Hi guys i am having trouble with deploying my ktor backend t kotlinlang #ktor

Hi guys i am having trouble with deploying my ktor...

bk9735732777

07/03/2025, 6:33 AM

Hi guys i am having trouble with deploying my ktor backend to render via Docker Neither port nor sslPort specified. Use command line options -port/-sslPort or configure connectors in application.conf I am getting this error.

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# Stage 1: Cache Gradle dependencies
FROM gradle:latest AS cache
RUN mkdir -p /home/gradle/cache_home
ENV GRADLE_USER_HOME=/home/gradle/cache_home
COPY build.gradle.* gradle.properties /home/gradle/app/
COPY gradle /home/gradle/app/gradle
WORKDIR /home/gradle/app
RUN gradle clean build -i --stacktrace

# Stage 2: Build Application
FROM gradle:latest AS build
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
# Build the fat JAR, Gradle also supports shadow
# and boot JAR by default.
RUN gradle buildFatJar --no-daemon

# Stage 3: Create the Runtime Image
FROM amazoncorretto:22 AS runtime
EXPOSE 8080
RUN mkdir /app
COPY --from=build /home/gradle/src/build/libs/*.jar /app/ktor-docker-sample.jar
ENTRYPOINT ["java","-jar","/app/ktor-docker-sample.jar"]

This is my docker file

bk9735732777

07/03/2025, 6:33 AM

i am able to build the fat.jar but that is not running propperly

bk9735732777

07/03/2025, 6:35 AM

Althogh i am able to run the project manually like starting the Application.kt file and the api works fine and all

gpopides

07/03/2025, 6:54 AM

If you use configuration in a file you need to specify the conf file when starting the docker container

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ENTRYPOINT ["java","-jar","/app/ktor-docker-sample.jar", "-config=application.conf"]

where conf:

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ktor {
  deployment {
    port = 8585
  }
}

bk9735732777

07/03/2025, 7:06 AM

@gpopides

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ktor {
    deployment {
        port = 8080
        port = ${?PORT}
    }
    application {
        modules = [ com.travelKmp.ApplicationKt.module ]
    }
}

this is mu application.comf file

gpopides

07/03/2025, 7:07 AM

You need to pass it as a parameter to the entrypoint of your docker image so ktor can load it

bk9735732777

07/03/2025, 7:12 AM

@gpopides got it i will test but for testing i just created a new peoject with nothing in it and added this docker file

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# Stage 1: Cache Gradle dependencies
FROM gradle:latest AS cache
RUN mkdir -p /home/gradle/cache_home
ENV GRADLE_USER_HOME /home/gradle/cache_home
COPY build.gradle.* gradle.properties /home/gradle/app/
COPY gradle /home/gradle/app/gradle
WORKDIR /home/gradle/app
RUN gradle clean build -i --stacktrace

# Stage 2: Build Application
FROM gradle:latest AS build
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY . /usr/src/app/
WORKDIR /usr/src/app
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
# Build the fat JAR, Gradle also supports shadow
# and boot JAR by default.
RUN gradle buildFatJar --no-daemon

# Stage 3: Create the Runtime Image
FROM amazoncorretto:22 AS runtime
EXPOSE 8080
RUN mkdir /app
COPY --from=build /home/gradle/src/build/libs/fat.jar /app/app.jar
ENTRYPOINT ["java","-jar","/app/app.jar"]

and

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ktor {
  deployment {
    port = 8080
    port = ${?PORT}
  }
  application {
    modules = [com.example.ApplicationKt.module]
  }
}

this was my cong file but this project ran perfectly

gpopides

07/03/2025, 7:14 AM

You are not passing the

application.conf

to the entrypoint, can you try the following?

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# Stage 1: Cache Gradle dependencies
FROM gradle:latest AS cache
RUN mkdir -p /home/gradle/cache_home
ENV GRADLE_USER_HOME /home/gradle/cache_home
COPY build.gradle.* gradle.properties /home/gradle/app/
COPY gradle /home/gradle/app/gradle
WORKDIR /home/gradle/app
RUN gradle clean build -i --stacktrace

# Stage 2: Build Application
FROM gradle:latest AS build
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY . /usr/src/app/
WORKDIR /usr/src/app
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
# Build the fat JAR, Gradle also supports shadow
# and boot JAR by default.
RUN gradle buildFatJar --no-daemon

# Stage 3: Create the Runtime Image
FROM amazoncorretto:22 AS runtime
EXPOSE 8080
RUN mkdir /app
COPY --from=build /home/gradle/src/build/libs/fat.jar /app/app.jar
COPY --from=build src/main/resources/application.conf application.conf
ENTRYPOINT ["java","-jar","/app/app.jar", "-config=application.conf"]

bk9735732777

07/03/2025, 7:24 AM

@gpopides i got this error 1 warning found (use docker --debug to expand): - LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 4) Dockerfile:26 -------------------- 24 | RUN mkdir /app 25 | COPY --from=build /home/gradle/src/build/libs/fat.jar /app/app.jar 26 | >>> COPY --from=build src/main/resources/application.conf application.conf 27 | ENTRYPOINT ["java","-jar","/app/app.jar", "-config=application.conf"] -------------------- ERROR: failed to solve: failed to compute cache key: failed to calculate checksum of ref nr26inj9zw5sjjsmriekk672t:zeo18yx4wvqp0qhfk2kk9q7hy "/src/main/resources/application.conf": not found View build details: docker-desktop://dashboard/build/default/default/v1zx04981epa6c8ujtn83vx56

