Accessing Openstack instances - openstack

As far as I know, Openstack is a platform for virtualization and helps in efficiently creating and managing virtual machines. After creating two virtual machines on how can I use them or how can I deploy them? Can I access those instances from other locations in a network using their IP addresses?

Openstack allows to access instances from external network's also (external to openstack).
But it completely depends on the on your flat network ( floating Ip address network ) . if those are public IP's then you can access your instances from anywhere.

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Migrating cloud VMs while maintaining internal IPs

I'm working on a migration plan in GCP where we have some VMs in a project that has its own VPC. We are setting up a Shared VPC and want to move the VMs to the new VPC. However, the system owners want to maintain the existing IPs (i.e. the VPCs each have the same subnet IP ranges). There are about 30 machines that need to be migrated so shutting everything off and migrating them would be challenging. The owners want us to migrate some of the VMs each day.
Of course, the current project has a VPN configured to connect the On-prem. When we stand up the VPN in the Shared VPC I believe that, alone, will cause problems, because the routes that are exchanged will cause the On-Prem to have two routes to the same subnet IP range.
Are there ways to configure the routes to tightly restrict this? For example, define routes for each IP as we move it from one VPC to another?
Scenario: The VMs are located in a Shared VPC.
Shared VPCs cannot have overlapping subnets. Therefore, you cannot migrate VMs between subnets and maintain the same private IP address.
Scenario: The VMs are located in independent VPCs.
You can allocate a private IP address when creating a new VM instance. Shut down the existing VM, create an image of the VM. Then create a new VM, reserve a static private IP address (under Primary Internal IP), and specify the image for the source boot disk.
However, you cannot specify overlapping or duplicate addresses for your VPN. This means that the migrated VMs will not be accessible to the VPN until you reconfigure the VPN.
My recommendation is to not even try to maintain the same private IP address. Migrate the VMs to the new VPC and reconfigure name resolution to use the new IP addressses.

Connect to OpenStack instance via the internet through the router

I've recently found out that the external network for our OpenStack (Ocata) setup has maxed out on the available IP addresses in its allocation table. In fact, it has over-allocated with -9 free IPs. So, to manage the limited IP addresses, is it possible to access an instance in a project directly from an external network (internet) via the project's router? This way only a single IP address needs to be allocated per project instead of allocating to multiple instances per project.
The short answer would be NO, but there are couple of workarounds that came to my mind (not that they will be good, but they will work).
In case any instance in your private network has floatingIP, you can use that host as a jump-host (bastion-host) to SSH into the target host. This also brings the benefits of port forwarding/SSH tunneling to the table if you want to access to some other port.
You can always access to any host on private networks through qdhcp or qrouter namespace from the network node
ip netns exec qdhcp-XXXXXXX ssh user#internal-IP

openstack and OVH vRack public ip pool configuration

We're setting up our own openstack cloud using OVH dedicated sever. We couldn't connect to our openstack instances using public ips. Because OVH allow traffic based on MAC-IP_Address binding match.
We've found this link useful but this is quite outdated.
=> https://dohuyhoang.github.io/openstack/ovh/neutron/2014/07/07/Configure-OpenStack-network-on-OVH.html
We use CentOS 7.7 and the openstack release is centos-release-openstack-stein-1-1.el7.centos.noarch
We have already configure xx.xx.xx.xx/29 public ip pool in neutron.However it doesn't connect from external world.
Anyone has experience in setting up vRack for OpenStack cloud environment ?
Thanks in advance.
If you're using vRack, you'll not need to used the MAC to IP Address static binding. However, you'll be limited in the traffic you can use to Internet (two years ago, the public IP traffic inside a vRack was limited to 300 or 500Mbps for the whole vrack.
To use vRack, you'll need compatible server (check OVH website for compatibility) and setup the secondary network Interface (vRack compatible servers come with at least two network card, one for the management traffic and one for the vRack traffic) and used it with neutron to host your IP pool.
You'll then need to move the IP Pool to your vRack in the OVH Control Panel.

How to access specific host and port of an environment's node on jelastic, from another environment?

I have two environments on jelastic 4.7. On one of them I have a Java Stack and a Redis server that need to be kept private without a public IP address. On the other environment, I have a Node.js Stack that have a Public IP.
So, Im searching the docs exhaustively and can't find the answer to the question.
Can I access the private IP and port of my Redis from the node app?? Every node on Jelastic has a local ip address. Can I access those between environments??
I think it's a simple question. I'm trying to avoid the overhead of creating a public IP Address for Redis.
Can I access the private IP and port of my Redis from the node app??
Every node on Jelastic has a local ip address. Can I access those
between environments??
Yes, you can connect to different nodes of different environments using just a local IP within one hosting provider or its regions (depends on providers setup). Also, you can use Endpoints in order to connect to local IPs of other providers or to the regions within one provider, if direct connection can't be established.
Besides that, you can use, for example, CNAME of database instead of a local IP.

Communication between tenant network and existing network in openstack

I am trying to make the tenant network communicate with an existing network which did not build in OpenStack. we all know we can allocate a floating IP to VM with external network, but now we have no need access Internet, so we would not allocate IP to VM, just want to make tenant VM can communicate with another network, how do I map the existing network to OpenStack and create router between them?
Any help would be appreciated.Thanks!
There are certain steps to do this.
You need to add a routing entry for the tenant network in compute nodes.
You need to use Masquerading on compute node.
I think with this configuration you will be able to establish communication between tenant network and existing physical network.

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