Module 3.1: What is GitOps?

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Discipline Module | Complexity: [MEDIUM] | Time: 30-35 min

Prerequisites

Before starting this module:

Required: Systems Thinking Track — Understanding feedback loops
Required: Basic Git knowledge (branches, commits, pull requests)
Recommended: Kubernetes Basics — Pod, Deployment, Service concepts
Helpful: Experience with CI/CD pipelines

What You’ll Be Able to Do

After completing this module, you will be able to:

Evaluate whether GitOps principles apply to your deployment workflows and infrastructure management
Design a GitOps architecture with clear separation between application and configuration repositories
Implement a basic GitOps workflow using Flux or Argo CD with automated reconciliation
Analyze the operational benefits and trade-offs of GitOps compared to traditional CI/CD push models

Why This Module Matters

You’ve built a great CI/CD pipeline. Code gets tested, images get built, deployments happen automatically.

Then someone runs kubectl apply directly in production. Your Git repo and production are now out of sync. Which one is “right”?

This is the problem GitOps solves.

GitOps makes Git the single source of truth for your infrastructure. Not your CI/CD tool. Not someone’s terminal. Git.

After this module, you’ll understand:

Why GitOps emerged and what problems it solves
The four core principles of GitOps
How GitOps differs from traditional CI/CD
When GitOps is (and isn’t) the right approach

The Origin Story

2017: Weaveworks’ Challenge

Weaveworks was running Kubernetes clusters at scale. They had a problem:

Traditional deployment workflow:

Developer → CI/CD Pipeline → kubectl apply → Cluster

This worked, but:

CI/CD systems had production credentials
Hard to know what’s actually deployed
Manual changes bypassed the pipeline
No easy way to recover from disasters

Their insight: What if the cluster continuously pulled its desired state from Git, instead of being pushed to?

They called this approach GitOps.

“GitOps is a way of implementing Continuous Deployment for cloud native applications.” — Weaveworks, 2017

The Evolution: From Blog Post to Industry Standard

The history of GitOps follows a clear arc:

2017: Alexis Richardson (Weaveworks CEO) publishes “GitOps - Operations by Pull Request,” coining the term. The core idea: combine Infrastructure as Code with pull-based delivery, using Git as the single source of truth.
2018-2020: Flux and ArgoCD emerge as the dominant GitOps operators. The community debates what “counts” as GitOps versus just “using Git for config.”
2021: The CNCF forms the OpenGitOps working group to create a vendor-neutral definition. This was critical because “GitOps” was becoming a marketing buzzword applied to any tool that touched Git.
2021: OpenGitOps publishes the four core principles (below), giving the community a clear standard. GitOps becomes a CNCF Sandbox project.
2023+: GitOps matures beyond Kubernetes. Teams apply the principles to infrastructure (Terraform + GitOps), databases, and even network configuration.

The key insight that made GitOps stick: it wasn’t just “store config in Git” (people had done that for years). It was the pull model with continuous reconciliation that made it fundamentally different from traditional CI/CD.

The Four GitOps Principles

From OpenGitOps.dev:

Principle 1: Declarative

“A system managed by GitOps must have its desired state expressed declaratively.”

What this means:

Describe what you want, not how to get there
YAML manifests, not shell scripts
The end state, not the steps

# Declarative (GitOps)
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  template:
    spec:
      containers:
        - name: app
          image: my-app:v1.2.3

# Imperative (NOT GitOps)
kubectl scale deployment my-app --replicas=3
kubectl set image deployment/my-app app=my-app:v1.2.3

Principle 2: Versioned and Immutable

“Desired state is stored in a way that enforces immutability, versioning and retains a complete version history.”

What this means:

Git as the storage system
Every change is a commit
Full audit trail
Easy rollback (git revert)

commit abc123: Update replicas to 5
commit def456: Update image to v1.2.4
commit ghi789: Add resource limits
commit jkl012: Rollback to v1.2.3  ← Easy!

Principle 3: Pulled Automatically

“Software agents automatically pull the desired state declarations from the source.”

What this means:

Agents in the cluster pull from Git
No push access needed to cluster
Continuous reconciliation
Cluster pulls what it needs

┌─────────────┐         ┌─────────────┐
│    Git      │ ◀────── │   Agent     │
│  (Source)   │  pulls  │ (in cluster)│
└─────────────┘         └─────────────┘
                              │
                              ▼
                        ┌─────────────┐
                        │  Cluster    │
                        │  Resources  │
                        └─────────────┘

Principle 4: Continuously Reconciled

“Software agents continuously observe actual system state and attempt to apply the desired state.”

