Querying database through hybrid connection from an azure node js backend - sql-server

Question

I need to query an on-premises SQL Server Express database from my Azure app service based on Nodejs. I followed this tutorial to add a hybrid connection.
I successfully connected and added this connection to my service. I also added the connection string as:
Server=LOCALHOST\\SQLEXPRESS,1433;Database=smartpointmovil_db;User ID=sa;Password=pass1009
Then, I wrote an easy api in node JS for my azure mobile app service:
"get": function (req, res, next) {
var sql = require("mssql");
var config = {
server: 'LOCALHOST\\SQLEXPRESS',
user: 'sa',
password: 'pass1009',
database: 'smartpointmovil_db',
port: 1433
};
var conn = new sql.Connection(config);
var req=new sql.Request(conn);
conn.connect(function(err){
if(err){
console.log("Error connectig: "+err);
return;
}
req.query('select * from smartpointmovil.cat_cadenas where id=1',function(err,results){
if(err){
console.log("Error during query: "+err);
return;
}
else{
console.log("Success: "+results[0].cadena);
res.json(results[0]);
}
conn.close();
});
});
}
Every time I call this API, I get the following error message:
Error connectig: ConnectionError: Failed to connect to
LOCALHOST:undefined in 15000ms
I did not find the way to define in my code the connection string to be used for the query, so I am including the configuration parameters.
Any idea how to write a node js code to query my local database from an Azure hosted service?

Answer 1

Use the hostname (Computer Name) of your on-prem server when defining the Hybrid Connection. Then use the same name to reference that machine in your App Service code.
e.g.
Server=SQL-SRV-01\SQLEXPRESS,1433; [...]
Hybrid Connections work by hooking the getaddrinfo system call, and it's probably unable to tell apart your LOCALHOST from the actual LOCALHOST (127.0.0.1) of the VM that App Service runs on top of.
Test with sqlcmd.exe from the Kudu Console:
D:\home>sqlcmd -S tcp:SQL-SRV-01,1433 -U {username} -P {password}
-Q "SELECT NAME FROM sys.sysdatabases"
NAME
-------------------
master
MobileServiceZZZ_db
(2 rows affected)

Answer 2

I got it working, these are the changes I did in my code to make it work:
Changed from server name from 'LOCALHOST' to my server host name: 'quandojhv' which is the same name used as host name in the hybrid connection.
I removed the instance name '\SQLEXPRESS' in the server configuration parameter.
New configuration parameters in my code are:
var config = {
server: 'quandojhv',
user: 'sa',
password: 'pass1009',
database: 'smartpointmovil_db',
options: {
encrypt: true
}};