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docs: retry doc fixes #2744
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@@ -6,7 +6,7 @@ weight: 46 | |
## Automatic Retries on Error | ||
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JOSDK will schedule an automatic retry of the reconciliation whenever an exception is thrown by | ||
your `Reconciler`. The retry is behavior is configurable but a default implementation is provided | ||
your `Reconciler`. The retry behavior is configurable, but a default implementation is provided | ||
covering most of the typical use-cases, see | ||
[GenericRetry](https://github.com/java-operator-sdk/java-operator-sdk/blob/master/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/retry/GenericRetry.java) | ||
. | ||
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@@ -22,7 +22,7 @@ You can also configure the default retry behavior using the `@GradualRetry` anno | |
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It is possible to provide a custom implementation using the `retry` field of the | ||
`@ControllerConfiguration` annotation and specifying the class of your custom implementation. | ||
Note that this class will need to provide an accessible no-arg constructor for automated | ||
Note that this class must provide an accessible no-arg constructor for automated | ||
instantiation. Additionally, your implementation can be automatically configured from an | ||
annotation that you can provide by having your `Retry` implementation implement the | ||
`AnnotationConfigurable` interface, parameterized with your annotation type. See the | ||
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@@ -32,41 +32,44 @@ Information about the current retry state is accessible from | |
the [Context](https://github.com/java-operator-sdk/java-operator-sdk/blob/master/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/Context.java) | ||
object. Of note, particularly interesting is the `isLastAttempt` method, which could allow your | ||
`Reconciler` to implement a different behavior based on this status, by setting an error message | ||
in your resource' status, for example, when attempting a last retry. | ||
in your resource status, for example, when attempting a last retry. | ||
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Note, though, that reaching the retry limit won't prevent new events to be processed. New | ||
reconciliations will happen for new events as usual. However, if an error also occurs that | ||
would normally trigger a retry, the SDK won't schedule one at this point since the retry limit | ||
is already reached. | ||
would trigger a retry, the SDK won't schedule one at this point since the retry limit | ||
has already been reached. | ||
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A successful execution resets the retry state. | ||
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### Setting Error Status After Last Retry Attempt | ||
### Reconciler Error Handler | ||
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In order to facilitate error reporting, `Reconciler` can implement the | ||
[ErrorStatusHandler](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/ErrorStatusHandler.java) | ||
interface: | ||
In order to facilitate error reporting you can override [`updateErrorStatus`](https://github.com/operator-framework/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/api/reconciler/Reconciler.java#L52) | ||
method in `Reconciler`: | ||
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```java | ||
public interface ErrorStatusHandler<P extends HasMetadata> { | ||
public class MyReconciler implements Reconciler<WebPage> { | ||
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ErrorStatusUpdateControl<P> updateErrorStatus(P resource, Context<P> context, Exception e); | ||
@Override | ||
public ErrorStatusUpdateControl<WebPage> updateErrorStatus( | ||
WebPage resource, Context<WebPage> context, Exception e) { | ||
return handleError(resource, e); | ||
} | ||
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} | ||
``` | ||
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The `updateErrorStatus` method is called in case an exception is thrown from the `Reconciler`. It is | ||
also called even if no retry policy is configured, just after the reconciler execution. | ||
`RetryInfo.getAttemptCount()` is zero after the first reconciliation attempt, since it is not a | ||
result of a retry (regardless of whether a retry policy is configured or not). | ||
result of a retry (regardless of whether a retry policy is configured). | ||
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`ErrorStatusUpdateControl` is used to tell the SDK what to do and how to perform the status | ||
update on the primary resource, always performed as a status sub-resource request. Note that | ||
this update request will also produce an event, and will result in a reconciliation if the | ||
controller is not generation aware. | ||
`ErrorStatusUpdateControl` tells the SDK what to do and how to perform the status | ||
update on the primary resource, which is always performed as a status sub-resource request. Note that | ||
this update request will also produce an event and result in a reconciliation if the | ||
controller is not generation-aware. | ||
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This feature is only available for the `reconcile` method of the `Reconciler` interface, since | ||
there should not be updates to resource that have been marked for deletion. | ||
There should not be updates to resources that have been marked for deletion. | ||
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Retry can be skipped in cases of unrecoverable errors: | ||
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@@ -76,40 +79,37 @@ Retry can be skipped in cases of unrecoverable errors: | |
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### Correctness and Automatic Retries | ||
