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Best Practices: Packer

This entry is part 1 of 4 in the series Best Practices

Synopsis

This technical guide provides a detailed overview of best practices for working with Packer in a busy DevOps team. It includes information on concepts such as idempotency and naming standards, as well as code examples and templates for organizing Packer code in a git repository. The guide also covers considerations for security and provides templates for a README file, HCL file, and .gitignore file for a Packer repository.

Summary

This technical guide provides best practices for working with Packer in a busy DevOps team. It covers important concepts such as idempotency and naming standards, as well as providing code examples and structured into appropriate sections. The guide also includes information on how to organize Packer code in a git repository, including considerations for security, as well as templates for a README file, HCL file, and .gitignore file for a Packer repository.

Introduction

Packer is a popular tool for automating the creation of machine images. In a busy DevOps team, it is important to follow best practices when working with Packer to ensure that the codebase is maintainable and easy to work with.

One key concept to keep in mind when working with Packer is idempotency. An idempotent operation is one that has the same result whether it is performed once or multiple times. In other words, if an operation is idempotent, it will not change the system state if it is run multiple times with the same parameters. This is important in Packer because it allows you to run builds multiple times without causing unintended changes to the system.

To ensure idempotency in Packer, it is important to use the only and except parameters in the provisioner block. The only and except parameters allow you to specify the conditions under which a provisioner should run, such as the operating system or the type of machine image being built. Using these parameters ensures that Packer will only run a provisioner if the specified conditions are met.

Naming standards are another important aspect of working with Packer in a busy DevOps team. It is a good idea to use consistent naming conventions for Packer templates and variables to make the codebase easier to read and understand.

Code Examples

Here is an example of a Packer template that follows a consistent naming convention:

{
  "variables": {
    "aws_access_key": "{{env `AWS_ACCESS_KEY_ID`}}",
    "aws_secret_key": "{{env `AWS_SECRET_ACCESS_KEY`}}",
    "aws_region": "us-east-1"
  },
  "builders": [
    {
      "type": "amazon-ebs",
      "access_key": "{{aws_access_key}}",
      "secret_key": "{{aws_secret_key}}",
      "region": "{{aws_region}}",
      "source_ami": "ami-0f2176987ee50226e",
      "instance_type": "t2.micro",
      "ssh_username": "ec2-user",
      "ami_name": "packer-example {{timestamp}}"
    }
  ],
  "provisioners": [
    {
      "type": "shell",
      "inline": [
        "sudo yum update -y",
        "sudo yum install -y nginx"
      ]
    }
  ]
}

In this example, the variables are named aws_access_key, aws_secret_key, and aws_region, and the Packer template is named packer-template.json.

Organizing Packer Code in a Git Repo

When working with Packer in a busy DevOps team, it is important to organize the codebase in a way that is maintainable and easy to work with. One way to do this is to split the Packer code into different files and directories within a git repository.

One way to organize the Packer code is to separate the provisioners, builders, and variables into different files. This can make it easier to find and modify specific parts of the codebase. For example, you could create a provisioners directory to store all of the provisioner scripts, a builders directory to store the Packer templates, and a variables directory to store the variable definitions.

It is also important to consider security when organizing the Packer code in a git repository. Sensitive information such as access keys and secrets should not be stored in the repository in plaintext. Instead, you can use tools such as Hashicorp’s Vault to securely store and manage sensitive information.

Template README.md for a Packer Repo:

# Packer Repository

This repository contains Packer templates and scripts for building machine images.

## Directory Structure

The repository is organized as follows:

- `builders`: Packer templates for building machine images
- `provisioners`: Scripts for provisioning machine images
- `variables`: Variable definitions for Packer templates

## Usage

To build a machine image using a Packer template, run the following command:

```bash
packer build -var-file=variables/example.json builders/example.json
```

Replace example.json with the appropriate file names for your build.

## Contributing

To contribute to this repository, follow these steps:

+ Fork the repository
+ Create a new branch for your changes
+ Make your changes and commit them to the new branch
+ Push the branch to your fork
+ Create a pull request from your fork to the main repository

Please make sure to follow the repository's style guidelines and to run any relevant tests before submitting a pull request.

## License

This repository is licensed under the MIT License.

## Template HCL file with Headers Summarized:

## Packer Template

This Packer template is used to build a machine image.

### Builders

The following builders are used in this template:

 + Amazon Elastic Block Store (EBS)

### Provisioners

The following provisioners are used in this template:

 + Shell

### Variables

The following variables are used in this template:

+ `aws_access_key: AWS access key`
+ `aws_secret_key: AWS secret key`
+ `aws_region: AWS region`

### Usage

To build a machine image using this Packer template, run the following command:

```bash
packer build -var-file=variables/example.json template.json
```

Replace example.json with the appropriate file name for your variables.

