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[Frontend] Add TLS support with certificate/key files#46350

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badrinatarajan:tls_rust_support
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[Frontend] Add TLS support with certificate/key files#46350
badrinatarajan wants to merge 1 commit into
vllm-project:mainfrom
badrinatarajan:tls_rust_support

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@badrinatarajan

@badrinatarajan badrinatarajan commented Jun 22, 2026 •
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  • Implement TLS listener configuration
  • Add unit tests for TLS settings
  • Support client certificate authentication modes

Co-authored-by: GitHub Copilot
Co-authored-by: Claude

Purpose

This PR adds TLS support to the vLLM Rust frontend, enabling secure HTTPS connections with certificate-based authentication.

Sample CLI command:
vllm serve --model Qwen/Qwen3-0.6B --dtype bfloat16 --ssl-certfile /tmp/server-cert.pem --ssl-keyfile /tmp/server-key.pem --ssl-ca-certs /tmp/ca-cert.pem --ssl-cert-reqs 2

Test Plan

New unit tests added covering:

  • Argument parsing for all TLS parameters
    • TLS listener configuration generation
    • Client authentication modes
    • Cipher validation and logging
    • JSON deserialization of TLS fields

Test Result

All unit tests passing - see below.
Also, added and executed tests with temporary certs and files to create valid and invalid client certs) and ensured that the behavior is as expected.

Unit tests:

    Finished `test` profile [unoptimized + debuginfo] target(s) in 3.15s
     Running unittests src/main.rs (target/debug/deps/vllm_rs-1d4a96ec22e445e3)

running 43 tests
test cli::tests::frontend_args_json_accepts_noop_fields ... ok
test cli::tests::frontend_args_json_accepts_tls_fields ... ok
test cli::tests::frontend_args_accept_json ... ok
test cli::tests::frontend_args_json_applies_defaults ... ok
test cli::tests::frontend_args_json_accepts_supported_non_default_fields ... ok
test cli::tests::frontend_args_json_aggregates_multiple_unsupported_fields ... ok
test cli::tests::frontend_args_json_accepts_tls_with_ca_certs ... ok
test cli::tests::frontend_args_json_passes_enable_request_id_headers_into_config ... ok
test cli::tests::frontend_args_json_ignores_unknown_fields ... ok
test cli::tests::frontend_args_reject_legacy_handshake_flags ... ok
test cli::tests::frontend_args_json_rejects_malformed_json ... ok
test cli::tests::frontend_config_uses_external_coordinator_when_coordinator_address_is_present ... ok
test cli::tests::frontend_args_json_rejects_unsupported_fields ... ok
test cli::tests::serve_args_accept_explicit_deepseek_v32_renderer ... ok
test cli::tests::serve_args_accept_data_parallel_primary_flags ... ok
test cli::tests::serve_args_accept_headless_mode ... ok
test cli::tests::serve_args_accept_handshake_aliases ... ok
test cli::tests::serve_args_accept_tls_arguments_with_cert_and_key ... ok
test cli::tests::serve_args_accept_none_reasoning_parser ... ok
test cli::tests::serve_args_auto_forward_enable_lora_to_python ... ok
test cli::tests::serve_args_accept_tls_with_client_auth_optional_mode ... ok
test cli::tests::serve_args_auto_forward_python_multi_char_alias_without_separator ... ok
test cli::tests::serve_args_accept_tls_with_ciphers ... ok
test cli::tests::serve_args_accept_tls_with_client_auth_required ... ok
test cli::tests::serve_args_auto_forward_negative_value_without_separator ... ok
test cli::tests::serve_args_auto_forward_unknown_flags_without_separator ... ok
test cli::tests::serve_args_auto_forward_python_flags_without_separator ... ok
test cli::tests::serve_args_forward_python_flags_with_separator ... ok
test cli::tests::serve_args_reject_flags_before_model ... ok
test cli::tests::serve_args_keep_python_multi_char_alias_after_separator ... ok
test cli::tests::serve_args_keep_frontend_arg_after_separator ... ok
test cli::tests::serve_args_keep_python_passthrough_flags_after_separator ... ok
test cli::tests::serve_args_reject_unknown_renderer_value ... ok
test cli::tests::serve_args_keep_python_multi_char_engine_aliases_after_separator ... ok
test cli::tests::serve_args_reject_unsupported_flag_arg ... ok
test cli::tests::serve_args_reject_unsupported_no_flag_alias ... ok
test cli::tests::serve_frontend_config_creates_tls_listener_mode ... ok
test cli::tests::serve_frontend_config_creates_tls_listener_with_client_auth ... ok
test cli::tests::serve_frontend_config_no_tls_without_cert ... ok
test cli::tests::serve_frontend_config_keeps_tcp_transport_for_non_local_only_topology ... ok
test cli::tests::serve_frontend_config_uses_unix_listener_when_uds_is_present ... ok
test cli::tests::serve_frontend_config_uses_dp_address_as_advertised_host ... ok
test cli::tests::serve_passes_enable_request_id_headers_into_config ... ok