What this means:

Agents compare desired vs actual state
Differences trigger reconciliation
Self-healing: drift is automatically corrected
Constant loop, not one-time action

         ┌──────────────────────────────────┐
         │                                  │
         ▼                                  │
   ┌──────────┐    Compare    ┌──────────┐  │
   │ Desired  │ ────────────▶ │  Actual  │  │
   │  State   │               │  State   │  │
   │  (Git)   │               │(Cluster) │  │
   └──────────┘               └──────────┘  │
                                   │        │
                         If different       │
                                   │        │
                                   ▼        │
                            ┌──────────┐    │
                            │  Apply   │ ───┘
                            │  Changes │
                            └──────────┘

Try This: GitOps Mental Model

Think about a service you manage. Answer these questions:

1. Where is the desired state defined?
   [ ] Git repo (declarative YAML)
   [ ] CI/CD pipeline scripts
   [ ] Someone's local machine
   [ ] It's... complicated

2. If I delete a pod manually, what happens?
   [ ] Agent recreates it from Git (GitOps)
   [ ] Nothing until next deploy
   [ ] Depends on who's watching

3. How do you know what's deployed in production?
   [ ] Check the Git repo
   [ ] Run kubectl commands
   [ ] Ask the last person who deployed
   [ ] Hope for the best

GitOps answers should be: Git repo, Agent recreates it, Check Git repo.

Pull vs Push: The Key Difference

Traditional CI/CD (Push Model)

┌──────┐    ┌────────┐    ┌─────────┐    ┌─────────┐
│ Dev  │───▶│   CI   │───▶│   CD    │───▶│ Cluster │
│      │    │ Build  │    │ Deploy  │    │         │
└──────┘    └────────┘    └─────────┘    └─────────┘
                               │
                          Has creds
                          to push

How it works:

Developer pushes code
CI builds and tests
CD has cluster credentials
CD pushes changes to cluster

Problems:

CD system needs cluster credentials
Credentials outside the cluster = attack surface
One-time push, no continuous reconciliation
Drift can occur between pushes

GitOps (Pull Model)

┌──────┐    ┌────────┐    ┌─────────┐
│ Dev  │───▶│   CI   │───▶│   Git   │
│      │    │ Build  │    │  Repo   │
└──────┘    └────────┘    └────┬────┘
                               │
                          Is pulled by
                               │
                               ▼
                         ┌─────────┐
                         │  Agent  │
                         │(in-cluster)│
                         └────┬────┘
                              │
                         Applies to
                              │
                              ▼
                         ┌─────────┐
                         │ Cluster │
                         └─────────┘

How it works:

Developer pushes code
CI builds, tests, pushes image, updates Git
Agent in cluster pulls from Git
Agent applies changes to cluster

Benefits:

No external system has cluster credentials
Agent only needs read access to Git
Continuous reconciliation (self-healing)
Git is always the truth

Did You Know?

The term “GitOps” was coined by Alexis Richardson (Weaveworks CEO) in a 2017 blog post. He was trying to describe how Weaveworks operated their own infrastructure.
GitOps isn’t Git-specific. While Git is the most common, the principles work with any version control system that provides immutability and history. Some teams use OCI registries for config storage.
Google’s Borg (Kubernetes’ predecessor) used a similar pattern — a central config system with continuous reconciliation — long before GitOps was named.
The OpenGitOps project became a CNCF Sandbox project in 2021, establishing GitOps as an industry-standard practice with formal principles rather than just a marketing term.

War Story: The Deployment That Fixed Itself

A company I worked with had just adopted GitOps with ArgoCD.

The Incident:

Friday afternoon. A developer was debugging a production issue. In desperation, they ran:

kubectl scale deployment api-server --replicas=10

The extra replicas helped temporarily. Developer went home for the weekend.

What Happened Next (Old World):

In the old CI/CD world, those 10 replicas would stay until someone noticed and asked “why do we have 10 replicas?” Probably Monday. Maybe never.

What Happened Next (GitOps World):

Within 3 minutes:

ArgoCD detected drift: Git said 3 replicas, cluster had 10
ArgoCD reconciled: scaled back to 3 replicas
Alert fired: “Deployment modified outside GitOps”

The developer got a Slack notification. They realized they needed to:

Fix the actual problem (not just scale)
If scaling was needed, do it through Git

The Lesson:

GitOps didn’t prevent the manual change — but it detected it immediately and corrected it automatically. The cluster state always matched Git.

Bonus: The audit trail showed exactly when the manual change happened, who the ArgoCD alert notified, and when it was corrected.

GitOps vs CI/CD

GitOps and CI/CD aren’t opposites — they’re complementary.

