How to deploy your Ktor application to Render?

Recently, after Heroku announced removal of their free plans, I migrated my hobby project from Heroku to Render.

Render, https://render.com/, is yet another cloud application hosting. According to the Internet, it’s a good alternative to Heroku. It doesn’t support Java out of the box, but you can host anything with Docker.

To deploy your Ktor application, we need two things. First, add io.ktor.plugin plugin to your root build.gradle file:

id("io.ktor.plugin") version "2.1.2"

This plugin adds buildFatJar Gradle task which creates an executable JAR with all dependencies.

Next, you create a new file in your root directory named Dockerfile. Dockerfile is a text file that describes how to create an image. In our case, we use Dockerfile from Ktor documentation:

FROM gradle:7-jdk11 AS build
COPY --chown=gradle:gradle . /home/gradle/src
WORKDIR /home/gradle/src
RUN gradle buildFatJar --no-daemon

FROM openjdk:11
EXPOSE 8080:8080
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"]

Keep in mind to replace the ktor-docker-sample with your project name.

Now it’s time to do git commit & git push.

Next, in the https://render.com/ dashboard, you select New -> Web Service and connect your GitHub/GitLab repo. Default options are good enough.

After that, the build should start, and at the end you should see a green tick with “Deploy live for XXX” text.

Happy building!