Error Handler Nodejs Redis Connect-domain fail

Question

Error Handler Nodejs Redis Connect-domain fail

I tried to use connect-domain to handling error. In most cases it ok, but it fail with redis callback. How to fix this?

Here's my app

var http = require('http');
var express = require('express');
var connectDomain = require('connect-domain');
var redis = require("redis").createClient();

var app = express();
app.use(connectDomain());

app.get('/', function (req, res) {
    throw new Error("Handler OK");
});

app.get('/error', function (req, res) {
    redis.get("akey", function(err, reply) {
        throw new Error("Handler error");
        res.end("ok");
    });
});

app.use(function (err, req, res, next) {
    res.end(err.message);
});

http.createServer(app).listen(8989, function() {
    console.log("Express server started ");
});

I use nodejs 0.8.16, all modules are latest

node.js
error-handling
node-redis

Answer 1

Not sure if the domain should be catching that or not - but you can capture redis errors by setting up an error handler, like this:

// handle redis connection temporarily going down without app crashing
redisClient.on("error", function(err) {
    console.error("Error connecting to redis", err);
});

While the connection is broken your handler will keep getting called as redis tries to reconnect. If it's eventually successful everything will come back online on it's own.

Answer 2

You can also try https://www.npmjs.org/package/wait-for-redis. It ensures clients can wait for server to be up in case when clients start early.