### Contributing

To contribute to this Packer template, follow these steps:

+ Fork the repository
+ Create a new branch for your changes
+ Make your changes and commit them to the new branch
+ Push the branch to your fork
+ Create a pull request from your

Conclusion

By following best practices such as ensuring idempotency and using consistent naming conventions, and organizing Packer code in a git repository in a structured and secure way, DevOps teams can effectively work with Packer to automate the creation of machine images. By following these guidelines, teams can ensure that their codebase is maintainable and easy to work with, enabling them to deliver new features and updates more efficiently.

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Getting Started with Python

This entry is part 4 of 5 in the series Learning Ansible

Synopsis

This guide provides a quick introduction to Python for new developers. It covers the basics of installing and configuring Python, including creating and activating virtual environments. It also covers some best practices for working with Python, including naming conventions and using virtual environments to maintain a consistent environment.

Introduction

Python is a popular programming language known for its simplicity, readability, and flexibility. It is used for a wide range of tasks, including web development, data analysis, and automation. In this guide, we’ll cover the basics of installing and configuring Python so you can get started using it in your own projects.

Best Practices

When working with Python, it’s important to follow some best practices to ensure your code is easy to read, maintain, and debug. Here are a few tips to keep in mind:

  • Use descriptive, snake_case names for files, functions, classes, and variables.
  • Use comments to explain what your code is doing.
  • Keep lines of code to a maximum of 79 characters to make them easier to read.
  • Use whitespace to separate logical blocks of code.
  • Use docstrings to document your functions and classes.

Installation

To install Python on your machine, you can use the following commands:

mkdir -p $HOME/projects/webapp
cd $HOME/projects/webapp
sudo apt update
sudo apt install python3 python3-pip python3-virtualenv

These commands will create a new directory for your projects, navigate to that directory, update your package manager, and install the latest versions of Python, pip, and virtualenv.

Configuration

One of the benefits of using Python is the ability to create and activate virtual environments. A virtual environment is an isolated environment that contains a specific version of Python and its dependencies. This can be useful for keeping your main Python installation clean and for developing multiple projects with different requirements.

To create and activate a new virtual environment, use the following commands:

virtualenv venv
source venv/bin/activate

To install and configure the necessary dependencies for your Python project, you can use the following commands:

pip3 install ansible==2.9.7
pip3 install pre-commit
pip3 install jinja2

These commands will install the specified versions of ansible, pre-commit, and jinja2 in your virtual environment.

You can view a list of all the packages installed in your virtual environment by using the following command:

pip3 freeze

This is useful for creating a requirements.txt file for your project, which lists all the necessary dependencies.

To deactivate your virtual environment, use the following command:

deactivate

It is not necessary for everyone to use virtual environments, but they can be helpful tools for maintaining a consistent environment and isolating different projects from each other.

Conclusion

In this guide, we covered the basics of installing and configuring Python, including creating and activating virtual environments. We also covered some best practices for working with Python, including naming conventions and using virtual environments to maintain a consistent environment. With this foundation, you should be ready to start using Python in your own projects.

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Setting Up Git with GitHub

This entry is part 3 of 5 in the series Learning Ansible

This article provides a guide for setting up Git on a machine and linking it to a GitHub account. It covers the installation of Git, the generation of SSH keys, and the addition of the public key to a GitHub account. The article also includes instructions for creating a test repository on GitHub and pushing a change to it.

Introduction

It is important to set up a version control system like Git to help you track and manage your code changes. Git is a popular choice for version control and is widely used by developers and organizations around the world. In this guide, we’ll walk you through the steps of installing Git on your machine and setting it up to work with your GitHub account.

Prerequisites

Before you can set up Git, you’ll need to have the following:

  • A GitHub account (sign up for one at github.com)
  • The Windows Subsystem for Linux (WSL) with the Ubuntu 20.04 distribution is installed on your machine.

Install Git

To install Git on your machine, open a terminal or command prompt and type the following command:

sudo apt-get install git

This will install Git on your machine. You may be prompted to enter your password to complete the installation.

Configuration

Once Git is installed, you’ll need to configure it with your username and email address. This will help Git identify you as the author of any changes you make to your code. To set your username and email, type the following commands in your terminal or command prompt:

git config --global user.name "Your Name"
git config --global user.email "youremail@domain.com"

Set Up SSH Keys

In order to securely connect to your GitHub repository from your local machine, you’ll need to set up Secure Shell (SSH) keys. SSH keys are a pair of unique cryptographic keys that are used to authenticate your connection to GitHub.

