63 lines
3.5 KiB
Markdown
63 lines
3.5 KiB
Markdown
# Canary Deployments **(PREMIUM)**
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> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/1659) in [GitLab Premium](https://about.gitlab.com/pricing/) 9.1.
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A popular [Continuous Deployment](https://en.wikipedia.org/wiki/Continuous_deployment)
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strategy, where a small portion of the fleet is updated to the new version of
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your application.
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## Overview
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When embracing [Continuous Delivery](https://about.gitlab.com/blog/2016/08/05/continuous-integration-delivery-and-deployment-with-gitlab/), a company needs to decide what
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type of deployment strategy to use. One of the most popular strategies is canary
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deployments, where a small portion of the fleet is updated to the new version
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first. This subset, the canaries, then serve as the proverbial
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[canary in the coal mine](https://en.wiktionary.org/wiki/canary_in_a_coal_mine).
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If there is a problem with the new version of the application, only a small
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percentage of users are affected and the change can either be fixed or quickly
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reverted.
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Leveraging [Kubernetes' Canary deployments](https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/#canary-deployments), visualize your canary
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deployments right inside the [Deploy Board](deploy_boards.md), without the need to leave GitLab.
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## Use cases
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Canary deployments can be used when you want to ship features to only a portion of
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your pods fleet and watch their behavior as a percentage of your user base
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visits the temporarily deployed feature. If all works well, you can deploy the
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feature to production knowing that it won't cause any problems.
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Canary deployments are also especially useful for backend refactors, performance
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improvements, or other changes where the user interface doesn't change, but you
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want to make sure the performance stays the same, or improves. Developers need
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to be careful when using canaries with user-facing changes, because by default,
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requests from the same user will be randomly distributed between canary and
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non-canary pods, which could result in confusion or even errors. If needed, you
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may want to consider [setting `service.spec.sessionAffinity` to `ClientIP` in
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your Kubernetes service definitions](https://kubernetes.io/docs/concepts/services-networking/service/#virtual-ips-and-service-proxies), but that is beyond the scope of
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this document.
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## Enabling Canary Deployments
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Canary deployments require that you properly configure Deploy Boards:
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1. Follow the steps to [enable Deploy Boards](deploy_boards.md#enabling-deploy-boards).
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1. To track canary deployments you need to label your Kubernetes deployments and
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pods with `track: canary`. To get started quickly, you can use the [Auto Deploy](../../topics/autodevops/stages.md#auto-deploy)
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template for canary deployments that GitLab provides.
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Depending on the deploy, the label should be either `stable` or `canary`.
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Usually, `stable` and blank or missing label means the same thing, and `canary`
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or any other track means canary/temporary.
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This allows GitLab to discover whether deployment is stable or canary (temporary).
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Once all of the above are set up and the pipeline has run at least once,
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navigate to the environments page under **Pipelines > Environments**.
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As the pipeline executes Deploy Boards will clearly mark canary pods, enabling
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quick and easy insight into the status of each environment and deployment.
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Canary deployments are marked with a yellow dot in the Deploy Board so that you
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can easily notice them.
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