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Glossary: Improved / polished a lot of the content
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Ticket: ENT-9076
Signed-off-by: Ole Herman Schumacher Elgesem <[email protected]>
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olehermanse committed Dec 4, 2023
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A piece of software that runs independently and automatically to carry out a task (think software robot).
In CFEngine, the agent is called `cf-agent` and is responsible for making changes to computers.

Historically, all the hosts in the infrastructure which are not hubs / policy servers have been referred to as agents.
(And the software you install on them agent packages, or agent only packages).
The preferred terms to distinguish between the different roles are hub and client.
See CFEngine roles.

#### Body

A promise body is the description of exactly what is promised (as opposed to what/who is making the promise).
The term `body` is used in the CFEngine syntax to mean a small template that can be used to contribute as part of a larger promise body.

#### Bootstrap

#### Bundle
After installing the CFEngine package, the software does not automatically start running.
It is missing some information, most notably where it should be fetching policy from.
In order to start CFEngine, you run the bootstrap command on all hosts in the infrastructure, with the IP address of the hub as an argument:

In CFEngine, a bundle refers to a collection of promises that has a name.
```
cf-agent --bootstrap <hub IP>
```

#### Call collect
After running this command, CFEngine knows where (which IP address) to use when fetching policy.
It can also infer its CFEngine role (hubs fetch policy from themselves, while clients fetch policy from a hub).
Having this information, it can start the various components in the background, causing policy to be fetched, enforced, and reported on regularly, every 5 minutes by default.

#### Class
#### Bundle

Classes are used to classify a system (or the state of it) and to make decisions in CFEngine policy.
Classes are sometimes referred to as contexts.
In CFEngine, a bundle refers to a collection of promises that has a name.

#### CDP
#### Contend driven policy (CDP)

Content Driven Policy.
A way of simplifying the way users provide information to CFEngine about policy by hiding the overhead of policy coding.
A CDP is a set of promises that is designed to solve a particular task in a standard way.
Users provide only a little data in the form of a simple spreadsheet of data in a table.

#### CFEngine

The name of the CFEngine Company, as well as the name of the Software.
CFEngine comes from a contraction of _ConFiguration Engine_.
The CFEngine software is maintained by Northern.tech (previously the CFEngine company).

#### CFEngine 3.x

Major version 3 of the CFEngine software, started in 2008 and going up to the present day.
This comes in several editions, both Open Source and Commercial.

#### CFEngine Community Edition
#### CFEngine Community

Free and Open Source edition of the CFEngine software, published under the GPL3 license, and optionally under the COSL license.

#### CFEngine Enterprise Editions
#### CFEngine Enterprise

Refers to commercial (paid) editions of the CFEngine software, published under the COSL license.
Refers to commercial (paid) editions of the CFEngine software.

#### CFEngine Nova

The lowest level enterprise edition of CFEngine, that automatically creates a simple _star network_ mangement model for hosts in an environment.
An older name for CFEngine Enterprise, which is no longer used.
See CFEngine Enterprise.

#### CFEngine role

As far as CFEngine is concerned, all hosts in your infrastructure can be thought of as having one of two possible roles.
The CFEngine role describes how a specific host interacts with other installations of CFEngine on other hosts.

The hub is the centralized place which serves policy and collects reports.
When starting out / for smaller infrastructures, it is common to have just 1 hub.
For larger / more complex infrastructures, multiple hubs are common.
Due to the multiple purposes this host serves, it is sometimes referred to as the policy server or the report collector, however _hub_ is the preferred term.

Clients are all the other hosts which fetch policy from the hub and deliver reporting data back.
In a typical setup, all hosts which are not hubs are considered clients.
Historically, clients were sometimes referred to as agents, however this can be confusing, as agent also refers to the software component `cf-agent` which is installed on all hosts, not just the clients.

Hub and client are the preferred terms when talking about the role a host performs, and which type of package to install on it.
See hub and client.

#### Changelog

A file used to describe the changes made since the last version of the software.

#### Class

Classes are used to classify a system (or the state of it) and to make decisions in CFEngine policy.
Classes are sometimes referred to as contexts.

#### Class expressions

Multiple classes separated by operators (and, or) to make more complex decisions.
Expand All @@ -71,15 +103,26 @@ Used to restrict when / where promises are evaluated.
Appear in front of promises in CFEngine policy, consisting of a class expression followed by two colons.
Class guards are sometimes called context class expressions.

