debugger seems not working on Deno v2 - supabase-cli

[kallebysantos]

Bug report

• I confirm this is a bug with Supabase, not with my own application.
• I confirm I have searched the Docs, GitHub Discussions, and Discord.

Describe the bug

Recently an user did post on Reddit that chrome debugger is not working when using Deno v2.

Expected behaviour

Expected that debugger console to stop and be able to set breakpoints

To Reproduce

Create a new supabase project:

supabase init

Ensures Deno v2 inside config.toml

[edge_runtime]
deno_version = 2

Add a new function:

supabase functions new "hello-world"

Follow the instructions from Local Debugging with DevTools guide

Then run with inspect mode:

supabase functions serve --inspect-mode brk

Call the function:

curl -i --location --request POST 'http://127.0.0.1:54321/functions/v1/hello-world' \
          --header 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzdXBhYmFzZS1kZW1vIiwicm9sZSI6ImFub24iLCJleHAiOjE5ODM4MTI5OTZ9.CRXP1A7WOeoJeXxjNni43kdQwgnWNReilDMblYTn_I0' \
          --header 'Content-Type: application/json' \
          --data '{"name":"Functions"}'

Functions log

❯ supabase functions serve --inspect-mode brk
Setting up Edge Functions runtime...
2025-09-19T12:50:28.057768398Z Serving functions on http://127.0.0.1:54321/functions/v1/<function-name>
2025-09-19T12:50:28.057790898Z  - http://127.0.0.1:54321/functions/v1/hello-world
2025-09-19T12:50:28.057799398Z Using supabase-edge-runtime-1.69.8 (compatible with Deno v2.1.4)
2025-09-19T12:50:45.846312853Z serving the request with supabase/functions/hello-world
2025-09-19T12:50:45.882565346Z Debugger listening on ws://0.0.0.0:8083/ws/8009a7cc-54d5-4619-b0d7-72ed5367903d
2025-09-19T12:50:45.882600096Z Visit chrome://inspect to connect to the debugger.
2025-09-19T12:50:45.882603596Z Worker is waiting for debugger to connect.
2025-09-19T12:50:46.309751611Z Debugger session started.
2025-09-19T12:50:46.433970238Z Debugger session ended

DevTools for Node

Additional context

Works when using v1 ✅

It works when setting the following on config.toml

[edge_runtime]
deno_version = 1

Functions log

❯ supabase functions serve --inspect-mode brk
Setting up Edge Functions runtime...
2025-09-19T12:35:18.511103362Z Serving functions on http://127.0.0.1:54321/functions/v1/<function-name>
2025-09-19T12:35:18.511135654Z  - http://127.0.0.1:54321/functions/v1/hello-world
2025-09-19T12:35:18.511144195Z Using supabase-edge-runtime-1.68.3 (compatible with Deno v1.45.2)
2025-09-19T12:43:35.026717197Z serving the request with supabase/functions/hello-world
2025-09-19T12:43:35.038306306Z Download https://jsr.io/@supabase/functions-js/meta.json
2025-09-19T12:43:35.325873338Z Download https://jsr.io/@supabase/functions-js/2.5.0_meta.json
2025-09-19T12:43:35.358095795Z Download https://jsr.io/@supabase/functions-js/2.5.0/src/edge-runtime.d.ts
2025-09-19T12:43:35.437479605Z Debugger listening on ws://0.0.0.0:8083/ws/77123729-cc26-49cd-ba40-efef32d666a7
2025-09-19T12:43:35.437502855Z Visit chrome://inspect to connect to the debugger.
2025-09-19T12:43:35.437505480Z Worker is waiting for debugger to connect.
2025-09-19T12:43:35.754201806Z Debugger session started.
2025-09-19T12:48:24.762411686Z Debugger session ended

DevTools for Node

System information

• OS: macOS
• Browser: brave
• Version of supabase-cli: 2.40.7

[nyannyacha]

Hey @kallebysantos Is this issue reproducible when using edge-runtime binary alone? Or is it only reproducible with supabase-cli?

[kallebysantos]

I didn't check from binary yet, is there any additional parameter for it?

[nyannyacha]

I think adding --inspect-brk when you execute edge-runtime should be sufficient.

[kallebysantos]

Hi Nya,
I was able to connect and set breakpoints with the bin version:

❯ cargo build --features cli/tracing && \
      RUST_BACKTRACE=full ./target/debug/edge-runtime start --port 9998 --inspect-brk="127.0.0.1:8083" \
          --main-service ./examples/main \
          --event-worker ./examples/event-manager

curl -X POST localhost:9998/hello-world --data '{"name": "kalleby"}'
{"message":"Hello kalleby from foo!"}

Full logs

❯ cargo build --features cli/tracing && \
      RUST_BACKTRACE=full ./target/debug/edge-runtime start --port 9998 --inspect-brk="127.0.0.1:8083" \
          --main-service ./examples/main \
          --event-worker ./examples/event-manager

