Learn how to deploy a blue-green infrastructure with the OVHcloud Load Balancer.
With this guide, we will explore a specific use for the OVHcloud 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.
Requirements
- access to the OVHcloud Control Panel or OVHcloud API
- an OVHcloud Load Balancer service
- a first server that hosts your production infrastructure
- a second server with a similar infrastructure, dedicated to development
Instructions
Scenario
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 regularly. 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:
Infrastructure A
This infrastructure is made up of a server cluster that will later be associated with a front-end of your IP Load Balancer. This server cluster will expose an HTTP or a TCP 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 components of the OVHcloud Load Balancer service, you can read the following guide: Introduction to the OVHcloud Load Balancer.
In our scenario, we will declare a server cluster of servers for the HTTP service. Please note that you can create as many clusters (as well as TCP services) as are required for your final service to be exposed to your customers.
From the OVHcloud API, create a server cluster using the command below:
| Setting | Meaning |
|---|---|
| serviceName | Your Load Balancer service ID |
With the additional calls listed below, you can list, modify, and delete your server clusters respectively.
From the OVHcloud Control Panel:
- Select
Bare Metal Cloudfrom the top navigation bar. - Click the
Networkheading in the left-hand menu. - Expand the
Load Balancermenu and select your Load Balancer server. - Choose the
Server clusterstab. - Click the
Add a server clusterbutton.
Provide or choose a Name, Protocol, Port, and Datacenter, and then click Add.
Associate a server with your server cluster, 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 cluster (to balance the load and/or offer higher fault tolerance, for ex.).
From the OVHcloud API, create a server associated to your server cluster using the command below:
| Setting | Required | Meaning | Example |
|---|---|---|---|
| serviceName | Required | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| farmId | Required | Your server cluster ID | 2359 |
| address | Required | Your server's IPv4 address | 10.1.1.xxx |
| displayName | The name of the server associated with your server cluster | Server HTTP A | |
| port | The server port associated with your server cluster | 8080 |
With the additional calls listed below, you can list, modify, and delete your servers respectively.
In the OVHcloud Control Panel:
From the Server clusters tab, expand the details of the cluster you just created and click Add a server.
Provide or choose a Name, IPv4 address, and Port, and then click Add.
Infrastructure B
Functionally, this second infrastructure is identical to the first. It is also composed of a server cluster that will later be associated with a second front-end of your IP Load Balancer. This server cluster exposes the same service to the front-end as the first server cluster. This service is supplied on the servers by port 8080.
Deploy the server cluster for the HTTP service (and/or any other TCP services required for your final service to be exposed to your customers).
From the OVHcloud API, create a second server cluster using the command below:
| Setting | Meaning |
|---|---|
| serviceName | Your Load Balancer service ID |
In the OVHcloud Control Panel, from the Server clusters tab, click Add a server cluster.
Provide or choose a Name, Protocol, Port, and Datacenter, and then click Add.
Associate a server with your server cluster. Here, it involves one or more physical servers hosting your development infrastructure.
From the OVHcloud API, use the following call to create a server associated to the second server cluster you created.
| Setting | Required | Meaning | Example |
|---|---|---|---|
| serviceName | Required | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| farmId | Required | Your server cluster ID | 2360 |
| address | Required | Your server's IPv4 address | 10.1.1.xxx |
| displayName | The name of the server associated with your server cluster | Server HTTP B | |
| port | The server port associated with your server cluster | 8080 |
In the OVHcloud Control Panel, from the Server clusters tab, expand the details of the second cluster you created and click Add a server.
Provide or choose a Name, IPv4 address, and Port, and then click Add.
At this stage, you should see two clusters with a server attached to each:
Front-ends
The magic of blue-green deployment lies in the configuration of your front-ends. At this stage, we have configured two functionally identical infrastructures. For both infrastructures, you have declared one or more server clusters, each with its 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.
front-end for each of your clusters.
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 an HTTP service, so we will use port 80 (443 if you would like an SSL termination).
From the OVHcloud API, use the following call:
| Setting | Required | Meaning | Example |
|---|---|---|---|
| serviceName | Required | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| defaultFarmId | Your production server cluster's ID | 2359 | |
| displayName | The name given to the front-end | Blue Front-End A | |
| 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 |
In the OVHcloud Control Panel, select the Front-ends tab and click Add a front-end.
Provide or choose a Name, Protocol, Port, Datacenter, and Default server cluster, and then click Add.
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.
From the OVHcloud API, use the following call:
| Setting | Required | Meaning | Example |
|---|---|---|---|
| serviceName | Required | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| defaultFarmId | Your production server cluster's ID | 2360 | |
| displayName | The name given to the front-end | Green Front-End B | |
| 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 |
In the OVHcloud Control Panel, from the Front-ends tab, click the Add a front-end button again.
Provide or choose a Name, Protocol, Port, Datacenter, and Default server cluster, and then click Add.
Manage the deployments
Initial deployment
Once you have finished configuring the components of the OVHcloud Load Balancer service, you now just need to apply your changes.
From the OVHcloud API, use the following call:
| Setting | Meaning |
|---|---|
| serviceName | Your Load Balancer service ID |
In the OVHcloud Control Panel, click the Apply configuration button in the yellow banner.
On the next screen, select ☑ your Datacenter and click the Apply configuration button.
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 server cluster to another.
Let’s take a look at our scenario:
- The production infrastructure (A) is deployed on the cluster
Infra A(id 2359), which in turn is attached toServer HTTP A. This infrastructure can be accessed through theblue front-end. - The development infrastructure (B) is deployed on the cluster
Infra B(id 2360), which in turn is attached toServer HTTP B. This infrastructure can be accessed through thegreen 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 clusters, you can simply update your different front-ends by modifying the ID of the server cluster it is attached to, and applying the modification.
The blue front-end (id 2473) will then be associated with Infra B (new production, id 2360).
The green front-end (id 2474) will then be associated with Infra A (new development, id 2359).
From the OVHcloud API, modify the associated cluster for each of the front-ends:
| Setting | Meaning | Example |
|---|---|---|
| serviceName | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| frontendId | Your production front-end ID | 2473 |
| defaultFarmId | Your development server cluster ID | 2360 |
| Setting | Meaning | Example |
|---|---|---|
| serviceName | Your Load Balancer service ID | loadbalancer-abcdef0123456789 |
| frontendId | Your production front-end ID | 2474 |
| defaultFarmId | Your development server cluster ID | 2359 |
To apply your changes and effectively switch over the production and development environments:
| Setting | Meaning |
|---|---|
| serviceName | Your Load Balancer service ID |
In the OVHcloud Control Panel, in the Front-ends tab, check that each of your front-ends is connected to the correct Default server cluster.
If not, you can use the more options ... buttons at the right edge of each row to edit the default server cluster for your front-ends.
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 clusters 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 clusters. This way, you can make your services more redundant (guaranteeing availability as a result), and also add a load balancing capacity.
For more information and tutorials, please see our other OVHcloud Load Balancer guides or explore the guides for other OVHcloud products and services.