I am using node-redis version 3.0.2. However, I was checking how my website will respond if the Redis server is down. I have this request handler where It calls a function that checks first if the provided key is in Redis, else make a database call and then save the fetched data in Redis.
const GetByPriority = model => async (req, res) => {
let { page=1, size=9 } = req.query;
size = parseInt(size);
page = parseInt(page);
try {
const doc = await SetOrGetCompanyCache(`companies-${page}-${size}`, async () => {
const query = await model
.find({})
.limit(size*1)
.skip((page-1)*size)
.sort({ p: -1, _id:1 })
.lean()
.exec()
return query;
})
if (!doc)
{
return res.status(404).end()
}
res.status(200).json({page:page, size:size, data: doc })
} catch (e) {
console.error(e)
res.status(400).end()
}
}
The problem is when the Redis server is down, there does not seem to be an error returned by redisClient's get method. I mean I don't get why it did not log the error. Also, It did not return InternalServerError.
export function SetOrGetCompanyCache (key, callback) {
return new Promise((resolve, reject)=>{
redisClient.get(key, async (error,data)=>{
if(error)
{
console.log(error) //It does not get here
return reject(createError.InternalServerError('Caching Error'))
}
//Cache hit
if(data != null)
{
return resolve(JSON.parse(data))
}
//Cache miss
//callback() --> MongoDB query
const queryData = await callback();
if(!queryData)
{
return reject(createError[404])
}
redisClient.setex(key,COMPANY_QUERY_EXP,JSON.stringify(queryData))
resolve(queryData)
})
})
}
It only logged the following snippet
Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
Redis connection to 127.0.0.1:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
I believe this is because I added the following listener inside redisClient file
redisClient.on('error', (err)=>{
console.error(err.message)
})
The problem now is that the set method does not return any error indicating that the Redis server is down, hence I can't even make the server perform a normal database call in that case.
