Aradhya Jain b1694e7a4c caddyhttp: add CEL expression support to the tls matcher (#8088)
* caddyhttp: add CEL expression support to the tls matcher

MatchTLS was the only core HTTP matcher without a CELLibrary() implementation,
so it could not be used inside an expression matcher. Every sibling matcher
(host, path, path_regexp, method, query, header, header_regexp, protocol,
remote_ip, client_ip, url_pattern, vars, vars_regexp, and the file-server's
file matcher) already has this.

Adds CELLibrary() to MatchTLS, exposing tls_handshake_complete('true') /
tls_handshake_complete('false') in CEL expressions. Mirrors MatchProtocol's
existing string-argument-macro pattern: CELMatcherImpl with cel.StringType,
parsing the argument with strconv.ParseBool and constructing a
MatchTLS{HandshakeComplete: &b} that reuses the matcher's own
MatchWithError. Adds the corresponding CELLibraryProducer interface guard.

Adds 6 cases to celmatcher_test.go's existing table-driven
TestMatchExpressionMatch/BenchmarkMatchExpressionMatch: match on
'true'/'false' against a complete/incomplete handshake, and three
invocation-error cases (no args, wrong arg type, non-boolean string).
Required adding a tlsHandshakeComplete *bool field to the shared test table
and wiring it into req.TLS.HandshakeComplete in both the test and benchmark
request-construction helpers.

Fixes #8087

* address review: use a native bool arg, rename to match the matcher's own name

francislavoie's review on #8088:
- "A boolean as a string argument is very strange." CELMatcherImpl only
  supported string/list(string)/map argument types, so the original
  implementation parsed a string literal with strconv.ParseBool to work
  around that. Instead, extends CELMatcherImpl itself with a cel.BoolType
  case (celMatcherBoolMacroExpander + isCELBoolExpr, mirroring the existing
  string equivalents), so a matcher can accept a real CEL bool literal.
  This is shared infrastructure, so any other matcher needing a bool
  argument in the future gets it for free.
- "I'm not sure why tls_handshake_complete was chosen when the matcher is
  named tls." Renamed the CEL function to tls(...), matching every other
  matcher's naming convention (the function name mirrors the matcher's own
  directive/module name: host(), path(), method(), protocol(), etc.).

Usage is now 'expression tls(true)' / 'expression tls(false)' instead of
'expression tls_handshake_complete(\'true\')'.

Updated the 6 existing test cases accordingly; still covers match/no-match
on both true/false and the two invocation-error cases (no args, wrong arg
type -- now a string instead of a bool, confirming the new type check).

* address review: cover tls() against a plain non-TLS request

steadytao asked for a test proving tls(false) doesn't treat the absence
of TLS as an incomplete handshake. MatchWithError already handles this
correctly (r.TLS == nil returns false regardless of HandshakeComplete),
this just adds the missing coverage for both tls(true) and tls(false)
against a plain http:// request.

Confirmed these tests catch a real regression: removing the r.TLS == nil
guard causes a nil pointer dereference panic, not just a wrong result.

* address review: redesign tls() CEL matcher to preserve all three Caddyfile states

The Caddyfile tls matcher has three states: bare `tls` (any TLS connection,
regardless of handshake completion), `tls early_data` (handshake not yet
complete), and the implicit "handshake complete" case. The previous
tls(true)/tls(false) design could only express the latter two, with no way
to express "any TLS, don't care about handshake state" from CEL.

Redesigns the macro to:

  tls()               -- any TLS connection (mirrors bare `tls`)
  tls('complete')      -- handshake complete
  tls('early_data')    -- handshake not yet complete (mirrors `tls early_data`)

tls() is implemented as sugar for tls('any'): a zero-arg macro that expands
to the same 2-arg call the one-arg string macro produces, just with the
literal injected by the macro itself. Both macros share one function
registration and one matcher factory, so there's a single source of truth
for the string-to-MatchTLS mapping.

