#Packer

Question count - 0     Last updated    - V2 (19-Nov-2023)

Packer =Reusable machine image. Image is pre-configure by default. We can use that pre-configured image no need to go from starting like install step. Image =Saving the time on installation. One time we install it and next time we take image A tool from Hashicorp to build machine images for most platforms (AWS, Google Cloud, Digital Ocean, Docker, Azureetc.) and automate configurations and installation of software?s that need to be present. We define how to build the image in a JSON template file. This should be version controlled and is treated like any other code. Sections of Packer template Variables Packer template should be made generic so it can be used in different environment and keeping secrets/credentials secure by not providing them in the template file. Use user variables in place of such configurations. Builders A builder takes care of creating an image. Packer provides builders for various platforms. For this example we will be using amazon-ebs as builder. We provide platform specific configurations in the builder section of the template. Like what type of instance (t2-micro m4-large etc) to spin up to create the image, SSH/Access details or credentials. Builders use Communicators to establish connection with the created instance. Either it can be a SSH connection or WINRM for Windows machine. Provisioners Once a machine is created by the builder we will use provisioners to install software?s and configure the machine to a desired state. Packer provide provisioners for configuration management tools like Chef / Puppet / Ansible or good old shell script. Post-Processors Once the machine is created and software is installed and configurations applied by Provisioners Post-Processors are run. We can use them for example to push a docker image to a registry. So what exactly does Packer do? Packer will spin up an instance for the specified platform based on the type of builder. Use the Communicator specified to connect to the machine. Run all the provisioners to configure and install software?s. It the runs any post-processors specified in the JSON template. Finally it terminates machines and any temporary resources it created in the process e.g. security group, temporary ssh key-pair etc.