OVH Guides

Deploying a blue-green infrastructure

This guide will show you how to deploy a blue-green infrastructure with the OVH Load Balancer

Objective

With this guide, we will explore a specific use for the OVH Load Balancer service — configuring a service to manage production/development infrastructures easily. This is also called a blue-green infrastructure.

With a blue-green infrastructure, you can stop your infrastructure from experiencing any downtime. The main benefit of this deployment type is that you can prepare updates and/or maintenance in an environment that is isolated from your production environment. This way, you can test your changes before they are put into production, undo them quickly if you detect any faults, and do all of this with virtually zero downtime.

This guide will show you how to deploy a blue-green infrastructure with the OVH Load Balancer.

Requirements

To deploy a blue-green infrastructure, you need the following components:

  • an OVH Load Balancer service
  • a first server that hosts your production infrastructure
  • a second server with a similar infrastructure, dedicated to development

Instructions

Scenario

The scenario we’ll describe here is as follows...

You have an infrastructure that you can use to put your website online.

This infrastructure hosts your website’s code, and it also hosts the applications (web servers, database servers, etc.) required to put your website online. You need to update your applications and/or your code on a regular basis. You want to be able to test your updates without the risk of affecting your website’s availability to customers, or stopping the website from working properly.

One way to achieve this is by deploying a blue-green infrastructure.

The principle of a blue-green deployment involves being able to switch easily from a development infrastructure to a production infrastructure, and vice versa. This switch must be done in a way that is transparent for your users. To do this, we will assign the standard HTTP port 80 for access to the production infrastructure, and the arbitrary port 8888 to access the development infrastructure.

Deploy the infrastructures.

In the scenario we are using, your IP Load Balancer service plays a central role. It is the element you use to expose your two infrastructures (production and development) to different users at the same time.

The production infrastructure can be accessed by your customers on the standard HTTP service (port 80), and your development infrastructure can be accessed by developers and admins on the non-standard port 8888.

During the initial setup phase, we will arbitrarily assign a role to each of the parts of our infrastructure. Infrastructure A will be assigned to production, while infrastructure B will be assigned to development. At this stage, we will consider them to be similar to one another.

A blue-green infrastructure involves switching from infrastructure A to infrastructure B, when infrastructure B is ready to expose your website after your changes have been applied and tested. The IP Load Balancer will manage this switch.

The diagram below gives a general idea of the architecture:

General diagram of blue-green architecture

Infrastructure A.

This infrastructure is made up of a server farm that will later be associated with a front-end of your IP Load Balancer. This farm will expose an HTTP, TCP or UDP service to the front-end. It also balances loads by sending the front-end’s incoming traffic to the servers. For more detail on the role of various component of the OVH Load Balancer service, you can read the following guide: .

In our scenario, we will declare a farm of servers for the HTTP service. Please note that you can create as many farms (as well as TCP and/or UDP services) as are required for your final service to be exposed to your customers.

Via the OVH Control Panel:

Add a new HTTP farm dedicated to infrastructure A

Enter the farm’s configuration

Via the API:

Setting Meaning
serviceName Your Load Balancer service ID

With the additional calls listed below, you can list, modify and delete your server farms respectively.

Associate a server with your farm, if it is a physical server hosting your production infrastructure. The service exposed to the front-end is supplied by the server’s port 8080. Please note that you can associate one or more servers with each farm (to balance the load and/or offer higher fault tolerance, for ex.).

Via the OVH Control Panel:

Add a new server to the farm HTTP A

Enter the HTTP A server’s configuration

Via the API:

Setting Required Meaning Example
serviceName Required Your Load Balancer service ID loadbalancer-abcdef0123456789
farmId Required Your server farm ID 77212
address Required Your server's IPv4 address 10.10.1.100
displayName The name of the server associated with your farm HTTP A server
port The server port associated with your farm 8080

With the additional calls listed below, you can list, modify and delete your servers respectively.

Infrastructure B.

Functionally, this second infrastructure is identical to the first. It is also composed of a server farm that will later be associated with a second front-end of your IP Load Balancer. This server farm exposes the same service to the front-end as the first server farm. This service is supplied on the servers by port 8080.

Deploy the server farm for the HTTP service (and/or any other TCP or UDP services required for your final service to be exposed to your customers).

Via the Sunrise Control Panel:

Add a new HTTP farm dedicated to infrastructure B

Create a second farm dedicated to infrastructure B

Via the API:

Setting Meaning
serviceName Your Load Balancer service ID

Associate a server with your farm. Here, it involves one or more physical servers hosting your development infrastructure.

