Do you enjoy escaping quotes inside strings? I sure don’t, and I really appreciate the flexibility CFEngine provides with 3 different quoting characters (", ', ` ). Let’s take a look. This came up in the post show discussion for The agent is in, episode 39. If you have a string that contains double quotes you might see it written with escaped quotes like this:
CFEngine works by defining a desired state for a given context and converging towards that goal. Given there is no fixed starting point and that the current context might change wildly it can be challenging to succinctly answer the question “What would CFEngine do?”. In Feature Friday #22: Don’t fix, just warn we saw how an individual promise could be made to warn instead of trying to automatically converge towards the desired state, a granular --dry-run mode. This time, let’s take a look at the --simulate option of cf-agent.
Implicit list iteration in CFEngine is quite a unique and novel feature. Today we look at a practice example showing how lists can improve the readability and maintainability of your policy. A novel feature in CFEngine is how a list variable is iterated when referenced as a scalar ($(variable)). Let’s take a look at a contrived example. Here we see a list of strings (slist) defined as toys and we have a single reports promise to emit toys we want to play with.
We are pleased to announce two new patch releases for CFEngine, version 3.21.6 and 3.24.1! These patch releases contain bug fixes and dependency updates. Changes In 3.24.1, Mission Portal has one new feature, requested by our users, which we’d like to highlight - When logging in to the CFEngine Enterprise web UI, Mission Portal, we now support 2FA using a time-based one time password (TOTP). Aside from this, these are patch releases which mainly focus on bugfixes, not new features.
Recently we had a Fireside Chat with long-time contributor and CFEngine Champion Bas Van der Vlies. During that talk he mentioned a Build module he developed: promise-type-docker-compose. For this month’s Module Monday post I thought I would take this promise type for a spin alongside the Docker Compose Quickstart tutorial. Setup For this blog I brought up a libvirt vagrant VM with Debian 12 and installed the latest LTS (3.24.0) with cf-remote. To install docker I follow the instructions at Install Docker Engine. I was using Debian 12 “bookworm” and found that the default packages docker.io and docker-compose are rather old and were not compatible with the promise-type-docker-compose module. Additionally, the module relies on the jq utility, so I install that as well. I may write policy some time to take care of these dependencies but especially the Docker Engine install involves quite a few steps so will leave that for another time.
CFEngine build modules are great for quickly integrating 3rd party policy into your policy set. Module input (not to be confused with inputs in body common control or body file control which are the list of policy files to load) allows you to define values that apply for a particular module as it’s integrated into your policy set. Let’s take a look at a case of extending a module to support input.
Nick and Cody celebrate Thanksgiving with a holiday special reviewing some policy related questions Nick recently received. Get the list of all network interfaces present default:sys.interfaces only contains configured interfaces, not configured interfaces. default:sys.interfaces_data at least for Linux systems, this variable contains much more information. /tmp/getindices-sys.interfaces_data.cf bundle agent __main__ { vars: "sys_interfaces_data_keys" slist => getindices( "sys.interfaces_data" ); reports: "$(sys_interfaces_data_keys)"; } command cf-agent --no-lock --log-level info --file /tmp/getindices-sys.interfaces_data.cf output R: lo R: enx0892048803e7 R: enx5cff35c6864b R: wlp0s20f3 R: virbr0 R: docker0 R: br-a7d465b9949b R: vboxnet0 R: tun0 cf-promises can be very useful for reviewing the first order variables that are defined using the --show-vars option.
Ever need to make a decision based on the version of something? The version_compare() function might be useful for you.1 Over time, software changes and features are added and removed. Sometimes, we need to make a decision based on versions. For example, the Include directive in ssh_config was introduced in OpenSSH 7.3.2 Let’s take a look at how we could possibly use it. This example illustrates the basic use of version_compare():
Looking for a tool to help you format your CFEngine policy? Have you heard of cffmt? You might recall that we had a chat with the author, Miek Gieben in The agent is in - Episode 24.1 In case you missed it, cffmt is a command line tool for formatting CFEngine policy files, like gofmt for .cf files.2 Let’s take a look. Consistent formatting can really ease reading of policy, but sometimes editors are configured differently and you can end up with inconsistently formatted policy. For example, here is a contrived policy file with some irregular formatting:
Have you seen the new Groups feature in CFEngine Enterprise Mission Portal? It was first released in 3.23.0 and it’s part of the 3.24 LTS series released earlier this year, let’s check it out. Groups in Mission Portal can be based on any host reported data. They can be dynamic (hosts can come and go from a group) or they can be static and tied to specific hosts by hostname, mac address, IP or CFEngine’s public key. By default groups are not shared with other users and they can be used any place where you would use a filter constraining the scope of hosts based on various conditions related to the hosts reported data. If a group is shared it can have data associated with it.
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