This replaces the native-bool design from the prior commit, so also removes
the generic bool-argument support (celMatcherBoolMacroExpander,
isCELBoolExpr, and the CELMatcherImpl case for cel.BoolType) added for it,
since nothing else in the codebase used it and it would otherwise ship as
unreviewed, unused surface area.

Rewrites the existing tls(...) test cases for the new string-based calls,
and adds coverage for the new tls() form: matches regardless of handshake
state (both complete and incomplete), and still correctly fails to match a
plain non-TLS request. Also covers the new invocation-error cases: a
boolean argument is no longer valid, and an unrecognized string (anything
other than 'complete'/'early_data') is now a Provision-time error instead
of silently doing the wrong thing.

Verified: full caddyhttp test suite passes, and confirmed each new/changed
test fails when its corresponding implementation piece is reverted
(the zero-arg macro, and the complete/early_data boolean mapping).

* address review: document and test tls('any') as a supported literal form

steadytao pointed out that the zero-arg tls() macro expands internally to
the same tls_request_string(req, "any") call that the one-arg form uses,
which means tls('any') was already silently reachable as a literal string
even though it was never documented or tested as part of the public API.

Rather than special-casing the macro to bypass the shared string factory
(which would need a second function/overload just for the zero-arg case),
document and test tls('any') as a real, supported third spelling alongside
tls() -- they're already fully equivalent, so there's nothing to hide.
2026-10-24 08:01:24 -04:00
…
2026-10-17 19:49:32 +10:00
…

Caddy

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Caddy is an extensible server platform that uses TLS by default.

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Features

  • Easy configuration with the Caddyfile
  • Powerful configuration with its native JSON config
  • Dynamic configuration with the JSON API
  • Config adapters if you don't like JSON
  • Automatic HTTPS by default
    • ZeroSSL and Let's Encrypt for public names
    • Fully-managed local CA for internal names & IPs
    • Can coordinate with other Caddy instances in a cluster
    • Multi-issuer fallback
    • Encrypted ClientHello (ECH) support
  • Stays up when other servers go down due to TLS/OCSP/certificate-related issues
  • Production-ready after serving trillions of requests and managing millions of TLS certificates
  • Scales to hundreds of thousands of sites as proven in production
  • HTTP/1.1, HTTP/2, and HTTP/3 all supported by default
  • Highly extensible modular architecture lets Caddy do anything without bloat
  • Runs anywhere with no external dependencies (not even libc)
  • Written in Go, a language with higher memory safety guarantees than other servers
  • Actually fun to use
  • So much more to discover

Install

The simplest, cross-platform way to get started is to download Caddy from GitHub Releases and place the executable file in your PATH.

See our online documentation for other install instructions.

Build from source

Requirements:

For development

Note: These steps will not embed proper version information. For that, please follow the instructions in the next section.

$ git clone "https://github.com/caddyserver/caddy.git"
$ cd caddy/cmd/caddy/
$ go build

When you run Caddy, it may try to bind to low ports unless otherwise specified in your config. If your OS requires elevated privileges for this, you will need to give your new binary permission to do so. On Linux, this can be done easily with: sudo setcap cap_net_bind_service=+ep ./caddy

If you prefer to use go run which only creates temporary binaries, you can still do this with the included setcap.sh like so:

$ go run -exec ./setcap.sh main.go

If you don't want to type your password for setcap, use sudo visudo to edit your sudoers file and allow your user account to run that command without a password, for example:

username ALL=(ALL:ALL) NOPASSWD: /usr/sbin/setcap

replacing username with your actual username. Please be careful and only do this if you know what you are doing! We are only qualified to document how to use Caddy, not Go tooling or your computer, and we are providing these instructions for convenience only; please learn how to use your own computer at your own risk and make any needful adjustments.

Then you can run the tests in all modules or a specific one:

$ go test ./...
$ go test ./modules/caddyhttp/tracing/

With version information and/or plugins

Using our builder tool, xcaddy...

