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Deploy Spring Boot Project to Azure App Service

Nowadays, most of the web applications are hosted on cloud because it is more cost-effective, safe, reliable, high speed etc. In this ariticle, I will show you how to deploy a simple spring boot project to the Azure App Service at no cost. Before that, you need to create a Azure account first. By default, Azure grants everyone two hundred dollars credit! Next, we create a very simple Spring Boot project from spring initializer and add the Spring Web dependency.

Complete pom.xml example #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.6.0</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>com.caizhenhua</groupId>
  <artifactId>azure.appservice.demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>azure.appservice.demo</name>
  <description>Demo project for Spring Boot</description>
  <properties>
    <java.version>16</java.version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

</project>

Add a test endpoint #

Next we add a simple endpoint that simply return Hello World message.

package com.caizhenhua.azure.appservice.demo.web;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

  @GetMapping("/hello")
  public String hello() {
    return "Hello World";
  }
}

Create Dockerfile #

To deploy our spring boot application, we can either use code or container. For this tutorial, I will use container because we dont have to configure any hardware settings ourselves. Therefore, you need to install the Docker first. After that, we need to build our project and create an execution jar file. Next copy the following Dockerfile and build the image by the following command.

docker build -t yourdockerhubusername/simplespringboot .

Docker Hub is a place that helps developers to manage containers. It also offers one free private repository, therefore we can push the image to Docker Hub such that Azure can pull and build our image and be able to run the container. Note that you can use another container registry like Azure Container Registry (not free), just replace the name yourdockerhubusername.

FROM adoptopenjdk/openjdk16:alpine

EXPOSE 80
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar

ENTRYPOINT ["java","-jar","/app.jar"]

Push your newly created image #

You can push the image by Docker Desktop or using the following command.

docker push yourdockerhubusername/simplespringboot:latest

Use Azure Portal for deployment #

Now you can go to the Azure Portal, select App Service and create your web app! The process is straightforward, make sure you select test plan and clean up (delete) your resources (App Service & App Service Plan) to avoid further charges. To check the deployment status, navigate to the Deployment Center and select Logs. Deployment is successful if you can see logs similar to 2021-11-23T06:17:55.509Z INFO - Container xxx for site xxx initialized successfully and is ready to serve requests.

Enable SSH #

By default, SSH is not enabled for custom containers. We have to do some settings:

Dockerfile

FROM adoptopenjdk/openjdk16:alpine

# Install OpenSSH and set the password for root to "Docker!". In this example, "apk add" is the install instruction for an Alpine Linux-based image.
RUN apk add openssh \
     && echo "root:Docker!" | chpasswd 

# Copy the sshd_config file to the /etc/ssh/ directory
COPY sshd_config /etc/ssh/

# Copy and configure the ssh_setup file
RUN mkdir -p /tmp
COPY ssh_setup.sh /tmp
RUN chmod +x /tmp/ssh_setup.sh \
    && (sleep 1;/tmp/ssh_setup.sh 2>&1 > /dev/null)

EXPOSE 80 2222
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} app.jar

COPY start.sh /scripts/start.sh
RUN ["chmod", "+x", "/scripts/start.sh"]
ENTRYPOINT ["/scripts/start.sh"]

sshd_config

Port 			2222
ListenAddress 		0.0.0.0
LoginGraceTime 		180
X11Forwarding 		yes
Ciphers aes128-cbc,3des-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr
MACs hmac-sha1,hmac-sha1-96
StrictModes 		yes
SyslogFacility 		DAEMON
PasswordAuthentication 	yes
PermitEmptyPasswords 	no
PermitRootLogin 	yes
Subsystem sftp internal-sftp

ssh_setup.sh

#!/bin/sh

if [ ! -f "/etc/ssh/ssh_host_rsa_key" ]; then
    # generate fresh rsa key
    ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa
fi

if [ ! -f "/etc/ssh/ssh_host_dsa_key" ]; then
    # generate fresh dsa key
    ssh-keygen -f /etc/ssh/ssh_host_dsa_key -N '' -t dsa
fi

if [ ! -f "/etc/ssh/ssh_host_ecdsa_key" ]; then
    # generate fresh ecdsa key
    ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -t dsa
fi

if [ ! -f "/etc/ssh/ssh_host_ed25519_key" ]; then
    # generate fresh ecdsa key
    ssh-keygen -f /etc/ssh/ssh_host_ed25519_key -N '' -t dsa
fi

#prepare run dir
    if [ ! -d "/var/run/sshd" ]; then
    mkdir -p /var/run/sshd
fi

start.sh

#!/bin/sh
/usr/sbin/sshd

java -jar /app.jar

Please note that the above settings only works for the Alpine Linux linux distribution only, hence you have to update the settings to enable the SSH server if you switch to another Linux distribution such as CentOS or Ubuntu.