Add required API calls to retrieve configuration from Fleet.

x-pack/agent/pkg/fleetapi/action.go

@@ -0,0 +1,128 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package fleetapi
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// Action base interface for all the implemented action from the fleet API.
+type Action interface {
+	fmt.Stringer
+	Type() string
+	ID() string
+}
+
+// ActionBase is the base of all actions to be executed.
+type ActionBase struct {
+	ActionID   string
+	ActionType string
+}
+
+// Type returns the action type.
+func (a *ActionBase) Type() string {
+	return a.ActionType
+}
+
+// ID returns the action ID.
+func (a *ActionBase) ID() string {
+	return a.ActionID
+}
+
+// ActionUnknown is an action that is not know by the current version of the Agent and we don't want
+// to return an error at parsing time but at execution time we can report or ignore.
+//
+// NOTE: We only keep the original type and the action id, the payload of the event is dropped, we
+// do this to make sure we do not leak any unwanted information.
+type ActionUnknown struct {
+	*ActionBase
+	originalType string
+}
+
+// Type returns the type of the Action.
+func (a *ActionUnknown) Type() string {
+	return "UNKNOWN"
+}
+
+func (a *ActionUnknown) String() string {
+	var s strings.Builder
+	s.WriteString("action_id: ")
+	s.WriteString(a.ID())
+	s.WriteString(", type: ")
+	s.WriteString(a.Type())
+	s.WriteString(" (original type: ")
+	s.WriteString(a.OriginalType())
+	s.WriteString(")")
+	return s.String()
+}
+
+// OriginalType returns the original type of the action as returned by the API.
+func (a *ActionUnknown) OriginalType() string {
+	return a.originalType
+}
+
+// ActionPolicyChange is a request to apply a new
+type ActionPolicyChange struct {
+	*ActionBase
+	Policy map[string]interface{} `json:"policy"`
+}
+
+func (a *ActionPolicyChange) String() string {
+	var s strings.Builder
+	s.WriteString("action_id: ")
+	s.WriteString(a.ID())
+	s.WriteString(", type: ")
+	s.WriteString(a.Type())
+	return s.String()
+}
+
+// Actions is a list of Actions to executes and allow to unmarshal heterogenous action type.
+type Actions []Action
+
+// UnmarshalJSON takes every raw representation of an action and try to decode them.
+func (a *Actions) UnmarshalJSON(data []byte) error {
+	type r struct {
+		ActionType string          `json:"type"`
+		ActionID   string          `json:"id"`
+		Data       json.RawMessage `json:"data"`
+	}
+
+	var responses []r
+
+	if err := json.Unmarshal(data, &responses); err != nil {
+		return errors.Wrap(err, "fail to decode actions")
+	}
+
+	actions := make([]Action, 0, len(responses))
+	var action Action
+
+	for _, response := range responses {
+		switch response.ActionType {
+		case "POLICY_CHANGE":
+			action = &ActionPolicyChange{
+				ActionBase: &ActionBase{
+					ActionID:   response.ActionID,
+					ActionType: response.ActionType,
+				},
+			}
+			if err := json.Unmarshal(response.Data, action); err != nil {
+				return errors.Wrap(err, "fail to decode POLICY_CHANGE action")
+			}
+		default:
+			action = &ActionUnknown{
+				ActionBase:   &ActionBase{ActionID: response.ActionID, ActionType: "UNKNOWN"},
+				originalType: response.ActionType,
+			}
+		}
+		actions = append(actions, action)
+	}
+
+	*a = actions
+	return nil
+}

x-pack/agent/pkg/fleetapi/checkin_cmd.go

@@ -8,67 +8,47 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"net/http"
+	"time"
 
 	"github.com/pkg/errors"
 )
 
 // CheckinRequest consists of multiple events reported to fleet ui.
-//
-// Example:
-// POST /api/fleet/agents/a4937110-e53e-11e9-934f-47a8e38a522c/checkin
-// {
-//   "events": [{
-//     "type": "STATE",
-//     "subtype": "STARTING",
-//     "message": "state changed from STOPPED to STARTING",
-//     "timestamp": "2019-10-01T13:42:54.323Z",
-//     "payload": {},
-//     "data": "{}"
-//   }]
-// }
 type CheckinRequest struct {
-	Events []Event `json:"events"`
+	Events []SerializableEvent `json:"events"`
 }
 
-// Event is a single event out of collection of reported events.
-type Event struct {
-	EventType string                 `json:"type"`
-	Timestamp string                 `json:"timestamp"`
-	SubType   string                 `json:"subtype"`
-	Message   string                 `json:"message"`
-	Payload   map[string]interface{} `json:"payload,omitempty"`
-	Data      string                 `json:"data,omitempty"`
+// SerializableEvent is a representation of the event to be send to the Fleet API via the checkin
+// endpoint, we are liberal into what we accept to be send you only need a type and be able to be
+// serialized into JSON.
+type SerializableEvent interface {
+	// Type return the type of the event, this must be included in the serialized document.
+	Type() string
+
+	// Timestamp is used to keep track when the event was created in the system.
+	Timestamp() time.Time
+
+	// Message is a human readable string to explain what the event does, this would be displayed in
+	// the UI as a string of text.
+	Message() string
 }
 
 // Validate validates the enrollment request before sending it to the API.
 func (e *CheckinRequest) Validate() error {
-	if len(e.Events) == 0 {
-		return errors.New("no events to report")
-	}
-
 	return nil
 }
 
-// CheckinResponse is a fleets response to checking API request.
-//
-// Example:
-// 	{
-// 		"action": "checkin",
-// 		"success": true,
-// 		"policy": {
-// 		},
-// 		"actions": []
-//  }
+// CheckinResponse is the response send back from the server which contains all the action that
+// need to be executed or proxy to running processes.
 type CheckinResponse struct {
-	Action  string `json:"action"`
-	Success bool   `json:"success"`
+	Actions Actions `json:"actions"`
+	Success bool    `json:"success"`
 }
 
 // Validate validates the response send from the server.
 func (e *CheckinResponse) Validate() error {
-	var err error
-
-	return err
+	return nil
 }
 
 // CheckinCmd is a fleet API command.
@@ -100,10 +80,14 @@ func (e *CheckinCmd) Execute(r *CheckinRequest) (*CheckinResponse, error) {
 
 	resp, err := e.client.Send("POST", e.checkinPath, nil, nil, bytes.NewBuffer(b))
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "fail to checkin to fleet")
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode != http.StatusOK {
+		return nil, extract(resp.Body)
+	}
+
 	checkinResponse := &CheckinResponse{}
 	decoder := json.NewDecoder(resp.Body)
 	if err := decoder.Decode(checkinResponse); err != nil {