Which Continuous Delivery Strategy Fits Your Team? A Deep Dive into 4 Deployment Methods

When deploying projects, teams often wonder which continuous delivery (CD) method to adopt. This article outlines four widely used CD deployment types, explains how each works, and lists their pros and cons.

Continuous Delivery Deployment Types

We examine four main deployment types and summarize their advantages and disadvantages.

1. Minimum Service Deployment

This approach keeps a minimum number of service instances running while updating the rest, gradually replacing all servers with the new version.

Example: With five containers running version A, we set a minimum of two healthy instances. Three containers are taken offline, updated to version B, and brought back online before updating the remaining two.

Cons: Requires coordination and health checks outside of Swarm. Not effective for infrastructure changes. If a failure occurs on a running server, recovery time is needed.

Pros: Fewer moving parts, easier testing; allows code changes during the process. No downtime and no extra infrastructure cost. Usually faster than rolling deployments.

2. Rolling Application Update

This extends the minimum‑service concept by specifying how many containers can be updated simultaneously, rather than fixing a minimum number of online containers.

Example: With five containers, we allow two to update at a time, moving the update batch until all servers run the new version.

Cons: Docker handles failures by pausing for manual intervention or continuing, which may hide runtime issues. More complex than minimum‑service deployment. Potentially the least efficient in deployment time due to staged updates. Still benefits from external coordination and health checks.

Pros: No downtime required. Can pause to allow limited multi‑version testing. Supports automated testing before proceeding.

3. Blue/Green Deployment

The blue/green (also called red/black) method duplicates the entire platform, deploying the new version to a separate environment while the old version continues serving traffic. After testing, traffic is switched to the new environment, and the old one is retired.

Cons: Requires advanced orchestration tools. May involve additional database risks. Incurs extra short‑term cost. Unnatural traffic patterns can overload servers.

Pros: Infrastructure becomes immutable, reducing risk. Provides near‑zero downtime. Switches are clean and controllable via DNS changes. Fully automated process with a larger validation window. Allows health and performance testing before cut‑over.

4. A/B Testing

A/B testing is similar to blue/green but routes only a portion of traffic to the new (green) environment, enabling more precise evaluation before full migration.

Cons: More moving parts than other methods. Higher complexity. Requires full automation. Unnatural traffic can overwhelm servers.

Pros: All benefits of blue/green plus the ability to predict scaling capacity and pre‑heat jobs. Enables gradual performance, stability, and health evaluation. Provides customer validation while mitigating blast impact and widespread errors.

Conclusion

The best deployment method depends on your specific business and technical requirements. If it aligns with your application and user base, we strongly recommend leveraging A/B testing to maximize flexibility and risk mitigation.