Hello guys. I have been trying to build a Docker image for my ktor server application and i keep on getting an error. This is the Docker and the .yml file:

FROM openjdk:13 AS builder
RUN java --version
RUN mkdir /application
WORKDIR /application
COPY ./ ./
RUN ./gradlew clean build
RUN ls -al build/libs/

...

version: "3"
services:
  myapp:
    build: .

And this is the error i keep getting:

ERROR [6/7] RUN ./gradlew clean build                                                                                                                     1.9s
------
 > [6/7] RUN ./gradlew clean build:
#10 1.339 /bin/sh: ./gradlew: No such file or directory
------
executor failed running [/bin/sh -c ./gradlew clean build]: exit code: 127
ERROR: Service 'myapp' failed to build : Build failed

After trying lots of solutions, i decided to use another approach:

FROM openjdk:8-jre-alpine
ENV APPLICATION_USER ktor
RUN adduser -D -g '' $APPLICATION_USER
RUN mkdir /app
RUN chown -R $APPLICATION_USER /app
USER $APPLICATION_USER
COPY ./build/libs/app.jar /app/app.jar
WORKDIR /app
CMD ["java","-server","-XX:+UnlockExperimentalVMOptions","-XX:+UseCGroupMemoryLimitForHeap","-XX:InitialRAMFraction=2","-XX:MinRAMFraction=2","-XX:MaxRAMFraction=2","-XX:+UseG1GC","-XX:MaxGCPauseMillis=100","-XX:+UseStringDeduplication","-jar","app.jar"]

And i also got a similar error:

ERROR [5/6] COPY ./build/libs/app.jar /app/app.jar                                                                                                        0.0s
------
 > [5/6] COPY ./build/libs/app.jar /app/app.jar:
------
failed to compute cache key: "/build/libs/app.jar" not found: not found

FROM openjdk:13 AS builder
RUN java --version
RUN mkdir /application
WORKDIR /application
COPY . .     <- use .
RUN ./gradlew clean build
RUN ls -al build/libs/

Did you add the

.gradlew

to

.dockerignore

? If you want to use a

builder

you have to include the consumer too 😄 Just check your paths with

ls

. Guess: in 2nd COPY:

COPY ./build/libs/app.jar /app/app.jar

should it not be

COPY build/libs/app.jar /app/app.jar

?

Hey, i think i forgot to mention that i am a docker novice.. but i tried both your suggestions and non seems to work... i am still getting the same errors with both approach

Try google jib, it'll make docker images for you without all the manual configs