Is it possible to host multiple vps within a virtual dedicated server? - virtual-machine

Is it possible to host multiple vps within a virtual dedicated server? I have 3 virtual servers and I have to make a choice between 3 vps and one virtual dedicated server

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Use different network interface for RabbitMQ virtual hosts

I have 4 network interface on the server and I want to use 40,000 socket per virtual host and bind each virtual host to specific network interface in RabbitMQ on CentOS.
RabbitMQ does not support binding virtual hosts with network interfaces.
You can specify multiple network interfaces RabbitMQ server would be listening on (see documentation), but as long as client connects and authenticates properly, it can access any virtual hosts it is authorized to.
The only possible solution would be to deploy 4 separate RabbitMQ server instances, each with different virtual host & listening on a different interface. With shovel plugin doing the mirroring between brokers (if you need messages to be transferred between virtual hosts).

How to access a web application via (Server Name Indication) SNI?

I have a requirement to host multiple applications on same public IP and port. I'm new to this area and I figure out that SNI can be used to achieve my requirement. I decided to use Microsoft application gateway as the load balancer. I can configure 2 apps with 2 SSL certificates. My question is how can i access it via browser ? ex: if server FQDN is www.example.com, Since there are 2 applications running in it. how can I mention which application to load ?.
Each certificate needs to be associated with a specific FQDN for one application. Since you have 2 applications on the same IP and TCP port, you need to create two FQDN (i.e. www.my1stappli.mydomain.com and www.my2ndappli.mydomain.com), generate two certificates (one for each FQDN) and configure the Azure Application Gateway to handle each application with its own certificate. If you have only one virtual machine to handle those 2 applications, configure the Azure Application Gateway to redirect one application to port 80 of your virtual machine and to redirect the other application to port 81 of the same virtual machine.
Thus,
https://www.my1stappli.mydomain.com will be redirected to port 80 of your virtual machine
and https://www.my2ndappli.mydomain.com to port 81 of the same virtual machine

What will be the DNS name for Virtual Machine instance created in IBM Bluemix?

I have created a Virtual Machine in Bluemix. I have installed NGINX web server on it. To access the web application that is deployed on NGINX, should I use a public IP address (for e.g. http://123.456.78.9) or is there a domain name associated with the instance (something like http://abcxyz.bluemix.net)?
When you launch any VM in cloud by default they should be not accessible from public internet unless you attach a public ip address to them.
Once you have attached a public ip address to your instance and configured the firewalls to allow incoming connections (http, ssh etc) you can update your DNS server to redirect traffic there.
AWS create a public FQDN at the time of launching the ec2 instances as
ec2-nn-nn-nn-nn-region-compute.com (where nn are ip address bits), not sure any similar thing with bluemix but it is less likely to have abcxyz.bluemix.

Can a Virtual Host on Apache access the files of another Virtual Host?

I'm looking to set up a few virtual hosts for different domains for a few friends, and want to know if one virtual host can access files from another host, whether it be via PHP or any other option or if it's totally isolated, so any scripts they can run would only affect their area.
An Apache "virtual host" is just a mapping of a hostname (or ip address or port) to a particular set of configuration directives. There is no "containment" or isolation implied by this; everything is still running on the same host.
If you want to actually isolate applications, consider investigating container technology like Docker (or a virtual machine solution), with a front-end proxy directing traffic as necessary to the appropriate backend.

Memcached in a trusted shared environment?

We are a university IT organization that hosts all of the university's websites on several shared servers on our server room floor. We have several VMs, each running its own instance of Apache as a web server for each respective server.
If we were going to setup a memcached server, is it feasible to use it as a shared instance?
If shared by several servers, or even multiple web apps running on the same server, what's the best way to keep each app's cache stores separate? Prefix the key?
Would each VM require its own instance of memcached, or could we setup 1 memcached server and allow our multiple VMs to read/write to it?
We wrote bucket engine specifically to allow for a large number of memcached virtual instances running under a single process.