What CI Does

Build code
Run tests
Create artifacts (images, packages)
Scan for vulnerabilities

What CD Does (Traditional)

Deploy artifacts to environments
Manage credentials
Execute deployment scripts

What GitOps Does

Store desired state in Git
Continuously reconcile cluster to match Git
Detect and fix drift
Provide audit trail

The Combined Model

┌───────────────────────────────────────────────────────┐
│                         CI                             │
│  Code → Build → Test → Image → Push to Registry        │
└───────────────────────────┬───────────────────────────┘
                            │
                            ▼
                    Update image tag in Git
                            │
                            ▼
┌───────────────────────────────────────────────────────┐
│                       GitOps                           │
│  Git Repo ← Agent → Reconcile → Cluster                │
└───────────────────────────────────────────────────────┘

CI builds. GitOps deploys.

When GitOps Works Best

Good Fit

Scenario	Why GitOps Helps
Kubernetes workloads	Native YAML, reconciliation-friendly
Multiple environments	Same process, different configs
Compliance requirements	Built-in audit trail
Team collaboration	PRs for infrastructure changes
Disaster recovery	Redeploy from Git
Multi-cluster	Single source of truth

Less Good Fit

Scenario	Challenge
Stateful systems	State in cluster != state in Git
Real-time config	Git commit latency
Legacy systems	May not be declarative
Secrets (naively)	Can’t store plaintext in Git
One-off scripts	Imperative by nature

The Hybrid Reality

Most organizations use GitOps for:

Kubernetes manifests
Infrastructure as Code
Configuration management

But keep traditional approaches for:

Secrets management (with integration)
Stateful operations
Emergency fixes (then sync to Git)

GitOps Tooling Landscape

Several tools implement GitOps principles:

Flux

CNCF graduated project
Kubernetes-native
Composable toolkit
Git + Helm + Kustomize support

ArgoCD

CNCF incubating project
Web UI included
Application-centric model
Popular in enterprises

Others

Rancher Fleet: Multi-cluster focus
Jenkins X: Full CI/CD + GitOps
Werf: Integrated CI/CD
Codefresh: Commercial GitOps platform

We’ll explore specific tools in the GitOps Tools Toolkit.

Common Mistakes

Mistake	Problem	Solution
Storing secrets in Git	Security breach	Use Sealed Secrets, External Secrets, or SOPS
Push model labeled “GitOps”	Missing reconciliation benefits	True GitOps is pull-based with continuous reconciliation
Manual kubectl “just this once”	Drift, confusion	All changes through Git, enforce with policies
No drift detection alerts	Don’t know when drift occurs	Configure alerts for reconciliation failures
Giant monorepo	Slow sync, coupling	Consider repo structure carefully
Branch-per-environment	Merge conflicts, confusion	Directory-per-environment preferred

Quiz: Check Your Understanding

Question 1

What makes GitOps different from traditional CI/CD deployment?

Show Answer

Key differences:

Pull vs Push: GitOps agents pull from Git; traditional CD pushes to cluster
Continuous reconciliation: GitOps constantly syncs, not just at deploy time
Self-healing: Drift is automatically corrected
Credentials location: Agent in cluster vs CD system outside cluster

Traditional CI/CD can be part of GitOps (for building), but deployment works differently.

Question 2

Someone manually runs kubectl delete pod my-app-xyz in a GitOps-managed cluster. What should happen?

Show Answer

Kubernetes recreates the pod (from the Deployment controller)
GitOps agent detects this is consistent with desired state (still 3 replicas)
No action needed — the Deployment still matches Git

However, if someone ran kubectl scale deployment my-app --replicas=10:

Kubernetes would scale to 10
GitOps agent would detect drift (Git says 3, cluster has 10)
Agent would scale back to 3
Alert would fire (drift detected)

GitOps manages the Deployment spec, not individual pods.

Question 3

Why is “Git as source of truth” valuable for disaster recovery?

Show Answer

If you lose a cluster entirely:

Spin up new cluster
Install GitOps agent
Point agent at Git repo
Agent recreates everything

No need to:

Remember what was deployed
Find old CI/CD logs
Hope someone documented it
Restore from cluster backups

The entire desired state is in Git. The agent rebuilds the cluster to match.

This also works for:

Cluster migrations
Multi-region deployments
Compliance audits (prove what’s deployed)

Question 4

Which GitOps principle addresses security concerns about deployment credentials?

Show Answer

Principle 3: Pulled Automatically

“Software agents automatically pull the desired state declarations from the source.”

This means:

The agent lives inside the cluster
The agent only needs read access to Git
No external system has write access to the cluster
Cluster credentials stay inside the cluster

Compare to traditional CD:

CD system outside cluster
CD needs write credentials to cluster
Credentials stored in CI/CD platform
Larger attack surface

Hands-On Exercise: GitOps Readiness Assessment

Evaluate your current deployment process against GitOps principles.