test result: ok. 43 passed; 0 failed; 0 ignored; 0 measured; 5 filtered out; finished in 0.02s```



---
<details>
- **Rust Frontend (TLS Implementation)**
  - Support for passing in a cert and key via CLI args (see below for the new args)
  - Added `HttpListenerMode::BindTcpTls` variant for TLS configuration
  - Support for client certificate authentication (CERT_NONE, CERT_REQUIRED)
  - Comprehensive TLS error handling with recursive fallback on handshake failures
  - SSL cipher validation and logging (rustls uses hardcoded secure defaults)

- **CLI Arguments**
  - Added `--ssl-certfile`, `--ssl-keyfile`, `--ssl-ca-certs` arguments
  - Added `--ssl-cert-reqs` for client authentication modes (0=CERT_NONE, 2=CERT_REQUIRED)
  - Added `--ssl-ciphers` for CLI compatibility with Python/Uvicorn (validation/logging only)
  - Updated docstrings to document TLS limitations in rustls
  
Parity with Uvicorn and known limitations:
Feature                          Uvicorn    Rust       Notes
========================================================================
TLS/HTTPS Binding                ✓          ✓          Supported
ssl_certfile                     ✓          ✓          Supported. PEM format (PKCS8, RSA, EC, Ed25519)
ssl_keyfile                      ✓          ✓          Supported                                                     
ssl_ca_certs                     ✓          ✓          Supported 
ssl_cert_reqs                    ✓          ✓          Supported ; 3 modes (NONE/OPTIONAL/REQUIRED);
                                                       (Note: Optional defaults to NONE)
ssl_ciphers                     ✓ enforced ✓ logging  Rust 0.23 does not seem to provide selection of cipther suites;
                                                       But only strong ciphers are supported. Can remove/warn if args are provided```

<summary> Essential Elements of an Effective PR Description Checklist </summary>

- [ ] The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
- [ ] The test plan, such as providing test command.
- [ ] The test results, such as pasting the results comparison before and after, or e2e results
- [ ] (Optional) The necessary documentation update, such as updating `supported_models.md` and `examples` for a new model.
</details>

@badrinatarajan
[Frontend] Add TLS support with certificate/key files
54ac36a 
- Implement TLS listener configuration
- Add unit tests for TLS settings
- Support client certificate authentication modes

Co-authored-by: GitHub Copilot
Co-authored-by: Claude
Signed-off-by: Badri Natarajan <badri.natarajan@gmail.com>
@github-actions

github-actions Bot commented Jun 22, 2026

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👋 Hi! Thank you for contributing to the vLLM project.

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@mergify

mergify Bot commented Jun 22, 2026

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This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @badrinatarajan.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

@mergify mergify Bot added the needs-rebase label Jun 22, 2026
@njhill

njhill commented Jun 29, 2026

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Thanks @badrinatarajan, but we do already have a PR for this: #45890.

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@badrinatarajan @njhill