types.go

package v1alpha1

import (
	"encoding/json"
	"fmt"
	"hash/fnv"

	apiv1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// TemplateType is the type of a template
type TemplateType string

// Possible template types
const (
	TemplateTypeContainer TemplateType = "Container"
	TemplateTypeSteps     TemplateType = "Steps"
	TemplateTypeScript    TemplateType = "Script"
	TemplateTypeResource  TemplateType = "Resource"
	TemplateTypeDAG       TemplateType = "DAG"
	TemplateTypeSuspend   TemplateType = "Suspend"
)

// NodePhase is a label for the condition of a node at the current time.
type NodePhase string

// Workflow and node statuses
const (
	NodeRunning   NodePhase = "Running"
	NodeSucceeded NodePhase = "Succeeded"
	NodeSkipped   NodePhase = "Skipped"
	NodeFailed    NodePhase = "Failed"
	NodeError     NodePhase = "Error"
)

// NodeType is the type of a node
type NodeType string

// Node types
const (
	NodeTypePod       NodeType = "Pod"
	NodeTypeSteps     NodeType = "Steps"
	NodeTypeStepGroup NodeType = "StepGroup"
	NodeTypeDAG       NodeType = "DAG"
	NodeTypeRetry     NodeType = "Retry"
	NodeTypeSkipped   NodeType = "Skipped"
	NodeTypeSuspend   NodeType = "Suspend"
)

// Workflow is the definition of a workflow resource
// +genclient
// +genclient:noStatus
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
type Workflow struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata"`
	Spec              WorkflowSpec   `json:"spec"`
	Status            WorkflowStatus `json:"status"`
}

// WorkflowList is list of Workflow resources
// +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
type WorkflowList struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata"`
	Items           []Workflow `json:"items"`
}

// WorkflowSpec is the specification of a Workflow.
type WorkflowSpec struct {
	// Templates is a list of workflow templates used in a workflow
	Templates []Template `json:"templates"`

	// Entrypoint is a template reference to the starting point of the workflow
	Entrypoint string `json:"entrypoint"`

	// Arguments contain the parameters and artifacts sent to the workflow entrypoint
	// Parameters are referencable globally using the 'workflow' variable prefix.
	// e.g. {{workflow.parameters.myparam}}
	Arguments Arguments `json:"arguments,omitempty"`

	// ServiceAccountName is the name of the ServiceAccount to run all pods of the workflow as.
	ServiceAccountName string `json:"serviceAccountName,omitempty"`

	// Volumes is a list of volumes that can be mounted by containers in a workflow.
	Volumes []apiv1.Volume `json:"volumes,omitempty"`

	// VolumeClaimTemplates is a list of claims that containers are allowed to reference.
	// The Workflow controller will create the claims at the beginning of the workflow
	// and delete the claims upon completion of the workflow
	VolumeClaimTemplates []apiv1.PersistentVolumeClaim `json:"volumeClaimTemplates,omitempty"`

	// Parallelism limits the max total parallel pods that can execute at the same time in a workflow
	Parallelism *int64 `json:"parallelism,omitempty"`

	// Suspend will suspend the workflow and prevent execution of any future steps in the workflow
	Suspend *bool `json:"suspend,omitempty"`

	// NodeSelector is a selector which will result in all pods of the workflow
	// to be scheduled on the selected node(s). This is able to be overridden by
	// a nodeSelector specified in the template.
	NodeSelector map[string]string `json:"nodeSelector,omitempty"`

	// Affinity sets the scheduling constraints for all pods in the workflow.
	// Can be overridden by an affinity specified in the template
	Affinity *apiv1.Affinity `json:"affinity,omitempty"`

	// ImagePullSecrets is a list of references to secrets in the same namespace to use for pulling any images
	// in pods that reference this ServiceAccount. ImagePullSecrets are distinct from Secrets because Secrets
	// can be mounted in the pod, but ImagePullSecrets are only accessed by the kubelet.
	// More info: https://kubernetes.io/docs/concepts/containers/images/#specifying-imagepullsecrets-on-a-pod
	ImagePullSecrets []apiv1.LocalObjectReference `json:"imagePullSecrets,omitempty"`

	// OnExit is a template reference which is invoked at the end of the
	// workflow, irrespective of the success, failure, or error of the
	// primary workflow.
	OnExit string `json:"onExit,omitempty"`
}

