GitHub Discussions - Spring Boot Demo App

Now Announcing GitHub Discussions

GitHub features a Discussions pane on code repositories so that communities can share thoughts and feedback without having to open a new issue.

This post is to announce that I want YOU to leave a comment on my announcement post over on GitHub. My blog is more informative than interactive (and I like it that way) but GitHub as a tool for organizing community around code is right up my alley. I hope you’ll join me and we can connect.

Follow this link to see the Discussion announcement.

Leave a comment on my announcement post

And when you’re done, check out the repo! I’ve enabled Discussion on my Spring Boot Demo app and there’s simply no reason you shouldn’t pull the code, try it out yourself, and then come back to the Discussions pane to tell me what you learned.

BE KIND ONLINE

Valheim - Dedicated Server

Valheim

A brutal exploration and survival game from Iron Gate AB and published by Coffee Stain Publishing for 1-10 players, set in a procedurally-generated purgatory inspired by viking culture. Battle, build, and conquer your way to a saga worthy of Odin’s patronage!

The game was released Feb 2, 2021 and has received very positive reviews on Steam and in C Spire Gaming’s Discord server.

Some college buddies and I first played on a world we’d been passing around via Google Drive. I was then volunteered to host the world on a dedicated server and I wanted to build a small system to check on the status of the server such that I could make it easy for my friends to know its uptime status.

In version 1.14.0 of Uptime Kuma a new feature was introduced which enabled serving new status pages from an existing app instance. Utilizing this, I created valheim.michaellamb.dev which is a status page for our dedicated server.

Uptime Kuma - cloudflared integration

Uptime Kuma, the project behind status.michaellamb.dev, recently merged a pull request which adds an interesting ease-of-use feature: integration with Cloudflare’s tunneling technology using cloudflared, a tunnel client which simplifies proxying requests from behind a firewall by leveraging the Cloudflare network.

Pros:

• Free of charge
• Full GUI, zero-config files
• You can put your Uptime Kuma behind firewall
• No need to expose your real IP
• No need nginx, caddy, traefik etc
• Zero-config SSL
• Free SSL

Cons:

• (Not a con if you are already using Cloudflare) Your domain’s nameserver have to move to Cloudflare
• add 30MB to the docker base image

Once installed, you can authenticate cloudflared into your Cloudflare account and begin creating Tunnels to serve traffic to your origins.

1. Create a Tunnel with these instructions
2. Route traffic to that Tunnel:

• Via public DNS records in Cloudflare
• Or via a public hostname guided by a Cloudflare Load Balancer
• Or from WARP client private traffic

Featured Project - the fuck

But first, coffee

I’m writing to you live from Urban Foxes in Belhaven Heights.

Featured Projects

This is my first Featured Project post. Once a week I want to highlight an interesting software project I find. This week’s is one which has been hilarious to read up on this morning over coffee at Urban Foxes: The Fuck.

the fuck

From the GitHub repo:

The Fuck is a magnificent app, inspired by a @liamosaur

tweet, that corrects errors in previous console commands.

The most eye-catching and hilarious part of the project’s README is the example gif, clearly demonstrating what I find so funny about this project.

I installed The Fuck using Homebrew on Mac OS.

meme update

I don’t have enough outlets for sharing memes, and especially spicy memes like this one (sent to me by Matthew Lewis) need a special memorialization.

Docker Buildx and Platform-specific Images

Problem

I am playing around with a new build pipeline. I want to be able to create Spring Boot applications and build Docker images that can run on a Raspberry Pi computer. Because the Pi uses an ARM processor the image build step is more involved. In this post, I will outline how I built an ARM-specific image from my Spring Boot demo codebase.

