Amazon ELB - Sticky session lost of cookie - amazon-web-services

Question

I have a Node.js app on Elastic Beanstalk running on multiple ec2 instance behind a load balancer(elb).
Cause of the need of my app, i had to activate the session stickiness.
I activated the "AppCookieStickinessPolicy" using my custom cookie "sails.sid" as reference.
The problem is that my app need this cookie to work proprely, but as the moment I activate the session stickness (via Duration-Based Session Stickiness or in my case : Application-Controlled Session Stickiness), the headers going to my server are modified and I lost my custom cookie, who is replaced by the AWSELB (amazon ELB) cookie.
How can I configure the loadbalancer to not replace my cookie?
If I understood well, the AppCookieStickinessPolicies must keep my custom cookie but it's not the case.
I am doing wrong somewhere?
Thanks in advance
Description of my load balancer :
{
"LoadBalancerDescriptions": [
{
"AvailabilityZones": [
"us-east-1b"
],
....
"Policies": {
"AppCookieStickinessPolicies": [
{
"PolicyName": "AWSConsole-AppCookieStickinessPolicy-awseb-e-y-AWSEBLoa-175QRBIZFH0I8-1452531192664",
"CookieName": "sails.sid"
}
],
"LBCookieStickinessPolicies": [
{
"PolicyName": "awseb-elb-stickinesspolicy",
"CookieExpirationPeriod": 0
}
],
"OtherPolicies": []
},
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"InstanceProtocol": "HTTP",
"Protocol": "HTTP"
},
"PolicyNames": [
"AWSConsole-AppCookieStickinessPolicy-awseb-e-y-AWSEBLoa-175QRBIZFH0I8-1452531192664"
]
}
]
....
}
]
}

Answer 1

The sticky session cookie set by the ELB is used to identify what node in the cluster to route request to.
If you are setting a cookie in your application that you need to rely on, then expecting the ELB to use that cookie, it is going to overwrite the value you're setting.
Try simply allowing the ELB to manage the session cookie.

Answer 2

I spent a lot of time trying out the ELB stickiness features and routing requests from the same client to the same machine in a back-end cluster server.
Problem is, it didn't always work 100%, so I had to write a backup procedure using sessions stored in MySQL. But then, I realised I didn't need the ELB stickiness functionality, I could just use the MySQL session system.
It is more complex to write a database session system, and there is an overhead of course in that every http call will inevitably involve a database query. However, if this is query uses a Primary Index, it's not so bad.
The big advantage is that any request can go to any server. OR if one of your servers dies, the next one can handle the job just as well. For truly resilient applications, a database session system is inevitable.