// Template is a reusable and composable unit of execution in a workflow
type Template struct {
	// Name is the name of the template
	Name string `json:"name"`

	// Inputs describe what inputs parameters and artifacts are supplied to this template
	Inputs Inputs `json:"inputs,omitempty"`

	// Outputs describe the parameters and artifacts that this template produces
	Outputs Outputs `json:"outputs,omitempty"`

	// NodeSelector is a selector to schedule this step of the workflow to be
	// run on the selected node(s). Overrides the selector set at the workflow level.
	NodeSelector map[string]string `json:"nodeSelector,omitempty"`

	// Affinity sets the pod's scheduling constraints
	// Overrides the affinity set at the workflow level (if any)
	Affinity *apiv1.Affinity `json:"affinity,omitempty"`

	// Deamon will allow a workflow to proceed to the next step so long as the container reaches readiness
	Daemon *bool `json:"daemon,omitempty"`

	// Steps define a series of sequential/parallel workflow steps
	Steps [][]WorkflowStep `json:"steps,omitempty"`

	// Container is the main container image to run in the pod
	Container *apiv1.Container `json:"container,omitempty"`

	// Script runs a portion of code against an interpreter
	Script *ScriptTemplate `json:"script,omitempty"`

	// Resource template subtype which can run k8s resources
	Resource *ResourceTemplate `json:"resource,omitempty"`

	// DAG template subtype which runs a DAG
	DAG *DAGTemplate `json:"dag,omitempty"`

	// Suspend template subtype which can suspend a workflow when reaching the step
	Suspend *SuspendTemplate `json:"suspend,omitempty"`

	// Sidecars is a list of containers which run alongside the main container
	// Sidecars are automatically killed when the main container completes
	Sidecars []Sidecar `json:"sidecars,omitempty"`

	// Location in which all files related to the step will be stored (logs, artifacts, etc...).
	// Can be overridden by individual items in Outputs. If omitted, will use the default
	// artifact repository location configured in the controller, appended with the
	// <workflowname>/<nodename> in the key.
	ArchiveLocation *ArtifactLocation `json:"archiveLocation,omitempty"`

	// Optional duration in seconds relative to the StartTime that the pod may be active on a node
	// before the system actively tries to terminate the pod; value must be positive integer
	// This field is only applicable to container and script templates.
	ActiveDeadlineSeconds *int64 `json:"activeDeadlineSeconds,omitempty"`

	// RetryStrategy describes how to retry a template when it fails
	RetryStrategy *RetryStrategy `json:"retryStrategy,omitempty"`

	// Parallelism limits the max total parallel pods that can execute at the same time within the
	// boundaries of this template invocation. If additional steps/dag templates are invoked, the
	// pods created by those templates will not be counted towards this total.
	Parallelism *int64 `json:"parallelism,omitempty"`

	// Tolerations to apply to workflow pods.
	Tolerations []apiv1.Toleration `json:"tolerations,omitempty"`
}

// Inputs are the mechanism for passing parameters, artifacts, volumes from one template to another
type Inputs struct {
	// Parameters are a list of parameters passed as inputs
	Parameters []Parameter `json:"parameters,omitempty"`

	// Artifact are a list of artifacts passed as inputs
	Artifacts []Artifact `json:"artifacts,omitempty"`
}

// Parameter indicate a passed string parameter to a service template with an optional default value
type Parameter struct {
	// Name is the parameter name
	Name string `json:"name"`

	// Default is the default value to use for an input parameter if a value was not supplied
	Default *string `json:"default,omitempty"`

	// Value is the literal value to use for the parameter.
	// If specified in the context of an input parameter, the value takes precedence over any passed values
	Value *string `json:"value,omitempty"`

	// ValueFrom is the source for the output parameter's value
	ValueFrom *ValueFrom `json:"valueFrom,omitempty"`
}

// ValueFrom describes a location in which to obtain the value to a parameter
type ValueFrom struct {
	// Path in the container to retrieve an output parameter value from in container templates
	Path string `json:"path,omitempty"`

	// JSONPath of a resource to retrieve an output parameter value from in resource templates
	JSONPath string `json:"jsonPath,omitempty"`

	// JQFilter expression against the resource object in resource templates
	JQFilter string `json:"jqFilter,omitempty"`

