Glossary

agent

The process that enforces the desired state described by resources by executing handlers. Each agent is responsible for all resources that go to a single device or API endpoint.

configuration model

The desired state of the an environment is expressed in the configuration model. This model defines the desired state of all resources that need to be managed by Inmanta.

desired state

The desired state expresses the state of all resources that Inmanta manages. Expressing a configuration in function of desired state makes the orchestrator more robust to failures compared to imperative based orchestration. An agent uses a handler to read the current state of the a resource and derive from the difference between current and desired state the actions required to change the state of the resource. Desired state has the additional benefit that Inmanta can show a dry run or execution plan of what would change if a new configuration is deployed.

Imperative solutions require scripts that execute low level commands and handle all possible failure conditions. This is similar to how a 3D printer functions: a designer send the desired object (desired state) to the 3D printer software and this printer converts this to layers that need to be printed. An imperative 3D model, would require the designer to define all layers and printer head movements.

DSL

Domain specific language. An Inmanta configuration model is written in a the Inmanta modelling DSL.

entity

Concepts in the infrastructure are modelled in the configuration with entities. An entity defines a new type in the configuration model. See Entities.

environment

Each environment represents a target infrastructure that inmanta manages. At least one environment is required, but often multiple environments of the same infrastructure are available such as development, integration and testing.

expert feature

A feature that is stable, but requires great care and/or knowledge to use properly.

facts

A resource in an infrastructure may have multiple properties that are not managed by Inmanta but their value is required as input in the configuration or for reporting purposes. handlers take care of extracting these facts and reporting them back to the server. More information in the using facts section.

handler

A handler provides the interface between a resource in the model and the resource in the infrastructure. The agent loads the handler and uses it to read the current state, discover facts and make changes to the real resource.

infrastructure

This is what Inmanta manages. This could be virtual machines with resources in these virtual machines. Physical servers and their os. Containers or resources at a cloud provider without any servers (e.g. “serverless”)

infrastructure-as-code

Wikepedia defines “Infrastructure as code” as the process of managing and provisioning computer data centers through machine-readable definition files, rather than physical hardware configuration or interactive configuration tools. Inmanta achieves this by using a desired state configuration model that is entirely expressed in code.

instance

An instance of an entity. See also Instantiation.

main.cf

The file that defines the starting point of a configuration model. This file often only instantiates some high level entities and imports specific module.

module

A configuration model consists of multiple configuration modules. A module provides a partial and reusable configuration model and its related resources such as files, templates, … The module developer guide provides more details.

orchestration

Orchestration is the process of provisioning resources in the correct order and when they are available configuring them. Inmanta support both provisioning and configuring resources but can also delegate tasks to other (existing) tools.

plugin

A plugin is a python function that can be used in the DSL. This function recieves arguments from the configuration model and navigate relations and read attributes in the runtime model. Each function can also return a value to the model. Plugins are used for complex transformation based on data in the configuration model or to query external systems such as CMDBs or IPAM tools.

project

The management server of the Inmanta orchestrator can manage distinctive infrastructures. Each distinct infrastructure is defined in the server as a project. Each project consists of one or more environment such as development, integration and production.

relation

An attribute of an entity that references an other entity. Plugins, such as templates, can navigate relations. See also Relations.

resource

Inmanta orchestrates and manages resources, of any abstraction level, in an infrastructure. Examples of resources are: files and packages on a server, a virtual machine on a hypervisor, a managed database as a PaaS provider, a switch port on a switch, …

A resource has attributes that express the desired value of a property of the resource it represents in the infrastructure. For example the memory_mb attribute of the vcenter::VirtualMachine resource. This attribute indicates the memory size of a virtual machine.

A resource needs to have a unique identifier in an environment. This identifier needs to be derived from attributes of the resource. This ensures that the orchestrator can (co-)manage existing resources and allows quick recovery of the orchestrator in failure conditions. This unique identifier consists of multiple fields. For example, vcenter::VirtualMachineFromTemplate[lab,name=srv_test] This id contains the type of the resource, the name of the agent and the unique id with its value for this resource. The resource designer determines how this id is derived.

The fields in the id are:

• The first field is the type of the resource. For example: vcenter::VirtualMachineFromTemplate

• The second field is the name of the agent that manages/groups the resource. For example: the name of the vcenter cluster on which the virtual machine is defined lab

• The third field is the identifying attribute and the value of this attribute. For example: the name of the virtual machine uniquely identifies a virtual machine on a vcenter cluster.

resource handler

See handler

unknown

A user always provides a complete configuration model to the orchestrator. Depending on what is already deployed, Inmanta will determine the correct order of provisioning and configuration. Many configuration parameters, such a the IP address of a virtual machine at a cloud provider will not be known upfront. Inmanta marks this parameters as unknown. The state of any resource that uses such an unknown parameter becomes undefined.