spud/service_definition/fetcher.go

// Definition fetcher
//
// Handles fetching and building ServiceDefinition structs from different
// data sources.

package service_definition

import (
	"github.com/goccy/go-yaml"
	"os"
	git "spud/git"
	"strings"
)

type DefinitionFetcher struct {
	Git git.GitClient
}

func NewDefinitionFetcher() DefinitionFetcher {
	return DefinitionFetcher{
		Git: git.Git{},
	}
}

// Gets a ServiceDefinition from the given location.
//
// Depending on location prefix, different sources are used:
// git+: Clones the target git repository and extracts a service definition from it.
// <no-prefix>: Uses the location as a filepath to the service definition.
func (f DefinitionFetcher) GetDefinition(path string) (ServiceDefinition, error) {
	if strings.HasPrefix(path, "git+") {
		return f.getDefinitionFromGit(path)
	}

	return f.getDefinitionFromFile(path)
}

// Clones the target git repository and uses it as a basis to extract
// a service definition.
func (f DefinitionFetcher) getDefinitionFromGit(path string) (ServiceDefinition, error) {
	dir, err := os.MkdirTemp("/tmp", "spud-service-")

	if err != nil {
		return ServiceDefinition{}, err
	}

	if _, err := f.Git.Clone(strings.TrimPrefix(path, "git+"), dir); err != nil {
		return ServiceDefinition{}, err
	}

	return f.getDefinitionFromFile(dir + "/service.yml")
}

// Extracts a service definition from the given filepath.
func (f DefinitionFetcher) getDefinitionFromFile(path string) (ServiceDefinition, error) {
	var definition ServiceDefinition

	defData, err := os.ReadFile(path)

	if err != nil {
		return ServiceDefinition{}, &FileDoesNotExistError{Message: "Could not find service configuration file", ExpectedPath: path}
	}

	if err = yaml.Unmarshal(defData, &definition); err != nil {
		return ServiceDefinition{}, &InvalidServiceDefinitionError{Path: path}
	}

	return definition, nil
}