#### CMDB
#### Client

A Configuration Management Database.
A term coined as part of the IT Infrastructure Library (ITIL) as an outgrowth of an inventory database.
In traditional computer networks and software, the client is the program which connects to a server, i.e. the software which initiates the connection in a networked system.
We say that a server is listening for incoming connections, and servers frequently serve thousands or even millions of clients simultaneously.

In CFEngine, we use the word client to describe all of the hosts which are not hubs.
A CFEngine hub runs a policy server, which all clients connect to in order to fetch policy.

Historically, the term agent has sometimes been used for this same meaning.
However, agent also refers to the agent component (the `cf-agent` binary), and thus, when discussing the role of a CFEngine host, _client_ is the preferred term for these hosts which are not hubs, and which packages to install on them.

#### CMS
#### Client initiated reporting

Content Management System.
A kind of editor for maintaining something (often web pages).
A mode where you change the configuration so that the hub does not initiate connections to client hosts to fetch reports.
Instead, the clients will establish a connection, and leave it open, until the hub is ready to use it to query for reporting data.
Sometimes referred to as call collect.

#### Configuration management database (CMDB)

A term coined as part of the IT Infrastructure Library (ITIL) as an outgrowth of an inventory database.

#### Code branch

Expand All @@ -98,59 +141,61 @@ Daemons include `cf-execd`, `cf-monitord`, and `cf-serverd`

The Commercial Open Source License used for the CFEngine.

#### CSS

Cascading Style Sheets.
Part of Web technology used to describe page design.

#### Datatypes

CFEngine's data types describe what a variable can contain.
A variable can't be assigned a different type once it's been set.
The commonly used data types are `string`, `slist`, `int`, `real`, and `data`.
The commonly used data types are `string`, `slist` (string list), `int`, `real`, and `data`.

#### Diff

A `diff` is a report (originally that generated by the UNIX diff command) that
details the differences between two files.
A `diff` is a report (originally that generated by the UNIX diff command) that details the differences between two files.
The term is often used as slang meaning a file comparison.

#### Directories

#### Distribution

#### Enterprise API

#### Enterprise reporting

#### File structure
The Enterprise API is a JSON HTTP REST API, allowing users to access CFEngine's functionality and reporting data programmatically.
It can be used to generate reports, query data, create alerts, manage users, etc.

#### Frequency
#### Enterprise reporting

#### Functions
CFEngine's reporting system allows you to access information about your hosts as well as the results of your policy in a centralized system.
On the hub, you have access to the reporting system through the JSON REST API, the Web UI, the SQL database, as well as generated PDF / CSV reports.

#### GPL3

The GNU Public License, version 3.

#### GUI
#### Graphical user interface (GUI)

As opposed to text / command line based interfaces, GUIs use icons, images, color, spacing, and more complex layouts to improve the user experience.

Graphical User interface.
The CFEngine GUI is called Mission Portal and is accessible via a web browser.
It shows you useful information about your infrastructure, and provides easy ways to make changes.

#### Host

UNIX terminology for a computer the runs _guest programs_.
In practice, _host_ is a synonym for _computer_.

In CFEngine, all machines (physical or virtual) which have an installation of CFEngine are considered _hosts_.
We split them into 2 roles (categories) - hubs and clients.

#### Hub

A software component in CFEngine Enterprise that acts as a single point of management in a local "star-network."
The term "hub" is sometimes used to mean policy distribution server, but more commonly a running `cf-hub` process that does report collection from all CFEngine managed hosts.
The term hub means the centre of a wheel, from which multiple spokes emerge.
The term hub means the center of a wheel, from which multiple spokes emerge.

In CFEngine, the hub is the host responsible for collecting reports from hosts and serving them policy.
In addition to the components installed on other CFEngine hosts (clients), the hub runs a database (PostgreSQL), a web server (Apache) and a few additional CFEngine components, most notably `cf-hub` which connects to hosts and retrieves their reporting data.

Due to the multiple purposes this host serves, it is sometimes referred to as the policy server, the reporting hub, or the report collector.
In typical CFEngine Enterprise setups, all hubs are policy servers and all policy servers are hubs, so the distinction is not so important.
In general, hub is the preferred term to describe the role of what this host does, and which package to install on it.

#### LDAP
See CFEngine role.

#### Lightweight directory access protocol (LDAP)

The Lightweight Directory Access Protocol.
A kind of _phone book_ service providing information about persons and computers in an organization.

