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fix(serve): honour HOSTNAME from .env instead of hardcoding 0.0.0.0 (#5134) #5170

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Merged
diegosouzapw merged 2 commits into from
Jun 27, 2026
Merged

fix(serve): honour HOSTNAME from .env instead of hardcoding 0.0.0.0 (#5134) #5170

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fix(serve): honour HOSTNAME from .env instead of hardcoding 0.0.0.0 (…
anki1kr Jun 27, 2026
ceed24d
test(cli): regression guard for HOSTNAME env override in serve (#5134)
anki1kr Jun 27, 2026
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2 changes: 1 addition & 1 deletion bin/cli/commands/serve.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ export async function runServe(opts = {}) {
PORT: String(dashboardPort),
DASHBOARD_PORT: String(dashboardPort),
API_PORT: String(apiPort),
HOSTNAME: "0.0.0.0",
HOSTNAME: process.env.HOSTNAME || "0.0.0.0",

@gemini-code-assist gemini-code-assist Bot Jun 27, 2026

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critical

⚠️ Critical Binding Issue with OS-Inherited HOSTNAME\n\nUsing process.env.HOSTNAME || \"0.0.0.0\" introduces a critical bug in environments where the OS or container runtime automatically exports the HOSTNAME environment variable (such as Docker, systemd, or various cloud VMs).\n\n#### The Problem:\n1. Docker Containers: Docker automatically sets HOSTNAME to the container ID (e.g., 3a4b5c6d7e8f). With this change, the server will attempt to bind to 3a4b5c6d7e8f (the container's internal IP) instead of 0.0.0.0. This completely breaks port forwarding, making the dashboard inaccessible from the host machine.\n2. Linux/macOS VPS: Many systems export the machine's hostname in the environment. If the hostname does not resolve to a local bindable interface, the server will fail to start with an EADDRNOTAVAIL error.\n\n#### The Solution:\nWe should only honor process.env.HOSTNAME if it is a user-configured bind address (like an IP or localhost) and not the system's default hostname. We can achieve this by comparing process.env.HOSTNAME against os.hostname().

Suggested change
HOSTNAME: process.env.HOSTNAME || "0.0.0.0",
HOSTNAME: (process.env.HOSTNAME && process.env.HOSTNAME !== (await import("node:os")).hostname()) ? process.env.HOSTNAME : "0.0.0.0",

@gemini-code-assist gemini-code-assist Bot Jun 27, 2026

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medium

⚠️ Style Guide Violation: Missing Tests for Production Code\n\nAccording to the Repository Style Guide (Rule 9):\n> "Always include tests when changing production code (src/, open-sse/, electron/, bin/)."\n\nSince this PR modifies bin/cli/commands/serve.mjs (which is under bin/), you must include corresponding unit or integration tests (e.g., under tests/) to verify that the HOSTNAME environment variable is correctly respected and handled by the CLI command.

References
  1. Always include tests when changing production code (src/, open-sse/, electron/, bin/). (link)

NODE_ENV: "production",
NODE_OPTIONS: `--max-old-space-size=${memoryLimit}`,
};
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29 changes: 29 additions & 0 deletions tests/unit/cli-serve-hostname.test.ts
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@@ -0,0 +1,29 @@
import test from "node:test";
import assert from "node:assert/strict";

/**
* Replicate the HOSTNAME resolution from bin/cli/commands/serve.mjs to verify
* that the spawned server honours a HOSTNAME provided via env/.env instead of
* always hardcoding "0.0.0.0" (#5134). Mirrors the in-file replication pattern
* used by cli-serve-port.test.ts (serve.mjs spawns processes, so the logic is
* tested in isolation rather than imported).
*/
function resolveHostname(envHostname: string | undefined): string {
return envHostname || "0.0.0.0";
}

test("serve hostname: honours HOSTNAME env var when set", () => {
assert.equal(resolveHostname("127.0.0.1"), "127.0.0.1");
});

test("serve hostname: honours a specific bind interface", () => {
assert.equal(resolveHostname("192.168.0.15"), "192.168.0.15");
});

test("serve hostname: falls back to 0.0.0.0 when HOSTNAME is unset", () => {
assert.equal(resolveHostname(undefined), "0.0.0.0");
});

test("serve hostname: falls back to 0.0.0.0 when HOSTNAME is an empty string", () => {
assert.equal(resolveHostname(""), "0.0.0.0");
});