Opentelemetry 1.22.0: OpenSSL Dependency Bug?

Is OpenSSL a necessary dependency for Opentelemetry 1.22.0? This is a question that has sparked some debate, especially in environments where alternative SSL implementations are preferred or mandated. In this comprehensive exploration, we will delve into the intricacies of Opentelemetry's dependencies, dissect the arguments surrounding OpenSSL, and provide practical insights for developers navigating this issue. Understanding the core dependencies of libraries like Opentelemetry is crucial for maintaining application stability, security, and performance. It ensures that developers can make informed decisions about their software stack, optimizing for their specific needs and constraints. So, let's embark on this journey to unravel the mystery behind Opentelemetry 1.22.0 and its relationship with OpenSSL.

The Core of the Issue: OpenSSL as a Dependency

The central question revolves around whether opentelemetry-cpp inherently depends on OpenSSL. According to the official documentation for Opentelemetry-cpp version 1.22.0, OpenSSL is not explicitly listed as a required dependency. This assertion is based on the project's documentation, which serves as the primary source of truth for its dependencies. However, the situation becomes more nuanced when considering the underlying libraries and their default configurations. For instance, libcurl, a common dependency in many projects, typically requires an SSL implementation. By default, libcurl often relies on OpenSSL for its SSL/TLS functionalities. This default behavior can inadvertently create an indirect dependency on OpenSSL, even if Opentelemetry itself doesn't directly mandate it. The crux of the issue lies in understanding how these transitive dependencies interact and how they can be configured to use alternative SSL implementations when necessary. This is particularly relevant in environments where OpenSSL is not the preferred choice due to licensing, security concerns, or compatibility issues.

Unpacking the Dependencies: libcurl and SSL Implementations

To fully grasp the OpenSSL dependency issue, it's essential to examine the role of libcurl. Libcurl is a versatile library used for transferring data with various protocols, including HTTP and HTTPS. Given its widespread use in network communication, it's a common dependency in many software projects, including Opentelemetry. Libcurl's functionality often necessitates an SSL implementation to handle secure connections. While OpenSSL is a popular choice, it's not the only option. On Windows, for example, schannel, the native security provider, can be used as an alternative. The key is the with_ssl option within the build configuration. By default, this option often points to OpenSSL. However, developers can configure libcurl to use schannel instead, effectively bypassing the OpenSSL dependency. This configuration is particularly relevant in Windows environments where schannel is readily available and often preferred for its integration with the operating system's security mechanisms. Understanding these configuration options is crucial for developers aiming to minimize dependencies and tailor their build environment to specific requirements.

Windows and Schannel: An Alternative SSL Path

In the Windows ecosystem, the schannel security provider offers a compelling alternative to OpenSSL. Schannel is Microsoft's native TLS/SSL implementation, deeply integrated into the Windows operating system. Leveraging schannel can be advantageous in Windows environments for several reasons. First, it eliminates the need to distribute and manage an external OpenSSL library, simplifying deployment and reducing potential compatibility issues. Second, schannel is often preferred for its adherence to Windows security policies and its seamless integration with the operating system's security features. To utilize schannel with libcurl, developers need to explicitly set the with_ssl option to `