The endpoint `_snapshottable_features` is long and implies incorrect
things about this API - it is used not just for snapshots, but also for
the upcoming reset API. Following discussions on the team, this commit
changes the endpoint to `_features` and removes the connection between
this API and snapshots, as snapshots are not the only use for the output
of this API.
This PR expands the meaning of `include_global_state` for snapshots to include system indices. If `include_global_state` is `true` on creation, system indices will be included in the snapshot regardless of the contents of the `indices` field. If `include_global_state` is `true` on restoration, system indices will be restored (if included in the snapshot), regardless of the contents of the `indices` field. Index renaming is not applied to system indices, as system indices rely on their names matching certain patterns. If restored system indices are already present, they are automatically deleted prior to restoration from the snapshot to avoid conflicts.
This behavior can be overridden to an extent by including a new field in the snapshot creation or restoration call, `feature_states`, which contains an array of strings indicating the "feature" for which system indices should be snapshotted or restored. For example, this call will only restore the `watcher` and `security` system indices (in addition to `index_1`):
```
POST /_snapshot/my_repository/snapshot_2/_restore
{
"indices": "index_1",
"include_global_state": true,
"feature_states": ["watcher", "security"]
}
```
If `feature_states` is present, the system indices associated with those features will be snapshotted or restored regardless of the value of `include_global_state`. All system indices can be omitted by providing a special value of `none` (`"feature_states": ["none"]`), or included by omitting the field or explicitly providing an empty array (`"feature_states": []`), similar to the `indices` field.
The list of currently available features can be retrieved via a new "Get Snapshottable Features" API:
```
GET /_snapshottable_features
```
which returns a response of the form:
```
{
"features": [
{
"name": "tasks",
"description": "Manages task results"
},
{
"name": "kibana",
"description": "Manages Kibana configuration and reports"
}
]
}
```
Features currently map one-to-one with `SystemIndexPlugin`s, but this should be considered an implementation detail. The Get Snapshottable Features API and snapshot creation rely upon all relevant plugins being installed on the master node.
Further, the list of feature states included in a given snapshot is exposed by the Get Snapshot API, which now includes a new field, `feature_states`, which contains a list of the feature states and their associated system indices which are included in the snapshot. All system indices in feature states are also included in the `indices` array for backwards compatibility, although explicitly requesting system indices included in a feature state is deprecated. For example, an excerpt from the Get Snapshot API showing `feature_states`:
```
"feature_states": [
{
"feature_name": "tasks",
"indices": [
".tasks"
]
}
],
"indices": [
".tasks",
"test1",
"test2"
]
```
Co-authored-by: William Brafford <william.brafford@elastic.co>
* We now have concurrent repository operations so the one at a time limit does not apply any longer
* Initialization was never slow solely due to loading information about all existing snaphots (though this contributed)
but also because two cluster state updates and a few writes to the repository had to happen before initialization could return
* Repo data necessary for a snapshot create operation is now cached on heap so loading it is effectively instant
* Snapshot initialization is just a single CS update now
* Initialization does no writes to the repository whatsoever
* Fixed missing `repository`
* Adding create index snapshot API page.
* Condense API description.
* Remove parameter from query.
* Add POST method and remove `-name` from the snapshot variable.
* Expand description of `<snapshot>`.
* Add data streams to introduction and expand the overall description.
* Add support for data streams.
* Add support for data streams.
* Add data stream and reference for "point-in-time view".
* Add data streams.
* Change `my_backup` to `my_repository`.
* Add description of boolean options for `wait_for_completion` parameter.
* Change command --> response
* Clarify `indices` parameter description
* Update `ignore-unavailable` parameter description
* Reword example description
* Remove "index" from API name
* Incorporating review comments from James R.
* Adding a much better request + response
* Clarify `include_global_state` description
* Incorporating additional edits.
* Changing my_backup to my_repository in example.
* Update snippet test to avoid failures
* Update TESTRESPONSE snippets
* Remove errant space
* Removing the parameter per reviewer comments
