There are a few servers behind AWS load balancer. I want to find a way to replicate certain directories that may contain credentials across the four servers.
In my application, once I add the build to a server, it stores the files in directories - since it has credentials I am not sure if I can use git to sync the files across servers.
Trying to figure out the best way to replicate the directories across multiple servers and keep things in sync.
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I have node.js an application running on several instances under a load balancer.
Each instance is homogeneous (same code running on different servers). Users can be placed on different servers by the load balancer.
The problem is that when 2 users need to interact together, they need to be on the same instance (because they need to communicate together through websockets on the same server). So, I will need to swap the user into another server. I don't know which 2 users are going to interact together, so I don't know before hand which users need to be on the same server.
I haven't seen any configuration in any load balancers to handle this case. I will probably need to create one.
I can also try to use a cache (or any memory accessed by the all the servers), so the users that need to communicate together can do it through the cache, but I'm not sure if that's the best route.
I will appreciate any advice.
I am creating an Angular 6 frontend application. My backend api are created in DotNet. Assume the application is similar to https://www.amazon.com/.
My query is related to frontend portion deployment related only, on AWS. Large number of users with variable count pattern are expected on my portal. I thought of using AWS elastic beanstalk as PAAS web server.
Can AWS S3/ ELB be used instead of PAAS beanstalk without any limitations?
I'm not 100% sure what you mean by combining an Elastic Load Balancer with S3. I think you may be confused as to the purpose of the ELB, which is to distribute requests to multiple servers e.g. NodeJS servers, but cannot be used with S3 which is already highly available.
There are numerous options when serving an Angular app:
You could serve the files using a nodejs app, but unless you are doing server-side rendering (using Angular Universal), then I don't see the point because you are just serving static files (files that don't get stitched together by a server such as when you use PHP). It is more complicated to deploy and maintain a server, even using Elastic Beanstalk, and it is probably difficult to get the same performance as you could do with other setups (see below).
What I suspect most people would do is to configure an S3 bucket to host and serve the static files of your Angular app (https://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteHosting.html). You basically configure your domain name to resolve to the S3 bucket's url. This is extremely cheap, as you are not paying for a server which is running constantly, but rather only have to pay the small storage cost and plus a data transfer fee which would be directly proportional to your traffic.
You can further improve on the S3 setup by creating a CloudFront distribution that uses your S3 bucket as it's origin (the location that it get files from). When you configure your domain name to resolve to your CloudFront distribution, then instead of a user's request getting the files from the S3 bucket (which could be in a region on the other side of the world and so slower), the request will be directed to the closest "edge location" which will be much closer to your user, and check if files are cached there first. It is basically a global content delivery network for your files. This is a bit more expensive than S3 on it's own. See https://aws.amazon.com/premiumsupport/knowledge-center/cloudfront-serve-static-website/.
I have a cluster of EC2 servers spun up with Ubuntu 12.04. This will be a dev environment where several developers will be ssh-ing in. I would like to set it up where the /home directory is shared across all 4 of these servers. I want to do this to A) ease the deployment of the servers, and B) make it easier on the devs so that everything in their homedir is available to them on all servers.
I have seen this done in the past with a NetApp network attached drive, but I can't seem to figure out how to create the equivalent using AWS components.
Does anyone have an idea of how I can create this same setup using Amazon services?
You'll probably need to have a server host an NFS share to store the home directories. I'd try out what this guy has done in his answer https://serverfault.com/questions/19323/is-it-feasible-to-have-home-folder-hosted-with-nfs.
I am trying to understand how CouchDB work. Does it come bundled up with separate Apache or does it use the Apache in the system. I am trying to understand how it determines where to serve the site and how are different directions done. This is important information because I am trying to understand how to implement the Apache 2.2 mod-proxy -module here with it. Do I need to tune CouchDB or do I need to tune a separate Apache process? Suppose you have 10 CouchDB processes and you want to direct their results to siteA, how can you do that?
Sorry I am now vague but I am trying to understand how to combine different things from one Site to another, having different authorization-cookies etc. I am having a problem where I have two separates sites hello.com/myCouchDb/ and hallo.de/someOthersite.html working separately. When I merge the codes, the authentication fails -- I think there are at least three different solution candidates:
A) redirect the verification things from the other site to another (a bit hackish) and/or
B) somehow configure the CouchDB Apache -settings, I have tried in Futon but failed.
C) store the authentication cookies to some dir or db and refresh them when they become old (or use never-old cookies)
So how can I merge different CouchDB -instances together with different authentication settings? Suppose you have ten people with different authentication cookies and you want to get them somehow incorporated to the same site. How can you do it? Do you tune network -settings, Apache -settings or CouchDB -settings? Or do you just stores the cookies to some directory or DB that you refresh every time they become old?
P.s. I am the admin so do not worry about the OAuth2.0, I have the authentication-cookies to do whatever I want with the different instances. I just cannot understand how to merge the different instances.
Perhaps related
CouchDB proxy? Apache As a Reverse Proxy?
https://stackoverflow.com/questions/12398389/different-definitions-of-the-term-proxy
What is a proxy? What is it in Apache? Does it have many different meanings?
It sounds like you're confused about the structure of CouchDB. CouchDB is a native JSON Database that has an HTTP API. That API is provided via Mochiweb, an Erlang based webserver that is bundled inside CouchDB. There's only one CouchDB server running, but it runs inside the Erlang Virtual Machine (BEAM) and has a fundamentally different architecture to the typical Apache httpd approach.
Regarding authentication, CouchDB has a per-instance (server) _users database that contains passwords and minimal account details. As an admin you can see this using Futon, although normal users only have access to their own profile. You can assign users into various roles, and then apply those roles and users to each database. Once the _security object is set on a DB, you need to be authenticated to read, and you can use validation update functions to enforce constraints on write. Some brief information on http://blog.couchbase.com/what%E2%80%99s-new-couchdb-10-%E2%80%94-part-4-security%E2%80%99n-stuff-users-authentication-authorisation-and-permissions and http://blog.mattwoodward.com/2012/03/definitive-guide-to-couchdb.html as well as on the wiki.
what's the best way to achieve high availability for a dynamic website? If I create a second copy on another server and do not wish to use a load balancer since it will mess up user sessions, what are the best alternatives?
You can store session data in a database instead, which gets around that problem, then you can round-robin the requests to the application servers.
(Good) Load Balancers can be configured to be "sticky" which means they send requests from the same IP to the same server each time.
Even if you have a load balancer sitting infront of two backend webservers, you just move the single point of failure onto the load balancer instead of the webserver. So your application would still not be highly available.
I highly recommend using a load balancer and at least a pair of web servers. At work, we use HA Proxy, which is fully capable of ensuring sessions are 'sticky', and are sent to the same web server unless it goes down, where it will fail over.
To make your load balancer highly available, you can set up two load balancing servers which are a mirror image of each other. Assign a single virtual IP to both of your load balancers. Write a script that will poll the other server to check if it's down; if it's down, have that script pick up that virtual IP address. The script should be running on both servers.
This link describes one way of managing a virtual IP address. Similar articles have been written for a large number of linux distros, but they are all based on the same method.
Loadbalancers. They should be configured in such a way that they can handle the sessions. Maybe by sending the same ip to the same backend every time. Or store them inside a database, or some shared memory if it needs to be really fast for some reason i haven't thought of.