	// Parameter reference to a step or dag task in which to retrieve an output parameter value from
	// (e.g. '{{steps.mystep.outputs.myparam}}')
	Parameter string `json:"parameter,omitempty"`
}

// Artifact indicates an artifact to place at a specified path
type Artifact struct {
	// name of the artifact. must be unique within a template's inputs/outputs.
	Name string `json:"name"`

	// Path is the container path to the artifact
	Path string `json:"path,omitempty"`

	// mode bits to use on this file, must be a value between 0 and 0777
	// set when loading input artifacts.
	Mode *int32 `json:"mode,omitempty"`

	// From allows an artifact to reference an artifact from a previous step
	From string `json:"from,omitempty"`

	// ArtifactLocation contains the location of the artifact
	ArtifactLocation `json:",inline"`
}

// ArtifactLocation describes a location for a single or multiple artifacts.
// It is used as single artifact in the context of inputs/outputs (e.g. outputs.artifacts.artname).
// It is also used to describe the location of multiple artifacts such as the archive location
// of a single workflow step, which the executor will use as a default location to store its files.
type ArtifactLocation struct {
	// S3 contains S3 artifact location details
	S3 *S3Artifact `json:"s3,omitempty"`

	// Git contains git artifact location details
	Git *GitArtifact `json:"git,omitempty"`

	// HTTP contains HTTP artifact location details
	HTTP *HTTPArtifact `json:"http,omitempty"`

	// Artifactory contains artifactory artifact location details
	Artifactory *ArtifactoryArtifact `json:"artifactory,omitempty"`

	// Raw contains raw artifact location details
	Raw *RawArtifact `json:"raw,omitempty"`
}

// Outputs hold parameters, artifacts, and results from a step
type Outputs struct {
	// Parameters holds the list of output parameters produced by a step
	Parameters []Parameter `json:"parameters,omitempty"`

	// Artifacts holds the list of output artifacts produced by a step
	Artifacts []Artifact `json:"artifacts,omitempty"`

	// Result holds the result (stdout) of a script template
	Result *string `json:"result,omitempty"`
}

// WorkflowStep is a reference to a template to execute in a series of step
type WorkflowStep struct {
	// Name of the step
	Name string `json:"name,omitempty"`

	// Template is a reference to the template to execute as the step
	Template string `json:"template,omitempty"`

	// Arguments hold arguments to the template
	Arguments Arguments `json:"arguments,omitempty"`

	// WithItems expands a step into multiple parallel steps from the items in the list
	WithItems []Item `json:"withItems,omitempty"`

	// WithParam expands a step into from the value in the parameter
	WithParam string `json:"withParam,omitempty"`

	// When is an expression in which the step should conditionally execute
	When string `json:"when,omitempty"`
}

// Item expands a single workflow step into multiple parallel steps
// The value of Item can be a map, string, bool, or number
type Item struct {
	Value interface{}
}

// DeepCopyInto is an custom deepcopy function to deal with our use of the interface{} type
func (i *Item) DeepCopyInto(out *Item) {
	inBytes, err := json.Marshal(i)
	if err != nil {
		panic(err)
	}
	err = json.Unmarshal(inBytes, out)
	if err != nil {
		panic(err)
	}
}

// UnmarshalJSON implements the json.Unmarshaller interface.
func (i *Item) UnmarshalJSON(value []byte) error {
	return json.Unmarshal(value, &i.Value)
}

// MarshalJSON implements the json.Marshaller interface.
func (i Item) MarshalJSON() ([]byte, error) {
	return json.Marshal(i.Value)
}

// OpenAPISchemaType is used by the kube-openapi generator when constructing
// the OpenAPI spec of this type.
// See: https://github.com/kubernetes/kube-openapi/tree/master/pkg/generators
func (i Item) OpenAPISchemaType() []string { return []string{"string"} }

// OpenAPISchemaFormat is used by the kube-openapi generator when constructing
// the OpenAPI spec of this type.
func (i Item) OpenAPISchemaFormat() string { return "item" }

// Arguments to a template
type Arguments struct {
	// Parameters is the list of parameters to pass to the template or workflow
	Parameters []Parameter `json:"parameters,omitempty"`

	// Artifacts is the list of artifacts to pass to the template or workflow
	Artifacts []Artifact `json:"artifacts,omitempty"`
}

