The latest updates about everything CFEngine

Feature Friday #13: classesmatching()

Did you know you can find classes by name and tag? classesmatching() dynamically sources information from the current state. For example, let’s say you have classes representing a system’s role. Furthermore, let’s say that we want a host to only have a single role class defined. Finally, if we have more than one role class defined, then we don’t want to proceed. To achieve this without classesmatching(), we might have a policy file that looks like this (/tmp/feature-friday-13/tags-on-classes-0.

Posted by Nick Anderson
June 7, 2024

Use Ansible playbooks in CFEngine policy with promise-type-ansible module

Whether you are migrating from Ansible to CFEngine to gain some of the benefits of scale or autonomy or just need some functionality in an Ansible module, the ansible promise type can be a great tool to utilize. It also provides a compelling alternative to ansible-pull and works around some of the caveats included with that strategy. CFEngine has battle-tested features needed for the pull architecture: cf-execd handles scheduling periodic runs as ansible-pull suggests using cron cf-agent handles locking to avoid concurrent runs of the same playbooks A tiny Ansible project example Taking some first-step tips from 5 ways to harden a new system with Ansible let’s make a sample playbook project which patches Linux systems.

Posted by Craig Comstock
June 3, 2024

Feature Friday #12: special variables

Are you familiar with CFEngines special variables? Probably you are familiar with sys variables like sys.fqhost (the fully qualified host name) and sys.policy_hub (the IP address of the machine the host is bootstrapped to) but I want to highlight a few other special variables you may not be so familiar with. sys Sys variables are derived from the system discovery done by the agent as it initializes. sys.os_release - A data structure derived from /etc/os-release /etc/os-release, introduced by systemd provides a nice record of the current distributions release information.

Posted by Nick Anderson
May 31, 2024

Show notes: The agent is in - Episode 37 - Windows package management

Curious about package management with CFEngine on Windows? After sharing some history on Microsoft’s global advertising campaign for “Where do you want to go today?” Craig shared some of his recent experiments with several windows based package managers as well as their related challenges. Craig discussed difficulties with the msiexec package module, such as distinguishing which packages need installation through msi while also identifying software for removal by name, a task that can be challenging.

Posted by Nick Anderson
May 30, 2024

Feature Friday #11: namespaces

Did you know that CFEngine has namespaces? Let’s see how they can facilitate policy sharing while avoiding “duplicate definitions of bundle” errors. Most of the Masterfiles Policy Framework (MPF) and policy examples for CFEngine use the default namespace. However, body file control allows you to specify a namespace that applies for the rest of the file or until it’s set again by another body file control. Let’s consider a contrived example.

Posted by Nick Anderson
May 24, 2024

Feature Friday #10: cf-support

Found a bug, asking for help? Use cf-support to collect info quickly. cf-support was born from interactions supporting Enterprise customers to streamline data collection and was introduced in late 2022 with the release of 3.18.31 and 3.21.02. Furthermore, it was featured on The Agent is In3 episode 21 Troubleshooting with cf-support. It gathers various details about the system and creates an archive that you can attach to your ticket. While its inception was geared towards Enterprise customers, it’s still both useful and available for community users as well.

Posted by Nick Anderson
May 17, 2024

Efficient data/file copying on modern Linux

Editing and copying large files or large numbers of files is slow. For a configuration management tool, it is probably one of the slowest things we do, apart from waiting for other programs to finish or waiting for network communication. In this blog post, we look at how to copy files. More specifically, the most performant approaches available on modern Linux systems. We are working on implementing these techniques so CFEngine and all your policy will copy files more efficiently.

May 15, 2024

Feature Friday #9: body file control - inputs

Did you know you can include one policy file from another? Traditionally you specify the files you want to make up a policy set using inputs in body common control found in your policy entry (promises.cf by default). body common control { # Paths are relative to $(sys.policy_entry_dirname) if not # fully qualified inputs => { "path/to/policy-1.cf", "path/to/policy-2.cf", }; } body file control lets you specify additional inputs from any file that’s included in the policy and those files can include other files.

Posted by Nick Anderson
May 10, 2024

Configure which hosts can participate in CFEngine infrastructure management

Two modules are available for this task: allow-all-hosts and allow-hosts. The first module, allow-all-hosts, configures the most open situation which is to accept hosts from anywhere. This is only recommended in network restricted environments such as a local machine’s virtual machine network or other such closed down situations. The second module, allow-hosts, uses cfbs module input to let you decide which hosts (specified by IP addresses and subnets) are allowed to connect to your hub, authenticate, fetch policy, etc.

Posted by Craig Comstock
May 6, 2024

Feature Friday #8: bundlesequence

Ever want to run just a one or a few select bundles from your policy? While developing policy it’s common to run cf-agent -KI so that you can quickly iterate on changes and the run the policy without locks. But if you are focused on select bundles you may not need the full policy to run, you can use the --bundlesequence option to specify one or more bundles overriding the bundlesequence defined in body common control.

Posted by Nick Anderson
May 3, 2024