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Jacky
Jacky

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Deploy Spring boot 3 application to Dokku environment with Dockerfile in 15 minutes

#java #dokku #deployment #webdev

What you need

About 15 minutes

IDE

  • Spring Tool Suite (STS)
  • IntelliJ
  • VSCode

Environment

  • Java 17
  • Gradle 7.5+ or Maven 3.5+

A little knowledge about dokku and docker Here I use the ready-made Public IP with Ubuntu 22.04 TLS: 64.176.80.xxx

Create a Spring boot 3

Source of web application creation from Spring homepage: https://start.spring.io/

Quick create link: Link

If you use IntelliJ IDE to manage code and compile, you may encounter some errors like this:

No matching variant of org.springframework.boot:spring-boot-gradle-plugin:3.1.2 was found

The workaround is pretty simple:

Ctrl + Alt + S > Build, Execution, Deployment > Gradle > Gradle JVM -> java 17

Add a class HomeController.java in the directory /src/main/java/com/jackynote/dokkudemo/springdokkudemo with the following content, the goal is to see the application page The application can return a request with the complete response:

package com.jackynote.dokkudemo.springdokkudemo;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping
public class HomeController {
    @GetMapping
    ResponseEntity<String> getHome() {
        return ResponseEntity.accepted().body("Hello world!");
    }
}
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You can then run the application using the Command line:

./gradlew bootRun
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Run the application on the browser at port: http://localhost:8080 and get the results returned from the browser as Hello world

Build the application and package it (jar file), the packaged application will be built in the folder: build/libs and you can find it:

./gradlew build
# Run the jar file to see if it is correct for the debuging environment.
java -jar build/libs/spring-dokku-demo-0.0.1-SNAPSHOT.jar
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Deploy the application to Dokku with Dockerfile

To setup Dokku environment, you can read from official website: https://dokku.com/

Create Dockerfile

cd /home/dokku/first-app
vi Dockerfile
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And copy the content below or you can write your own script if you already have knowledge of docker and use them proficiently:

FROM openjdk:17
MAINTAINER Andy <jackynote.pro@gmail.com>

RUN mkdir /app
WORKDIR /app/
ADD ./spring-dokku-demo-0.0.1-SNAPSHOT.jar /app/

CMD java -jar spring-dokku-demo-0.0.1-SNAPSHOT.jar

EXPOSE 8080
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Push the jar file from the local environment on the prepared server at the directory created for the application using Dokku:

# copy from the project folder to the application folder on the server
scp ~/<Project_Folder>/build/libs/spring-dokku-demo-0.0.1-SNAPSHOT.jar root@64.176.80.xxx:/home/dokku/first-app
root@64.176.80.xxx's password: ...
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Deploy Web Application

SSH into the prepared server and execute the following scripts to deploy the application:

# go to the project's folder
cd /home/dokku/first-app
# build app with pushed jar file and generated Dockerfile
docker build -t dokku/first-app .
# some settings like nginx, port mapping from docker to public environment
dokku proxy:set first-app nginx
dokku ports:add first-app http:8080:8080
# deploy application
dokku deploy first-app
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After successfully deploying you will get the following successful results:

-----> Deploying web (count=1)
       Attempting pre-flight checks (1.)
-----> Executing 1 healthchecks                                                        
       Running healthcheck name='default' type='uptime' uptime=10                      
       Healthcheck succeeded name='default'                                            
       All checks successful (1.)
=====> Start of first-app container output (1.)
         .   ____          _            __ _ _
        /\\\\\\\\ / ___'_ __ _ _(_)_ __  __ _ \\\\ \\\\ \\\\ \\\\
       ( ( )\\\\___ | '_ | '_| | '_ \\\\/ _` | \\\\ \\\\ \\\\ \\\\
        \\\\\\\\/  ___)| |_)| | | | | || (_| |  ) ) ) )
         '  |____| .__|_| |_|_| |_\\\\__, | / / / /
        =========|_|==============|___/=/_/_/_/
        :: Spring Boot ::                (v3.1.2)
       2023-08-22T09:41:22.960Z  INFO 6 --- [           main] c.j.d.s.SpringDokkuDemoApplication       : Starting SpringDokkuDemoApplication v0.0.1-SNAPSHOT using Java 17.0.2 with PID 6 (/app/spring-dokku-demo-0.0.1-SNAPSHOT.jar started by root in /app)
       2023-08-22T09:41:22.967Z  INFO 6 --- [           main] c.j.d.s.SpringDokkuDemoApplication       : No active profile set, falling back to 1 default profile: "default"
       2023-08-22T09:41:25.282Z  INFO 6 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
       2023-08-22T09:41:25.306Z  INFO 6 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
       2023-08-22T09:41:25.307Z  INFO 6 --- [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.11]
       2023-08-22T09:41:25.583Z  INFO 6 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
       2023-08-22T09:41:25.586Z  INFO 6 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2495 ms
       2023-08-22T09:41:26.906Z  INFO 6 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
       2023-08-22T09:41:26.943Z  INFO 6 --- [           main] c.j.d.s.SpringDokkuDemoApplication       : Started SpringDokkuDemoApplication in 4.908 seconds (process running for 6.896)
=====> End of first-app container output (1.)
=====> Triggering early nginx proxy rebuild
-----> Running post-deploy
 !     Detected IPv4 domain name with nginx proxy enabled.
 !     Ensure the default nginx site is removed before continuing.
-----> Renaming containers
       Container type (1) is no longer defined. Removing state
-----> Checking for postdeploy task
       No postdeploy task found, skipping
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Try accessing the application from the browser via the address: http://64.176.80.xxx:8080/

If you cannot access the application from the internet with a public IP, then it may be necessary to open port 8080 from your server:

sudo ufw allow 80
sudo ufw allow 443
sudo ufw allow 8080
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Top comments (2)

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cicirello profile image
Vincent A. Cicirello •

Hi. Consider using syntax highlighting with your code examples. It will improve readability. Here is how to do it.

```Java
public class Foo {

}
```
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The above produces:

public class Foo {

}
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It works for most languages. Just change Java to relevant language name.

```Docker
FROM alpine
```
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Produces:

FROM alpine
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For the shell

```Shell
java -jar some.jar
```
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Produces:

java -jar some.jar
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jackynote profile image
Jacky •

Wow, thanks for your suggestion. I will be really grateful for this

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