This is the second blog post in a short series about processes on UNIX-like systems. It is a followup to the previous post which focused on basic definitions, creation of processes and relations between them. This time we analyze the semantics of two closely related system calls that play major roles in process creation and program execution.
fork() and exec() The UNIX-based operating systems provide the fork() system call1 to create a clone of an existing process and the execve() system call to start executing a program in a process. Windows, on the other hand, provide the CreateProcess() function which starts a given program in a newly created process. Why are UNIX-based systems doing things in a more complicated way? There are many reasons for that, some simply historical, as described in The Evolution of the Unix Time-sharing System:
How can I run my own bundles automatically, like autorun from the MPF (Masterfiles Policy Framework), but with different logic?
Cody Valle (Head of community), Criag Comstock (Digger), Ole Herman Elgesem (Product Manager) and Nick Anderson (Doer of Things) review the existing capabilities and limitations of autorun in the MPF. After reaching the limits offered by the stock framework they explore implementing a custom autorun, for example recursively finding policy files or only including policy files with associated enablement classes.
While working on the integration of CFEngine Build into Mission Portal we came to the point where we needed to start executing separate tools from our recently added daemon - cf-reactor. Although it may seem like nothing special, knowing a bit about the process creation and program execution specifics (and having to fight some really hard to solve bugs in the past) we spent a lot of time and effort on this step. Now we want to share the story and the results of the effort, but since understanding of the reasons behind the work together with how the implementation works requires quite deep knowledge of how processes are being created and programs are being started on UNIX-like systems, we first start with a series of blog posts focused on this seemingly simple area. They cover the basics as well as some advanced topics in two parts:
Since joining the CFEngine team in 2019 I’ve heard and read numerous times that the configuration management market is dying and becoming obsolete. While I and many others don’t personally adopt this line of thinking, I can understand why one would come to this conclusion being that we’re in an ever-changing industry and talking about solutions that have been around for decades. Configuration management solutions like CFEngine are certainly not a new concept, however there are many changes that are happening across the industry that will continue to drive usage and will ultimately pave the way for a new era in this market.
Today, we are pleased to announce the release of CFEngine 3.20.0! Over the past few years we’ve focused on ease of use, new user experience, and out of the box value, giving you the ability to do much more through only the Mission Portal Web UI. This has resulted in several important steps forward; policy analyzer, compliance reports, host specific data (CMDB), and CFEngine Build with custom promise types and other modules. In this release we take this one step further, focusing on modules and modularity, and the ability to find and use modules, making changes to your infrastructure, directly from Mission Portal (API or GUI). The 3.20 release is not supported, but it’s an excellent opportunity for our users to see and test what will be in the next release - CFEngine 3.21 LTS, about 6 months from now.
Interested in seeing what’s around the corner in CFEngine Enterprise?
Herman (Product Manager) walks us through the features that we will find in the upcoming release of CFEngine 3.20. Being a non-LTS release, it’s a great opportunity to try out new features and get your feedback in before our next LTS series.
Video The video recording is available on YouTube:
At the end of every webinar, we stop the recording for a nice and relaxed, off-the-record chat with attendees. Join the next webinar to not miss this discussion.
We are pleased to announce two new patch releases for CFEngine, version 3.15.6 and 3.18.2! These releases mainly contain bug fixes and dependency updates.
What’s new Some smaller features and improvements were added to 3.18.2. Most of these are centered around newer functionality, such as compliance reports.
Compliance report widgets and improved UI Compliance reports are one of our most powerful report types, allowing you to compile all your security and compliance requirements into one checklist, and easily see exactly how many hosts are failing and passing each check. These reports can now be turned into widgets on your Mission Portal dashboard:
Recently we introduced new feature where you can trigger agent runs and report collection from the Mission Portal UI.
This required our daemon cf-execd to behave a bit differently when periodic agent runs occur. Previously the daemon would create a new thread in which to run cf-agent, capture output, wait for completion and move on.
We changed the behavior so that the daemon forks itself and then fork/execs cf-agent as before, with the forked cf-execd processing agent run output. When the agent is finished the forked cf-execd process is left a zombie/defunct. The daemon wakes up every minute to see if it should do an agent run. The next time the original daemon cf-execd “wakes up” it will clean up that defunct forked cf-execd.
A while back we released version 2 of cfbs, and even though we release versions of this tool quite frequently, without announcing it on the blog, we thought this was a good opportunity to talk a bit about the tool, what’s new and our direction with it in the future. The reason why we called this the “2.0” release is that we are trying to follow semantic versioning, and there were some big new features in the release which could be considered breaking changes.
Interested in extending the CFEngine DSL to support your own custom promise types?
Herman (Product Manager) walks us through implementing custom promise type in python.
Video The video recording is available on YouTube:
At the end of every webinar, we stop the recording for a nice and relaxed, off-the-record chat with attendees. Join the next webinar to not miss this discussion.