  1. In your terminal or command prompt, type the following command to generate an SSH key:
ssh-keygen -t ed25519 -C "youremail@example.com"
  1. Press Enter to accept the default file location for the key.
  2. Type a passphrase for your SSH key and press Enter. Make sure to choose a strong, unique passphrase that you will remember.
  3. Type the passphrase again to confirm it and press Enter.
  4. Type the following command to view your public key:
cat ~/.ssh/id_ed25519.pub
  1. Select and copy the entire output.
  2. Go to your GitHub account settings and click on the “SSH and GPG keys” tab.
  3. Click on the “New SSH key” button.
  4. Type a name for your key in the “Title” field (e.g. “My local machine”).
  5. Paste your public key into the “Key” field.
  6. Click on the “Add SSH key” button.

Test Your Connection

To test your connection to GitHub, type the following command in your terminal or command prompt:

ssh -T git@github.com

If you are prompted to “continue connecting,” type “yes” and press Enter. If your connection is successful, you should see a message saying “Hi username! You’ve successfully authenticated, but GitHub does not provide shell access.”

Create a Test Repository

Now that you have Git and SSH set up, you can create a test repository on GitHub and push a change to it.

  1. In the GitHub web interface, create a new repository by clicking on the “New” button in the top-right corner of the page.
  2. Type a name for your repository and click on the “Create repository” button.
  3. Follow the instructions provided by GitHub to push a change to your repository.

The following steps walk through an example of creating a repository and pushing an update over to GitHub

  1. In the terminal or command prompt, navigate to the directory where you want to create your repository.
  2. Type the following commands to initialize your repository, add a file, and commit your changes:
# Initialize the repository
git init

# Add a file to the repository
echo "# test" >> README.md

# Add the file to the staging area
git add README.md

# Commit the file to the repository
git commit -m "first commit"
  1. Type the following command to create a main branch for your repository:
git branch -M main
  1. Type the following command to link your repository to the one you created on GitHub:
git remote add origin git@github.com:adamfordyce11/test.git
  1. Type the following command to push your changes to the main branch of your repository on GitHub:
git push -u origin main

This will push your changes to the main branch of your repository on GitHub. You can verify that the changes were successful by checking the repository on the GitHub web interface.

Conclusion

Congratulations! You have successfully set up Git and linked it to your GitHub account. You are now ready to track and manage your code changes with Git. Make sure to keep your private SSH key and passphrase secure, as anyone with access to them will be able to access your repositories.

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Setting Up Visual Studio Code (VSCode)

This entry is part 1 of 5 in the series Learning Ansible

This article explains how to install and configure Visual Studio Code (VSCode) on a machine. It discusses some of the features that make VSCode a useful tool for ansible practitioners, such as excellent git integration and support for various programming languages. The article also provides a list of recommended extensions to install in order to optimize the development environment for working with ansible and other tools. The article also mentions the special relationship between VSCode and GitHub, which allows users to open their GitHub projects in a web-based version of the editor.

Prerequisites

Before setting up VSCode, make sure that you have already set up WSL and installed the Ubuntu 20.04 distribution.

Introduction

Visual Studio Code (VSCode) is a popular text editor that offers many useful features for developers. Some of the features that are particularly useful for Ansible practitioners include:

  • Excellent git integration
  • GitHub integration
  • YAML support
  • Python support
  • Integration with WSL/WSL2
  • Built-in terminal

Additionally, GitHub has a special relationship with VSCode that allows you to open any of your GitHub projects in a web-based version of the editor simply by replacing the “www” in the GitHub URL with “dev”. This is a convenient feature that allows you to develop on devices such as iPads and Android tablets that may not have native VSCode support.

Installation

If you do not already have VSCode installed on your machine, you can download the latest version from the following website:

code.visualstudio.com

Run the installer and follow the prompts, accepting the default options.

Configuration

Once VSCode is installed, you can install the following extensions to enhance your development environment:

  • Remote WSL
  • YAML
  • Prettier
  • Ansible
  • Jinja2

For more information on setting up VSCode to work with WSL, see Get started using Visual Studio Code with WSL.

Conclusion

By following the steps outlined in this guide, you should now have VSCode installed and configured on your machine. You should also have the necessary extensions installed to optimize your development environment for working with ansible and other tools. VSCode’s integration with WSL and its various features for working with git and GitHub make it a valuable tool for any ansible practitioner.

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