package azure
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"strings"
"time"
"github.com/Azure/go-autorest/autorest"
"github.com/Azure/go-autorest/autorest/date"
)
const (
headerAsyncOperation = "Azure-AsyncOperation"
)
const (
methodDelete = "DELETE"
methodPatch = "PATCH"
methodPost = "POST"
methodPut = "PUT"
methodGet = "GET"
operationInProgress string = "InProgress"
operationCanceled string = "Canceled"
operationFailed string = "Failed"
operationSucceeded string = "Succeeded"
)
// DoPollForAsynchronous returns a SendDecorator that polls if the http.Response is for an Azure
// long-running operation. It will delay between requests for the duration specified in the
// RetryAfter header or, if the header is absent, the passed delay. Polling may be canceled by
// closing the optional channel on the http.Request.
func DoPollForAsynchronous(delay time.Duration) autorest.SendDecorator {
return func(s autorest.Sender) autorest.Sender {
return autorest.SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
resp, err = s.Do(r)
if err != nil {
return resp, err
}
pollingCodes := []int{http.StatusAccepted, http.StatusCreated, http.StatusOK}
if !autorest.ResponseHasStatusCode(resp, pollingCodes...) {
return resp, nil
}
ps := pollingState{}
for err == nil {
err = updatePollingState(resp, &ps)
if err != nil {
break
}
if ps.hasTerminated() {
if !ps.hasSucceeded() {
err = ps
}
break
}
r, err = newPollingRequest(resp, ps)
if err != nil {
return resp, err
}
delay = autorest.GetRetryAfter(resp, delay)
resp, err = autorest.SendWithSender(s, r,
autorest.AfterDelay(delay))
}
return resp, err
})
}
}
func getAsyncOperation(resp *http.Response) string {
return resp.Header.Get(http.CanonicalHeaderKey(headerAsyncOperation))
}
func hasSucceeded(state string) bool {
return state == operationSucceeded
}
func hasTerminated(state string) bool {
switch state {
case operationCanceled, operationFailed, operationSucceeded:
return true
default:
return false
}
}
func hasFailed(state string) bool {
return state == operationFailed
}
type provisioningTracker interface {
state() string
hasSucceeded() bool
hasTerminated() bool
}
type operationResource struct {
// Note:
// The specification states services should return the "id" field. However some return it as
// "operationId".
ID string `json:"id"`
OperationID string `json:"operationId"`
Name string `json:"name"`
Status string `json:"status"`
Properties map[string]interface{} `json:"properties"`
OperationError ServiceError `json:"error"`
StartTime date.Time `json:"startTime"`
EndTime date.Time `json:"endTime"`
PercentComplete float64 `json:"percentComplete"`
}
func (or operationResource) state() string {
return or.Status
}
func (or operationResource) hasSucceeded() bool {
return hasSucceeded(or.state())
}
func (or operationResource) hasTerminated() bool {
return hasTerminated(or.state())
}
type provisioningProperties struct {
ProvisioningState string `json:"provisioningState"`
}
type provisioningStatus struct {
Properties provisioningProperties `json:"properties,omitempty"`
ProvisioningError ServiceError `json:"error,omitempty"`
}
func (ps provisioningStatus) state() string {
return ps.Properties.ProvisioningState
}
func (ps provisioningStatus) hasSucceeded() bool {
return hasSucceeded(ps.state())
}
func (ps provisioningStatus) hasTerminated() bool {
return hasTerminated(ps.state())
}
func (ps provisioningStatus) hasProvisioningError() bool {
return ps.ProvisioningError != ServiceError{}
}
type pollingResponseFormat string
const (
usesOperationResponse pollingResponseFormat = "OperationResponse"
usesProvisioningStatus pollingResponseFormat = "ProvisioningStatus"
formatIsUnknown pollingResponseFormat = ""
)
type pollingState struct {
responseFormat pollingResponseFormat
uri string
state string
code string
message string
}
func (ps pollingState) hasSucceeded() bool {
return hasSucceeded(ps.state)
}
func (ps pollingState) hasTerminated() bool {
return hasTerminated(ps.state)
}
func (ps pollingState) hasFailed() bool {
return hasFailed(ps.state)
}
func (ps pollingState) Error() string {
return fmt.Sprintf("Long running operation terminated with status '%s': Code=%q Message=%q", ps.state, ps.code, ps.message)
}
// updatePollingState maps the operation status -- retrieved from either a provisioningState
// field, the status field of an OperationResource, or inferred from the HTTP status code --
// into a well-known states. Since the process begins from the initial request, the state
// always comes from either a the provisioningState returned or is inferred from the HTTP
// status code. Subsequent requests will read an Azure OperationResource object if the
// service initially returned the Azure-AsyncOperation header. The responseFormat field notes
// the expected response format.
