Lifecycle methods: stages, versions, and strategy

In this chapter you replace the first three empty methods with real ones. Together they tell piped which stages the plugin provides, which versions it is deploying, and which deployment strategy to use. None of them run a deployment yet; they give piped the information it needs before a deployment starts.

Declare the stages

FetchDefinedStages returns the names of the stages the plugin provides. The file plugin defines three: FILE_DIFF and FILE_SYNC for the two deployment stages, and FILE_ROLLBACK for the stage that runs when a deployment fails and needs to roll back.

Define the stage names as constants, because other methods refer to them too, and return them from FetchDefinedStages:

const (
	stageDiff     = "FILE_DIFF"
	stageSync     = "FILE_SYNC"
	stageRollback = "FILE_ROLLBACK"
)

func (p *plugin) FetchDefinedStages() []string {
	return []string{stageDiff, stageSync, stageRollback}
}

Report the deployed version

DetermineVersions reports the versions of the artifacts a deployment uses, computed from the deployment source for each deployment. The file plugin uses the Git commit hash from the deployment source as its version and does not set a name or URL:

func (p *plugin) DetermineVersions(ctx context.Context, _ *sdk.ConfigNone, input *sdk.DetermineVersionsInput[applicationConfig]) (*sdk.DetermineVersionsResponse, error) {
	return &sdk.DetermineVersionsResponse{
		Versions: []sdk.ArtifactVersion{{Version: input.Request.DeploymentSource.CommitHash}},
	}, nil
}

Choose a deployment strategy

DetermineStrategy decides how a deployment runs. It is only called when piped’s built-in checks - pipeline length, whether this is the first deployment, and similar - do not determine a strategy on their own. There are two strategies:

• Pipeline sync runs the deployment pipeline the user defines in the application configuration.
• Quick sync skips the user’s pipeline and runs a fixed set of stages the plugin defines, which is useful for small changes that do not need a full pipeline.

A plugin only needs to implement DetermineStrategy when it has its own logic for choosing between the two. The file plugin does not, so it returns nil, nil. Returning nil, nil means no custom logic: the SDK answers piped on the plugin’s behalf with pipeline sync.

func (p *plugin) DetermineStrategy(ctx context.Context, _ *sdk.ConfigNone, input *sdk.DetermineStrategyInput[applicationConfig]) (*sdk.DetermineStrategyResponse, error) {
	return nil, nil
}

Build the project again to confirm the three methods compile:

go build ./...

The plugin now reports its stages, version, and strategy. In the next chapter you build the stage lists that these strategies run, starting with the pipeline sync stages.