gpopides

07/03/2025, 7:26 AM

you need to specify the path of the application.conf so it can be copied. I cannot give you an exact path since i don't really know where you have the file. The idea is that you need to copy your conf file to the docker image you are building and then pass it as a parameter to the java command

bk9735732777

07/03/2025, 7:31 AM

the application.conf is in my resources but i am still getting the error

bk9735732777

07/03/2025, 7:34 AM

@gpopides also i have another wuestion that my other progect where i built a new peoject the docker file is the same as what i gave first without copying the application.conf that projhect throws no error and works fine

gpopides

07/03/2025, 7:37 AM

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# Stage 1: Cache Gradle dependencies
FROM gradle:latest AS cache
RUN mkdir -p /home/gradle/cache_home
ENV GRADLE_USER_HOME /home/gradle/cache_home
COPY build.gradle.* gradle.properties /home/gradle/app/
COPY gradle /home/gradle/app/gradle
WORKDIR /home/gradle/app
RUN gradle clean build -i --stacktrace

# Stage 2: Build Application
FROM gradle:latest AS build
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY . /usr/src/app/
WORKDIR /usr/src/app
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
# Build the fat JAR, Gradle also supports shadow
# and boot JAR by default.
RUN gradle buildFatJar --no-daemon

# Stage 3: Create the Runtime Image
FROM amazoncorretto:22 AS runtime
EXPOSE 8080
RUN mkdir /app
COPY --from=build /home/gradle/src/build/libs/fat.jar /app/app.jar
COPY --from=build /home/gradle/src/main/resources/application.conf application.conf
ENTRYPOINT ["java","-jar","/app/app.jar", "-config=application.conf"]

can you try with this dockerfile?

bk9735732777

07/03/2025, 7:39 AM

@gpopides already did not working i tried

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/home/src/main/resources/application.conf
/home/gradle/src/main/resources/application.conf

both

bk9735732777

07/03/2025, 7:40 AM

ok at last

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COPY --from=build /home/gradle/src/build/resources/main/application.conf application.conf

this worked but still i have the error Exception in thread "main" java.lang.IllegalArgumentException: Neither port nor sslPort specified. Use command line options -port/-sslPort or configure connectors in application.conf 2025-07-03T073936.919776256Z at io.ktor.server.engine.CommandLineKt.CommandLineConfig(CommandLine.kt:74) 2025-07-03T073936.919781631Z at io.ktor.server.netty.EngineMain.createServer(EngineMain.kt:37) 2025-07-03T073936.919782881Z at io.ktor.server.netty.EngineMain.main(EngineMain.kt:24) 2025-07-03T073936.919926090Z at com.travelKmp.ApplicationKt.main(Application.kt:5)

gpopides

07/03/2025, 8:00 AM

i setup a new project and used the following docker file:

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# Stage 1: Cache Gradle dependencies
FROM gradle:latest AS cache
RUN mkdir -p /home/gradle/cache_home
ENV GRADLE_USER_HOME /home/gradle/cache_home
COPY build.gradle.* gradle.properties /home/gradle/app/
COPY gradle /home/gradle/app/gradle
WORKDIR /home/gradle/app
RUN gradle build -i --stacktrace

# Stage 2: Build Application
FROM gradle:latest AS build
COPY --from=cache /home/gradle/cache_home /home/gradle/.gradle
COPY . /usr/src/app/
WORKDIR /usr/src/app
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
# Build the fat JAR, Gradle also supports shadow
# and boot JAR by default.
RUN gradle buildFatJar --no-daemon

# Stage 3: Create the Runtime Image
FROM eclipse-temurin:23-jre AS runtime
EXPOSE 8080
RUN mkdir /app
COPY --from=build /home/gradle/src/build/libs/ktor-sample-all.jar /app/app.jar
COPY --from=build /usr/src/app/src/main/resources/application.yaml application.yaml
ENTRYPOINT ["java","-jar","/app/app.jar", "-config=application.yaml"]

and got it running. If you change

application.yaml

application.conf

and

ktor-sample-all.jar

fat.jar

it should work I also used temurin instead of correto so you can change that too

bk9735732777

07/03/2025, 9:04 AM

did not work i think my problem is project specific but i am not able to understand https://github.com/PalankiBharat/Travel-Kmp-Backend

gpopides

07/03/2025, 9:44 AM

Looking at the project, you are missing the the

package

in all of your files. I believe this is the reason

bk9735732777

07/03/2025, 10:49 AM

okk but i dotn have any problem running locally

bk9735732777

07/03/2025, 10:50 AM

also my dir looks like this they all are in root dir the default project is also like this so what should i add in packjage

gpopides

07/03/2025, 11:55 AM

I noticed 2 things. For some reason (one of the dependencies) requires the

yaml

file to be present, so you need to add an

application.yaml

file

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ktor:
  application:
    modules:
      - com.example.ApplicationKt.module
  deployment:
    port: 8080

You also need to set the main class name in

build.gradle.kts

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application {
    mainClass = "com.example.ApplicationKt"
}

and also move everything under a package

com.example

and then change

application.conf

application.yaml

inside your dockerfile

gpopides

07/03/2025, 11:56 AM

image.png

bk9735732777

07/03/2025, 1:52 PM

how did you know that one dependency needs yaml file to be present? @gpopides

gpopides

07/03/2025, 1:57 PM

based on this https://stackoverflow.com/a/78729436

bk9735732777

07/03/2025, 4:06 PM

@gpopides yes the package was a major issue and i have changed to yaml file it is fixed. really thanks for the time and effort you gave to solve my problem

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