Required

• Java 8
• Maven (mvnw packaged with repo)
• Docker

Build Steps

Maven

First, we use Maven to compile the Java code into a JAR. This can be accomplished from the commandline.

mvnw spring-boot:build-image

Successful build console output:

[INFO] Scanning for projects...
[INFO]
[INFO] --------------------------< dev.michael:demo >--------------------------

[INFO] Building demo 0.0.1

[INFO] --------------------------------[ jar ]---------------------------------
[INFO]

[INFO] >>> spring-boot-maven-plugin:2.6.3:build-image (default-cli) > package @ demo >>>

[INFO]

[INFO] --- maven-resources-plugin:3.2.0:resources (default-resources) @ demo ---

[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] Copying 1 resource
[INFO] Copying 0 resource
[INFO]

[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ demo ---

[INFO] Changes detected - recompiling the module!
[INFO] Compiling 5 source files to C:\Workspace\demo\demo\target\classes
[INFO]

[INFO] --- maven-resources-plugin:3.2.0:testResources (default-testResources) @ demo ---

[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Using 'UTF-8' encoding to copy filtered properties files.
[INFO] skip non existing resourceDirectory C:\Workspace\demo\demo\src\test\resources
[INFO]

[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ demo ---

[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to C:\Workspace\demo\demo\target\test-classes
[INFO]

[INFO] --- maven-surefire-plugin:2.22.2:test (default-test) @ demo ---

[INFO]
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running dev.michael.demo.DemoApplicationTests
... (tests omitted)

[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 5.863 s - in dev.michael.demo.DemoApplicationTests

[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  01:23 min
[INFO] Finished at: 2022-03-11T22:08:02-06:00
[INFO] ------------------------------------------------------------------------

Docker

Docker users may be familiar with the docker build command. buildx is “build extended” which is an experimental CLI command to enable the creation of platform-specific Docker images. Here’s the command I used to generate one for the 32-bit OS running on my Pis.

docker buildx build --push --platform=linux/arm/v7 --tag=michaellambgelo/demo:latest .

The output shows Docker using Buildkit. The dockerfile lets Docker know how to package and start an application container. With openjdk:8-jdk-alpine included as the container OS runtime the Spring Boot application is then pushed to the Docker registry. From the registry, the image can be downloaded to whatever Pi/Docker configuration I want.

[+] Building 38.7s (11/11) FINISHED

 => [internal] booting buildkit                                                                                                                                                                                         1.5s
 => => starting container buildx_buildkit_magical_thompson0                                                                                                                                                             1.5s
 => [internal] load build definition from Dockerfile                                                                                                                                                                    0.1s
 => => transferring dockerfile: 141B                                                                                                                                                                                    0.0s
 => [internal] load .dockerignore                                                                                                                                                                                       0.1s
 => => transferring context: 2B                                                                                                                                                                                         0.0s
 => [internal] load metadata for docker.io/library/openjdk:8-jdk-alpine                                                                                                                                                 3.1s
 => [auth] library/openjdk:pull token for registry-1.docker.io                                                                                                                                                          0.0s
 => [internal] load build context                                                                                                                                                                                       0.8s
 => => transferring context: 30.75MB                                                                                                                                                                                    0.7s
 => [1/2] FROM docker.io/library/openjdk:8-jdk-alpine@sha256:94792824df2df33402f201713f932b58cb9de94a0cd524164a0f2283343547b3                                                                                           7.1s
 => => resolve docker.io/library/openjdk:8-jdk-alpine@sha256:94792824df2df33402f201713f932b58cb9de94a0cd524164a0f2283343547b3                                                                                           0.1s
 => => sha256:43ff02e0daa55f3a4df7eab4f7128e6b39b03ece75dfeedb53bf646fce03529c 67.40MB / 67.40MB                                                                                                                        6.4s
 => => sha256:962e53e3f8337e63290eb26703e31f0e87d70db371afae581ad3898b1dccb972 238B / 238B                                                                                                                              0.1s
 => => sha256:856f4240f8dba160c5323506c1e9a4dbaaca840bf1b0c244af3b8d1b42b0f43b 2.35MB / 2.35MB                                                                                                                          0.9s
 => => pushing layers                                                                                                                                                                                                  22.4s
 => => pushing manifest for docker.io/michaellambgelo/demo:latest@sha256:87640f491f579237e378aa832614df036720da21ed0d74cbe248ba1ed6ae4acb                                                                               0.3s
 => [auth] michaellambgelo/demo:pull,push token for registry-1.docker.io                                                                                                                                                0.0s
 => [auth] michaellambgelo/demo:pull,push token for registry-1.docker.io

Future

I want to look into using Spotify Dockerfile Maven which takes an opinionated view of the Maven and Docker build processes, enabling users to combine the two build steps into one.