#### Libraries
Expand All @@ -160,31 +205,39 @@ This might be bundles of promises, or reusable body-parts.

#### Logs

#### Mission Portal
Log files tell you some historic, usually timestamped, information about events which happened in the past.
In CFEngine, there are a few notable log files:

* `/var/logs/CFEngineInstall.log` - Information about the installation, especially useful if installing the package failed.
* `/var/cfengine/outputs/` - Output logs of previous scheduled agent runs (if any).
* `/var/cfengine/httpd/logs/error_log` - Apache errors (Mission Portal / API)

#### Mission Portal (MP)

The name given to the user interface used in commercial CFEngine editions,
where all reports and progress summaries are kept.

#### Modular license
#### Namespaces

A license granting partial functionality to an Enterprise Edition of CFEngine.
Namespaces allow you to define new scopes for bundles, variables, and classes.
By using a specific name for the namespace, you can use short and generic names for the identifiers inside of it.

#### Monitoring
By default, if you don't specify a namespace, you are using the namespace called `default`.
The CMDB (group data / host specific data in Mission Portal) uses the `cmdb` namespace, unless you specify a namespace.

#### Namespaces
You can think of namespaces in a similar way as putting files inside folders, instead of having all of your files in one folder.
The result is that things are more organized and less chances of files / classes / variables / bundles having conflicting names.

#### Normal ordering

#### Operators
In CFEngine, the promises you write in policy files are evaluated according to a predetermined order, not from top to bottom of your policy file.

#### Packages

Software binaries or executable files.
The CFEngine company compiles and tests
software into packages suitable for different platforms.

#### Pattern matching

#### PCI compliance

Payment Card Industry Data Security Standard (PCI DSS) is a set of requirements designed to ensure that ALL companies that process, store or transmit credit card information maintain a secure environment.
Expand All @@ -207,8 +260,20 @@ A policy is not a standard, but the result of specific organizational management

#### Promise attributes

As opposed to the promiser string (which is usually the unique identifier of a resource), promise attributes specify the desired specifics for that resource.
A basic example is that if you want to ensure a file has a specific set of permissions, you would make a promise where the promiser string is the filename, and the desired permissions are specified as attributes.

Sometimes referred to as promise constraints.

#### Promise types

Different types of resources you can manage with CFEngine.
Typical examples include files, users, services, packages, etc.
Making promises with these types results in CFEngine checking the state of those resources and making changes on the system if necessary.

There are also promise types which are not traditional resources on a system, but rather just for managing state within the CFEngine binaries, such as variables, classes, meta, etc.
Setting a class or a variable will not alter the system directly, but makes that information available for further policy and promise types in the same execution.

#### Promise

The CFEngine software manages every intended system outcome as "promises" to be kept.
Expand All @@ -219,22 +284,11 @@ Promises are idempotent, meaning they can be executed many times with the same o
They are also convergent, meaning they can only nudge the system closer to a steady state, never destabilize it.
While there are ways a user could override this, it's almost never a good idea to do so.

#### Referencing

#### Report collector

#### Reporting

#### Reports

#### Role-Based Access Control (RBAC)
#### Role based access control (RBAC)

#### Scope

#### Semantic web

A form of web content in which hyperlinks always explain the meaning of the information they point to, in relation to the subject of interest.
Semantic web technologies include RDF, Topic Maps etc.
RBAC allows you to control the level of access granted to individuals at a granular level.
Each user can have one or more roles, and each role can grant them access to specific resources as well as actions.
A flexible RBAC system improves the security of the system, especially when combined with a principle of least privilege approach.

#### Server

Expand All @@ -256,8 +310,6 @@ In the CFEngine Mission Portal, the service catalogue (for maintenance) treats p
Sarbanes-Oxley Act compliance.
An audited accolade for financial data security required by all companies on the New York stock exchange.

#### Special variables

#### Standard library

The standard library lives in a `masterfiles/lib` subdirectory.
Expand All @@ -269,8 +321,7 @@ A template is an incomplete piece of CFEngine code, with blanks to fill in.
It is often a policy fragment that can be re-used in different scenarios.
This is often used interchangeably with the term _library_.

#### UI

User interface.

#### Variables

Variables have a name, a type, and a value (and some optional metadata).
In CFEngine policy language, variables are similar to variables in other programming languages, they can hold strings, lists, omplext data structures, etc.

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