docker/swarmkit

package exec

import "github.com/pkg/errors"

var (
    // ErrRuntimeUnsupported encountered when a task requires a runtime
    // unsupported by the executor.
    ErrRuntimeUnsupported = errors.New("exec: unsupported runtime")

    // ErrTaskPrepared is called if the task is already prepared.
    ErrTaskPrepared = errors.New("exec: task already prepared")

    // ErrTaskStarted can be returned from any operation that cannot be
    // performed because the task has already been started. This does not imply
    // that the task is running but rather that it is no longer valid to call
    // Start.
    ErrTaskStarted = errors.New("exec: task already started")

    // ErrTaskUpdateRejected is returned if a task update is rejected by a controller.
    ErrTaskUpdateRejected = errors.New("exec: task update rejected")

    // ErrControllerClosed returned when a task controller has been closed.
    ErrControllerClosed = errors.New("exec: controller closed")

    // ErrTaskRetry is returned by Do when an operation failed by should be
    // retried. The status should still be reported in this case.
    ErrTaskRetry = errors.New("exec: task retry")

    // ErrTaskNoop returns when the a subsequent call to Do will not result in
    // advancing the task. Callers should avoid calling Do until the task has been updated.
    ErrTaskNoop = errors.New("exec: task noop")

    // ErrDependencyNotReady is returned if a given dependency can be accessed
    // through the Getter, but is not yet ready to be used. This is most
    // relevant for Volumes, which must be staged and published on the node.
    ErrDependencyNotReady error = errors.New("dependency not ready")
)

// ExitCoder is implemented by errors that have an exit code.
type ExitCoder interface {
    // ExitCode returns the exit code.
    ExitCode() int
}

// Temporary indicates whether or not the error condition is temporary.
//
// If this is encountered in the controller, the failing operation will be
// retried when this returns true. Otherwise, the operation is considered
// fatal.
type Temporary interface {
    Temporary() bool
}

// MakeTemporary makes the error temporary.
func MakeTemporary(err error) error {
    if IsTemporary(err) {
        return err
    }

    return temporary{err}
}

type temporary struct {
    error
}

func (t temporary) Unwrap() error   { return t.error }
func (t temporary) Cause() error    { return t.error }
func (t temporary) Temporary() bool { return true }

// IsTemporary returns true if the error or a recursive cause returns true for
// temporary.
func IsTemporary(err error) bool {
    var tmp Temporary
    if errors.As(err, &tmp) {
        return tmp.Temporary()
    }
    return false
}