Specifying custom `host` for Data Connect emulator causes crash

[OutdatedGuy]

[REQUIRED] Environment info

firebase-tools: 14.0.0

Platform: macOS

[REQUIRED] Test case

N/A

[REQUIRED] Steps to reproduce

1. Create a firebase project with Data Connect using:

   firebase init dataconnect

2. Update the firebase.json file to configure port and host:

   {
     "emulators": {
       "dataconnect": {
         "dataDir": "dataconnect/.dataconnect/pgliteData",
         "port": 9399,
         "host": "192.168.1.2" // <- change this to your local IP
       }
     }
   }

3. Start the emulator with:

   firebase emulators:start --only dataconnect

4. See the error:

    i  emulators: Starting emulators: dataconnect
    i  dataconnect: downloading dataconnect-emulator-2.0.0...
    Progress: ===============================================================================================> (100% of 27MB)
    i  dataconnect: Removing outdated emulator files: dataconnect-emulator-1.8.5
    i  dataconnect: Data Connect Emulator logging to dataconnect-debug.log
    i  dataconnect: Started up Postgres server, listening on {"address":"192.168.1.2","family":"IPv4","port":5432}
    i  emulators: Shutting down emulators.
    i  dataconnect: Stopping Data Connect Emulator
    ⚠  Data Connect Emulator has exited upon receiving signal: SIGINT
   
    Error: Data Connect emulator: undefined

[REQUIRED] Expected behavior

The Data Connect emulator should start successfully without any errors on the specified host and port.

[REQUIRED] Actual behavior

Emulator fails to start when custom (local IP) host is specified in firebase.json.

Additional Info

dataconnect-debug.log

I0327 23:52:07.432635    2723 load.go:37] Reloading schema and connectors...
I0327 23:52:07.465153    2723 control.go:71] [/emulator/dataconnect 9059] UpdateResources(): done
Schema: sources: schema/schema.gql [2088B] 
Connector "default": sources: connector/mutations.gql [1233B] connector/queries.gql [1802B] 
I0327 23:52:07.489910    2723 collector.go:107] schema extensions wrote into ".../dataconnect/.dataconnect/schema"
Generated sources: prelude.gql [67159B] 
I0327 23:52:07.490551    2723 load.go:115] Finished reloading
I0327 23:52:07.494261    2723 dev.go:95] Listening on address (HTTP + gRPC): 192.168.1.2:9399

[aalej]

Hey @OutdatedGuy, thanks for the report. Discussed this with our engineering team and our initial guess is that this might be a port forwarding issue. Could you try setting emulators.dataconnect.host to 0.0.0.0 to see if you'd be able to start the emulators and successfully make a request to the Data Connect emulator? The firebase.json would look somewhat like

{
  "emulators": {
    "dataconnect": {
      "dataDir": "dataconnect/.dataconnect/pgliteData",
      "port": 9399,
      "host": "0.0.0.0"
    },
    ...
  },
  "dataconnect": {
    "source": "dataconnect"
  }
}

Also, I think we should improve that error message to give information on what error occurred.

[OutdatedGuy]

@aalej setting host to 0.0.0.0 works as the emulator is running without crashing and I can run queries using the VS Code Firebase Data Connect extension.

[joehan]

@OutdatedGuy Glad to hear that you've found a working solution here - for anyone else running into this, using 0.0.0.0 will most likely fix your problem. However, I did some digging into the root cause here:

On my machine, when I point at my local private IP, I get a 503 from /emulator/configure withe the following message: transport: authentication handshake failed: local credentials rejected connection to non-local address

This message is coming from the grpc library that the Data Connect emulator uses - it does not recognize the private IP as a local address, so it rejects local (fake) credentials. I believe this is actually WAI, since that IP is accessible by other machines in your network. Because of this, we won't be able to support setting host to 192.168.x.x - however, we should definitely have a better error message here tho.

[OutdatedGuy]

I believe this is actually WAI, since that IP is accessible by other machines in your network.

@joehan but all the other emulators support setting local IP as host, wouldn't it make sense for Data Connect to also support it?

Also I don't want to accept connections from all devices from my network to all of my assigned IP addresses. Just the one I would set.

[joehan]

Thinking about this more, we probably could just not use this host for communication between the data connect emulator and PGlite - that would circumvent the auth issues and still let you connect your app over 192.168.x.x.

