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Tag-based routing

As explained in Platform Engineering on Kubernetes

Tag-based routing directs requests to a specific Knative revision through a tag-associated URL or routing rule.

Tag-based routing gives a Knative revision a named route and URL without sending production traffic to it. Teams can validate a revision, run A/B tests, or prepare blue/green deployments while another revision continues serving requests. section 8.2.2

A typical routing workflow:

  • Keep the stable revision at 100% traffic and assign the candidate revision a tag with 0% traffic. section 8.2.2
  • Use the generated tagged URL to call the candidate directly, or configure header-based routing when enabled. section 8.2.2
  • Switch the tag or traffic percentages declaratively after validation. section 8.2.2

Named revision route

A Knative Service can retain all production traffic on one revision while exposing another through a named route: revisionName: frontend-00001, latestRevision: true, percent: 0, tag: version110. Knative provides a URL such as http://version110-frontend.default.127.0.0.1.sslip.io. section 8.2.2

Listing 8.7 Traffic rules when using tags
Traffic:
    Latest Revision:  false
    Percent:          100
    Revision Name:    frontend-00001
    Latest Revision:  true
    Percent:          0
    Revision Name:    frontend-00001
    Tag:              version110
    URL:              http://version110-frontend.default.127.0.0.1.sslip.io #1

Inspect the traffic table showing a tagged revision, its percentage, and the generated route URL. section 8.2.2

How Platform Engineering on Kubernetes covers it

How deep it goes
Shows declarative traffic rules, tagged URLs, header routing, and traffic switching without detailing routing internals.
Examples
Uses frontend revision YAML, version110 tagged URLs, HTTP headers, and blue/green traffic definitions.
What it assumes
Assumes familiarity with Knative Services, revisions, traffic rules, and Kubernetes-style configuration.
What you can do after
Operate tagged Knative routes and switch revision traffic declaratively after targeted validation.
How it connects
Connects Knative Services, revisions, traffic splitting, A/B testing, header-based routing, and blue/green deployments.
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Platform Engineering on Kubernetes. The section links point to the parts of the book it draws on.