This topic explains the key differences between GitOps and CD services in Harness, helping you understand which approach best fits your deployment needs.
Overview
Harness supports two primary approaches for continuous delivery:
- CD Services: The Harness deployment approach that uses pipelines to define and execute deployment steps explicitly
- GitOps Services: A declarative approach that continuously synchronizes your deployments with Git repository manifests
While both approaches achieve the goal of deploying applications, they differ significantly in philosophy, workflow, and implementation.
Key Differences
Deployment Philosophy
| CD Services | GitOps Services |
|---|
| Push-based: Changes are actively pushed through the pipeline to target environments | Pull-based: The GitOps Agent continuously pulls the desired state from Git |
| Procedural: Defines a sequence of steps to perform the deployment | Declarative: Defines the desired end-state in Git, letting the system figure out how to achieve it |
| Event-triggered: Deployments start when triggered by events (Git changes, webhooks, schedules) | Continuously reconciled: Automatically ensures the cluster matches the state defined in Git |
Service Definition
| CD Services | GitOps Services |
|---|
| Focused on artifact sources, manifests, and variable definitions | Primarily focused on linking to Git repositories and manifests (Release Repo and Deployment Repo) |
| Requires explicit specification of deployment steps | Uses a GitOps agent to sync with Git repositories automatically |
| Service definition specifies exactly how deployment happens | Service definition points to where the desired state is defined |
| Configuration changes require updating the service or pipeline | Configuration changes are made directly in the Git repository |
Service Variables
| CD Services | GitOps Services |
|---|
| Variables defined directly in the service | Variables can reference configuration files stored in Git |
| Variable overrides managed in pipeline executions | Variable overrides can be managed through PR pipelines |
| Fixed variable references | Dynamic variable resolution using expressions like <+env.name> and <+cluster.name> |
| Variables typically used for single environment deployments | Variables designed to support multi-environment deployments through expressions |
Implementation in Harness
| CD Services | GitOps Services |
|---|
| Uses Harness Delegates for deployments | Uses GitOps Agents (based on Argo CD) for deployments |
| Deployment executed through CD pipelines with explicit steps | Deployment continuously reconciled by the GitOps Agent |
| Service variables managed through Harness | Service variables can reference configuration files in Git |
| Dashboard shows deployment executions and pipeline runs | Dashboard shows sync status, health, and resource utilization |
Architecture Components
| CD Services | GitOps Services |
|---|
| Harness Delegate handles deployment operations | GitOps Agent (with Application Controller, Repo Server) handles deployments |
| Configuration stored primarily in Harness | Configuration primarily stored in Git repositories |
| Pipelines define deployment flow | Git commits drive deployment changes |
| Direct interaction with target environments | GitOps Agent mediates interaction with target environments |
When to Use Each Approach
Choose CD Services When You:
- Need fine-grained control over deployment steps
- Require complex deployment orchestration
- Have approval processes that must gate deployments
- Need to integrate with multiple systems during deployment
- Want explicit control over when deployments occur
Choose GitOps Services When You:
- Want Git to be the single source of truth for your deployments
- Prefer a declarative approach to defining application state
- Need continuous reconciliation between Git and your clusters
- Have multiple teams working on the same deployments
- Want automated drift detection and correction
Hybrid Approaches
You can also combine both approaches in Harness:
- GitOps for application deployments, CD for infrastructure: Use GitOps for application services while managing infrastructure with CD pipelines
- CD pipelines that trigger GitOps synchronization: Create pipelines that interact with your GitOps services through PR pipelines
- Mixed environment strategy: Use GitOps for some environments (e.g., development) and CD for others (e.g., production)
Next Steps