A Technical I.T./DevOps Blog
SaltStack provides for more complex configuration management than Ansible (another Python-based) configuration management tool. Some people have criticized Salt for having too many new vocabulary words. Like all complex technologies, they take time getting used to. To help learn about Salt, I thought I’d provide an overview.
An SLS file is a SaltStack State file. This file is the basis for determining the desired configuration of the client servers that are called Salt Minions.
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Containers, such as Docker, communicate to each other through a shared kernel. Guest virtual machines communicate to each other through the hypervisor or host operating system. Containers enjoy faster communication as staying within a shared kernel allows for more rapid communication than leaving a virtual machine and going out to a hypervisor (or host operating system) to communicate with another virtual machine. Containers allow for sequestration of processes and fewer operating systems licenses compared to having a comparable solution with virtual machines.
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Continue reading “Containerization Has Its Advantages Over Virtualization”
Extract-Transform-Load workflows involve considerable architecture including a workflow over a network to take data from a flat file and ingest it into a database. Automation is one way to manage the ETL support system. DevOps Engineers commonly support database installations and configurations. DevOps engineers commonly support continual delivery pipelines. This automated process (involving automatic deployments) is often similar to automating an ETL process. DevOps engineering, build and release engineering, automation development, and ETL design are all interdisciplinary fields of information technology.
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When writing a Puppet manifest you can use the “content” reserved word. You then have quotes around the actual text content of this file right in the manifest itself. This works for a file that you want to create on a Puppet Agent server as long as the content is roughly one line of text. But for a binary file, this will not work (as it cannot appear in the manifest). The “source” reserved word allows you to point to a specific file on the Puppet Master server.
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Continue reading “How do you use the source keyword in Puppet’s DSL (when writing a manifest)?”
Deploying Puppet Master and Puppet Agents for the first time can involve a significant amount of troubleshooting. In this post, I want to review six miscellaneous points that may arise. These are somewhat random, but they can serve in the rudimentary stages of quickly getting a proof of concept established.
1. With a default configuration, Puppet Master on Linux will run manifests with only one name in only one location: /etc/puppet/manifests/site.pp
Many DevOps engineers do use manifests with different names.
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While as of right now, there is not a great way to install Ansible on Windows servers (because you have to install cygwin). Ansible running on Linux can readily configure Windows servers and push files down to them. There are some things to look out for when setting this up. It is not overly documented on Ansible’s website. Some documentation (on various websites) tells DevOps engineers (or the professional using Ansible) to use a windows.yml file in a group_vars directory.
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Problem scenario
Are are asking yourself “why am I being prompted for a password when my SSH keys were set up correctly?” When the contents of the .pub file (the public key) are placed into the authorized_keys file (in the /home/jdoe/.ssh/ folder of a client machine), the user should be able to SSH over to the server with no password — unless the SSH key was generated with a passphrase. Assuming the SSH key was generated with an ssh-keygen command and no corresponding passphrase was entered at the time of creation,
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Continue reading “How Do You Set Up Passwordless SSH to a Windows Server?”
Problem scenario: When you move a Windows .txt file to a Linux server, new characters can be introduced. For example, the content of the file can have a “^M” (with no quotes) at the end of every line. Sometimes tr, sed, and awk won’t work to remove this new jibberish (extraneous characters). Moreover, sometimes the substitute command in vi will fail to do anything about these extraneous characters (^M). How do you eliminate these extra characters at the end of every line?
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Continue reading “Moving a Windows .txt file to a Linux Server”
“Documentation plays a great role in the maintenance of a project.” (Page 19, Learn Apache Ant, Tutorialspoint.com, 2014)
The open source movement is no exception. As much as we admire The Apache Software Foundation, we are disappointed that they don’t correct errors. We’ve submitted the first two errors below to them. However, mistakes remain. Here are some errors to help other people who may be confused:
#1 was corrected. (We removed the error from this page.)
#2 Error on web page for Apache Ant
Specific location: http://ant.apache.org/projects.html
What is wrong:
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Continue reading “Apache Software Foundation Has Imperfect Websites”
Sometimes you cannot edit and save a single file in Linux. For example, if you boot into maintenance mode after the /etc/fstab is corrupt, you cannot edit the very file that is causing the problem. To overcome this problem, you will need to log in as root and issue a command. You will need to manually edit the /etc/fstab. To do this in maintenance mode you need to issue this command from the prompt:
mount -o remount,rw /
After this,
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Continue reading “What To Do When Linux Files Are Read Only”