Continuous Delivery is a software methodology where the code is build, test and deploy automatically and ready to release on production. Its an integral part of DevOps. Continuous delivery ensures that whenever a release goes to any environment, proper test suites are run to test the application. Only if the test cases are passed successfully then only deployment is done on the production environment. With the implementation of the continuous delivery we can deploy the application at a faster pace. We can even automate the whole process so that there is no downtime and outages when the deployment goes on.
The goal of Continuous delivery is to deliver the continuous changes in the application on the different environments. Continuous delivery provides the instant feedbacks to various software teams so that they will respond to market demands and resolve problems quickly. Continuous Delivery enables the launching of new functionalities and features that are better than previous version of application, therefore gradually refining and incorporating the continuous delivery principle throughout the organization.
Best Practices to achieve Continuous Delivery:
The Biggest challenge to achieve Continuous Delivery is to find out the effective way of doing build, test and deploy on the various environments in a shortest and simplest way. This can be done in two steps — creating a Build Pipeline and then create a Delivery Pipeline.
Build Pipeline: In the build pipeline we are creating the build for the application and deploy it on one environment. Build pipeline is divided in the various stages. On every stage one important part of the pipeline is done.
- Stage 1 → Pull the code from the Code Repo. It may be from Bitbucket, Github etc. These are the Version Control Systems (VCS) where a group of team members writes codes on the same of different area of the projects concurrently. It also tracks all the changes and therefore very easy to find the changes. Stage 1 pulls the code from VCS whenever there is a code change.
- Stage 2 → Second stage consists of the unit test cases which is used to check that whether new code is satisfying all the requirements and should not conflict with the previous codes.
- Stage 3 → Third stage is the build automator step. When the test cases are passed then it’s time to create the executable by compiling, linking & binding the code and packages. There are various tools in the market for the building like MAVEN, ANT, GRADLE for the java based projects. For Node based projects we have Yarn, NPM etc.
- Stage 4 → It is very important to follow certain style and procedures of coding for the projects. In the stage 4 we will make the code analysis to detect and find the quality of code in order to find potential errors or poor coding style and practices. There are various code analysis tools which use a collection of algorithms and techniques to analyze the source code. SONARQUBE is open source tool for the continuous inspection of the code.
- Stage 5 → Fifth stage is all about the deployment. We can use various tools so that deployment is done on the various servers at the same time. Tools like Ansible unites the workflow orchestration with provisioning, configuration management and application deployment.
Delivery Pipeline: After the deployment is done on one environment, We can test the application by deploying it on the various environments and tests it gradually. Once the deployment is successful on the various environment then only we deploy on the production environment.