Application Dependencies in the LAMP Stack
Tags: opensource, linux
Published: 2022-12-22 06:30:00


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## What is LAMP?
LAMP is an open source web development stack with four layers—it uses Linux as its operating system, Apache as its web server, MySQL as its relational database management system, and PHP as its object-oriented scripting language. You can also use Perl or Python instead of PHP.

Developers use the LAMP stack to create, host, and maintain web content. It is a popular solution used by many large websites.

## LAMP Stack Architecture
A software stack consists of layered tools, programming languages, technologies, and libraries that work together to build, manage, and run an application. It includes software components that support the application in various ways, including security, database, and networking.

The LAMP architecture includes four software technologies—Linux, Apache, MySQL, and PHP (LAMP)—working together to create a working web application. It defines how each technology interacts with the others in a computer server. 

**Linux**
The LAMP stack architecture uses Linux as the operating system layer. This open source operating system has a flexible and customizable nature, making it an ideal choice for running LAMP components. Since PHP and MySQL provide the best results on Linux, they fit well into the LAMP stack.

**Apache**
The LAMP stack uses the Apache open source web server as the second layer. It stores website files and exchanges information with browsers using HTTP, an Internet protocol that enables transferring website information in plain text. 

**MySQL**
MySQL is an open source database management system that supports relational tables and the SQL querying language. It is ideal for creating and maintaining dynamic enterprise-grade databases. Since MySQL is cross-platform compatible, it suits the web development stacks that target multiple operating systems, including LAMP. [MySQL can be deployed in Amazon Web Services (AWS)](https://bluexp.netapp.com/blog/aws-cvo-blg-aws-mysql-two-ways-to-enjoy-mysql-as-a-service), Microsoft Azure, Google Cloud, and almost every other public cloud platform.

**PHP**
The LAMP stack uses PHP as the fourth layer because it interacts well with MySQL. Hypertext Preprocessor (PHP) is a programming language that uses elements in the LAMP stack to enable web applications and websites to run efficiently. Once a user opens a webpage, the server processes PHP commands and sends the results to the user’s browser.

The P in the LAMP stack acronym can also refer to other programming languages—Perl and Python. These programming languages serve as dynamic tools that help create environments for effective application development.

## What Is a Software Dependency?
Most software written today relies on the work of other developers in the form of libraries and packages that support various tasks. These additional libraries (called dependencies) can add functionality to an application easily without requiring developers to build it themselves. 

The growing use of dependencies means that codebases are becoming opaque even to their own developers. Also, because dependencies are software itself, they are vulnerable to bugs and security vulnerabilities and are inherited by the software that uses them.

## Common Risks of Software Dependencies
“Dependency hell” refers to problems that arise when software depends on other dependencies. This third-party software can malfunction, introducing bugs into other programs and applications, which can be very difficult to resolve. Software dependencies can also significantly [increase the attack surface](https://www.hackerone.com/knowledge-center/attack-surface-and-how-analyze-manage-and-reduce-it) of software based on the LAMP stack.

Understanding the causes of dependency hell is critical to avoiding or reducing the problem. However, here are some of the most common root causes:

- **Poorly written code**—it is a best practice to use popular, generic libraries that are in wide use. But these libraries might also have quality issues. To avoid this, scan new libraries for code quality before adopting them in your project.
- **Outdated codebase**—in some cases, packages or libraries might be abandoned by their contributors, who stop updating them. Adopting this type of code exposes your project to vulnerabilities.
- **Dead code**—dependencies might require you to download and use unnecessary dead code, which is never exercised by your application. This can create overlapping dependencies, and unnecessarily increase the attack surface.
- **Poor documentation**—in some cases, documentation of the dependency is poor or non-existent. Evaluating and reconciling these software dependencies can be difficult without proper documentation, and in some cases they will need to be replaced just for this reason.

## Best Practices and Strategies for Dependency Management
**Vulnerability Scanning**
Vulnerability scanning allows you to automatically and consistently evaluate whether a dependency has security vulnerabilities that could affect your application. Vulnerability scanners evaluate lockfiles to pinpoint the artifacts they depend on, notify when new vulnerabilities arise, and in some cases provide recommended upgrade paths. Vulnerability scanning tools can also be useful to scan container images in containerized environments.

**Version Pinning**
Version pinning means limiting the versions of an application's dependencies to one or more specific versions (ideally a single version).

Pinning a dependency to a fixed version is a good approach, which provides more predictability in a software project. The downside is that dependencies won't get updates which can include security fixes, bug fixes, or general improvements.

This can be mitigated by applying [automatic dependency management tools](https://faddom.com/application-dependency-mapping/) to your source control repositories. These tools monitor dependencies on new versions, update requirements files, and upgrade to these new versions as needed. These tools provide change logs for visibility.

**Artifact Verification via Hashes and Signatures**
There are several ways to verify the authenticity of an artifact, to ensure you are really installing the required artifact for a specific version of a package. 

Hash validation allows you to compare the hash of a given artifact with a known hash from the artifact repository. Enabling hash validation prevents man-in-the-middle attacks or artifact store corruption, which can replace dependencies with other, possibly malicious files. This requires assurance that the hash received from the Artifact repository at validation (or initial retrieval) is also intact.

Cryptographic signature verification adds security to the verification process. Artifacts can be signed by an artifact repository, software maintainers, or both.

**Mixing Private and Public Dependencies**
Modern cloud-native applications often rely on both open-source third-party code and closed-source internal libraries. The latter is especially useful if you need to share business logic across multiple applications, or if you want to reuse the same tools and install external and internal libraries.

However, beware of dependency confusion attacks—if you publish a project to an open source repository, using the same name as an internal project, attackers can use a misconfigured installer to install malicious libraries, overwriting an internal package. To prevent this type of attack:

- Include and verify dependent signatures or hashes in lockfiles.
- Split third-party and internal dependency installation into two separate steps.
- Explicitly mirror any required third-party dependencies to your private repository, either manually or by using a pass-through proxy.

## Conclusion
In conclusion, the LAMP stack is a powerful platform for developing and deploying web applications. However, managing software dependencies in the LAMP stack can be complex and time-consuming, and can pose risks to the security and stability of the overall system. 

By following best practices and strategies for dependency management, such as keeping dependencies up-to-date, using version control, and vulnerability scanning, organizations can minimize these risks and ensure that their LAMP-based applications are stable and secure.