Call Ethereum using web3.js on Azure Function

Question

I am trying to use Azure Function to call Ethereum using Web3.js, code seems to be working fine in the command shell but I get an error when I run it as a function.

On Azure Portal create a new Javascript Azure Function:

1. Go to Platform Features --> Development Tools --> Advanced Tools (kudu) --> Debug Console --> CMD

   cd site cd wwwroot cd npm install web3@^0.20.0

2. Create a new code.js file

   const Web3 = require('web3'); var web3 = new Web3(); const httpProv = new Web3.providers.HttpProvider("http://:8545"); web3.setProvider(httpProv); console.log(web3.eth.blockNumber);

3. Execute this file in CMD shell

   node code.js

4. Works fine, I can see a HTTP Post request

   Request:

   POST / HTTP/1.1 User-Agent:node-XMLHttpRequest Accept: / Content-Type: application/json Host: : Content-Length:63 Connection:close

   {"jsonrpc":"2.0", "id":1,"method":"eth_blockNumber","params":[]}

Response:

HTTP/1.1 200 OK
Content-Type: application/json
Vary: Origin
Date:
Content-Length:
Connection:close

{"jsonrpc":"2.0", "id":1,"result":"bla"}

I have created a package.json file inside wwwroot directory

{
  "frameworks": {
    "net46":{
      "dependencies": {
        "web3": "^0.20.0"        
      }
    }
  }
}

and ran

npm install

When I execute the Azure Function I get this error:

2017-10-30T08:31:44.291 Function started (Id=f28edf73-fa02-406d-868e-0f23cd41e6e0)
2017-10-30T08:31:44.338 Exception while executing function: Functions.AZURE_FUNCTION. mscorlib: Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.
    at Object.InvalidConnection (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\errors.js:31:16)
    at HttpProvider.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\httpprovider.js:84:18)
    at RequestManager.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\requestmanager.js:58:32)
    at Eth.get [as blockNumber] (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\property.js:107:62)
    at module.exports (D:\home\site\wwwroot\AZURE_FUNCTION\index.js:8:25)
    at D:\Program Files (x86)\SiteExtensions\Functions\1.0.11296\bin\azurefunctions\functions.js:99:24.
2017-10-30T08:31:44.385 Function completed (Failure, Id=f28edf73-fa02-406d-868e-0f23cd41e6e0, Duration=94ms)
2017-10-30T08:31:44.385 Exception while executing function: Functions.AZURE_FUNCTION
2017-10-30T08:31:44.385 Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.
    at Object.InvalidConnection (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\errors.js:31:16)
    at HttpProvider.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\httpprovider.js:84:18)
    at RequestManager.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\requestmanager.js:58:32)
    at Eth.get [as blockNumber] (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\property.js:107:62)
    at module.exports (D:\home\site\wwwroot\AZURE_FUNCTION\index.js:8:25)
    at D:\Program Files (x86)\SiteExtensions\Functions\1.0.11296\bin\azurefunctions\functions.js:99:24
2017-10-30T08:31:44.385 Function completed (Failure, Id=f28edf73-fa02-406d-868e-0f23cd41e6e0, Duration=94ms)
2017-10-30T08:31:44.385 Executed 'Functions.AZURE_FUNCTION' (Failed, Id=f28edf73-fa02-406d-868e-0f23cd41e6e0)
2017-10-30T08:31:44.385 Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.
    at Object.InvalidConnection (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\errors.js:31:16)
    at HttpProvider.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\httpprovider.js:84:18)
    at RequestManager.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\requestmanager.js:58:32)
    at Eth.get [as blockNumber] (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\property.js:107:62)
    at module.exports (D:\home\site\wwwroot\AZURE_FUNCTION\index.js:8:25)
    at D:\Program Files (x86)\SiteExtensions\Functions\1.0.11296\bin\azurefunctions\functions.js:99:24
2017-10-30T08:31:44.385 Function had errors. See Azure WebJobs SDK dashboard for details. Instance ID is 'f28edf73-fa02-406d-868e-0f23cd41e6e0'
2017-10-30T08:31:44.385 Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.
    at Object.InvalidConnection (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\errors.js:31:16)
    at HttpProvider.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\httpprovider.js:84:18)
    at RequestManager.send (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\requestmanager.js:58:32)
    at Eth.get [as blockNumber] (D:\home\site\wwwroot\AZURE_FUNCTION\node_modules\web3\lib\web3\property.js:107:62)
    at module.exports (D:\home\site\wwwroot\AZURE_FUNCTION\index.js:8:25)
    at D:\Program Files (x86)\SiteExtensions\Functions\1.0.11296\bin\azurefunctions\functions.js:99:24
2017-10-30T08:31:44.400 {"id":"4e755d0e-a2cf-4c4a-a734-aa750555a948","requestId":"4fa42aca-ff49-487a-a543-8f82295a1e5c","statusCode":500,"errorCode":0,"message":"Exception while executing function: Functions.AZURE_FUNCTION -> Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.\n    at Object.InvalidConnection (D:\\home\\site\\wwwroot\\AZURE_FUNCTION\\node_modules\\web3\\lib\\web3\\errors.js:31:16)\n    at HttpProvider.send (D:\\home\\site\\wwwroot\\AZURE_FUNCTION\\node_modules\\web3\\lib\\web3\\httpprovider.js:84:18)\n    at RequestManager.send (D:\\home\\site\\wwwroot\\AZURE_FUNCTION\\node_modules\\web3\\lib\\web3\\requestmanager.js:58:32)\n    at Eth.get [as blockNumber] (D:\\home\\site\\wwwroot\\FUNCTION_NAME\\node_modules\\web3\\lib\\web3\\property.js:107:62)\n    at module.exports (D:\\home\\site\\wwwroot\\FUNCTION_NAME\\index.js:8:25)\n    at D:\\Program Files (x86)\\SiteExtensions\\Functions\\1.0.11296\\bin\\azurefunctions\\functions.js:99:24"}
2017-10-30T08:31:44.400 Error: CONNECTION ERROR: Couldn't connect to node http://IP_ADDR:8545.
    at Object.InvalidConnection (D:\home\site\wwwroot\FUNCTION_NAME\node_modules\web3\lib\web3\errors.js:31:16)
    at HttpProvider.send (D:\home\site\wwwroot\FUNCTION_NAME\node_modules\web3\lib\web3\httpprovider.js:84:18)
    at RequestManager.send (D:\home\site\wwwroot\FUNCTION_NAME\node_modules\web3\lib\web3\requestmanager.js:58:32)
    at Eth.get [as blockNumber] (D:\home\site\wwwroot\FUNCTION_NAME\node_modules\web3\lib\web3\property.js:107:62)
    at module.exports (D:\home\site\wwwroot\FUNCTION_NAME\index.js:8:25)
    at D:\Program Files (x86)\SiteExtensions\Functions\1.0.11296\bin\azurefunctions\functions.js:99:24
2017-10-30T08:31:44  PID[10332] Information Sending response: 200.0 OK
2017-10-30T08:31:44  PID[10332] Information Sending response: 200.0 OK

Answer 1

Below are my steps to workaround this issue.

1. create an Azure Function App on App Service Plan (instead of Consumption plan)
2. Enable websocket
3. Switch runtime version to Beta

Note that Websock and Runtime version option available only on App Service plan.