Add support for Function and Trigger domain objects (#1060)

Vast commit, includes:

 * Introduces the Trigger domain entity.
 * Introduces the Fns domain entity.
 * V2 of the API for interacting with the new entities in swaggerv2.yml
 * Adds v2 end points for Apps to support PUT updates.
 * Rewrites the datastore level tests into a new pattern.
 * V2 routes use entity ID over name as the path parameter.

api/models/trigger.go

@@ -0,0 +1,180 @@
+package models
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"time"
+	"unicode"
+
+	"github.com/fnproject/fn/api/common"
+)
+
+type Trigger struct {
+	ID          string          `json:"id" db:"id"`
+	Name        string          `json:"name" db:"name"`
+	AppID       string          `json:"app_id" db:"app_id"`
+	FnID        string          `json:"fn_id" db:"fn_id"`
+	CreatedAt   common.DateTime `json:"created_at,omitempty" db:"created_at"`
+	UpdatedAt   common.DateTime `json:"updated_at,omitempty" db:"updated_at"`
+	Type        string          `json:"type" db:"type"`
+	Source      string          `json:"source" db:"source"`
+	Annotations Annotations     `json:"annotations,omitempty" db:"annotations"`
+}
+
+func (t *Trigger) Equals(t2 *Trigger) bool {
+	eq := true
+	eq = eq && t.ID == t2.ID
+	eq = eq && t.Name == t2.Name
+	eq = eq && t.AppID == t2.AppID
+	eq = eq && t.FnID == t2.FnID
+
+	eq = eq && t.Type == t2.Type
+	eq = eq && t.Source == t2.Source
+	eq = eq && t.Annotations.Equals(t2.Annotations)
+
+	return eq
+}
+
+var triggerTypes = []string{"http"}
+
+func ValidTriggerTypes() []string {
+	return triggerTypes
+}
+
+func ValidTriggerType(a string) bool {
+	for _, b := range triggerTypes {
+		if b == a {
+			return true
+		}
+	}
+	return false
+}
+
+var (
+	ErrTriggerIDProvided = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("ID cannot be provided for Trigger creation"),
+	}
+	ErrTriggerIDMismatch = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("ID in path does not match ID in body"),
+	}
+	ErrTriggerMissingName = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Missing name on Trigger")}
+	ErrTriggerTooLongName = err{
+		code:  http.StatusBadRequest,
+		error: fmt.Errorf("Trigger name must be %v characters or less", MaxTriggerName)}
+	ErrTriggerInvalidName = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Invalid name for Trigger")}
+	ErrTriggerMissingAppID = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Missing App ID on Trigger")}
+	ErrTriggerMissingFnID = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Missing Fn ID on Trigger")}
+	ErrTriggerFnIDNotSameApp = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Invalid Fn ID - not owned by specified app")}
+	ErrTriggerTypeUnknown = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Trigger Type Not Supported")}
+	ErrTriggerMissingSource = err{
+		code:  http.StatusBadRequest,
+		error: errors.New("Missing Trigger Source")}
+	ErrTriggerNotFound = err{
+		code:  http.StatusNotFound,
+		error: errors.New("Trigger not found")}
+	ErrTriggerExists = err{
+		code:  http.StatusConflict,
+		error: errors.New("Trigger already exists")}
+)
+
+func (t *Trigger) Validate() error {
+	if t.Name == "" {
+		return ErrTriggerMissingName
+	}
+
+	if t.AppID == "" {
+		return ErrTriggerMissingAppID
+	}
+
+	if len(t.Name) > MaxTriggerName {
+		return ErrTriggerTooLongName
+	}
+	for _, c := range t.Name {
+		if !(unicode.IsLetter(c) || unicode.IsNumber(c) || c == '_' || c == '-') {
+			return ErrTriggerInvalidName
+		}
+	}
+
+	if t.FnID == "" {
+		return ErrTriggerMissingFnID
+	}
+
+	if !ValidTriggerType(t.Type) {
+		return ErrTriggerTypeUnknown
+	}
+
+	if t.Source == "" {
+		return ErrTriggerMissingSource
+	}
+
+	err := t.Annotations.Validate()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (t *Trigger) Clone() *Trigger {
+	clone := new(Trigger)
+	*clone = *t // shallow copy
+
+	if t.Annotations != nil {
+		clone.Annotations = make(Annotations, len(t.Annotations))
+		for k, v := range t.Annotations {
+			// TODO technically, we need to deep copy the bytes
+			clone.Annotations[k] = v
+		}
+	}
+	return clone
+}
+
+func (t *Trigger) Update(patch *Trigger) {
+
+	original := t.Clone()
+	if patch.AppID != "" {
+		t.AppID = patch.AppID
+	}
+
+	if patch.FnID != "" {
+		t.FnID = patch.FnID
+	}
+
+	if patch.Name != "" {
+		t.Name = patch.Name
+	}
+
+	if patch.Source != "" {
+		t.Source = patch.Source
+	}
+
+	t.Annotations = t.Annotations.MergeChange(patch.Annotations)
+
+	if !t.Equals(original) {
+		t.UpdatedAt = common.DateTime(time.Now())
+	}
+}
+
+type TriggerFilter struct {
+	AppID string // this is exact match
+	FnID  string // this is exact match
+	Name  string // exact match
+
+	Cursor  string
+	PerPage int
+}