Prometheus operates on a pull-based model where it scrapes (retrieves) metrics from target applications. The fundamental requirement for an application to be monitored by Prometheus is its ability to expose these metrics over an HTTP endpoint. When Prometheus scrapes a target, it sends an HTTP GET request to a specific path (conventionally /metrics). The application must respond with its current metrics in the Prometheus text-based exposition format. This mechanism is platform-agnostic and does not depend on the application's architecture, operating system, or its accessibility from the public internet.

A. The application only needs to be network-accessible to the Prometheus server, which is typically on a private network, not the public Internet.

B. The CPU architecture (e.g., 64-bit, 32-bit, ARM) of the target application is irrelevant to the text-based HTTP scraping mechanism.

D. Prometheus and its targets are cross-platform. An application can expose metrics on any operating system (like Windows or macOS), not just Linux.

1. Prometheus Official Documentation, "Exposition formats": "Prometheus scrapes metrics from instrumented jobs... These jobs expose their metrics via an HTTP endpoint. This document specifies the format that Prometheus expects these metrics to be in." This confirms the requirement is to expose metrics via an HTTP endpoint in a specific text format.

Source: Prometheus Authors. (n.d.). Exposition formats. Prometheus documentation. Retrieved from https://prometheus.io/docs/instrumenting/expositionformats/

2. Prometheus Official Documentation, "Concepts - Architecture": The architectural overview explicitly describes the core mechanism: "Prometheus scrapes metrics from instrumented jobs". The diagram illustrates this as an HTTP pull from the Prometheus server to the jobs/exporters.

Source: Prometheus Authors. (n.d.). Concepts - Architecture. Prometheus documentation. Retrieved from https://prometheus.io/docs/introduction/overview/#architecture

3. The Linux Foundation, Cloud Native Computing Foundation (CNCF) Archives: Prometheus, a CNCF graduated project, is fundamentally designed around this HTTP pull model. The project's core design documents emphasize this principle. "All Prometheus components are available to run on a variety of operating systems... The only requirement for monitoring a service with Prometheus is that the metrics are available via HTTP."

Source: Cloud Native Computing Foundation. (n.d.). Prometheus Project Journey Report. The Linux Foundation. (Reference to the core design principles documented within the project's CNCF graduation materials).