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Merge pull request #606 from weaveworks/waiters-pkg
Refactor waiter helpers into a separate package
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| package waiters | ||
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| import ( | ||
| "context" | ||
| "fmt" | ||
| "math/rand" | ||
| "strings" | ||
| "time" | ||
|
|
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| "github.com/aws/aws-sdk-go/aws/request" | ||
| "github.com/kris-nova/logger" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
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| // Wait for something with a name to reach status that is expressed by acceptors using newRequest | ||
| // until we hit waitTimeout, on unexpected status troubleshoot will be called with the desired | ||
| // status as an argument, so that it can find what migth have gone wrong | ||
| func Wait(name, msg string, acceptors []request.WaiterAcceptor, newRequest func() *request.Request, waitTimeout time.Duration, troubleshoot func(string)) error { | ||
| desiredStatus := fmt.Sprintf("%v", acceptors[0].Expected) | ||
| msg = fmt.Sprintf("%s to reach %q status", msg, desiredStatus) | ||
| name = strings.Join([]string{"wait", name, desiredStatus}, "_") | ||
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| ctx, cancel := context.WithTimeout(context.Background(), waitTimeout) | ||
| defer cancel() | ||
| startTime := time.Now() | ||
| w := makeWaiter(ctx, name, msg, acceptors, newRequest) | ||
| logger.Debug("start %s", msg) | ||
| if waitErr := w.WaitWithContext(ctx); waitErr != nil { | ||
| if troubleshoot != nil { | ||
| troubleshoot(desiredStatus) | ||
| } | ||
| return errors.Wrap(waitErr, msg) | ||
| } | ||
| logger.Debug("done after %s of %s", time.Since(startTime), msg) | ||
| return nil | ||
| } | ||
|
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| func makeWaiter(ctx context.Context, name, msg string, acceptors []request.WaiterAcceptor, newRequest func() *request.Request) request.Waiter { | ||
| return request.Waiter{ | ||
| Name: name, | ||
| MaxAttempts: 1024, // we use context deadline instead | ||
| Delay: makeWaiterDelay(), | ||
| Acceptors: acceptors, | ||
| NewRequest: func(_ []request.Option) (*request.Request, error) { | ||
| logger.Debug(msg) | ||
| req := newRequest() | ||
| req.SetContext(ctx) | ||
| return req, nil | ||
| }, | ||
| } | ||
| } | ||
|
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| // MakeAcceptors constructs a slice of request acceptors | ||
| func MakeAcceptors(statusPath string, successStatus string, failureStates []string, extraAcceptors ...request.WaiterAcceptor) []request.WaiterAcceptor { | ||
| acceptors := []request.WaiterAcceptor{makeStatusAcceptor(successStatus, statusPath)} | ||
| acceptors[0].State = request.SuccessWaiterState | ||
|
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| for _, s := range failureStates { | ||
| acceptors = append(acceptors, makeStatusAcceptor(s, statusPath)) | ||
| } | ||
|
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| acceptors = append(acceptors, extraAcceptors...) | ||
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| return acceptors | ||
| } | ||
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| func makeStatusAcceptor(status string, statusPath string) request.WaiterAcceptor { | ||
| return request.WaiterAcceptor{ | ||
| Matcher: request.PathAllWaiterMatch, | ||
| Argument: statusPath, | ||
| Expected: status, | ||
| State: request.FailureWaiterState, | ||
| } | ||
| } | ||
|
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| // makeWaiterDelay returns delay ranging between 15s and 20s | ||
| func makeWaiterDelay() request.WaiterDelay { | ||
| const ( | ||
| base = 15 * time.Second | ||
| offsetSteps = 200 | ||
| offsetMax = 5000 | ||
| stepMult = offsetMax / offsetSteps | ||
| ) | ||
|
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| offsets := rand.Perm(offsetSteps) | ||
|
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| return func(attempt int) time.Duration { | ||
| s := rand.Intn(offsetSteps) | ||
| d := stepMult * offsets[s] | ||
|
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| offset := time.Duration(d) * time.Millisecond | ||
|
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| return base + offset | ||
| } | ||
| } |