// Sidecar is a container which runs alongside the main container
type Sidecar struct {
	apiv1.Container `json:",inline"`

	// MirrorVolumeMounts will mount the same volumes specified in the main container
	// to the sidecar (including artifacts), at the same mountPaths. This enables
	// dind daemon to partially see the same filesystem as the main container in
	// order to use features such as docker volume binding
	MirrorVolumeMounts *bool `json:"mirrorVolumeMounts,omitempty"`
}

// WorkflowStatus contains overall status information about a workflow
// +k8s:openapi-gen=false
type WorkflowStatus struct {
	// Phase a simple, high-level summary of where the workflow is in its lifecycle.
	Phase NodePhase `json:"phase"`

	// Time at which this workflow started
	StartedAt metav1.Time `json:"startedAt,omitempty"`

	// Time at which this workflow completed
	FinishedAt metav1.Time `json:"finishedAt,omitempty"`

	// A human readable message indicating details about why the workflow is in this condition.
	Message string `json:"message,omitempty"`

	// Nodes is a mapping between a node ID and the node's status.
	Nodes map[string]NodeStatus `json:"nodes"`

	// PersistentVolumeClaims tracks all PVCs that were created as part of the workflow.
	// The contents of this list are drained at the end of the workflow.
	PersistentVolumeClaims []apiv1.Volume `json:"persistentVolumeClaims,omitempty"`
}

// GetNodesWithRetries returns a list of nodes that have retries.
func (wfs *WorkflowStatus) GetNodesWithRetries() []NodeStatus {
	var nodesWithRetries []NodeStatus
	for _, node := range wfs.Nodes {
		if node.RetryStrategy != nil {
			nodesWithRetries = append(nodesWithRetries, node)
		}
	}
	return nodesWithRetries
}

// RetryStrategy provides controls on how to retry a workflow step
type RetryStrategy struct {
	// Limit is the maximum number of attempts when retrying a container
	Limit *int32 `json:"limit,omitempty"`
}

// NodeStatus contains status information about an individual node in the workflow
// +k8s:openapi-gen=false
type NodeStatus struct {
	// ID is a unique identifier of a node within the worklow
	// It is implemented as a hash of the node name, which makes the ID deterministic
	ID string `json:"id"`

	// Name is unique name in the node tree used to generate the node ID
	Name string `json:"name"`

	// DisplayName is a human readable representation of the node. Unique within a template boundary
	DisplayName string `json:"displayName"`

	// Type indicates type of node
	Type NodeType `json:"type"`

	// TemplateName is the template name which this node corresponds to. Not applicable to virtual nodes (e.g. Retry, StepGroup)
	TemplateName string `json:"templateName,omitempty"`

	// Phase a simple, high-level summary of where the node is in its lifecycle.
	// Can be used as a state machine.
	Phase NodePhase `json:"phase"`

	// BoundaryID indicates the node ID of the associated template root node in which this node belongs to
	BoundaryID string `json:"boundaryID,omitempty"`

	// A human readable message indicating details about why the node is in this condition.
	Message string `json:"message,omitempty"`

	// Time at which this node started
	StartedAt metav1.Time `json:"startedAt,omitempty"`

	// Time at which this node completed
	FinishedAt metav1.Time `json:"finishedAt,omitempty"`

	// PodIP captures the IP of the pod for daemoned steps
	PodIP string `json:"podIP,omitempty"`

	// Daemoned tracks whether or not this node was daemoned and need to be terminated
	Daemoned *bool `json:"daemoned,omitempty"`

	// RetryStrategy contains retry information about the node
	RetryStrategy *RetryStrategy `json:"retryStrategy,omitempty"`

	// Inputs captures input parameter values and artifact locations supplied to this template invocation
	Inputs *Inputs `json:"inputs,omitempty"`

	// Outputs captures output parameter values and artifact locations produced by this template invocation
	Outputs *Outputs `json:"outputs,omitempty"`

	// Children is a list of child node IDs
	Children []string `json:"children,omitempty"`

