Josh McKinney
76d8d174b1
## Stacked PRs This work is split across three stacked PRs: - #14178: add custom CA support for browser and device-code login flows, docs, and hermetic subprocess tests - #14239: broaden the shared custom CA path from login to other outbound `reqwest` clients across Codex - #14240: extend that shared custom CA handling to secure websocket TLS so websocket connections honor the same CA env vars Review order: #14178, then #14239, then #14240. Supersedes #6864. Thanks to @3axap4eHko for the original implementation and investigation here. Although this version rearranges the code and history significantly, the majority of the credit for this work belongs to them. ## Problem Login flows need to work in enterprise environments where outbound TLS is intercepted by an internal proxy or gateway. In those setups, system root certificates alone are often insufficient to validate the OAuth and device-code endpoints used during login. The change adds a login-specific custom CA loading path, but the important contracts around env precedence, PEM compatibility, test boundaries, and probe-only workarounds need to be explicit so reviewers can understand what behavior is intentional. For users and operators, the behavior is simple: if login needs to trust a custom root CA, set `CODEX_CA_CERTIFICATE` to a PEM file containing one or more certificates. If that variable is unset, login falls back to `SSL_CERT_FILE`. If neither is set, login uses system roots. Invalid or empty PEM files now fail with an error that points back to those environment variables and explains how to recover. ## What This Delivers Users can now make Codex login work behind enterprise TLS interception by pointing `CODEX_CA_CERTIFICATE` at a PEM bundle containing the relevant root certificates. If that variable is unset, login falls back to `SSL_CERT_FILE`, then to system roots. This PR applies that behavior to both browser-based and device-code login flows. It also makes login tolerant of the PEM shapes operators actually have in hand: multi-certificate bundles, OpenSSL `TRUSTED CERTIFICATE` labels, and bundles that include well-formed CRLs. ## Mental model `codex-login` is the place where the login flows construct ad hoc outbound HTTP clients. That makes it the right boundary for a narrow CA policy: look for `CODEX_CA_CERTIFICATE`, fall back to `SSL_CERT_FILE`, load every parseable certificate block in that bundle into a `reqwest::Client`, and fail early with a clear user-facing error if the bundle is unreadable or malformed. The implementation is intentionally pragmatic about PEM input shape. It accepts ordinary certificate bundles, multi-certificate bundles, OpenSSL `TRUSTED CERTIFICATE` labels, and bundles that also contain CRLs. It does not validate a certificate chain or prove a handshake; it only constructs the root store used by login. ## Non-goals This change does not introduce a general-purpose transport abstraction for the rest of the product. It does not validate whether the provided bundle forms a real chain, and it does not add handshake-level integration tests against a live TLS server. It also does not change login state management or OAuth semantics beyond ensuring the existing flows share the same CA-loading rules. ## Tradeoffs The main tradeoff is keeping this logic scoped to login-specific client construction rather than lifting it into a broader shared HTTP layer. That keeps the review surface smaller, but it also means future login-adjacent code must continue to use `build_login_http_client()` or it can silently bypass enterprise CA overrides. The `TRUSTED CERTIFICATE` handling is also intentionally a local compatibility shim. The rustls ecosystem does not currently accept that PEM label upstream, so the code normalizes it locally and trims the OpenSSL `X509_AUX` trailer bytes down to the certificate DER that `reqwest` can consume. ## Architecture `custom_ca.rs` is now the single place that owns login CA behavior. It selects the CA file from the environment, reads it, normalizes PEM label shape where needed, iterates mixed PEM sections with `rustls-pki-types`, ignores CRLs, trims OpenSSL trust metadata when necessary, and returns either a configured `reqwest::Client` or a typed error. The browser login server and the device-code flow both call `build_login_http_client()`, so they share the same trust-store policy. Environment-sensitive tests run through the `login_ca_probe` helper binary because those tests must control process-wide env vars and cannot reliably build a real reqwest client in-process on macOS seatbelt runs. ## Observability The custom CA path logs which environment variable selected the bundle, which file path was loaded, how many certificates were accepted, when `TRUSTED CERTIFICATE` labels were normalized, when CRLs were ignored, and where client construction failed. Returned errors remain user-facing and include the relevant path, env var, and remediation hint. This gives enough signal for three audiences: - users can see why login failed and which env/file caused it - sysadmins can confirm which override actually won - developers can tell whether the failure happened during file read, PEM parsing, certificate registration, or final reqwest client construction ## Tests Pure unit tests stay limited to env precedence and empty-value handling. Real client construction lives in subprocess tests so the suite remains hermetic with respect to process env and macOS sandbox behavior. The subprocess tests verify: - `CODEX_CA_CERTIFICATE` precedence over `SSL_CERT_FILE` - fallback to `SSL_CERT_FILE` - single-certificate and multi-certificate bundles - malformed and empty-bundle errors - OpenSSL `TRUSTED CERTIFICATE` handling - CRL tolerance for well-formed CRL sections The named PEM fixtures under `login/tests/fixtures/` are shared by the tests so their purpose stays reviewable. --------- Co-authored-by: Ivan Zakharchanka <3axap4eHko@gmail.com> Co-authored-by: Codex <noreply@openai.com>
Codex CLI (Rust Implementation)
We provide Codex CLI as a standalone, native executable to ensure a zero-dependency install.