Part 1: Current State Assessment

For a service you manage, answer:

## Service: _________________

### Principle 1: Declarative
- Is the desired state in declarative YAML/config? [ ] Yes [ ] Partial [ ] No
- Are there imperative scripts in the deploy process? [ ] Yes [ ] No
- Could someone recreate the deployment from config alone? [ ] Yes [ ] No

Declarative Score: ___/3

### Principle 2: Versioned and Immutable
- Is the config in Git? [ ] Yes [ ] Partial [ ] No
- Is every change a commit? [ ] Yes [ ] No
- Can you see full change history? [ ] Yes [ ] No

Versioned Score: ___/3

### Principle 3: Pulled Automatically
- Does an agent pull from Git? [ ] Yes [ ] No
- Or does CI/CD push to cluster? [ ] Push [ ] Pull
- Who has cluster credentials? [ ] Only in-cluster [ ] External systems

Pull Model Score: ___/3

### Principle 4: Continuously Reconciled
- Is there continuous sync? [ ] Yes [ ] No (only at deploy)
- Is drift detected automatically? [ ] Yes [ ] No
- Is drift corrected automatically? [ ] Yes [ ] No

Reconciliation Score: ___/3

Total Score: ___/12

Part 2: Gap Analysis

Based on your scores, identify:

## Biggest Gaps

1. Lowest scoring principle: _________________
   - What's missing: _________________
   - What would fix it: _________________

2. Second lowest: _________________
   - What's missing: _________________
   - What would fix it: _________________

## Quick Wins (easy improvements)

1. _________________
2. _________________
3. _________________

## Blockers (hard to change)

1. _________________
   - Why it's hard: _________________

Part 3: Migration Sketch

If you were to adopt GitOps fully:

## GitOps Migration Plan (Sketch)

### Repository Structure
- Where would config live? _________________
- Monorepo or polyrepo? _________________

### Tool Selection
- GitOps operator: [ ] Flux [ ] ArgoCD [ ] Other: _____
- Why: _________________

### Migration Approach
- [ ] Big bang (convert everything at once)
- [ ] Incremental (one service at a time)
- [ ] Parallel (run both, compare)

### First Service to Migrate
- Service: _________________
- Why this one: _________________

Success Criteria

Assessed all four principles honestly
Identified top 2 gaps
Listed at least 3 quick wins
Sketched high-level migration approach

Key Takeaways

GitOps = Git as source of truth — all changes through Git, continuously reconciled
Four principles: Declarative, Versioned, Pulled, Continuously Reconciled
Pull > Push: Agent in cluster pulls from Git, no external credentials needed
Self-healing: Drift is detected and corrected automatically
CI builds, GitOps deploys: They’re complementary, not competing

Summary

GitOps is an operational model where:

Git is the single source of truth
Desired state is declarative and versioned
Agents pull and apply changes continuously
Drift is detected and corrected automatically

It’s not just “using Git for config” — it’s a fundamentally different deployment model that provides:

Better security (no external cluster credentials)
Better reliability (self-healing)
Better auditability (full Git history)
Better disaster recovery (rebuild from Git)

GitOps transforms how you think about deployments: from “push changes to production” to “declare what production should be.”

Next Module

Continue to Module 3.2: Repository Strategies to learn how to structure your Git repositories for GitOps.

“The Git repository is the source of truth. The cluster is just a reflection.” — GitOps Proverb

Module 3.1: What is GitOps?

Prerequisites

What You’ll Be Able to Do

Why This Module Matters

The Origin Story

2017: Weaveworks’ Challenge

The Evolution: From Blog Post to Industry Standard

The Four GitOps Principles

Principle 1: Declarative

Principle 2: Versioned and Immutable

Principle 3: Pulled Automatically

Principle 4: Continuously Reconciled

Try This: GitOps Mental Model

Pull vs Push: The Key Difference

Traditional CI/CD (Push Model)

GitOps (Pull Model)

Did You Know?

War Story: The Deployment That Fixed Itself

GitOps vs CI/CD

What CI Does

What CD Does (Traditional)

What GitOps Does

The Combined Model

When GitOps Works Best

Good Fit

Less Good Fit

The Hybrid Reality

GitOps Tooling Landscape

Flux

ArgoCD

Others

Common Mistakes

Quiz: Check Your Understanding

Question 1

Question 2

Question 3

Question 4

Hands-On Exercise: GitOps Readiness Assessment

Part 1: Current State Assessment

Part 2: Gap Analysis

Part 3: Migration Sketch

Success Criteria

Key Takeaways

Further Reading

Summary

Next Module