How to properly check if files are readable
Opening and reading files may cause your program to block indefinitely. In this blogpost we'll discuss how to work around this issue.
Opening and reading files may cause your program to block indefinitely. In this blogpost we'll discuss how to work around this issue.
Our beloved cfbs CLI tool for working with CFEngine Build is rapidly evolving. At the time of writing, we are currently at version 3.2.1. Thus I would like to take this opportunity to talk a bit about the latest and greatest features; including support for users to manipulate input parameters in modules, as well as a couple of new build steps. If you haven’t yet got a hold of the latest version of cfbs, you can update it with pip using the following command:
In the upcoming CFEngine 3.20 release we are making a change in the behaviour of the create attribute for the files promises that manage the entire content of a file. This includes promises with the template methods mustache, inline_mustache and cfengine; as well as promises with the content attribute. The motivation behind these new changes is two-fold; make it easier to learn CFEngine policy language and understand what policy is doing, and to prevent CFEngine from creating empty configuration files.
Last year we had a look at managing local groups with the custom groups promise type. As you may or may not recall, we used JSON-strings to imitate CFEngine bodies. This was due to the fact that the promise module protocol did not support bodies at that time. Today, on the other hand, we’re happy to announce that as of CFEngine 3.20, this will no longer be the case. In this blog post we’ll introduce the long awaited feature; custom bodies.
Manually managing groups on a large infrastructure can be a tedious task, and is therefore best suited through automation software like CFEngine. Unfortunately - at time of writing - CFEngine does not have any built-in promise types for managing groups. But fear not; in CFEngine 3.17, custom promise types were introduced. This new exhilarating feature does not only allow for members of our community to make their own custom promise types, but also lets the CFEngine Core developers prototype new future promise types.
I recently had a minor task involving changing an option - on one of our command line tools - from taking a required argument, to taking an optional argument. This should be easy they said; just change the respective option struct to take an optional argument, add a colon to the optstring, and get on with your life. Well, it proved to be easier said than done. My initial expectation was that a solution similar to the one below should just work.