fix: dynamically report backend_host in terminal logs #6165

[pranavmanglik]

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Type of change

• Bug fix (non-breaking change which fixes an issue)

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Pull Request Details

Descriptive Title

fix: accurately report configured backend_host in terminal logs

Description of Changes

Currently, the notify_backend function in reflex/utils/exec.py has the backend IP hardcoded as 0.0.0.0. This leads to misleading terminal output when a user has explicitly configured a custom backend_host (e.g., 127.0.0.1 for local-only development) in their rxconfig.py.

This PR modifies the notification logic to dynamically pull the backend_host from the Reflex configuration, ensuring the logs match the actual network binding. This improves developer clarity and assists in verifying security configurations.

Testing performed:

• Verified on EndeavourOS by setting backend_host="127.0.0.1" in rxconfig.py.
• Confirmed terminal output correctly displays http://127.0.0.1:8000 instead of the hardcoded 0.0.0.0.
• Ensured local linting (ruff) passes.

Closing Issues

Closes #6165

[greptile-apps]

Greptile Summary

Fixes the notify_backend() function in reflex/utils/exec.py to dynamically display the configured backend_host instead of a hardcoded 0.0.0.0 in terminal logs. This ensures developer-facing output matches the actual server binding when a custom host is set in rxconfig.py or via the --backend-host CLI flag.

• Replaces 0.0.0.0 with get_config().backend_host in the log message
• Minimal, well-scoped change — only the notification string is affected, not actual server binding logic
• No new dependencies or architectural changes

Confidence Score: 4/5

• This PR is safe to merge — it only changes a log message string with no impact on server binding behavior.
• Score of 4 reflects that this is a trivial, single-line change affecting only terminal output. The get_config().backend_host value is already used elsewhere for actual server binding, so using it in the notification is correct and consistent. Minor style note: get_config() is called twice in one f-string, but this matches the prior pattern and get_config() is cached.
• No files require special attention.

Important Files Changed

Filename	Overview
reflex/utils/exec.py	Single-line change in notify_backend() replaces hardcoded 0.0.0.0 with get_config().backend_host so terminal logs reflect the configured backend host. Correct and low-risk.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["rxconfig.py / CLI / Env Var"] -->|"sets backend_host"| B["Config.backend_host"]
    B -->|"used by"| C["run_backend() / run_backend_prod()"]
    C -->|"binds server to"| D["uvicorn / granian / gunicorn"]
    B -->|"displayed by (this PR fix)"| E["notify_backend()"]
    E -->|"prints"| F["Terminal: Backend running at http://host:port"]

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_{Last reviewed commit: 8d83e61}

[codspeed-hq]

Merging this PR will not alter performance

✅ 8 untouched benchmarks

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_{Comparing pranavmanglik:fix-backend-host-hardcoding-in-logs (8d83e61) with main (7607fa3)}

[masenf]

instead of calling get_config() twice, cache the returned config and reference it in both places.

[pranavmanglik]

Thanks for your response, i actually new to open source. I thought about it but then had doubt if it was that necessary as it was being called twice only.