Traffic Splitting Strategies¶

Traffic Splitting Strategies are techniques used in system deployment to control the distribution of incoming network traffic across different versions of a service^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. These strategies are essential for implementing release patterns such as Canary Deployments, allowing teams to mitigate risk by shifting user volume gradually rather than all at once^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

In environments like Kubernetes, these strategies are often implemented at the Layer 7 (HTTP/HTTPS) level using an Ingress Controller^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

Implementation via Ingress ¶

An Ingress acts as the entry point for external traffic and defines rules to forward that traffic to specific services^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. To support traffic splitting, mechanisms such as the Nginx Ingress Controller provide specific annotations that allow administrators to define how requests are routed^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

Common Strategies¶

Traffic can be split based on several criteria. The following methods are commonly supported:

Percentage-based Splitting¶

This method divides traffic based on a specified weight. For example, an administrator might configure the system to route 10% of requests to a new version (v2) and 90% to the stable version (v1)^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. This is typically controlled via an annotation such as nginx.ingress.kubernetes.io/canary-weight, which accepts an integer between 0 and 100^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

Header-based Splitting¶

Requests are routed to a specific version only if they contain a particular HTTP header matching a predefined value^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. This is useful for internal testing, such as allowing only employees or QA teams to access the new features.

This method directs traffic based on the presence or value of a specific cookie within the request^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. This enables "sticky" sessions where specific users are consistently routed to the new version for the duration of their session.

Canary Deployment Process¶

The strategies described above are often utilized within a Canary Deployment workflow^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. Unlike blue-green deployments, which switch traffic entirely (all-or-nothing), canary deployments allow for a smooth transition between versions^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

The general process involves: 1. Deploying the new version (v2) alongside the existing version (v1). 2. Configuring the Ingress to split a small percentage of traffic to v2^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]. 3. Monitoring the system for errors or anomalies. 4. Gradually increasing the traffic weight to v2 as confidence grows. 5. Eventually switching the Ingress to point entirely to v2 and decommissioning v1^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md].

Prioritization¶

When multiple rules are configured simultaneously, they typically follow a strict order of precedence to determine which backend handles the request. For example, in Nginx Ingress, the priority from highest to lowest is: 1. Header matches 2. Cookie matches 3. Percentage weights^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]

Sources¶

^[400-devops__06-Kubernetes__k8s-ithelp__Day15__README.md]