GitLab CI/CD: Architecting, Deploying, and Optimizing Pipelines
Architecture Core Concepts
Types of Runners
Building on pipeline definitions and execution concepts, GitLab CI/CD consists of three core components:
- GitLab Server
- Runner
- Executor
In this guide, we’ll dive into Runners—the agents that pick up and execute your CI/CD jobs. You can choose between Shared Runners hosted by GitLab or Self-Managed Runners on your own infrastructure.
Runner Options at a Glance
| Aspect | Shared Runners | Self-Managed Runners |
|---|---|---|
| Hosting | Hosted by GitLab | On your own servers or cloud instances |
| Setup & Maintenance | Fully managed by GitLab | Requires in-house installation and upkeep |
| Configuration | Predefined, limited customization | Fully configurable environment |
| Scalability | Auto-scaled to meet demand | Manual scaling and provisioning |
| Security Boundary | Shared across multiple projects | Isolated per project or group |
| Cost | Included in GitLab subscription tiers | Infrastructure, licensing, and maintenance costs |
| Ideal Use Case | General-purpose workloads, small teams | Strict compliance, custom tooling, high control |
Choosing between Shared and Self-Managed Runners depends on your organization’s size, security requirements, and operational preferences.
Shared Runners
Shared Runners are provided as a service by GitLab. They serve jobs from any project in a GitLab SaaS instance on a first-come, first-served basis.
Pros
- Zero setup: Ready to use out of the box.
- Cost-effective: Included in most GitLab subscription tiers.
- Auto-scaled: Capacity adjusts automatically to meet job demand.
Cons
- Limited customization: Cannot install additional software or change low-level settings.
- Resource contention: Performance may vary under heavy load.
- Shared security boundary: All projects share the same runner environment.
Note
Shared Runners are ideal for small teams or open-source projects where ease of use outweighs the need for deep customization.
Self-Managed Runners
Self-Managed Runners run on your own infrastructure—whether on-premises or in the cloud—giving you total control over configuration, security, and performance.
Pros
- Full control: Install custom software, tune performance, and manage updates.
- Dedicated resources: Reduce job wait times and ensure consistent build performance.
- Isolated environment: Minimize cross-project interference and meet strict compliance requirements.
Cons
- Operational overhead: Requires expertise to set up, monitor, and maintain.
- Manual scaling: You must provision or decommission machines as demand fluctuates.
- Additional costs: Includes hardware, licensing, and ongoing maintenance expenses.
Warning
Ensure you implement proper security measures (firewalls, secrets management, network policies) when exposing self-managed runners to public or untrusted networks.
Links and References
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