As a quick blog post, these are some notes and steps I used to create a Scala JAR file, put that in a Docker image, and then push it up to Google Cloud Run. Rather than add a lot of description here, I’ll just share my notes in a numbered order.
Note that I have cross-posted this article on my Valley Programming website at Pushing a Scala JAR/Docker file to Google Cloud Run to create a service.
1.Create my Scala web app and JAR file
As the first step, I use an old Scala webserver I wrote, and then built a JAR file from it using sbt and sbt-assembly. The resulting JAR file is below the current project directory, and has this name/path:
2. Create a Dockerfile for it
Next, create a Dockerfile that describes what I want in my Docker image:
FROM openjdk:11 WORKDIR /home COPY target/scala-3.1.0/WebServerDocker3-assembly-0.1.0.jar WebServerDocker3-assembly-0.1.0.jar EXPOSE 8080 CMD ["java", "-jar", "WebServerDocker3-assembly-0.1.0.jar"] #CMD java -jar WebServerDocker3-assembly-0.1.0.jar
I kept that last comment in there because it shows another way to run the JAR file.
3. Build my Docker image
Build my image with this new command (adding in
$ docker build --platform linux/amd64 -t scala-webserver-1 .
4. Make sure I’m authenticated to Google Cloud
Make sure I’m authenticated to the Google Cloud. I don’t remember if this is the correct command, and note that it also depends on the location of the servers you set up through the Google Cloud web interface:
$ gcloud auth configure-docker us-central1-docker.pkg.dev
5. Determine/calculate what the Docker image needs to be
My Docker image name starts like this:
Then you have to name it per the Google Cloud specs to be like this:
Note that in January, 2022, I’m using the Google Cloud Artifact Registry. (Note: Container Registry is OLD, Artifact Registry is NEW.)
6. Tag the local Docker image with the GCP repository name
Next, you also have to tag the Docker image with the correct Google Cloud name:
# EXAMPLE: $ docker tag SOURCE-IMAGE LOCATION-docker.pkg.dev/PROJECT-ID/REPOSITORY/IMAGE # MINE: $ docker tag scala-webserver-1 us-central1-docker.pkg.dev/cloud-run-1st-java-project/first-jar-repo/scala-webserver-1
Now you should see something like this:
# WORKED (there is no output from that command, but it works, as shown here) $ docker images REPOSITORY TAG IMAGE ID CREATED SIZE scala-webserver-1 latest ef18f546c1ca 6 minutes ago 667MB us-central1-docker.pkg.dev/cloud-run-project-name/my-repo-name/scala-webserver-1 latest ef18f546c1ca 6 minutes ago 667MB
7. Do the push to Google Cloud Run
After following those steps you can do the push to the Google Cloud:
$ docker push us-central1-docker.pkg.dev/cloud-run-project-name/my-repo-name/scala-webserver-1 Using default tag: latest The push refers to repository [us-central1-docker.pkg.dev/cloud-run-1st-java-project/first-jar-repo/scala-webserver-1] 7720f7deb6fc: Pushed more output here ... more output here ... 11936051f93b: Pushed latest: digest: sha256:854adc82b72ac3fe72da8a... size: 2212
8. Go back to the Google Cloud Run GUI and re-create a service
In the Google Cloud Run web app. The two main parts are:
- Container image URL
- Use the "SELECT" button to find the new Docker image in the Artifact Repository
- Service name
- Choose to run the web app on one server, 10, 100, 1,000, etc.
If all goes well, after you submit the form you’ll be given a custom URL where your web-app is running. Then you can go to that URL, test your app, and also look at the logs.
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These are just my notes — this isn’t a tutorial — but if you ever need to run a Scala JAR file on Google Cloud Run, I hope these notes are helpful.
- https://cloud.google.com/run/docs/deploying (deploying container images)