	// OutboundNodes tracks the node IDs which are considered "outbound" nodes to a template invocation.
	// For every invocation of a template, there are nodes which we considered as "outbound". Essentially,
	// these are last nodes in the execution sequence to run, before the template is considered completed.
	// These nodes are then connected as parents to a following step.
	//
	// In the case of single pod steps (i.e. container, script, resource templates), this list will be nil
	// since the pod itself is already considered the "outbound" node.
	// In the case of DAGs, outbound nodes are the "target" tasks (tasks with no children).
	// In the case of steps, outbound nodes are all the containers involved in the last step group.
	// NOTE: since templates are composable, the list of outbound nodes are carried upwards when
	// a DAG/steps template invokes another DAG/steps template. In other words, the outbound nodes of
	// a template, will be a superset of the outbound nodes of its last children.
	OutboundNodes []string `json:"outboundNodes,omitempty"`
}

func (n NodeStatus) String() string {
	return fmt.Sprintf("%s (%s)", n.Name, n.ID)
}

// Completed returns whether or not the node has completed execution
func (n NodeStatus) Completed() bool {
	return n.Phase == NodeSucceeded ||
		n.Phase == NodeFailed ||
		n.Phase == NodeError ||
		n.Phase == NodeSkipped
}

// IsDaemoned returns whether or not the node is deamoned
func (n NodeStatus) IsDaemoned() bool {
	if n.Daemoned == nil || !*n.Daemoned {
		return false
	}
	return true
}

// Successful returns whether or not this node completed successfully
func (n NodeStatus) Successful() bool {
	return n.Phase == NodeSucceeded || n.Phase == NodeSkipped
}

// CanRetry returns whether the node should be retried or not.
func (n NodeStatus) CanRetry() bool {
	// TODO(shri): Check if there are some 'unretryable' errors.
	return n.Completed() && !n.Successful()
}

// S3Bucket contains the access information required for interfacing with an S3 bucket
type S3Bucket struct {
	// Endpoint is the hostname of the bucket endpoint
	Endpoint string `json:"endpoint"`

	// Bucket is the name of the bucket
	Bucket string `json:"bucket"`

	// Region contains the optional bucket region
	Region string `json:"region,omitempty"`

	// Insecure will connect to the service with TLS
	Insecure *bool `json:"insecure,omitempty"`

	// AccessKeySecret is the secret selector to the bucket's access key
	AccessKeySecret apiv1.SecretKeySelector `json:"accessKeySecret"`

	// SecretKeySecret is the secret selector to the bucket's secret key
	SecretKeySecret apiv1.SecretKeySelector `json:"secretKeySecret"`
}

// S3Artifact is the location of an S3 artifact
type S3Artifact struct {
	S3Bucket `json:",inline"`

	// Key is the key in the bucket where the artifact resides
	Key string `json:"key"`
}

// GitArtifact is the location of an git artifact
type GitArtifact struct {
	// Repo is the git repository
	Repo string `json:"repo"`

	// Revision is the git commit, tag, branch to checkout
	Revision string `json:"revision,omitempty"`

	// UsernameSecret is the secret selector to the repository username
	UsernameSecret *apiv1.SecretKeySelector `json:"usernameSecret,omitempty"`

	// PasswordSecret is the secret selector to the repository password
	PasswordSecret *apiv1.SecretKeySelector `json:"passwordSecret,omitempty"`
}

// ArtifactoryAuth describes the secret selectors required for authenticating to artifactory
type ArtifactoryAuth struct {
	// UsernameSecret is the secret selector to the repository username
	UsernameSecret *apiv1.SecretKeySelector `json:"usernameSecret,omitempty"`

	// PasswordSecret is the secret selector to the repository password
	PasswordSecret *apiv1.SecretKeySelector `json:"passwordSecret,omitempty"`
}

// ArtifactoryArtifact is the location of an artifactory artifact
type ArtifactoryArtifact struct {
	// URL of the artifact
	URL             string `json:"url"`
	ArtifactoryAuth `json:",inline"`
}

// RawArtifact allows raw string content to be placed as an artifact in a container
type RawArtifact struct {
	// Data is the string contents of the artifact
	Data string `json:"data"`
}

// HTTPArtifact allows an file served on HTTP to be placed as an input artifact in a container
type HTTPArtifact struct {
	// URL of the artifact
	URL string `json:"url"`
}

// ScriptTemplate is a template subtype to enable scripting through code steps
type ScriptTemplate struct {
	apiv1.Container `json:",inline"`

	// Source contains the source code of the script to execute
	Source string `json:"source"`
}

