refactor(database): move step logic into separate package

[jbrockopp]

Based off of #574, #663, #687, #692, #721, #722 and #782

This change continues the refactor efforts initially introduced in the above PRs.

This adds a new step package to the github.com/go-vela/server/database package.

This contains a StepService interface declaring all functions necessary for step based interactions with the database:

server/database/step/service.go

Lines 11 to 49 in cc2aa4b

	// StepService represents the Vela interface for step
	// functions with the supported Database backends.
	//
	//nolint:revive // ignore name stutter
	type StepService interface {
	// Step Data Definition Language Functions
	//
	// https://en.wikipedia.org/wiki/Data_definition_language
	// CreateStepTable defines a function that creates the steps table.
	CreateStepTable(string) error
	// Step Data Manipulation Language Functions
	//
	// https://en.wikipedia.org/wiki/Data_manipulation_language
	// CountSteps defines a function that gets the count of all steps.
	CountSteps() (int64, error)
	// CountStepsForBuild defines a function that gets the count of steps by build ID.
	CountStepsForBuild(*library.Build, map[string]interface{}) (int64, error)
	// CreateStep defines a function that creates a new step.
	CreateStep(*library.Step) error
	// DeleteStep defines a function that deletes an existing step.
	DeleteStep(*library.Step) error
	// GetStep defines a function that gets a step by ID.
	GetStep(int64) (*library.Step, error)
	// GetStepForBuild defines a function that gets a step by number and build ID.
	GetStepForBuild(*library.Build, int) (*library.Step, error)
	// ListSteps defines a function that gets a list of all steps.
	ListSteps() ([]*library.Step, error)
	// ListStepsForBuild defines a function that gets a list of steps by build ID.
	ListStepsForBuild(*library.Build, map[string]interface{}, int, int) ([]*library.Step, int64, error)
	// ListStepImageCount defines a function that gets a list of all step images and the count of their occurrence.
	ListStepImageCount() (map[string]float64, error)
	// ListStepStatusCount defines a function that gets a list of all step statuses and the count of their occurrence.
	ListStepStatusCount() (map[string]float64, error)
	// UpdateStep defines a function that updates an existing step.
	UpdateStep(*library.Step) error
	}

This package also contains the engine which implements the above service interface:

server/database/step/step.go

Lines 23 to 38 in cc2aa4b

	// engine represents the step functionality that implements the StepService interface.
	engine struct {
	// engine configuration settings used in step functions
	config *config
	// gorm.io/gorm database client used in step functions
	//
	// https://pkg.go.dev/gorm.io/gorm#DB
	client *gorm.DB
	// sirupsen/logrus logger used in step functions
	//
	// https://pkg.go.dev/github.com/sirupsen/logrus#Entry
	logger *logrus.Entry
	}
	)

This engine contains no raw SQL queries for integrating with the steps table.

Instead, we leverage our DB library's (https://gorm.io/) agnostic abstraction for integrating with that table.

[codecov]

Codecov Report

Merging #810 (fadf283) into main (05371c1) will decrease coverage by 0.22%.
The diff coverage is 81.97%.

@@            Coverage Diff             @@
##             main     #810      +/-   ##
==========================================
- Coverage   58.12%   57.91%   -0.22%     
==========================================
  Files         255      263       +8     
  Lines       15892    15862      -30     
==========================================
- Hits         9238     9187      -51     
- Misses       6249     6261      +12     
- Partials      405      414       +9     

Impacted Files	Coverage Δ
api/build.go	1.48% <0.00%> (ø)
api/metrics.go	0.00% <0.00%> (ø)
api/step.go	0.00% <0.00%> (ø)
database/step/step.go	56.00% <56.00%> (ø)
database/sqlite/sqlite.go	69.49% <62.50%> (+0.52%)	⬆️
database/postgres/postgres.go	71.26% <70.00%> (+0.67%)	⬆️
database/step/list.go	72.72% <72.72%> (ø)
database/step/list_build.go	79.06% <79.06%> (ø)
database/step/get.go	81.25% <81.25%> (ø)
database/step/get_build.go	85.00% <85.00%> (ø)
... and 10 more

[cognifloyd]

Just a few nits.

[cognifloyd]

Nits resolved. No changes needed. LGTM!

Thanks again for doing all this refactoring. The database and API layers are feeling much cleaner.

[wass3rw3rk]

super minor copy pasta error, but i don't want to hold back merge

[wass3rw3rk]

Suggested change

	// https://pkg.go.dev/github.com/go-vela/server/database/repo#New
	// https://pkg.go.dev/github.com/go-vela/server/database/step#New

[jbrockopp]

good catch 😄 I've addressed this within 19c554e as a part of #816

My line of thinking is we can merge this one as-is and that PR will resolve the typo