    Skipping git submodule `https://github.com/denoland/chromium_build.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/src/buildtools.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/src/third_party/abseil-cpp.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/external/github.com/fastfloat/fast_float.git` due to update strategy in .gitmodules
    Skipping git submodule `https://github.com/Maratyszcza/FP16.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/deps/icu.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/src/third_party/jinja2.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libcxx.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libcxxabi.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libunwind.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/src/third_party/markupsafe.git` due to update strategy in .gitmodules
    Skipping git submodule `https://chromium.googlesource.com/chromium/src/tools/clang.git` due to update strategy in .gitmodules
    Skipping git submodule `https://github.com/nyannyacha/v8.git` due to update strategy in .gitmodules
warning: unused import: `tokio::sync::Mutex`
 --> crates/cpu_timer/src/lib.rs:8:5
  |
8 | use tokio::sync::Mutex;
  |     ^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused variable: `tx`
   --> crates/cpu_timer/src/lib.rs:134:10
    |
134 |     let (tx, rx) = mpsc::unbounded_channel();
    |          ^^ help: if this is intentional, prefix it with an underscore: `_tx`
    |
    = note: `#[warn(unused_variables)]` on by default

warning: `cpu_timer` (lib) generated 2 warnings (run `cargo fix --lib -p cpu_timer` to apply 1 suggestion)
warning: use of deprecated function `libc::mach_host_self`: Use the `mach2` crate instead
  --> ext/node/ops/os/cpus.rs:81:13
   |
81 |       libc::mach_host_self(),
   |             ^^^^^^^^^^^^^^
   |
   = note: `#[warn(deprecated)]` on by default

warning: use of deprecated function `libc::mach_task_self`: Use the `mach2` crate instead
   --> ext/node/ops/os/cpus.rs:114:13
    |
114 |       libc::mach_task_self(),
    |             ^^^^^^^^^^^^^^

warning: `ext_node` (lib) generated 2 warnings
warning: `ext_node` (lib) generated 2 warnings (2 duplicates)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.63s
event manager running
main function started
{
  deno: "supabase-edge-runtime-0.1.0 (compatible with Deno v2.1.4)",
  v8: "11.6.189.12",
  typescript: "5.1.6"
}
Debugger listening on ws://127.0.0.1:8083/ws/5ac435c3-b01e-461f-b38e-c40a620cfb3b
Visit chrome://inspect to connect to the debugger.
Worker is waiting for debugger to connect.
{
  timestamp: "2025-09-19T13:34:37.733Z",
  event_type: "Boot",
  event: [Object: null prototype] { boot_time: 42 },
  metadata: [Object: null prototype] {
    service_path: "./examples/hello-world",
    execution_id: "e33c76af-e2d7-445d-bcf7-8fd98085a81e",
    otel_attributes: [Object: null prototype] { "edge_runtime.worker.kind": "user" }
  }
}
Debugger session started.
2025-09-19T13:34:38.591606Z ERROR tokio-runtime-worker cpu_timer: CPU timer: not enabled (need Linux)
2025-09-19T13:34:38.593930Z ERROR ThreadId(134) cpu_timer: CPU timer: not enabled (need Linux)
2025-09-19T13:34:43.736178Z ERROR ThreadId(02) opentelemetry_sdk:  name="BatchSpanProcessor.Flush.ExportError" reason="Other(hyper_util::client::legacy::Error(Connect, ConnectError(\"tcp connect error\", Os { code: 61, kind: ConnectionRefused, message: \"Connection refused\" })))" Failed during the export process
2025-09-19T13:35:13.750864Z ERROR ThreadId(02) opentelemetry_sdk:  name="BatchSpanProcessor.Flush.ExportError" reason="Other(hyper_util::client::legacy::Error(Connect, ConnectError(\"tcp connect error\", Os { code: 61, kind: ConnectionRefused, message: \"Connection refused\" })))" Failed during the export process
2025-09-19T13:36:13.776647Z ERROR ThreadId(02) opentelemetry_sdk:  name="BatchSpanProcessor.Flush.ExportError" reason="Other(hyper_util::client::legacy::Error(Connect, ConnectError(\"tcp connect error\", Os { code: 61, kind: ConnectionRefused, message: \"Connection refused\" })))" Failed during the export process
2025-09-19T13:37:07.733578Z ERROR        sb-supervisor base::worker::supervisor::strategy_per_worker: wall clock duration warning: isolate: e33c76af-e2d7-445d-bcf7-8fd98085a81e

Debugger screenshot

[nyannyacha]

Just a gut feeling, but it seems CLI doesn't expose the inspector port it listens on within the edge-runtime container to the external.

[kallebysantos]

I notice the following at config.toml:

[edge_runtime]
enabled = true
# Configure one of the supported request policies: `oneshot`, `per_worker`.
# Use `oneshot` for hot reload, or `per_worker` for load testing.
policy = "oneshot"
# Port to attach the Chrome inspector for debugging edge functions.
inspector_port = 8083
# The Deno major version to use.
deno_version = 2

[nyannyacha]

I notice the following at config.toml:

yep, I'll keep that in mind.

I will do some extra checking for the cli.

[kallebysantos]

Sure! I'll try to check it also from my side

[nyannyacha]

@kallebysantos I just checked, and I think debugging through the CLI seems to be working normally?

[kallebysantos]

I think that figured out!!

The problem seems to be related with the request policy.
Since old versions was using the "oneshot" as default policy the debugger is not connecting when is Deno v2.

But if you create a new project with the latest version of the cli, the policy will be set as per_worker as default - Debugger could successfully connect on this one.

---

With that said, so old users should change the policy to "per_worker" instead of "oneshot"