What Are Software Dependencies?

Understand and manage the dependencies in your software supply chain.

What is a software dependency?

A software dependency is a relationship between software components where one component relies on the other to work properly. For example, if a software application uses a library to query a database, the application depends on that library.

Suppose the library is unavailable or not working correctly. In that case, the application cannot make queries to the database and will not function as intended.

A software dependency can be external or internal. External dependencies are from a third party, while internal dependencies exist within the software. Managing these is an important part of the software development process because it helps to ensure that the software can be built, deployed, and maintained predictably and reliably.

What types of software dependencies are there?

There are two broad classifications: direct and transitive.

Direct dependency

A software dependency explicitly defined and used by a software component.

Example: a JavaScript function may require the lodash library, meaning the file has a direct dependency on that library. The library can be imported using require, like this:

const lodash = require("lodash");

Transitive dependency

A library or module indirectly used by a software component.

In the direct dependency example, the function uses the lodash library. But suppose the lodash library itself uses the underscore library. This means that the function has a transitive dependency on the underscore library. It might not be explicitly declared in the JavaScript file, but it is indirectly used by the lodash library.

What is software dependency analysis?

This refers to identifying and analyzing the dependencies of a software system or application. This involves:

  • Identifying all the components, libraries, frameworks, and other resources the software depends on to function properly.

  • Analyzing the relationships and interactions between these dependencies.

Software dependency analysis can be performed at different stages of the software development life cycle (SDLC); it depends on the needs and goals of the project.

It might be performed:

  • During the planning phase to identify potential risks and develop mitigation strategies.

  • During the design phase to create a detailed architecture for the software.

Software dependency analysis helps to ensure that software is reliably built, deployed, and maintained. By understanding the dependencies of a software system, developers can avoid conflicts and errors and make informed decisions about how to manage and maintain software.

What is “dependency hell”?

Dependency hell is a situation that can arise in software development when the dependencies of a software system or application become difficult to manage.

This can happen when the dependencies of the software are not well-defined or well-managed, resulting in conflicts, errors, and other problems that make it hard to build, deploy, or maintain the software.

If dependencies are not properly identified and managed, it's difficult to avoid conflicts or errors when updating or changing the software. It can also be difficult for other developers to understand how the software works and how to make changes.

How do I manage dependency at scale?

It's important to carefully plan and manage a software system's dependencies and to use tools and techniques to help avoid conflicts and errors. By following best practices for managing dependencies, it’s possible to avoid the headaches associated with dependency hell.

Identify and document

The first step in managing dependencies is identifying the components, libraries, frameworks, and any other resources the software relies on to work properly. This involves conducting a thorough analysis of the software and creating a detailed list of the dependencies, along with their versions and other relevant information. By documenting these, developers can prevent conflicts and errors and make informed choices about how best to manage the software.

Use a package manager

A package manager is a software tool that helps to manage the dependencies of a software system or application. These tools are commonly used in programming languages such as npm for JavaScript and Python. They have the ability to manage dependencies and automate installation, updates, and removal.

Use a dependency management tool

Similar to a package manager, these tools help handle the dependencies of a software system or application.

Dependency management tools can:

  • Help avoid bugs and errors.

  • Manage different versions of dependencies.

  • Track changes and updates.

Developers can utilize a package manager, such as npm, to manage direct dependencies in JavaScript. These tools allow companies to adhere to explicit code requirements by installing, updating, and removing dependencies.

To manage transitive dependencies, developers can use dependency management tools such as Webpack or Browserify. Tools like these can analyze the dependencies of code and ensure that they are compatible and consistent.

Use a dependency injection framework

A dependency injection framework is a software framework that helps to manage the dependencies of a software system or application. They use dependency injection, which involves passing a component's dependencies as parameters to the component rather than hardcoding the dependencies in the component's source code. This makes the component more flexible and modular, and makes it easier to manage the dependencies of the software.

Use a build tool

A build tool also helps manage the dependencies of a software system or application. These tools are commonly used in programming languages such as Java and C++. They can manage the dependencies, and automate building and deploying the software.

Managing software dependencies and securing the dependencies of a software system application helps ensure that software is reliable, maintainable, and scalable.