Hera CLI design

[elliotgunton]

Following a catchup with @flaviuvadan and @samj1912, this issue is to expand/formalise the idea of a Hera CLI, features it should support and a small roadmap/priority list for the CLI.

Feature (priority order)	Depends on	Impact	T shirt size	Proof of concept / PR / links
CLI framework	-	Required to enable features	S
WT stub gen	CLI	Medium/high - would make TemplateRef usage much better, key part of WorkflowTemplate use/distribution	M
Detect Workflows / WorkflowTemplates	To be part of CLI but can figure out functionality in parallel	Low/Medium (might be required to enable features. Ease of use feature)	S/M
Submit from WT	CLI, Detect Workflows / WorkflowTemplates	Medium - would improve dev ex a lot	S	As a function on WorkflowTemplates, issue/suggestion here https://github.com/argoproj-labs/hera/issues/521 -> Done in - https://github.com/argoproj-labs/hera/pull/669
Python to YAML converter	CLI	Low/Medium - to_yaml() already exists on Workflows, this puts convenience in the CLI. Could be used to generate many at once. Useful for CI/CD and DevOps use cases	S
YAML to Python converter	CLI	Medium - existing users of Argo can instantly convert to using Hera, opens the door for better integrations	M	https://github.com/argoproj-labs/hera/issues/609 and https://github.com/argoproj-labs/hera/pull/673
User Workflow automatic documentation generator	CLI	Medium - we love docs!	S

Example CLI Usage

WorkflowTemplate Stub gen

hera generate stubs <template-name> [--namespace <namespace>] [--cluster-template]

Comments:

• Stubs wouldn’t be useful for Workflows, so just WTs and CWTs are accepted

Submit from WorkflowTemplate

hera submit --from <python-file-with-def>/<template-name> --e <entrypoint> --namespace <namespace>

Comments:

• Unsure of the --from syntax - pass a file + template name? Separate args for each?

Python to YAML converter

hera generate yaml --from <python-file-with-def>[/<template-name>] [--to <filepath>]

Comments:

• Allows you to generate from many WTs from one file, optional /template-name

YAML to Python converter

hera generate python --from <yaml-file> [--to <filepath>]

Comments:

• Implicitly allows you to generate whatever’s in the yaml file (i.e. one or many of Workflows, WTs, CWTs etc)

Doc Gen

hera generate docs --from <python-file-with-def> [--to <filepath>]

Comments:

• Should the output be basic? JSON instead of to file? Should we assume anything?