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Clarify behavior of ensure_delivery flag

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Fixes #10754
This commit is contained in:
Dan Hermann 2019-05-03 07:13:44 -05:00
parent 5e1dc1f6a3
commit 32934e6775
1 changed files with 13 additions and 5 deletions
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18
docs/static/pipeline-pipeline-config.asciidoc vendored
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@ -35,13 +35,21 @@ The `pipeline` plugin may be the most efficient way to communicate between pipel
[[delivery-guarantees]]
===== Delivery Guarantees
In its standard configuration the `pipeline` input/output has at-least-once delivery guarantees. The output will be blocked if the address is blocked or unavailable.
In its standard configuration the `pipeline` input/output has at-least-once delivery guarantees. The output will be
blocked if the address is blocked or unavailable.
By default, the `ensure_delivery` option on the `pipeline` output is set to `true.` If you change the `ensure_delivery` flag to `false`, an unavailable downstream pipeline causes the sent message to be discarded. Use `ensure_delivery => false` when you want the ability to temporarily disable a downstream pipeline without the upstream one waiting for it.
By default, the `ensure_delivery` option on the `pipeline` output is set to `true.` If you change the
`ensure_delivery` flag to `false`, an _unavailable_ downstream pipeline causes the sent message to be discarded. Note
that a pipeline is considered unavailable only when it is starting up or reloading, not when any of the plugins it
may contain are blocked. A _blocked_ downstream pipeline blocks the sending output/pipeline regardless of the value of
the `ensure_delivery` flag. Use `ensure_delivery => false` when you want the ability to temporarily disable a
downstream pipeline without blocking any upstream pipelines sending to it.
A blocked downstream pipeline blocks the sending output/pipeline regardless of the value of the `ensure_delivery` flag.
These delivery guarantees also inform the shutdown behavior of this feature. When performing a pipeline reload, changes will be made immediately as the user requests, even if that means removing a downstream pipeline an upstream pipeline sends to. This will cause the upstream pipeline to block. You must restore the downstream pipeline to cleanly shutdown Logstash. You may issue a force kill, but inflight events may be lost, unless the persistent queue is in use.
These delivery guarantees also inform the shutdown behavior of this feature. When performing a pipeline reload, changes
will be made immediately as the user requests, even if that means removing a downstream pipeline receiving events from
an upstream pipeline. This will cause the upstream pipeline to block. You must restore the downstream pipeline to
cleanly shut down Logstash. You may issue a force kill, but inflight events may be lost unless the persistent queue is
enabled for that pipeline.
[[avoid-cycles]]
===== Avoid cycles