Error: proto: don't know how to compare [], CEL request matcher expects return type of bool

[noelforte]

Environment:

Ubuntu 18.04.4 LTS (Bionic Beaver)

---

Caddy Version:

2020/06/28 21:27:23 WARNING: proto: file "pb.proto" is already registered
A future release will panic on registration conflicts. See:
https://developers.google.com/protocol-buffers/docs/reference/go/faq#namespace-conflict

v2.1.0 h1:MC4d65RCVaEKy1iOFjsD51mybOwS8qdEVBi7ESDhUfE=

---

Caddyfile used (as a reduced test case, error can still be replicated):

:443 {
  handle @v2 {
    root * /path/to/v2
  }
  handle {
    root * /path/to/v1
  }
  file_server

  @v2 { 
    expression {http.request.cookie.v2} == 'yes'
  }
}

Details

Steps to reproduce:

1. Run caddy validate --config <path/to/caddyfile> on the Caddyfile above

Expected output:

Valid configuration.

Actual output:

[...]
proto: don't know how to compare []
[...]
...http.matchers.expression: CEL request matcher expects return type of bool, not primitive:BOOL

Full log:

$ caddy validate --config ./Caddyfile2
2020/06/28 21:31:12 WARNING: proto: file "pb.proto" is already registered
A future release will panic on registration conflicts. See:
https://developers.google.com/protocol-buffers/docs/reference/go/faq#namespace-conflict

2020/06/28 21:31:12.253 INFO    using provided configuration    {"config_file": "./Caddyfile2", "config_adapter": ""}
2020/06/28 21:31:12 [INFO][cache:0xc0004a7a40] Started certificate maintenance routine
2020/06/28 21:31:12 proto: don't know how to compare []
2020/06/28 21:31:12 [INFO][cache:0xc0004a7a40] Stopped certificate maintenance routine
validate: loading http app module: provision http: server srv0: setting up route matchers: route 0: loading matcher modules: module name 'expression': provision http.matchers.expression: CEL request matcher expects return type of bool, not primitive:BOOL

[francislavoie]

Unfortunately, this is a known regression. A fix is proposed in #3526, and some discussion in #3525 but it still needs to be evaluated.

You can use the CI artifact from that PR for the time being until we have a release that otherwise fixes it: https://github.com/caddyserver/caddy/actions/runs/149591246