> For the complete documentation index, see [llms.txt](https://docs.serverlessapigateway.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.serverlessapigateway.com/glossary/e/environment-variables.md). # Environment Variables Key-value pairs in the operating system that are used to store information about the environment that the system is running in. Environment variables are key-value pairs set in the operating system or runtime environment that configure application behavior without hardcoding values in source code. They are used to store configuration such as database connection strings, API keys, feature flags, and service URLs. Environment variables follow the twelve-factor app methodology, which recommends strict separation of configuration from code. This allows the same application code to run in different environments (development, staging, production) with different configurations. Sensitive values like secrets and credentials should be stored as environment variables rather than committed to source control. In serverless platforms, environment variables are configured through the platform's interface or deployment configuration. Cloudflare Workers uses "secrets" and "vars" in the wrangler.toml configuration file. API gateways and serverless functions commonly use environment variables to store backend service URLs, authentication tokens for upstream services, and feature toggles that control routing or processing behavior. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.serverlessapigateway.com/glossary/e/environment-variables.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.