What is an Application User?
An application user or a system user is a user account created on the server's operating system. An application user can have access to their own directory on the operating system. That directory is called the Home directory in Ubuntu.
It is exactly like sharing an office computer using different user accounts on an operating system. The only difference is that we share an office computer for different use cases. Here we share server resources between different developers, organization members, or any other type of users who need access to the server.
For example, imagine you want to start three projects on a specific server, and you have three different developers to develop those projects. In this case, you create each application under an application user account.
You can share account information with the appropriate developer.
One application user cannot access/see/edit the files of another application user.
You can create multiple application users on a single server.
Authentication Methods
An application user can have SSH and SFTP access on the server only if you allow it from the ServerAvatar. You can enable or disable access to the server for each application user individually.
A system user can access files on the server via the following authentication methods:
- Password authentication
- SSH Key authentication
And yes, you can enable/disable password authentication as well as set the SSH keys for a user.
Access
An application user can have one or more than one applications. It means that if you want one developer to manage multiple projects, you can create multiple applications under a single application user. As mentioned above, you can enable/disable SSH/SFTP access as well as enable/disable password login.
In the final document of this section, You will learn more about Isolated Environments on ServerAvatar.