## GitOps continuous integration

You will also learn about different promotion strategies and how to revert, reset, or roll back application changes.


PREBUILD STAGES

*Vulnerability scan*: Integrating an open source library scanning tool like Nexus Vulnerability Scanner can detect known vulnerabilities and licensing issues.

*Code analysis*: an automated linting or code analysis .

BUILD STAGES

*Unit test*: verify a small piece of code doing what it is supposed to do.

*Code coverage*: measure the percentage of code that is covered by automated unit tests.

*Docker build and push*: build container image and push to registry.

GITOPS CI STAGES

POSTBUILD STAGES

*Publish CI metrics*: build issues, CI build time, compliance requirements (build information such as test results, who did the release).

*Build notification*: send noti


QUESTION

If the CI/CD pipeline typically takes an hour to run, what other tasks can developers do during that time? What if the CI/CD pipeline takes 10 minutes instead?

## GitOps continuous delivery


The boxes in gray are new stages for a complete CD solution (depending on your company).

GITOPS CD STAGES

*Git clone config repo*

*Discover manifests*: determines any delta between the manifests in Kubernetes versus the latest manifests from Git repo. If there is no difference, the GitOps operator stops at this point.

*Kubectl apply*

POSTDEPLOYMENT STAGES

*Tests*

*Run-time vulnerability*: also called pen testing or ethical hacking.

*Publish CD metrics*: run-time issues, compliance requirements.

## Rollback
Since our production environment consists of the manifest and the application configuration for the environment, the rollback process could roll back the app config, manifest, or both repos.

With GitOps, our rollback process is once again controlled by Git changes, and the GitOps operator will take care of the eventual deployment. Git Revert and Git Reset are two ways to roll back changes in Git.


For example of a rollback pipeline. This pipeline will start with `git revert` and `git commit` to roll back the manifest to the previously known good state. After a pull request is generated from the `revert` commit, approver(s) can approve and merge the PR to the manifest master branch.


git log --pretty=oneline

eb1a692029a9f4e4ae65de8c11135c56ff235722 (HEAD -> master) guestbook with image hash <HASH>

git revert eb1a692029a9f4e4ae65de8c11135c56ff235722

Now we are ready to push the revert of the manifest by pushing back to the repo and let the GitOps operator do its deployment.

git push https://<GIT_USERNAME>:<GIT_PASSWORD>@<your repo> master

## Compliance pipeline
A compliance pipeline essentially needs to ensure second-person approval for production release and record by whom, when, and what gets released.


When the approver wants to release a particular image to production, he/she can simply approve the respective PR and the Prod environment will be updated by the GitOps operator.


## Deployment strategies
Argo Rollout:
+ Blue-green
+ Canary
+ Progressive delivery

Progressive delivery can also be viewed as a fully automated version of canary deployment. Argo Rollouts uses the canary strategy along with *AnalysisTemplate* to achieve progressive delivery.


We need to create the *AnalysisTemplate* for Rollout to collect metrics and determine the health of the Pods.

apiVersion: argoproj.io/v1alpha1
kind: AnalysisTemplate
metadata:
  name: pass
spec:
  metrics:
  - name: pass
    interval: 15s
    failureLimit: 1
    provider:
      job:
        spec:
          template:
            spec:
              containers:
              - name: sleep
                image: alpine:3.8
                command: ... # command here
                args: ... # arg here
              restartPolicy: Never
          backoffLimit: 0

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: demo
spec:
  replicas: 3
  revisionHistoryLimit: 1
  selector:
    matchLabels:
      app: demo
  strategy:
    canary:
      analysis:
        templateName: pass ## Specifies the AnalysisTemplate
      steps:
      - setWeight: 10
      - pause:
          duration: 20      
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - image: argoproj/rollouts-demo:blue
        imagePullPolicy: Always
        name: demo
        ports:
        - containerPort: 8080