Vector attempts to make it clear which guarantees you can expect from it. We categorize all components by their targeted delivery guarantee and also by their general stability. This helps you make the appropriate trade-offs for your use case.

Here you can find an overview of delivery guarantee types and their meaning as well as how we label the stability of our components. Next, you can head over to the components page and use filters to see which components support specific guarantees.

Delivery guarantees


The at-least-once delivery guarantee ensures that an event received by a Vector component is ultimately delivered at least once. While rare, it is possible for an event to be delivered more than once. See the Does Vector support exactly-once delivery? FAQ below).

In order to achieve at-least-once delivery between restarts your source must be configured to use disk-based buffers:

    type = "disk"
    when_full = "block"
    max_size = 104900000 # 100MiB

Refer to each sink’s documentation for further guidance on its buffer options.

Best effort

A best-effort delivery guarantee means that a Vector component makes a best effort to deliver each event but it can’t guarantee delivery. This is usually due to limitations of the underlying protocol, which is outside Vector’s control.

Note that this is not the same as at-most-once delivery, as it’is still possible for Vector to introduce duplicates under extreme circumstances.

Stability guarantees


The stable status is a subjective status defined by the Vector team. It’s intended to give you a general idea of a feature’s suitability for production environments. A feature is considered stable if it meets the following criteria:

  1. A meaningful number of users (generally over 50) have been using the feature in a production environment for a sustained period of time without issue.

  2. The feature has had sufficient time (generally more than 4 months) to be community tested.

  3. The feature API is stable and unlikely to change.

  4. There are no major open bugs for the feature.


The beta status means that a feature has not met the criteria outlined in the stable section and therefore should be used with caution in production environments.


The deprecated status means that a feature will be removed in the next major version of Vector. We will provide ample time to transition and, when possible, strive to retain backward compatibility.


Do I need at-least-once delivery?

One of the unique advantages of the metrics and logging use cases is that data is usually used for diagnostic purposes only. Therefore, losing the occasional event has little impact on your business. This affords you the opportunity to provision your pipeline towards performance, simplicity, and cost reduction. On the other hand, if you’re using your data to perform business critical functions, then data loss is not acceptable and therefore requires “at-least-once” delivery.

To clarify, even though a source or sink is marked as “best effort” it doesn’t mean Vector takes delivery lightly. In fact, once data is within the boundary of Vector it won’t be lost if you’ve configured on-disk buffers. Data loss for “best-effort” sources and sinks is almost always due to the limitations of the underlying protocol.

Does Vector support exactly-once delivery?

No, Vector does not support exactly once delivery. There are future plans to partially support this for sources and sinks that support it, for example Kafka, but it remains unclear if Vector will ever be able to achieve this. We recommend subscribing to our mailing list, which will keep you in the loop if this ever changes.

How can I find components that meet these guarantees?

Head over to the components page and use the guarantee filters.