Via the OVH Control Panel:

Add a new server to the farm HTTP B

Enter the HTTP B server’s configuration

Via the API:

Setting Required Meaning Example
serviceName Required Your Load Balancer service ID loadbalancer-abcdef0123456789
farmId Required Your server farm ID 77213
address Required Your server's IPv4 address 10.10.2.100
displayName The name of the server associated with your farm HTTP B server
port The server port associated with your farm 8080

At this stage, here is the configuration status for your two farms:

Farm configuration

Front-ends.

The magic of blue-green deployment lies in the configuration of your front-ends. At this stage, we have configure two functionally identical infrastructures. For both infrastructures, you have declared one or more server farms, each with their own set of associated servers.

To switch simply from one infrastructure to another, we will use front-ends.

To do this, we need to declare two front-ends. The first one will give you access to your production infrastructure, whereas the second will give you access to your development infrastructure. You can control access to one infrastructure or the other using the ports you expose to your customers.

If the final service you expose to your customers requires several server farms (e.g. ports 80 and 443), you will need to declare a front-end for each of your farms.

Blue front-end.

This front-end is dedicated to accessing the production infrastructure. The ports exposed to your customers are the standard ports for accessing the service. In this case, we are exposing a HTTP service, so we will use port 80 (443 if you would like an SSL termination).

Via the OVH Control Panel:

Adding a front-end dedicated to production, a blue front-end

Enter the blue front-end’s configuration

Via the API:

Setting Required Meaning Example
serviceName Required Your Load Balancer service ID loadbalancer-abcdef0123456789
defaultFarmId Your production farm’s ID 77212
displayName The name given to the front-end Blue front-end
port Required The port exposed to your customers by your front-end 80
zone Required The zone in which you want to deploy your front-end all

Green front-end.

This front-end is dedicated to accessing the development infrastructure. The ports exposed to your customers will be non-standard ports that you can choose arbitrarily. In this case, we will expose the HTTP development service on port 8888.

Via the OVH Control Panel:

Add the green front-end, dedicated to development

Enter the green front-end’s configuration

Via the API:

Setting Required Meaning Example
serviceName Required Your Load Balancer service ID loadbalancer-abcdef0123456789
defaultFarmId Your production farm’s ID 77213
displayName The name given to the front-end Green front-end
port Required The port exposed to your customers by your front-end 8888
zone Required The zone in which you want to deploy your front-end all

Manage the deployments.

Initial deployment.

Once you have finished configuring the components of the OVH Load Balancer service, you now just need to apply your changes.

Via the OVH Control Panel:

Apply your changes to the zone

Via the API:

Setting Meaning
serviceName Your Load Balancer service ID

The production/pre-production switch.

At this stage, our initial environment is deployed and ready to use. How do we use it?

To put it simply, you just need to switch over your front-ends from one server farm to another.

Let’s take a look at our scenario:

  • The production infrastructure (A) is deployed on HTTP farm A (id 77212), which in turn is attached to HTTP server A. This infrastructure can be accessed through the blue front-end.
  • The development infrastructure (B) is deployed on HTTP farm B (id 77213), which in turn is attached to HTTP server B. This infrastructure can be accessed through the green front-end.

Once you have modified/applied updates to infrastructure B and checked that the service is working properly, you decide to put it into production.

To switch between the two farms, you can simply update your different front-ends by modifying the ID of the farm it is attached to, and applying the modification.

The blue front-end (id 70089) will then be associated with Farm B (infrastructure B, new production, id 77213).

The green front-end (id 70090) will then be associated with Farm A (infrastructure A, new development, id 77212).

This should be the result on the Sunrise Control Panel after updating the front-ends and applying the new configuration:

Result after updating front-ends

Via the API: updating front-ends and applying modifications####

Setting Meaning Example
serviceName Your Load Balancer service ID loadbalancer-abcdef0123456789
frontendId Your production front-end ID 70089
defaultFarmId Your development server farm ID 77213
Setting Meaning Example
serviceName Your Load Balancer service ID loadbalancer-abcdef0123456789
frontendId Your production front-end ID 70090
defaultFarmId Your development server farm ID 77212

To apply your changes and effectively switch over the production and development environments:

Setting Meaning
serviceName Your Load Balancer service ID

Go further

You now have an infrastructure you can use to simply and efficiently manage blue-green deployments.

Developers have access to a development environment on port 8888 (or whichever other port you would prefer to define), while your customers continue to access the service in production via the standard HTTP port (80 in our case, for example).

The infrastructure presented here is limited to just one port, but it can be expanded by adding other ports. For example, you can also expose your website on the standard HTTPS port (443). You can do this by defining new farms dedicated to each port you want to expose, and associating them with their corresponding front-ends (one for the standard port exposed in production, the second for the arbitrary port dedicated to development).

Another way to consolidate your infrastructure even further is by multiplying the servers attached to your farms. This way, you can make your services more redundant (guaranteeing availability as a result), and also add a load balancing capacity.


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