Fabric2 Example

Example of how you can organize a set of fabric2 scripts. Mostly this is just how I organized my fabric build and release process and sharing to possibly help other folks get started.

Note: You should use Ansible + Ansistrano or Terraform if you need more support.

We want to use fabric2 to be able to handle the deprecation of Python 2.x. It will get harder and harder to install python 2.x into newer systems so we need to upgrade to be able to use Python 3.x that is now the default.

Old fabric 1.x example is here https://github.com/chrisgo/fabric-example

• Fabric: http://fabfile.org
• Fabric Docs: https://docs.fabfile.org/en/2.6/

This example using Python 3.x 100%. We are NOT doing any of the upgrades as described in the documentation.

• NOT "side-grading"
• NOT running 2 version of fabric simultaneously
• NOT using config objects from v1

On a Mac, you will need to run source ~/venv-fabric2/bin/activate on each terminal you start, see Mac Setup

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Mostly I deal with a standard LEMP stack (Linux, Nginx, MySQL and PHP-fpm) on Debian so please adapt for your own use. The original goal was to deal with Vagrant and Linode or Amazon AWS but I ended up just implementing Vagrant and DigitalOcean as "deployment targets". Currently, this example is for Debian 10 (bullseye)

These scripts should be run in the directory where the fabfile directory lives.
If you do an ls, you should see the directory called "fabfile"

Goals

1. Build servers quickly based on:

   • Environments => developer, dev, qa, stage, production
   • Roles => www, database, resque, balance

2. Normalize all the different cloud providers

   • Providers => digitalocean, ec2, linode, vagrant

3. Be able to customize each project while sharing core fabric files

   • Core: init.py, roles/, packages/ and providers/ folders
   • Per project: environments/ folder

Usage

fab <environment> <branch> release    # Release code
fab <environment> <role> <task>       # Builds servers

Examples:

fab dev master release                # standard release to dev
fab local --user=chris www release    # standard release to chris (developer)

fab dev www normalize                 # step 1 (normalize providers + basic)
fab dev www server                    # step 2 (server role specific)
fab dev www project                   # step 3 (project specific)

New Projects

1. Check project/init.py to make sure all project-specific settings are correct
2. Check environments/*.py to make sure all the servers are correct

New Hosts (Servers)

For new servers (new file environments), we need to do some setup:

• Create the appropriate settings for the system, usually this is for a new developer or a new server starting from scratch
• Make sure to note down the provider (Vagrant, Linode, etc.)
• Make sure this is unique across everything ever created for this project
• The fabric system will pick up the settings for that environment

Run through steps 1-3

1. fab normalize

• Normalizes each provider (Vagrant, Linode, etc)
• Installs basic setup for ALL servers

2. fab server

• Installs more software by server role

3. fab project

• Installs project-specific software by server role
• Also initializes the project on the server by server role

For normal releases to an environment (for example: dev), run

fab dev www release

and for PRODUCTION, run it with a group argument

fab production www release

Mac Setup

The easiest way to get your Mac setup is to use homebrew and venv.

• Install zsh https://github.com/ohmyzsh/ohmyzsh
  • sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"
  • In theory, this is recommended on MacOS as it adds some features on top of the default bash shell
• Install homebrew https://brew.sh/
• Install python3 using Homebrew
  • brew install python - this should install python 3.9.x (3.9.7)
• Use python3 to create a venv in a folder outside of the repository
  • https://towardsdatascience.com/virtual-environments-104c62d48c54
  • Note: venv needs to be activated on each terminal you start
  • To create your python3 virtual environment to run fabric2, run the following:
  • python3 -m venv ~/venv-fabric2 => creates this in your home directory
  • source ~/venv-fabric2/bin/activate => activates in current terminal
  • python -V => should say Python 3.9.x
• Install fabric
  • On the same terminal as above
  • pip install fabric => installs python3.x fab in ~/venv-fabric2/bin

TODO

• Create custom (own own) Connection that extends fabric2 Connection
  • This allows us to create more functions without passing c all over
• Move custom Connection object into core/connection.py
• Move packages/util.py into here into core/util.py
• Replace string manipulation with python f-strings
  • https://realpython.com/python-f-strings/
  • https://stackoverflow.com/questions/42097052/can-i-import-pythons-3-6s-formatted-string-literals-f-strings-into-older-3-x (see pip install future-fstrings above)
• Make the main init.py script have less code by moving code into core/*
  • Global config object hard to pass into a class outside main init.py
• Dashes for task names vs underscore for function name
  • http://docs.pyinvoke.org/en/stable/concepts/namespaces.html#dashes-vs-underscores

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Fabric2 Changes

• (1) Fabric2 is now broken into 3 distinct libraries
  • Fabric: https://www.fabfile.org/
  • Invoke: http://www.pyinvoke.org/
  • Patchwork: https://fabric-patchwork.readthedocs.io/en/latest/index.html
• (2) Might have to install more python libraries using pip (may need sudo)
  • pip install invoke
  • pip install patchwork
  • pip install colorama
  • IMPORTANT If by installing one of the libraries above, it ends up install fabric2 into you fab command (if you type fab --version, it shows Fabric 2.6.x), you can downgrade back to original fabric by typing pip install 'fabric<2.0' or a specific version like pip install fabric==1.14.1. Then type fab --version again and it should show that you are back to version 1.14.1
• (3) Fabtools no longer work
  • https://github.com/fabtools/fabtools
  • We are porting some of these over inside core/fatools/*
• (4) no more import *
  • from environments import * no longer works