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Helm - Application deployment management for Kubernetes
The document provides an overview of Helm, a package manager for Kubernetes, and its role in simplifying application deployment management within a Kubernetes environment. It highlights key features of Helm, including the concept of charts, releases, and templates, as well as best practices for utilizing Helm in microservice architectures. Additionally, it addresses some challenges and weaknesses associated with Kubernetes and Helm, emphasizing the importance of following community best practices.
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Helm - Application deployment management for Kubernetes
- 1. HELM Application deployment managementfor Kubernetes
- 2. About me… •Chief ofResearch @codefresh.io •github.com/alexei-led/pumba •github.com/codefresh-io/microci •#docker #k8s #golang #aws •medium.com/@alexeiled •@alexeiled
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- 4. What is Kubernetes? •Kubernetes is container orchestration. It’s how to run containers at scale. • It’s a very active open-source platform with lots of contributors • Originally developed by Google and donated to Cloud Native Computing Foundation (Linux Foundation)
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- 8. K8s Deployment Challenges •Move to microservice architecture • application consists from multiple components • each component has its own resources and can be scaled individually • It’s hard to … • … manage, edit and update multiple K8s configurations • … deploy multiple K8s configuration as a SINGLE application • … share and reuse K8s configurations and applications • … parametrize and support multiple environments • … manage application releases: rollout, rollback, diff, history • … define deployment lifecycle (control operations to be run in different phases) • … validate release state after deployment
- 9. Helm makes iteasy to start using Kubernetes with real applications
- 10. What is Helm? •Helm is a Package Manager for Kubernetes • package multiple K8s resources into a single logical deployment unit: Chart • … but it’s not just a Package Manager • Helm is a Deployment Management for Kubernetes • do a repeatable deployment • management dependencies: reuse and share • manage multiple configurations • update, rollback and test application deployments (Releases)
- 11. Helm Dictionary • Chart- a package; bundle of Kubernetes resources • Release - a chart instance is loaded into Kubernetes • same chart can be installed several times into the same cluster; each will have it’s own Release • Repository - a repository of published Charts • Template - a K8s configuration file mixed with Go/Sprig template
- 12. kubernetes/helm • Helm wasjointly started by Google and Deis • Helm is a Kubernetes project now (managed by CNCF) • Active community: Google, Microsoft, Bitnami, … • kubeapps.io - curated list (repository) of Helm Charts • Works with any K8s cluster: K8s, Minikube, GKE, ACS, …
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- 15. Using Helm # installhelm client brew install kubernetes-helm # install helm server helm init # show help helm --help # show helm version helm version # install shell autocompletion; add it to .bashrc source <(helm completion bash) # create new chart helm create mydemo # deploy new release helm install --name myrelease mydemo --namespace demo # list all releases helm list --all
- 16. Dependency Management • Helmsubcharts • requirements.yaml • helm dependency --help
- 17. Templates • The GoTemplate language: {{.foo | quote}} • Variables, simple control structures (looping, conditionals, nesting) • Pipelines - chain together templates functions • 50+ functions from Go/Sprig Template libraries • date, string, conversions, encoding, reflection, data structures (list, dict), math, crypto, semver
- 18. Values • Specify valuesthat should be injected into templates • Simple YAML with “namespaces” • Each subchart can have its own values.yaml file • Can use multiple Values files • Can override individual value for install/update
- 19. Helm Hooks • Perform"operation" at specific point of release lifecycle • "Operation" can be any K8s resource: job, config-map, secret, pod, ... • The resources that a hook creates are not tracked or managed as part of the release ... pre/post-install pre/post-delete pre/post-upgrade pre/post-rollback
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- 21. Helm Tips 1.Create Chartfor each (micro)service; keep it in same Git repository 2.Learn and practice Go Template language (and Sprig template library) 3.Use Helm hooks to control release flow 4.Use helm test to validate releases 5.Host your own Helm repository for private charts; just serve index.html and packaged charts (can be hosted on AWS S3, Google Storage, GH pages, or other web server) 6.Manage environments with multiple Values files 7.(!) Do not commit secrets into GitHub; or encrypt secrets with sops or similar tool 8.Follow community Helm best practices and conventions: take a look at docs and kubernetes/ charts examples 9.Use helm template plugin to debug Helm Charts; or use --dry-run flag
- 22. Helm Weaknesses • Projectrelative immaturity - it's a young project • No built-in environment support • Non informative logs on failures (it's also a K8s issue) • Weak linter: too many errors skip linter checks • Open Issues: • subcharts are ignored when there is a requirements.yaml • the --recreate-pods tag is does not recreate pods of statefulsets