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Steering the Course with Helm
- 1. Steering the course with Dirk Jablonski ePages GmbH
- 3. How we use Kubernetes BUILD ACCEPTANCE PRE-PROD PROD CREATE DEPLOY DEPLOY DEPLOY March 8, 2018 Motivation 3
- 4. How we want out deployments to be… DEV PROD March 8, 2018 Motivation 4
- 5. …and how it often ended up DEV PDPROD March 8, 2018 Motivation 5
- 6. What Kinds of Icebergs we hit handwritten manifests are error-prone March 8, 2018 Motivation 6
- 7. What Kinds of Icebergs we hit overriding values per environment is quirky March 8, 2018 Motivation 7
- 8. What Kinds of Icebergs we hit manifests are mostly duplicated code March 8, 2018 Motivation 8
- 9. to the rescue! March 8, 2018 9
- 10. What is Helm? “Kubernetes Package Manager” March 8, 2018 Helm to the rescue 10
- 11. What does Helm do? • bundles related manifests into charts, e.g. • deployment.yaml • service.yaml • ingress.yaml • etc. • when installing a chart, Helm creates a release March 8, 2018 Helm to the rescue 11
- 12. What does Helm do? • provides solid templating • utilizes Go templates & Sprig template library March 8, 2018 Helm to the rescue 12
- 13. What does Helm do? • allows to override values easily • overrides can originate from • child charts • additional values files • command-line values • override order is clearly defined March 8, 2018 Helm to the rescue 13
- 14. What does Helm do? • enables reuse & composition via dependencies March 8, 2018 Helm to the rescue 14
- 15. Use Cases? Managing your own charts • create charts for your own applications Utilizing community charts • easily install standard applications, e.g. Prometheus March 8, 2018 Helm to the rescue 15
- 16. How it works March 8, 2018 16
- 17. Initializing the Cluster API server $ helm init «Pod» tiller March 8, 2018 How it works 17
- 18. Installing a Chart API server $ helm install <chart> «Pod» tiller «service» xyz «deploym» xyz «secret» xyz Release March 8, 2018 How it works 18
- 19. Upgrading a Chart API server $ helm upgrade <release> <chart> «Pod» tiller «service» xyz «deploym» xyz «secret» xyz March 8, 2018 How it works 19
- 20. Charts March 8, 2018 20
- 21. Charts • bundle meta data, templates, default values & docs • use “helm create“ to generate skeleton • need semantic version numbers March 8, 2018 Charts 21
- 22. Chart.yaml • defines name & version • may include additional meta data, e.g. app version, maintainer etc. March 8, 2018 Charts 22
- 23. Templates • YAML files for whatever manifests you need to create • will be rendered as part of the release March 8, 2018 Charts 23
- 24. Template Example March 8, 2018 Charts 24
- 25. Helpers • files beginning with “_” will NOT be rendered as part of the release • contain helper templates used in multiple places within the chart • By convention end with “.tpl” March 8, 2018 Charts 25
- 26. values.yaml • contains default values for the chart March 8, 2018 Charts 26
- 27. requirements.yaml • lists dependencies for this chart March 8, 2018 Charts 27
- 28. How to organize Charts Chart per service One Chart to Rule Them All March 8, 2018 Charts 28
- 29. Chart per Service Pro • flexible • low complexity of charts • simple versioning Contra • huge amount of duplication • difficult to keep consistent • hard to introduce global changes March 8, 2018 Charts 29
- 30. One Chart to Rule Them All Pro • avoids unnecessary duplication • consistency • easy to introduce global changes Contra • high complexity of templates • tight coupling • less flexible March 8, 2018 Charts 30
- 31. Hybrid Approach • one “master” chart per service group • one dependent chart per service, containing • values • specific additions March 8, 2018 Charts 31
- 32. Writing Templates March 8, 2018 32
- 33. Built-in Objects • provide access to specific sets of values • the main ones are: • Chart • Release • Values March 8, 2018 Writing Templates 33
- 34. Control Structures • Go templates provide typical control structures: • if / else • range (loop) • with (scoping) March 8, 2018 Writing Templates 34
- 35. Functions • Go templates provide some basic functions • Sprig template library provide a lot of additions • Examples: • default • quote • b64enc • sha256sum • trim • … March 8, 2018 Writing Templates 35
- 36. Pipelines • most functions (and expressions) can be pipelined • provides the well-known benefits of composability March 8, 2018 Writing Templates 36
- 37. Checking the Results helm lint • examines a chart for possible issues • emits ERROR messages when the chart will fail • emits WARNING when conventions & best practices are violated helm template • locally render templates • does not require Tiller March 8, 2018 Writing Templates 37
- 38. Helpful Tools & Tricks March 8, 2018 38
- 39. kubeval • kubeval validates manifests against specific API versions • mostly provides detailed validation errors • pass a manifest file name or pipe to stdin: March 8, 2018 Helpful Tools & Tricks 39
- 40. kubetest • kubetest let‘s you write automatic tests to check the generated manifests • tests are written in Skylark, a lightweight Python dialect • can be used to verify some invariants, e.g. • existence of specific labels or annotations • minimum number of replicas • etc. March 8, 2018 Helpful Tools & Tricks 40
- 41. Tips & Tricks (1) If you want to override value lists… March 8, 2018 Helpful Tools & Tricks 41
- 42. Tips & Tricks (2) This way, you can override them indiviually, instead of only whole lists March 8, 2018 Helpful Tools & Tricks 42 …use hashes instead
- 43. Questions? March 8, 2018 43
- 44. Resources • Helm docs https://docs.helm.sh/ • Michael Goodness: One Chart to Rule Them All (YouTube) http://bit.ly/2DoERqM • kubeval https://github.com/garethr/kub eval • kubetest https://github.com/garethr/kub etest • Artifactory Helm integration https://jfrog.com/integration/k ubernetes-helm/ • ChartMuseum https://github.com/kubernetes -helm/chartmuseum March 8, 2018 44