Reflections on IaC using Terraform
Terraform has emerged as one of the top open source infrastructure as code (IaC) tools, since its initial release by Hashicorp back in 2014.
The design philosophy behind the tool is to have declarative, and stateful representation for the underlying IT infrastructure (whether it be on public, on-premise, or hybrid cloud), which in turns simplify the control, collaboration, and auditing of such resources.
The classical example for provisioning AWS EC2 instance concisely captures the design principles.
A Git Book on Linux SysOps Essentials
Resolving Image Creation Failure on DockerD due Pool Size Limit
Sometimes, when working with docker engine on CI systems, certain type of errors could arise from the challenging restrictions or limits on the environment. This is typical with the inherent server-client architecture of docker.
Here’s one of the problems that I’ve seen recently. When a client is connecting to
dockerdin order to build an application image or prepare and pull external images, the server reports this issue:
failed to prepare a4mv4dh8qcq283c7x47a4nwpg: devmapper: Thin Pool has 161986 free data blocks which is less than minimum required 163840 free data blocks. Create more free space in thin pool or use dm.min_free_space option to change behavior
Using UUIDs as Primary Key for Active Record Models
It’s advised that using universally unique identifiers (UUIDs) for exposed resource identifiers is more secure, and convenient for database distribution.
As expected, it’s relatively simple to configure Active Record to generate with
UUIDprimary key based migrations.
Here are the steps:
Setup the default generation inside
# config/application.rb module SampleApp class Application < Rails::Application ... # Change the primary key default type to UUIDs. config.generators do |g| g.orm :active_record, primary_key_type: :uuid end end end
Optimize Image Files from Your Terminal
In many times you may find yourself in need for optimzing rapidly a bunch of images in your hands. There are handy utility libraries that can help you reduce image sizes with simple commands in the terminal. The following lists some of these tools:
1. OptiPNG: Advanced PNG Optimizer:
Get it for Mac OS X:
brew install optipng
For Linux Ubuntu:
apt-get install optipng
To optimize an image, run: