---
title: Reference
description: CLI, actions, environment variables, and the engine API.
weight: 30
---

Technical reference for the apex fleet-operations framework surface: the command-line interface, the built-in [actions](/apex/glossary#action), the environment contract they consume, and the Python [engine](/apex/glossary#engine) API.

{{% cards %}}
{{< card link="cli" title="CLI reference" icon="terminal" subtitle="Command-line invocation, subcommands, and exit codes." >}}
{{< card link="actions" title="Actions reference" icon="play" subtitle="Built-in actions and their arguments." >}}
{{< card link="environment" title="Environment reference" icon="variable" subtitle="Environment variables exposed to actions and compositions." >}}
{{< card link="engine-api" title="Engine API reference" icon="code" subtitle="Python modules that power the engine." >}}
{{% /cards %}}

---

**See also:**

- [GitHub: apex.ermnvldmr.com](https://github.com/deytenit/apex.ermnvldmr.com)