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While it is possible to deactivate automatic retries, this is not desirable, unless for very | ||
specific reasons. Errors naturally occur, whether it be transient network errors or conflicts | ||
when a given resource is handled by a `Reconciler` but is modified at the same time by a user in | ||
a different process. Automatic retries handle these cases nicely and will usually result in a | ||
While it is possible to deactivate automatic retries, this is not desirable unless there is a particular reason. | ||
Errors naturally occur, whether it be transient network errors or conflicts | ||
when a given resource is handled by a `Reconciler` but modified simultaneously by a user in | ||
a different process. Automatic retries handle these cases nicely and will eventually result in a | ||
successful reconciliation. | ||
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## Retry and Rescheduling and Event Handling Common Behavior | ||
## Retry, Rescheduling and Event Handling Common Behavior | ||
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Retry, reschedule and standard event processing form a relatively complex system, each of these | ||
Retry, reschedule, and standard event processing form a relatively complex system, each of these | ||
functionalities interacting with the others. In the following, we describe the interplay of | ||
these features: | ||
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1. A successful execution resets a retry and the rescheduled executions which were present before | ||
the reconciliation. However, a new rescheduling can be instructed from the reconciliation | ||
outcome (`UpdateControl` or `DeleteControl`). | ||
1. A successful execution resets a retry and the rescheduled executions that were present before | ||
the reconciliation. However, the reconciliation outcome can instruct a new rescheduling (`UpdateControl` or `DeleteControl`). | ||
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For example, if a reconciliation had previously been re-scheduled after some amount of time, but an event triggered | ||
the reconciliation (or cleanup) in the mean time, the scheduled execution would be automatically cancelled, i.e. | ||
re-scheduling a reconciliation does not guarantee that one will occur exactly at that time, it simply guarantees that | ||
one reconciliation will occur at that time at the latest, triggering one if no event from the cluster triggered one. | ||
Of course, it's always possible to re-schedule a new reconciliation at the end of that "automatic" reconciliation. | ||
For example, if a reconciliation had previously been rescheduled for after some amount of time, but an event triggered | ||
the reconciliation (or cleanup) in the meantime, the scheduled execution would be automatically cancelled, i.e. | ||
rescheduling a reconciliation does not guarantee that one will occur precisely at that time; it simply guarantees that a reconciliation will occur at the latest. | ||
Of course, it's always possible to reschedule a new reconciliation at the end of that "automatic" reconciliation. | ||
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Similarly, if a retry was scheduled, any event from the cluster triggering a successful execution in the mean time | ||
Similarly, if a retry was scheduled, any event from the cluster triggering a successful execution in the meantime | ||
would cancel the scheduled retry (because there's now no point in retrying something that already succeeded) | ||
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2. In case an exception happened, a retry is initiated. However, if an event is received | ||
3. In case an exception is thrown, a retry is initiated. However, if an event is received | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Why did this get increase to 3. when there is no 2.? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. it is probably a mistake, will fix it There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. fixed. |
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meanwhile, it will be reconciled instantly, and this execution won't count as a retry attempt. | ||
3. If the retry limit is reached (so no more automatic retry would happen), but a new event | ||
4. If the retry limit is reached (so no more automatic retry would happen), but a new event | ||
received, the reconciliation will still happen, but won't reset the retry, and will still be | ||
marked as the last attempt in the retry info. The point (1) still holds, but in case of an | ||
error, no retry will happen. | ||
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The thing to keep in mind when it comes to retrying or rescheduling is that JOSDK tries to avoid unnecessary work. When | ||
you reschedule an operation, you instruct JOSDK to perform that operation at the latest by the end of the rescheduling | ||
delay. If something occurred on the cluster that triggers that particular operation (reconciliation or cleanup), then | ||
marked as the last attempt in the retry info. The point (1) still holds - thus successful reconciliation will reset the retry - but no retry will happen in case of an error. | ||
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The thing to remember when it comes to retrying or rescheduling is that JOSDK tries to avoid unnecessary work. When | ||
you reschedule an operation, you instruct JOSDK to perform that operation by the end of the rescheduling | ||
delay at the latest. If something occurred on the cluster that triggers that particular operation (reconciliation or cleanup), then | ||
JOSDK considers that there's no point in attempting that operation again at the end of the specified delay since there | ||
is now no point to do so anymore. The same idea also applies to retries. | ||
is no point in doing so anymore. The same idea also applies to retries. |
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