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Elastic Docs ›Elasticsearch Guide [8.11] ›Index modules

Index blocks

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Index blocks

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Index blocks limit the kind of operations that are available on a certain index. The blocks come in different flavours, allowing to block write, read, or metadata operations. The blocks can be set / removed using dynamic index settings, or can be added using a dedicated API, which also ensures for write blocks that, once successfully returning to the user, all shards of the index are properly accounting for the block, for example that all in-flight writes to an index have been completed after adding the write block.

Index block settings

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The following dynamic index settings determine the blocks present on an index:

index.blocks.read_only
Set to true to make the index and index metadata read only, false to allow writes and metadata changes.
index.blocks.read_only_allow_delete

Similar to index.blocks.write, but also allows deleting the index to make more resources available. The disk-based shard allocator may add and remove this block automatically.

Deleting documents from an index to release resources - rather than deleting the index itself - can increase the index size over time. When index.blocks.read_only_allow_delete is set to true, deleting documents is not permitted. However, deleting the index itself releases the read-only index block and makes resources available almost immediately.

Elasticsearch adds the read-only index block automatically when the disk utilization exceeds the flood stage watermark, controlled by the cluster.routing.allocation.disk.watermark.flood_stage and cluster.routing.allocation.disk.watermark.flood_stage.max_headroom settings, and removes the block automatically when the disk utilization falls under the high watermark, controlled by the cluster.routing.allocation.disk.watermark.high and cluster.routing.allocation.disk.watermark.high.max_headroom settings. Refer to Fix watermark errors to resolve watermark issues.

index.blocks.read
Set to true to disable read operations against the index.
index.blocks.write
Set to true to disable data write operations against the index. Unlike read_only, this setting does not affect metadata. For instance, you can adjust the settings of an index with a write block, but you cannot adjust the settings of an index with a read_only block.
index.blocks.metadata
Set to true to disable index metadata reads and writes.

Add index block API

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Adds an index block to an index.

PUT /my-index-000001/_block/write

Request

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PUT /<index>/_block/<block>

Path parameters

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<index>

(Optional, string) Comma-separated list or wildcard expression of index names used to limit the request.

By default, you must explicitly name the indices you are adding blocks to. To allow the adding of blocks to indices with _all, *, or other wildcard expressions, change the action.destructive_requires_name setting to false. You can update this setting in the elasticsearch.yml file or using the cluster update settings API.

<block>

(Required, string) Block type to add to the index.

Valid values for <block>
metadata
Disable metadata changes, such as closing the index.
read
Disable read operations.
read_only
Disable write operations and metadata changes.
write
Disable write operations. However, metadata changes are still allowed.

Query parameters

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allow_no_indices

(Optional, Boolean) If false, the request returns an error if any wildcard expression, index alias, or _all value targets only missing or closed indices. This behavior applies even if the request targets other open indices. For example, a request targeting foo*,bar* returns an error if an index starts with foo but no index starts with bar.

Defaults to true.

expand_wildcards

(Optional, string) Type of index that wildcard patterns can match. If the request can target data streams, this argument determines whether wildcard expressions match hidden data streams. Supports comma-separated values, such as open,hidden. Valid values are:

all
Match any data stream or index, including hidden ones.
open
Match open, non-hidden indices. Also matches any non-hidden data stream.
closed
Match closed, non-hidden indices. Also matches any non-hidden data stream. Data streams cannot be closed.
hidden
Match hidden data streams and hidden indices. Must be combined with open, closed, or both.
none
Wildcard patterns are not accepted.

Defaults to open.

ignore_unavailable
(Optional, Boolean) If false, the request returns an error if it targets a missing or closed index. Defaults to false.
master_timeout
(Optional, time units) Period to wait for a connection to the master node. If no response is received before the timeout expires, the request fails and returns an error. Defaults to 30s.
timeout
(Optional, time units) Period to wait for a response. If no response is received before the timeout expires, the request fails and returns an error. Defaults to 30s.

Examples

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The following example shows how to add an index block:

PUT /my-index-000001/_block/write

The API returns following response:

{
  "acknowledged" : true,
  "shards_acknowledged" : true,
  "indices" : [ {
    "name" : "my-index-000001",
    "blocked" : true
  } ]
}
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