The document presents an overview of Flux, a GitOps tool for Kubernetes that facilitates continuous delivery and infrastructure management through declarative configurations. It highlights the benefits of using Flux, including stronger security, increased productivity, and multi-tenancy capabilities, as well as best practices for achieving tenant isolation. Additionally, it provides resources for further exploration of Flux and its multi-cluster setup.

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Implementing Flux for Scale
with Soft Multi-tenancy
Russ Parmer
Senior Engineer, Weaveworks
Priyanka Ravi
Developer Experience Engineer, Weaveworks

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Weaveworks is founded on open source
● Flux & Flagger (CNCF): GitOps and Progressive Delivery for k8s
● Weave GitOps: A powerful extension & web UI for Flux
● Weave GitOps Terraform Controller: Flux controller for Terraform
resources
● GitOps Tools for Flux: VS Code extension
weave.works

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● Operating model for cloud native applications such as Kubernetes
● Utilizes a version controlled system (Commonly Git) as the “single
source of truth”
● Enables continuous delivery through automated deployment,
monitoring, and management by a version controlled system
● Managing your infrastructure and applications declaratively
What is GitOps

4. Source: GitOps Working Group
https://opengitops.dev/

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Individuals, teams, and organizations who implement GitOps experience
many benefits, including:
● Stronger Security Guarantees
● Increased Developer & Operational Productivity
● Enhanced Developer Experience
● Improved Stability
● Higher Reliability
● Consistency and Standardization
Why GitOps

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● A git centric package manager for your applications
● A set of continuous and progressive delivery solutions for Kubernetes
What is Flux
fluxcd.io

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🤝 Flux provides GitOps for both apps and infrastructure
🤖 Just push to Git and Flux does the rest
🔩 Flux works with your existing tools
☸ Flux works with any Kubernetes and all common Kubernetes tooling
🤹Flux does Multi-Tenancy (and “Multi-everything”)
📞 Flux alerts and notifies
👍 Users trust Flux
💖 Flux has a lovely community that is very easy to work with!
Flux in Short fluxcd.io

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● Reduces developer burden
● Extensible
● Comes with out of the box support for Kustomize and Helm
● Designed For Kubernetes
Benefits of Flux
fluxcd.io

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Overview of Flux
Source
controller
Notification
Controller
Image Reflector
& Automation
Controller
Flux
Flux is a set of
Kubernetes Controllers
fluxcd.io
Terraform
Controller
Helm
Controller
Kustomize
controller
VS Code
Extension

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What Flux’s Controllers do
Source Controller
- Fetch resources and store as
artifacts
Kustomize Controller
- Apply manifests, Run
manifest generation using
kustomize
Helm Controller
- Deployment of Helm Charts
Notification Controller
- Notification Dispatch
Image Reflector Controller
- Reflects Image metadata for
Automation Controller
Image Automation Controller
- Updates YAML when new
container images are
available
fluxcd.io

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● Helm
● Kustomize
● Prometheus
● Grafana
● Jenkins
● EKS
● AKS
● GCP
Flux Works with Other Tools
● Traefik
● Falco
● GitHub, GitLab, Bitbucket,
s3-compatible buckets
● Terraform
● …and more!!!
fluxcd.io

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● Makes life easier
● Multi-tenancy
● DependsOn
● Helm integration
● Notifications and Alerts
● Bootstrap
● Flux CLI
Reasons I and Others Love Flux fluxcd.io

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● There are two different forms of multi-tenancy
○ Hard multi-tenancy
■ Every tenant has their own cluster
○ Soft multi-tenancy
■ A cluster is shared across many different tenants
■ Tenants need to be isolated
What is Multi-Tenancy

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● Multi-tenancy lock down*
○ Ensure relevant controllers have cross namespace references disabled via
`--no-cross-namespace-refs=true`
● Resource Isolation
○ Ensure additional Flux instances are deployed when mission critical
tenants/workloads must be assured.
● Node Isolation
○ Ensure worker nodes are not being shared across tenants and the Flux
components.
● Network Isolation
○ Ensure the Container Network Interface (CNI) being used in the cluster
supports Network Policies.
Best Practices for Multi-Tenancy

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● Add `--no-cross-namespace-refs=true`
flag
○ Allow Flux to only reconcile Flux
resources that exist in the same
namespace
● Add `--default-service-account=default`
flag
○ Default Kustomization and HelmRelease
objects to not use the cluster scoped
service account
● Set the flux-system Kustomization
resource to use correct service account
○ This still needs cluster level access and
should not use the ‘default’ service
account
Enable Tenant Isolation for Flux

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Demo Time!

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Next Steps & Resources
● Try it yourself! Flux Docs: fluxcd.io/flux
○ Flux Multi-cluster setup:
■ https://fluxcd.io/flux/get-started/#multi-cluster-setup
■ https://github.com/fluxcd/flux2-kustomize-helm-example
○ Additional Best Practices for Shared Cluster Multi-tenancy:
https://fluxcd.io/flux/security/best-practices/#additional-best-practices-for
-shared-cluster-multi-tenancy
○ Flux Bootsrap Cheatsheet: https://fluxcd.io/flux/cheatsheets/bootstrap
● Kyverno Docs to Generate Flux Multi-tenant Resources
○ https://kyverno.io/policies/flux/generate-flux-multi-tenant-resources/gene
rate-flux-multi-tenant-resources/

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Confidential do not distribute 18
weave.works
Thank you