Category: Sysadmin

System administration is a special are of IT. It also has a special place in my heart. It is an interesting mixture of all the other disciplines, both common across the whole industry, and at the same time unique for each person, company, and geographical location. When I have something to say or share about system administration, I use this category.

Reboot and wait for reboot to complete in Ansible playbook

Jeff Geerling shares a handy tip on how to implement the configure-reboot-configure pattern in an Ansible playbook.

---
- name: Do something that requires a reboot when it results in a change.
  ...
  register: task_result

- name: Reboot immediately if there was a change.
  shell: "sleep 5 && reboot"
  async: 1
  poll: 0
  when: task_result is changed

- name: Wait for the reboot to complete if there was a change.
  wait_for_connection:
    connect_timeout: 20
    sleep: 5
    delay: 5
    timeout: 300
  when: task_result is changed

...

HTTP : The headers we want

“The headers we want” is a very simple, straight to the point blog post on the Fastly blog.  Unlike many other more generic articles on the subject, it doesn’t try to explain the meaning of every HTTP header out there, and it doesn’t go into deep theory or the meaning of life, the universe and everything.

Instead it tells you plain and clear which headers should be emitted by your website or web application.  And these cover everything from the usual Content-Type and Content-Length, all the way down to the CORS and Server-Timing.

Once the basic functionality of your website or web application is done and out of the way, this blog post comes in handy with the specific best practices to make your site more secure and much faster.

For more on the same subject, have a look at “The headers we don’t want” in the same blog.

Shell Style Guide from Google

For all of you out there writing millions and millions of shell scripts to glue the world together, here’s a useful Shell Style Guide from Google.  It is very Bash-centric and covers all the usual bits and pieces: comments, formatting, naming conventions, allowed features and recommended best practices.

 

git worktree – a better way for git stash abusers

If you constantly find yourself using “git stash” while working on a project, or, even worse – have multiple copies of the same project cloned on the same machine, “git worktree” might be a much better alternative for you.

Manage multiple working trees attached to the same repository.

A git repository can support multiple working trees, allowing you to check out more than one branch at a time. With git worktree add a new working tree is associated with the repository. This new working tree is called a “linked working tree” as opposed to the “main working tree” prepared by “git init” or “git clone”. A repository has one main working tree (if it’s not a bare repository) and zero or more linked working trees.

When you are done with a linked working tree you can simply delete it.

Here are a few links to get you started: