Power to the People: Combine Imperative with Declarative aspects

On a regular basis, articles and tweets pass by discussing whether some specific tool is imperative or declarative. It’s no surprise that Pulumi is often the tool being debated.

This talk will explain why the right combination of imperative and declarative implementation aspects on your tool(s) deliver the power you need to solve your problems.
Ringo will analyse the following tools and pinpoint which parts of them are imperative and declarative:

- an older tool (Chef)
- two current tools (Pulumi, Helm)
- a recent one from another domain (Dagger)

To wrap up, Ringo will reason why the introduction of imperative programming languages in our tooling solves our most pressing need: integration!

Talk given at CfgMgmtCamp 2023

Recording on YouTube

Transcript

1. Power to the people Combine imperative with declarative aspects Ringo De Smet @ringods @ringods@mastodon.social
7. Both terms refer to how the user provides direction to the automation platform. With an imperative tool, you define the steps to execute in order to reach the desired solution. With a declarative tool, you define the desired state of the final solution, and the automation platform determines how to achieve that state. Source: https://www.linode.com/blog/devops/declarative-vs-imperative-in-iac/
8. What is the behaviour when running multiple times? Imperative Run #1 all steps are executed and resources are created Run #2 All steps are executed and resources are created again Declarative Run #1 All resources are declared and converged Run #2 All resources are declared again, the tool remembers these are already converged, and does nothing
9. Imperative & Declarative aspects of tools in our toolbox Chef Helm Pulumi Dagger
10. Chef
11. Short recap • DSL in Ruby for configuration management • Resource • Recipe • Cookbook • And some more
12. Chef - single resource
13. Chef - collection of resources
14. Chef - remote collection of resources
15. Helm
16. Source: https://github.com/prometheus-community/helm-charts/blob/main/charts/prometheus/templates/service.yaml
17. Source: https://helm.sh/docs/chart_template_guide/functions_and_pipelines/
18. Source: https://helm.sh/docs/chart_template_guide/function_list/
19. Pulumi
20. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC Pulumi Architecture
22. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC VPC Register resource
23. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC VPC IG Register resource Register resource
24. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC VPC IG RT Register resource Register resource Register resource
25. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC VPC IG RT Register resource Register resource Register resource SG Register resource
26. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC VPC IG RT Register resource Register resource Register resource Create Resource Create Resource Create Resource 1 2 3 SG Create Resource 2 Register resource
27. Language Host Pulumi CLI + Engine Pulumi Providers gRPC gRPC Pulumi Architecture An imperative language setup drives a … … declarative engine, which uses … … imperative calls to fulfil the desired state
28. Dagger
29. Dagger (High Level) Architecture
31. Why do we want both aspects?
32. Integration!
35. Pulumi Automation API Allows you to embed Pulumi in bigger automations Pulumi Engine Your automation project Automation API
37. Thank you! @ringods @ringods@mastodon.social