Declarative Desired State

Declarative Desired State, Orchestrated Deployment

There are two distinct and important concepts to cover, Declarative & Desired State.

Declarative

Declarative is a style of implementation where you describe what you want to achieve, rather than how to achieve it. In a declarative approach, you specify the desired outcome or state of the system, and the underlying implementation takes care of the details.

Desired State

Desired State refers to the specific configuration or condition that you want a system to be in. It represents the target state that you want to achieve, and it is often used in the context of infrastructure management, configuration management, and orchestration.

Orchestrated Deployment

Orchestrated Deployment is a process of managing and automating the deployment of applications and services in a way that ensures they are deployed in the desired state. It involves coordinating various components and resources to achieve the desired outcome, often using tools and frameworks that support declarative configurations.

In an orchestrated deployment, you would typically define the desired state of your application, such as the number of replicas, resource requirements, and network configurations. The orchestration tool would then take care of deploying the application according to the specified desired state, ensuring that it is running and functioning as intended.

In summary, a declarative approach focuses on describing the desired state of the system, while an orchestrated deployment is a method of achieving that desired state through automation and coordination of resources.

What does it actually look like?

There are a variety of declarative notations:

• For virtual machine machines there are Chef, Salt, Puppet, Ansible, etc. and for Windows Desired State Configuration (DSC) or Active Directory Group Policies.
• For containers there are Kubernetes, Docker Compose, and HashiCorp Nomad. For serverless there are AWS CloudFormation, Azure Resource Manager, and Google Cloud Deployment Manager.
• For public cloud infrastructure and a broad range open-source and commercial production, Terraform has become the pseudo-standard.

This example is Puppet applying environment variables to a Tomcat server.

Declaration

Application of Desired State

Implementation Patterns with CDAF Declarative Release for implementation examples, which incorporate intermediary tools such Ansible Tower, Puppet Enterprise and Terraform Cloud