Reopening this issue.

[Hiraqui]

Hi, I'm having the same issue when trying to update firebase-tools from v 13.35.1 to any newer one. I tried the latest today (14.1.0) and had the same outcome, so I had to rollback to 13.35.1 again.
I usually run it without any host property at all, but I tried the 0.0.0.0 trick and it does not work either and the logs are not showing any useful info:

i  emulators: Starting emulators: auth, functions, firestore, database, hosting, storage, dataconnect, extensions
!  hosting: The hosting emulator is configured but there is no hosting configuration. Have you run firebase init hosting?
!  functions: The following emulators are not running, calls to these services from the Functions emulator will affect production: apphosting, hosting, pubsub
i  firestore: Firestore Emulator logging to firestore-debug.log
+  firestore: Firestore Emulator UI websocket is running on 9150.
!  database: Did not find a Realtime Database rules file specified in a firebase.json config file. The emulator will default to allowing all reads and writes. Learn more about this option: https://firebase.google.com/docs/emulator-suite/install_and_configure#security_rules_configuration.
i  database: Database Emulator logging to database-debug.log
i  dataconnect: Data Connect Emulator logging to dataconnect-debug.log
i  dataconnect: Started up Postgres server, listening on {"address":"0.0.0.0","family":"IPv4","port":5432}
i  emulators: Shutting down emulators.
i  extensions: Stopping Extensions Emulator
i  functions: Stopping Functions Emulator
i  database: Stopping Database Emulator
!  Database Emulator has exited upon receiving signal: SIGKILL
i  firestore: Stopping Firestore Emulator
!  Firestore Emulator has exited upon receiving signal: SIGKILL
i  auth: Stopping Authentication Emulator
i  eventarc: Stopping Eventarc Emulator
i  dataconnect: Stopping Data Connect Emulator
!  Data Connect Emulator has exited upon receiving signal: SIGKILL
i  tasks: Stopping Cloud Tasks Emulator
i  hub: Stopping emulator hub

Error: Data Connect emulator: undefined

Having trouble? Try firebase [command] --help

18:10:47.543 [NamespaceSystem-akka.actor.default-dispatcher-5] INFO akka.event.slf4j.Slf4jLogger - Slf4jLogger started
18:10:47.875 [main] INFO com.firebase.server.forge.App$ - Listening at 127.0.0.1:9000

NOTE: I'm on Windows

[Hiraqui]

Version 14.2.1 is having the same issue

Logs:

I0425 15:11:28.318946   13108 load.go:37] Reloading schema and connectors...
I0425 15:11:28.506778   13108 control.go:73] [/emulator/tool-data-connect eb22] UpdateResources(): done
Schema: sources: schema\schema.gql [3990B] 
Connector "tool-connector": sources: tool-connector\queries.gql [5693B] tool-connector\***.gql [646B] tool-connector\mutations.gql [1877B] 
Connector "functions-connector": sources: functions-connector\mutations.gql [2431B] functions-connector\queries.gql [397B] 
Connector "migrations-connector": sources: migrations-connector\mutations.gql [50630B] 
I0425 15:11:28.639142   13108 codegen.go:82] [connector "tool-connector" javascriptSdk] Generating sources into "***\\tool\\src\\lib\\firebase\\dataconnect-sdk"
I0425 15:11:28.648166   13108 codegen.go:82] [connector "functions-connector" javascriptSdk] Generating sources into "***\\tool\\functions\\src\\lib\\dataconnect-sdk"
I0425 15:11:28.657781   13108 collector.go:107] schema extensions wrote into "***\\tool\\dataconnect\\.dataconnect\\schema"
Generated sources: prelude.gql [71117B] main\mutation.gql [100314B] main\implicit.gql [11422B] main\input.gql [187996B] main\relation.gql [105358B] main\query.gql [36849B] 
I0425 15:11:28.660386   13108 collector.go:107] connector "tool-connector" javascriptSdk wrote into "***\\tool\\src\\lib\\firebase\\dataconnect-sdk"
Generated sources: esm\package.json [17B] index.cjs.js [5156B] package.json [652B] README.md [50823B] index.d.ts [14663B] esm\index.esm.js [4404B] 
I0425 15:11:28.695306   13108 installsdk.go:80] Running command: C:\Users\tincho\AppData\Local\pnpm\pnpm.cmd link src\lib\firebase\dataconnect-sdk

