Show posts tagged:
developers

Synchronize data between PostgreSQL and files

Databases are great for data processing and storage. However, in many cases it is better or easier to work with data in files on a file system, some tools even cannot access the data in any other way. When a database (DB) is created in a database management system (DBMS) using a file system as its data storage, it of course uses files on the given file system to store the data.

April 6, 2022

Trigger arbitrary code from PostgreSQL

In this blog post we show how it is possible to run an arbitrary program, script, or execute arbitrary code in reaction to changes and generally events in a PostgreSQL database. Triggers Database management systems (DBMS) provide mechanisms for defining reactions to certain actions or, in other words, for defining that specific actions should trigger specific reactions. PostgreSQL, the DBMS used by CFEngine Enterprise, is no exception. These triggers can be used for ensuring consistency between tables when changes in one table should be reflected in another table, for recording information about actions, and many other things.

March 31, 2022

CFEngine bootstrap with Ansible

CFEngine and Ansible are two complementary infrastructure management tools. Findings from our analysis show that they can be combined and used side by side with joint forces to handle all areas in the best possible way. Part of infrastructure management is hosts deployment, either when building a brand new infrastructure or when growing one by adding new hosts. This is something Ansible truly excels in as it makes it very easy to run a sequence of steps on all hosts to initialize (deploy) them and it only requires SSH access to the hosts and Python installed on them.

February 3, 2022

Static checking of CFEngine code

Software quality has been a topic and an area of interest since the dawn of software itself. And as software evolved so did the techniques and approaches to assuring its high quality. Better computers providing more computing power, bigger storage and faster communication have allowed software developers to detect issues in their code sooner and faster. And so we got from getting a syntax error after two days of waiting for the box of punch cards to go through the queue of boxes and get loaded into a computer running a compiler to getting such errors from a compiler in seconds or even in real-time from the code editor.

December 9, 2021

Announcing CFEngine Build

Earlier this year, we hinted at what we were working on - a place for users to find and share reusable modules for CFEngine. Today, the CFEngine team is pleased to announce the launch of CFEngine Build: The new website, build.cfengine.com, allows you to browse for modules, and gives you information about how to use each one of them. When you’ve found the module you were looking for, it can be downloaded and built using the command line tooling.

November 1, 2021

CFEngine for IoT

CFEngine is well suited for use in IoT environments due to it’s portability, size, and performance. There already exists a meta layer for including the CFEngine community client and Masterfiles Policy Framework in Yocto Project builds. This enables developing policy to: ensure a service stays running track changes to important files monitor a value over time for normalcy Let’s walk through bringing up a qemu environment with CFEngine and ensure that a few basic things work: ensure the udev service stays running, tracking changes to important files like /etc/group and a look at monitoring capabilities.

Posted by Craig Comstock
October 19, 2021

Optional arguments with getopt_long(3)

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.

Posted by Lars Erik Wik
August 13, 2021

How to implement CFEngine custom promise types in bash

This blog post will focus on the bash programming part of implementing a promise type. To understand what custom promise types are, and how to use them, you should read the introduction first. To implement a custom promise type in CFEngine, you need a promise module. The module is an executable, and can be written in any language. It’s possible to write one from scratch, but to make it as easy as possible, we decided to provide libraries for common programming languages.

January 29, 2021

How to implement CFEngine Custom Promise Types in Python

This tutorial focuses on how to write a promise module, implementing a new CFEngine promise type. It assumes you already know how to install promise modules and use custom promise types, as shown in the previous blog post. Why Python? Promise modules can be written in any programming language, but there are some advantages of using python: Readable and beginner friendly language / syntax Popular and familiar to a lot of people, also used in some CFEngine package modules Big standard library, allowing you to reuse data structures, parsers, etc.

December 8, 2020

Getting out from under a SIGBUS BUS_ADRALN on Solaris/HP-UX

Introduction In the CFEngine Core team, we have recently been working on a fix for our WaitForCriticalSection() function. In short, the function checks a timestamp in a chunk of (lock) data stored in a local LMDB database and if the timestamp is too old, it writes a new chunk of (lock) data with the new timestamp. However, this used to be done in separate steps - read the data from the DB and close DB, check the data and potentially write the new data into the DB.

June 8, 2020
Get in touch with us
to discuss how we can help!
Contact us
Sign up for
our newsletter
By signing up, you agree to your email address being stored and used to receive newsletters about CFEngine. We use tracking in our newsletter emails to improve our marketing content.