SuperGloo to the Rescue! Making it easier to write extensions for Service Mesh

Solo.io Engineering | May 17, 2019

SuperGloo is an open source project for service mesh orchestration at scale. SuperGloo provides an opinionated abstraction layer that simplifies the installation, management, and operations of one or more service meshes like IstioAWS App MeshLinkerd, and HashiCorp Consul deployed on-prem, in the cloud or any combination you need.

There are a growing number of articles on why SuperGloo, like Christian Posta’s “Solo.io Streamlines Service Mesh and Serverless Adoption for Enterprises in Google Cloud”. This article is going to focus on how SuperGloo can help software packages like Weaveworks Flagger work on multiple Services Meshes like Istio and AWS App Mesh that both support traffic shifting.

Flagger is a cool open source project that automates the promotion of Canary deployments of your Kubernetes services. You associate a Flagger Canary Kubernetes custom resource (CRD) with your deployment and Flagger follows your defined rules for helping roll out a new version. It detects when a new version of your service has deployed, instantiating your new version in parallel to your existing version, slowly shifting request traffic between the two versions, and using your defined Prometheus metric health checks to determine if Flagger should continue moving more traffic to the new version or roll back to the old version. Since a Canary CRD is a YAML file, this provides you a declarative way to ensure that all of your service upgrades follow your prescribed sophisticated rollout strategy and complements GitOps pipelines used in Weave Flux and JenkinsX.

More information on what Canary deployments and Traffic Shifting are is in the following posts. Gloo uses the same underlying data plane technology — Envoy — as Istio to provide traffic shifting capabilities used by Flagger and Knative. Gloo is an API/Function gateway and not a full Service Mesh, so Gloo can be used in use cases that do not require all of the power, and weight, of a full Service Mesh implementation.

This article quickly runs through setting up the Flagger podinfo example application on SuperGloo with Istio so you all can see what’s involved and try yourselves if you like.

Install Kubernetes and Helm

  • Creates a kind cluster with one control plane node and one worker node
  • Configures the KUBECONFIG as kind creates a separate kubeconfig file for each kind cluster
  • Installs Helm and Tiller with a service account for Tiller

Use SuperGloo to install and configure Istio

The first command supergloo init installs SuperGloo into your Kubernetes cluster that is equivalent to using Helm to install SuperGloo.

The second command kubectl --namespace supergloo-system rollout status deployment/supergloo --watch=true is a hack to wait till the SuperGloo deployment is fully deployed and running. It’s similar to using the --wait option on a Helm install.

The supergloo install istio ... command declares a custom resource and the SuperGloo controller installs and configures Istio as declared. In this case, we are installing Istio version 1.0.6 with Istio’s Prometheus installation and with Istio deploying sidecars in all pods within namespaces with the label istio-injection=enabled, i.e., Istio’s default behavior for auto-injecting sidecars. This imperative supergloo install istio command creates the following manifest that you could kubectl apply if you prefer. Refer to the full Install specification for more details.

Install Weaveworks Flagger

  1. Add a reference to Flagger helm repo
  2. Wait for Tiller to be fully running. Only an issue for quick scripts that create Kubernetes clusters from scratch
  3. Create a cluster role binding that allows Flagger to modify SuperGloo/Istio resources
  4. Install core Flagger referencing Istio’s provided Prometheus and telling Flagger that SuperGloo is the mesh controller
  5. Install Flagger’s Grafana dashboards which are not used as part of this demo
  6. Install Flagger’s LoadTester which can help generate test traffic during a Canary deployment if there is not enough user traffic

Install Weaveworks Flagger example application

  1. Install a test namespace, the example Kubernetes Deployment manifest and an (optional) horizontal pod autoscaler
  2. Deploy the Canary policy for the example application. More details on that in a moment
  3. Wait for the Canary controller to report that it’s fully ready, which means Istio and Flagger are fully deployed and running

The Canary manifest has a target reference that associates it with the podinfo deployment. The Canary analysis says that for every interval (1 minute) Flagger increment by stepWeight (10%) more request traffic to the new version up to maxWeight (50%) as long as the metrics stay within the defined healthy ranges. If more than threshold (5) health checks fail, then rollback to 100% of traffic to the old version and delete the new version deployment. There is also an optional section to allow the Flagger loadtester to generate additional traffic to help validate the new Canary version, i.e., hard to know if the new version works if it has not handled any requests.

Deploy a new image version and watch the canary deployment

Clean up Kubernetes

See Everything Together

Summary

SuperGloo provides a great abstraction and management layer to help extensions leverage one or more Service Meshes without needing to get deep into the weeds of the huge API surface area of any one of the meshes like Istio or App Mesh. SuperGloo makes it easy for applications to use just what they need of the underlying meshes. That helps with adoption on Service Meshes based on the feedback I’ve heard, that is, many are currently experimenting with Istio or App Mesh or Linkerd for just on capability, typically traffic shifting or mutual TLS, and they’re finding it difficult to manage and configure the whole mesh even though they aren’t using those other capabilities. SuperGloo to the rescue to help make it easier to use just the parts of Service Meshes that add value today, and allow you to add more as you need it including mixing and matching multiple service meshes easily to get the biggest return on your investment.

I strongly encourage you to learn more yourself as its fun to learn new technology, especially tech that helps you solve complex challenges and accelerates your ability to deploy larger and more sophisticated systems.

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