Methodology

"We used to design infrastructures that support applications. We are now developing new applications that support the cloud platforms".

• Think of devops as a workflow of tools.
• Make sure the tools are loosely coupled so they can be changed easily.

Devops consists of 2 parts: infrastructure as code, and deployment pipelines.

INFRASTRUCTURE AS CODE CONSISTS OF 2 PARTS

• Orchestrating the Infrastructure (ie defining network, security etc) - Terraform is a good choice. Build it in layers.
• Configuring Individual Servers. are you going to do immutable or mutable? use packer? use docker containers? use a config tool like Ansible, chef, puppet or salt?
• Both of these need to be stored in Git Repositories. I would start simply with a develop and master branch.

DEPLOYMENT PIPELINES

• Typically devs use a CI tool like Jenkins to create their pipelines.
• What is the deployable artifact? - zip file, jar file, or docker container.
• Where will the artifact be stored? - S3, Artifactory, Dockerhub.
• What is the version number strategy for the deployable artifact? - it should end in a build number that increments each build.
• The output of the build stage of pipeline is a deployable artifact.
• Other stages in the pipelines take the artifact through test, qa, uat and production.
• Use a git branch strategy and feature branches named after JIRA tickets.
• Use a git tagging strategy to drive the pipeline.

References
    A Plea for Idempotence and Immutability
    Code wise cloud foolish avoiding bad technology choices