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Java SE (AlmaLinux 8)

Java SE (AlmaLinux 8)

  • OS: almalinux 8

Description

Java SE (Java Standard Edition) is a platform that provides the tools for developing and deploying Java applications. It includes the Java Development Kit (JDK), which includes the Java Runtime Environment (JRE) and the Java Compiler, as well as a set of APIs (Application Programming Interfaces) that programmers can use to create Java programs. Java SE is widely used in a variety of applications, from desktop to mobile devices, and it is known for its cross-platform compatibility, security features, and robustness.

  1. Software included
  2. Initial start of the service
  3. Quick settings and frequently asked questions
    1. Additional helpful tips
  4. Working with Docker
    1. Restarting all services
    2. Recreating Docker containers
    3. Checking the status of the Docker application

Software included

Package Version
Java SE 19
Docker 3.20.10
Docker compose 2.12.2
containerd.io 1.6.10

Initial start of the service

This application uses Docker to provide faster startup of the underlying software (Java SE) and direct use. This eliminates the need to familiarize yourself with its specifics in terms of configuration and installation. To start working directly with the application, all you have to do is upload the content that you want to be served by Java SE to the /opt/java/data/ directory.

Quick settings and frequently asked questions

  • Logging into the cloud service is done using an SSH key or password that you have specified
  • Docker is installed as recommended by the official docker documentation.
  • The standard docker and docker compose commands are now available in this application.
  • When the virtual machine is first started, it takes a few minutes before a Docker container containing Java SE is started.
  • The Java SE data where you need to deploy your application is located in /opt/java/data/.
  • The port the service is running on is 8080.

Additional helpful tips

  • If you want to use the Java CLI, you can do it with the quick command docker exec -ti docker-java-java-1 java <COMMAND>.
  • If you often use the Java CLI, you can also make a quick shortcut by adding an alias as follows:
echo "alias java='docker exec -ti docker-java-java-1 java'" >> ~/.bashrc
source ~/.bashrc

Working with Docker

The organization of this application is entirely done using Docker. In this way, we can provide you with ready-made applications faster. In addition, their configuration is more flexible and quite controllable. To be able to control this application, however, you need to know some basic Docker functionalities and features.

Restarting all services

Restarting the database and the Docker container that contains Java SE itself, along with the rest of the software, can be done in two ways:

  1. By restarting the entire virtual machine
  2. Restarting the Docker containers, which is the faster option. To do this, access your machine via SSH, and run the following commands:
sudo su -
cd /opt/docker-java
docker compose restart

Recreating Docker containers

Recreation of a docker container may be necessary if you've changed the configuration inside the docker-compose.yml file. If there are changes, please follow these steps:

cd /opt/docker-java/
docker compose stop
docker compose up -d

Checking the status of the Docker application

To check, you need to run the following commands:

sudo su -
docker ps -a

Please pay attention to the STATUS column. It should show how long the service has been running, for example Up X minutes. If the status is Restarting then you need to check what is wrong with the application. In such a case, you can check by following the application logs as follows:

  1. Get the application name that you can see in the NAMES column from the output of the docker ps -a command. View the logs with the docker logs <NAME> command, where is the name of the container.