fix(startup): use stable internal service addresses

Co-authored-by: Releases Homarr <175486441+homarr-releases[bot]@users.noreply.github.com>

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -33,6 +33,7 @@ body:
       options:
         # The below comment is used to insert a new version with on-release.yml
         #NEXT_VERSION#
+        - 1.76.1
         - 1.76.0
         - 1.75.0
         - 1.74.0

apps/nextjs/src/app/api/mcp/[transport]/route.ts

@@ -14,6 +14,7 @@ import { db } from "@homarr/db";
 
 import { getPackageVersion } from "~/versions/package-reader";
 import { extractMcpTools } from "../_extract-tools";
+import { serializeMcpToolResult } from "../_serialize-result";
 
 const logger = createLogger({ module: "mcpRoute" });
 
@@ -203,7 +204,7 @@ const mcpHandler = createMcpHandler(
         const input = args && Object.keys(args).length > 0 ? args : undefined;
         const result = await procedure(input);
         return {
-          content: [{ type: "text" as const, text: JSON.stringify(result) }],
+          content: [{ type: "text" as const, text: serializeMcpToolResult(result) }],
         };
       } catch (error) {
         const message = sanitizeErrorMessage(error);

apps/nextjs/src/app/api/mcp/_serialize-result.spec.ts

@@ -0,0 +1,23 @@
+import { describe, expect, it } from "vitest";
+
+import { serializeMcpToolResult } from "./_serialize-result";
+
+describe("serializeMcpToolResult", () => {
+  it("serializes objects as JSON strings", () => {
+    expect(serializeMcpToolResult({ boardId: "1" })).toBe('{"boardId":"1"}');
+  });
+
+  it("serializes primitive values", () => {
+    expect(serializeMcpToolResult("hello")).toBe('"hello"');
+    expect(serializeMcpToolResult(42)).toBe("42");
+    expect(serializeMcpToolResult(true)).toBe("true");
+  });
+
+  it("serializes null as the string null", () => {
+    expect(serializeMcpToolResult(null)).toBe("null");
+  });
+
+  it("serializes void results as the string null so MCP content text is always a string", () => {
+    expect(serializeMcpToolResult(undefined)).toBe("null");
+  });
+});

apps/nextjs/src/app/api/mcp/_serialize-result.ts

@@ -0,0 +1,3 @@
+export function serializeMcpToolResult(result: unknown): string {
+  return JSON.stringify(result) ?? "null";
+}

nginx.conf

@@ -9,7 +9,7 @@ http {
 
         # Route websockets traffic to port 3001
         location /websockets {
-            proxy_pass http://${HOSTNAME}:3001;
+            proxy_pass http://127.0.0.1:3001;
             proxy_http_version 1.1;
             proxy_set_header Upgrade $http_upgrade;
             proxy_set_header Connection "Upgrade";
@@ -18,7 +18,7 @@ http {
 
         # Route all other traffic to port 3000
         location / {
-            proxy_pass http://${HOSTNAME}:3000;
+            proxy_pass http://127.0.0.1:3000;
             proxy_set_header Host $http_host;
             proxy_set_header X-Real-IP $remote_addr;
             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

packages/api/src/shared.ts

@@ -43,7 +43,7 @@ async function importCookiesAsync() {
 
 function getBaseUrl() {
   if (typeof window !== "undefined") return window.location.origin;
-  return `http://${process.env.HOSTNAME ?? "localhost"}:3000`;
+  return "http://127.0.0.1:3000";
 }
 
 export const trpcPath = "/api/trpc";

scripts/run.sh

@@ -21,20 +21,18 @@ fi
 export AUTH_SECRET=$(openssl rand -base64 32)
 
 # Start nginx proxy
-# 1. Replace the HOSTNAME in the nginx template file
-# 2. Create the nginx configuration file from the template
-# 3. Start the nginx server
+# 1. Create the nginx configuration file from the template
+# 2. Start the nginx server
 # Only listen on IPv6 when the host actually has IPv6 configured (#4596).
 # Otherwise nginx aborts with "socket() [::]:7575 failed (97: Address family
 # not supported by protocol)". Check HOMARR_DISABLE_IPV6 first so users can
 # force IPv4-only even when the host supports IPv6, then probe for IPv6
 # addresses via grep (not -s: proc files always report size 0).
-export HOSTNAME
 export NGINX_LISTEN_IPV6=''
 if [ "${HOMARR_DISABLE_IPV6:-false}" != "true" ] && grep -q . /proc/net/if_inet6 2>/dev/null; then
     NGINX_LISTEN_IPV6='listen [::]:7575;'
 fi
-envsubst '${HOSTNAME} ${NGINX_LISTEN_IPV6}' < /etc/nginx/templates/nginx.conf > /etc/nginx/nginx.conf
+envsubst '${NGINX_LISTEN_IPV6}' < /etc/nginx/templates/nginx.conf > /etc/nginx/nginx.conf
 # Start services in the background and store their PIDs
 nginx -g 'daemon off;' &
 NGINX_PID=$!
@@ -67,6 +65,9 @@ terminate() {
 
 trap terminate TERM INT
 
+# Next.js standalone uses HOSTNAME as its bind address. Docker's generated
+# hostname can be unresolvable, so bind explicitly while nginx uses loopback.
+export HOSTNAME=0.0.0.0
 node apps/nextjs/server.js &
 NEXTJS_PID=$!