Installing Codex
Today, the easiest way to install Codex is via npm:
npm i -g @openai/codex
codex
You can also install via Homebrew (brew install --cask codex) or download a platform-specific release directly from our GitHub Releases.
Documentation quickstart
- First run with Codex? Start with
docs/getting-started.md(links to the walkthrough for prompts, keyboard shortcuts, and session management). - Want deeper control? See
docs/config.mdanddocs/install.md.
What's new in the Rust CLI
The Rust implementation is now the maintained Codex CLI and serves as the default experience. It includes a number of features that the legacy TypeScript CLI never supported.
Config
Codex supports a rich set of configuration options. Note that the Rust CLI uses config.toml instead of config.json. See docs/config.md for details.
Model Context Protocol Support
MCP client
Codex CLI functions as an MCP client that allows the Codex CLI and IDE extension to connect to MCP servers on startup. See the configuration documentation for details.
MCP server (experimental)
Codex can be launched as an MCP server by running codex mcp-server. This allows other MCP clients to use Codex as a tool for another agent.
Use the @modelcontextprotocol/inspector to try it out:
npx @modelcontextprotocol/inspector codex mcp-server
Use codex mcp to add/list/get/remove MCP server launchers defined in config.toml, and codex mcp-server to run the MCP server directly.
Notifications
You can enable notifications by configuring a script that is run whenever the agent finishes a turn. The notify documentation includes a detailed example that explains how to get desktop notifications via terminal-notifier on macOS. When Codex detects that it is running under WSL 2 inside Windows Terminal (WT_SESSION is set), the TUI automatically falls back to native Windows toast notifications so approval prompts and completed turns surface even though Windows Terminal does not implement OSC 9.
codex exec to run Codex programmatically/non-interactively
To run Codex non-interactively, run codex exec PROMPT (you can also pass the prompt via stdin) and Codex will work on your task until it decides that it is done and exits. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on.
Use codex exec --ephemeral ... to run without persisting session rollout files to disk.
Experimenting with the Codex Sandbox
To test to see what happens when a command is run under the sandbox provided by Codex, we provide the following subcommands in Codex CLI:
# macOS
codex sandbox macos [--full-auto] [--log-denials] [COMMAND]...
# Linux
codex sandbox linux [--full-auto] [COMMAND]...
# Windows
codex sandbox windows [--full-auto] [COMMAND]...
# Legacy aliases
codex debug seatbelt [--full-auto] [--log-denials] [COMMAND]...
codex debug landlock [--full-auto] [COMMAND]...
Selecting a sandbox policy via --sandbox
The Rust CLI exposes a dedicated --sandbox (-s) flag that lets you pick the sandbox policy without having to reach for the generic -c/--config option:
# Run Codex with the default, read-only sandbox
codex --sandbox read-only
# Allow the agent to write within the current workspace while still blocking network access
codex --sandbox workspace-write
# Danger! Disable sandboxing entirely (only do this if you are already running in a container or other isolated env)
codex --sandbox danger-full-access
The same setting can be persisted in ~/.codex/config.toml via the top-level sandbox_mode = "MODE" key, e.g. sandbox_mode = "workspace-write".
In workspace-write, Codex also includes ~/.codex/memories in its writable roots so memory maintenance does not require an extra approval.
Code Organization
This folder is the root of a Cargo workspace. It contains quite a bit of experimental code, but here are the key crates:
core/contains the business logic for Codex. Ultimately, we hope this to be a library crate that is generally useful for building other Rust/native applications that use Codex.exec/"headless" CLI for use in automation.tui/CLI that launches a fullscreen TUI built with Ratatui.cli/CLI multitool that provides the aforementioned CLIs via subcommands.
If you want to contribute or inspect behavior in detail, start by reading the module-level README.md files under each crate and run the project workspace from the top-level codex-rs directory so shared config, features, and build scripts stay aligned.