Application Configuration

[ application analysis ]

Configuration file allows you to change application settings without modifying its source code. For example, switch the logging level from INFO to a more detailed DEBUG.

Let’s look at:

formats and examples of configuration files
where to find the configuration file
how to modify the configuration file

Configuration File Formats

Configuration files use a key-value structure regardless of the format, differing only in syntax.

JSON

JavaScript Object Notation

Explained in detail here. Used to describe configurations for applications in JavaScript, C#, and others.

YAML

YAML Ain't Markup Language

Syntax is based on indentation. A standard for configuring applications in Java, Kotlin, and more.

INI

Initialization File

A simple and outdated format. Still used in applications written in C, C++.

config.json

{
  "server": {
    "host": "localhost",
    "port": 8080
  },
  "logging": {
    "level": "info",
    "file": "/var/log/app.log"
  }
}

config.yml

server:
  host: localhost
  port: 8080

logging:
  level: info
  file: /var/log/app.log

config.ini

[server]
host = localhost
port = 8080

[logging]
level = info
file = /var/log/app.log

Here’s how the same configuration file looks in different formats.

Each example describes the server’s address and port, logging level, and application log file location.

Configuration File Location

Configuration files are usually stored next to the application itself, for example

/opt/application_name/config/config.json

/opt/application_name/config/config.yml

/opt/application_name/application.yml

/opt/application_name/config/config.ini

The exact path and filename can be clarified with the application developer or DevOps engineer.

Modifying the Configuration File

To modify a configuration file on a remote server, you can use the nano command:

nano /path/to/file

Save changes and exit nano:

Ctrl + O (сохранить) → Enter
Ctrl + X (выйти)

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