It also is creating unwanted dependencies in the package.json

    "dataconnect-sdk": "link:../../***/AppData/Local/pnpm/global/5/node_modules/src/lib/firebase/dataconnect-sdk",

...
    "overrides": {
      "@tool/dataconnect": "link:src\\lib\\firebase\\dataconnect-sdk",
      "dataconnect-sdk": "link:../../***/AppData/Local/pnpm/global/5/node_modules/src/lib/firebase/dataconnect-sdk"
    }

I have to keep rolling back to version 13.35.1 to make it work

[joehan]

@Hiraqui Could you open a separate issue for the the unwanted dependencies?

[Hiraqui]

Now the VSCode extension is giving a bit more info on the error:

[2025-05-05T11:25:51.921Z] Starting Data Connect Emulator with command {"binary":"C:\\Users\\\***\\.cache\\firebase\\emulators\\dataconnect-emulator-2.4.0.exe","args":["--logtostderr","-v=2","dev","--listen=127.0.0.1:9399,[::1]:9399","--config_dir=C:\\***\\dataconnect","--enable_output_schema_extensions=true","--enable_output_generated_sdk=true"],"optionalArgs":["listen","config_dir","enable_output_schema_extensions","enable_output_generated_sdk"],"joinArgs":true,"shell":false,"port":9399} {"metadata":{"emulator":{"name":"dataconnect"},"message":"Starting Data Connect Emulator with command {\"binary\":\"C:\\\\Users\\\\\***\\\\.cache\\\\firebase\\\\emulators\\\\dataconnect-emulator-2.4.0.exe\",\"args\":[\"--logtostderr\",\"-v=2\",\"dev\",\"--listen=127.0.0.1:9399,[::1]:9399\",\"--config_dir=C:\\\\WorkspaceFast\\\\circularity-tool\\\\dataconnect\",\"--enable_output_schema_extensions=true\",\"--enable_output_generated_sdk=true\"],\"optionalArgs\":[\"listen\",\"config_dir\",\"enable_output_schema_extensions\",\"enable_output_generated_sdk\"],\"joinArgs\":true,\"shell\":false,\"port\":9399}"}}
i  dataconnect: Data Connect Emulator logging to dataconnect-debug.log {"metadata":{"emulator":{"name":"dataconnect"},"message":"Data Connect Emulator logging to \u001b[1mdataconnect-debug.log\u001b[22m"}}
i  dataconnect: Started up Postgres server, listening on {"address":"127.0.0.1","family":"IPv4","port":5432} {"metadata":{"emulator":{"name":"dataconnect"},"message":"Started up Postgres server, listening on {\"address\":\"127.0.0.1\",\"family\":\"IPv4\",\"port\":5432}"}}
[2025-05-05T11:25:51.989Z] [Data Connect] Connecting to postgres://127.0.0.1:5432/circularity-tool-db?sslmode=disable}...
[2025-05-05T11:25:51.992Z] >>> [apiv2][query] POST http://127.0.0.1:9399/emulator/configure [none]
[2025-05-05T11:25:51.994Z] >>> [apiv2][body] POST http://127.0.0.1:9399/emulator/configure {"connectionString":"postgres://127.0.0.1:5432/tool-db?sslmode=disable","database":"tool-db","serviceId":"tool-data-connect","maxOpenConnections":1}   
[2025-05-05T11:25:52.003Z] *** [apiv2] error from fetch(http://127.0.0.1:9399/emulator/configure, {"headers":{},"method":"POST","body":"{\"connectionString\":\"postgres://127.0.0.1:5432/circularity-tool-db?sslmode=disable\",\"database\":\"circularity-tool-db\",\"serviceId\":\"circularity-tool-data-connect\",\"maxOpenConnections\":1}"}): FetchError: request to http://127.0.0.1:9399/emulator/configure failed, reason: connect ECONNREFUSED 127.0.0.1:9399
[2025-05-05T11:25:52.006Z] [Data Connect] Retrying connectToPostgress call (1 of 3 attempts): FirebaseError: Data Connect emulator: undefined

All 3 attempts fail

[Hiraqui]

@Hiraqui Could you open a separate issue for the the unwanted dependencies?

#8508