$ xcaddy build

...the following steps are automated:

  1. Create a new folder: mkdir caddy
  2. Change into it: cd caddy
  3. Copy Caddy's main.go into the empty folder. Add imports for any custom plugins you want to add.
  4. Initialize a Go module: go mod init caddy
  5. (Optional) Pin Caddy version: go get github.com/caddyserver/caddy/v2@version replacing version with a git tag, commit, or branch name.
  6. (Optional) Add plugins by adding their import: _ "import/path/here"
  7. Compile: go build -tags=nobadger,nomysql,nopgx

Quick start

The Caddy website has documentation that includes tutorials, quick-start guides, reference, and more.

We recommend that all users -- regardless of experience level -- do our Getting Started guide to become familiar with using Caddy.

If you've only got a minute, the website has several quick-start tutorials to choose from! However, after finishing a quick-start tutorial, please read more documentation to understand how the software works. 🙂

Overview

Caddy is most often used as an HTTPS server, but it is suitable for any long-running Go program. First and foremost, it is a platform to run Go applications. Caddy "apps" are just Go programs that are implemented as Caddy modules. Two apps -- tls and http -- ship standard with Caddy.

Caddy apps instantly benefit from automated documentation, graceful on-line config changes via API, and unification with other Caddy apps.

Although JSON is Caddy's native config language, Caddy can accept input from config adapters which can essentially convert any config format of your choice into JSON: Caddyfile, JSON 5, YAML, TOML, NGINX config, and more.

The primary way to configure Caddy is through its API, but if you prefer config files, the command-line interface supports those too.

Caddy exposes an unprecedented level of control compared to any web server in existence. In Caddy, you are usually setting the actual values of the initialized types in memory that power everything from your HTTP handlers and TLS handshakes to your storage medium. Caddy is also ridiculously extensible, with a powerful plugin system that makes vast improvements over other web servers.

To wield the power of this design, you need to know how the config document is structured. Please see our documentation site for details about Caddy's config structure.

Nearly all of Caddy's configuration is contained in a single config document, rather than being scattered across CLI flags and env variables and a configuration file as with other web servers. This makes managing your server config more straightforward and reduces hidden variables/factors.

Full documentation

Our website has complete documentation:

https://caddyserver.com/docs/

The docs are also open source. You can contribute to them here: https://github.com/caddyserver/website

Getting help

  • We advise companies using Caddy to secure a support contract through Ardan Labs before help is needed.

  • A sponsorship goes a long way! We can offer private help to sponsors. If Caddy is benefitting your company, please consider a sponsorship. This not only helps fund full-time work to ensure the longevity of the project, it provides your company the resources, support, and discounts you need; along with being a great look for your company to your customers and potential customers!

  • Individuals can exchange help for free on our community forum at https://caddy.community. Remember that people give help out of their spare time and good will. The best way to get help is to give it first!

Please use our issue tracker only for bug reports and feature requests, i.e. actionable development items (support questions will usually be referred to the forums).

About

Matthew Holt began developing Caddy in 2014 while studying computer science at Brigham Young University. (The name "Caddy" was chosen because this software helps with the tedious, mundane tasks of serving the Web, and is also a single place for multiple things to be organized together.) It soon became the first web server to use HTTPS automatically and by default, and now has hundreds of contributors and has served trillions of HTTPS requests.

The name "Caddy" is trademarked. The name of the software is "Caddy", not "Caddy Server" or "CaddyServer". Please call it "Caddy" or, if you wish to clarify, "the Caddy web server". Caddy is a registered trademark of Stack Holdings GmbH.

Caddy is a project of ZeroSSL, an HID Global company.

Debian package repository hosting is graciously provided by Cloudsmith. Cloudsmith is the only fully hosted, cloud-native, universal package management solution, that enables your organization to create, store and share packages in any format, to any place, with total confidence.

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