func updatePollingState(resp *http.Response, ps *pollingState) error {
// Determine the response shape
// -- The first response will always be a provisioningStatus response; only the polling requests,
// depending on the header returned, may be something otherwise.
var pt provisioningTracker
if ps.responseFormat == usesOperationResponse {
pt = &operationResource{}
} else {
pt = &provisioningStatus{}
}
// If this is the first request (that is, the polling response shape is unknown), determine how
// to poll and what to expect
if ps.responseFormat == formatIsUnknown {
req := resp.Request
if req == nil {
return autorest.NewError("azure", "updatePollingState", "Azure Polling Error - Original HTTP request is missing")
}
// Prefer the Azure-AsyncOperation header
ps.uri = getAsyncOperation(resp)
if ps.uri != "" {
ps.responseFormat = usesOperationResponse
} else {
ps.responseFormat = usesProvisioningStatus
}
// Else, use the Location header
if ps.uri == "" {
ps.uri = autorest.GetLocation(resp)
}
// Lastly, requests against an existing resource, use the last request URI
if ps.uri == "" {
m := strings.ToUpper(req.Method)
if m == methodPatch || m == methodPut || m == methodGet {
ps.uri = req.URL.String()
}
}
}
// Read and interpret the response (saving the Body in case no polling is necessary)
b := &bytes.Buffer{}
err := autorest.Respond(resp,
autorest.ByCopying(b),
autorest.ByUnmarshallingJSON(pt),
autorest.ByClosing())
resp.Body = ioutil.NopCloser(b)
if err != nil {
return err
}
// Interpret the results
// -- Terminal states apply regardless
// -- Unknown states are per-service inprogress states
// -- Otherwise, infer state from HTTP status code
if pt.hasTerminated() {
ps.state = pt.state()
} else if pt.state() != "" {
ps.state = operationInProgress
} else {
switch resp.StatusCode {
case http.StatusAccepted:
ps.state = operationInProgress
case http.StatusNoContent, http.StatusCreated, http.StatusOK:
ps.state = operationSucceeded
default:
ps.state = operationFailed
}
}
if ps.state == operationInProgress && ps.uri == "" {
return autorest.NewError("azure", "updatePollingState", "Azure Polling Error - Unable to obtain polling URI for %s %s", resp.Request.Method, resp.Request.URL)
}
// For failed operation, check for error code and message in
// -- Operation resource
// -- Response
// -- Otherwise, Unknown
if ps.hasFailed() {
if ps.responseFormat == usesOperationResponse {
or := pt.(*operationResource)
ps.code = or.OperationError.Code
ps.message = or.OperationError.Message
} else {
p := pt.(*provisioningStatus)
if p.hasProvisioningError() {
ps.code = p.ProvisioningError.Code
ps.message = p.ProvisioningError.Message
} else {
ps.code = "Unknown"
ps.message = "None"
}
}
}
return nil
}
func newPollingRequest(resp *http.Response, ps pollingState) (*http.Request, error) {
req := resp.Request
if req == nil {
return nil, autorest.NewError("azure", "newPollingRequest", "Azure Polling Error - Original HTTP request is missing")
}
reqPoll, err := autorest.Prepare(&http.Request{Cancel: req.Cancel},
autorest.AsGet(),
autorest.WithBaseURL(ps.uri))
if err != nil {
return nil, autorest.NewErrorWithError(err, "azure", "newPollingRequest", nil, "Failure creating poll request to %s", ps.uri)
}
return reqPoll, nil
}
