11-jre-slim as runtime
COPY --from=build /build/libs/gateway-0.0.1-SNAPSHOT.jar /usr/app/
WORKDIR /usr/app
ENTRYPOINT ["java", "-jar", "gateway-0.0.1-SNAPSHOT.jar"]
FROM openjdk:11 as build
COPY . .
RUN ./gradlew build --parallel
FROM openjdk:11-jre-slim as runtime
COPY --from=build /build/libs/api-0.0.1-SNAPSHOT.jar /usr/app/
WORKDIR /usr/app
ENTRYPOINT ["java", "-jar", "api-0.0.1-SNAPSHOT.jar"]
FROM node:12.7-alpine AS build
WORKDIR usr/src/app
COPY package.json package-lock.json ./
RUN npm install
COPY . .
RUN npm run build
FROM nginx:1.17.1-alpine
COPY nginx.conf /etc/nginx/nginx.conf
COPY --from=build /usr/src/app/dist/awards-frontend /usr/share/nginx/html
Thanks to @DavidMaze for making me notice this.
Seems like I was being a bit of a fool. My apps are sending network requests to localhost. This works fine when they are all running outside of a container. When in a container they need to be sending requests to the names of the other containers. For example:
app_1 runs on port 8080 app_2 runs on port 5000
When running outside of docker, app_1 could send a network request to app_2 via http://localhost:5000
. This does not work inside of a container as nothing is running on localhost:5000
in that container. Instead, it will need to reference the other container eg: http://app_2:5000
.
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