// ResourceTemplate is a template subtype to manipulate kubernetes resources
type ResourceTemplate struct {
	// Action is the action to perform to the resource.
	// Must be one of: get, create, apply, delete, replace
	Action string `json:"action"`

	// Manifest contains the kubernetes manifest
	Manifest string `json:"manifest"`

	// SuccessCondition is a label selector expression which describes the conditions
	// of the k8s resource in which it is acceptable to proceed to the following step
	SuccessCondition string `json:"successCondition,omitempty"`

	// FailureCondition is a label selector expression which describes the conditions
	// of the k8s resource in which the step was considered failed
	FailureCondition string `json:"failureCondition,omitempty"`
}

// GetType returns the type of this template
func (tmpl *Template) GetType() TemplateType {
	if tmpl.Container != nil {
		return TemplateTypeContainer
	}
	if tmpl.Steps != nil {
		return TemplateTypeSteps
	}
	if tmpl.DAG != nil {
		return TemplateTypeDAG
	}
	if tmpl.Script != nil {
		return TemplateTypeScript
	}
	if tmpl.Resource != nil {
		return TemplateTypeResource
	}
	if tmpl.Suspend != nil {
		return TemplateTypeSuspend
	}
	return "Unknown"
}

// DAGTemplate is a template subtype for directed acyclic graph templates
type DAGTemplate struct {
	// Target are one or more names of targets to execute in a DAG
	Targets string `json:"target,omitempty"`

	// Tasks are a list of DAG tasks
	Tasks []DAGTask `json:"tasks"`
}

// DAGTask represents a node in the graph during DAG execution
type DAGTask struct {
	// Name is the name of the target
	Name string `json:"name"`

	// Name of template to execute
	Template string `json:"template"`

	// Arguments are the parameter and artifact arguments to the template
	Arguments Arguments `json:"arguments,omitempty"`

	// Dependencies are name of other targets which this depends on
	Dependencies []string `json:"dependencies,omitempty"`
}

// SuspendTemplate is a template subtype to suspend a workflow at a predetermined point in time
type SuspendTemplate struct {
}

// GetArtifactByName returns an input artifact by its name
func (in *Inputs) GetArtifactByName(name string) *Artifact {
	for _, art := range in.Artifacts {
		if art.Name == name {
			return &art
		}
	}
	return nil
}

// GetParameterByName returns an input parameter by its name
func (in *Inputs) GetParameterByName(name string) *Parameter {
	for _, param := range in.Parameters {
		if param.Name == name {
			return &param
		}
	}
	return nil
}

// HasInputs returns whether or not there are any inputs
func (in *Inputs) HasInputs() bool {
	if len(in.Artifacts) > 0 {
		return true
	}
	if len(in.Parameters) > 0 {
		return true
	}
	return false
}

// HasOutputs returns whether or not there are any outputs
func (out *Outputs) HasOutputs() bool {
	if out.Result != nil {
		return true
	}
	if len(out.Artifacts) > 0 {
		return true
	}
	if len(out.Parameters) > 0 {
		return true
	}
	return false
}

// GetArtifactByName retrieves an artifact by its name
func (args *Arguments) GetArtifactByName(name string) *Artifact {
	for _, art := range args.Artifacts {
		if art.Name == name {
			return &art
		}
	}
	return nil
}

// GetParameterByName retrieves a parameter by its name
func (args *Arguments) GetParameterByName(name string) *Parameter {
	for _, param := range args.Parameters {
		if param.Name == name {
			return &param
		}
	}
	return nil
}

// HasLocation whether or not an artifact has a location defined
func (a *Artifact) HasLocation() bool {
	return a.S3 != nil || a.Git != nil || a.HTTP != nil || a.Artifactory != nil || a.Raw != nil
}

// GetTemplate retrieves a defined template by its name
func (wf *Workflow) GetTemplate(name string) *Template {
	for _, t := range wf.Spec.Templates {
		if t.Name == name {
			return &t
		}
	}
	return nil
}

// NodeID creates a deterministic node ID based on a node name
func (wf *Workflow) NodeID(name string) string {
	if name == wf.ObjectMeta.Name {
		return wf.ObjectMeta.Name
	}
	h := fnv.New32a()
	_, _ = h.Write([]byte(name))
	return fmt.Sprintf("%s-%v", wf.ObjectMeta.Name, h.Sum32())
}