122 lines
5.3 KiB
Go
122 lines
5.3 KiB
Go
package marathon
|
|
|
|
import (
|
|
"time"
|
|
|
|
"github.com/gambol99/go-marathon"
|
|
"github.com/traefik/traefik/v2/pkg/log"
|
|
)
|
|
|
|
const (
|
|
// readinessCheckDefaultTimeout is the default timeout for a readiness
|
|
// check if no check timeout is specified on the application spec. This
|
|
// should really never be the case, but better be safe than sorry.
|
|
readinessCheckDefaultTimeout = 10 * time.Second
|
|
// readinessCheckSafetyMargin is some buffer duration to account for
|
|
// small offsets in readiness check execution.
|
|
readinessCheckSafetyMargin = 5 * time.Second
|
|
readinessLogHeader = "Marathon readiness check: "
|
|
)
|
|
|
|
type readinessChecker struct {
|
|
checkDefaultTimeout time.Duration
|
|
checkSafetyMargin time.Duration
|
|
traceLogging bool
|
|
}
|
|
|
|
func defaultReadinessChecker(isTraceLogging bool) *readinessChecker {
|
|
return &readinessChecker{
|
|
checkDefaultTimeout: readinessCheckDefaultTimeout,
|
|
checkSafetyMargin: readinessCheckSafetyMargin,
|
|
traceLogging: isTraceLogging,
|
|
}
|
|
}
|
|
|
|
func (rc *readinessChecker) Do(task marathon.Task, app marathon.Application) bool {
|
|
if rc == nil {
|
|
// Readiness checker disabled.
|
|
return true
|
|
}
|
|
|
|
switch {
|
|
case len(app.Deployments) == 0:
|
|
// We only care about readiness during deployments; post-deployment readiness
|
|
// can be covered by a periodic post-deployment probe (i.e., Traefik health checks).
|
|
rc.tracef("task %s app %s: ready = true [no deployment ongoing]", task.ID, app.ID)
|
|
return true
|
|
|
|
case app.ReadinessChecks == nil || len(*app.ReadinessChecks) == 0:
|
|
// Applications without configured readiness checks are always considered
|
|
// ready.
|
|
rc.tracef("task %s app %s: ready = true [no readiness checks on app]", task.ID, app.ID)
|
|
return true
|
|
}
|
|
|
|
// Loop through all readiness check results and return the results for
|
|
// matching task IDs.
|
|
if app.ReadinessCheckResults != nil {
|
|
for _, readinessCheckResult := range *app.ReadinessCheckResults {
|
|
if readinessCheckResult.TaskID == task.ID {
|
|
rc.tracef("task %s app %s: ready = %t [evaluating readiness check ready state]", task.ID, app.ID, readinessCheckResult.Ready)
|
|
return readinessCheckResult.Ready
|
|
}
|
|
}
|
|
}
|
|
|
|
// There's a corner case sometimes hit where the first new task of a
|
|
// deployment goes from TASK_STAGING to TASK_RUNNING without a corresponding
|
|
// readiness check result being included in the API response. This only happens
|
|
// in a very short (yet unlucky) time frame and does not repeat for subsequent
|
|
// tasks of the same deployment.
|
|
// Complicating matters, the situation may occur for both initially deploying
|
|
// applications as well as rolling-upgraded ones where one or more tasks from
|
|
// a previous deployment exist already and are joined by new tasks from a
|
|
// subsequent deployment. We must always make sure that pre-existing tasks
|
|
// maintain their ready state while newly launched tasks must be considered
|
|
// unready until a check result appears.
|
|
// We distinguish the two cases by comparing the current time with the start
|
|
// time of the task: It should take Marathon at most one readiness check timeout
|
|
// interval (plus some safety margin to account for the delayed nature of
|
|
// distributed systems) for readiness check results to be returned along the API
|
|
// response. Once the task turns old enough, we assume it to be part of a
|
|
// pre-existing deployment and mark it as ready. Note that it is okay to err
|
|
// on the side of caution and consider a task unready until the safety time
|
|
// window has elapsed because a newly created task should be readiness-checked
|
|
// and be given a result fairly shortly after its creation (i.e., on the scale
|
|
// of seconds).
|
|
readinessCheckTimeoutSecs := (*app.ReadinessChecks)[0].TimeoutSeconds
|
|
readinessCheckTimeout := time.Duration(readinessCheckTimeoutSecs) * time.Second
|
|
if readinessCheckTimeout == 0 {
|
|
rc.tracef("task %s app %s: readiness check timeout not set, using default value %s", task.ID, app.ID, rc.checkDefaultTimeout)
|
|
readinessCheckTimeout = rc.checkDefaultTimeout
|
|
} else {
|
|
readinessCheckTimeout += rc.checkSafetyMargin
|
|
}
|
|
|
|
startTime, err := time.Parse(time.RFC3339, task.StartedAt)
|
|
if err != nil {
|
|
// An unparseable start time should never occur; if it does, we assume the
|
|
// problem should be surfaced as quickly as possible, which is easiest if
|
|
// we shun the task from rotation.
|
|
log.Warnf("Failed to parse start-time %s of task %s from application %s: %s (assuming unready)", task.StartedAt, task.ID, app.ID, err)
|
|
return false
|
|
}
|
|
|
|
since := time.Since(startTime)
|
|
if since < readinessCheckTimeout {
|
|
rc.tracef("task %s app %s: ready = false [task with start-time %s not within assumed check timeout window of %s (elapsed time since task start: %s)]", task.ID, app.ID, startTime.Format(time.RFC3339), readinessCheckTimeout, since)
|
|
return false
|
|
}
|
|
|
|
// Finally, we can be certain this task is not part of the deployment (i.e.,
|
|
// it's an old task that's going to transition into the TASK_KILLING and/or
|
|
// TASK_KILLED state as new tasks' readiness checks gradually turn green.)
|
|
rc.tracef("task %s app %s: ready = true [task with start-time %s not involved in deployment (elapsed time since task start: %s)]", task.ID, app.ID, startTime.Format(time.RFC3339), since)
|
|
return true
|
|
}
|
|
|
|
func (rc *readinessChecker) tracef(format string, args ...interface{}) {
|
|
if rc.traceLogging {
|
|
log.Debugf(readinessLogHeader+format, args...)
|
|
}
|
|
}
|