Dowser.
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What Dowser.Migrator needs from a backend package to run migrations
against its engine: the cluster requests, and where it keeps which
migrations ran.
A backend's repo names its adapter — use Dowser.OpenSearch.Repo defines
__migration_adapter__/0 — so an application never names one.
Every callback takes the repo to send the request to (anything a :repo
option takes) and returns :ok/{:ok, result} or {:error, reason}.
Index names are physical indices unless a callback says otherwise; settings
are flat and index.-prefixed ("index.number_of_replicas"), mappings and
bodies have string keys.
use Dowser.Migration.Adapter gives a default dynamic_setting?/1.
Tracking
The adapter keeps one record per migration run — %{"version" => integer, "name" => string, "indices" => [string], "dropped" => [string], "separators" => %{index => string}}, given and returned as they are — and one
lock: a document only one migrator can create, holding "owner" and
"state" — what a copy in progress has changed, for mix dowser.recover
after a crash.
Summary
Types
An index as get_indices/2 returns it: "mappings", "settings" (flat,
without the index. prefix) and "aliases" (names).
Callbacks
Blocks writes to an index, once the writes in flight are done (the add-block API, not the setting).
The migrations recorded as run, in any order.
Creates an index from a create-index request body.
Deletes an index.
Whether the engine changes setting key (relative to index) on a live
index; anything else is changed by copying the documents.
Creates what tracking needs (its index) when missing.
The indices matching names — aliases, index names or patterns — keyed by
physical name; none for a name matching nothing.
The lock in place, or nil.
A background task's status, as the tasks API returns it: "completed",
then "response" (with "failures", "total", "created") or "error".
Takes the lock, creating it with lock; {:error, {:locked, lock}} with
the one in place when another migrator holds it.
Adds fields — and replaces _meta — with a put-mapping request body.
Updates settings; a nil value resets one.
Records a migration as run.
Starts copying source into dest in the background, through script
when not nil; returns the task's id.
Lifts an index's write block.
Moves alias name from index from to index to, atomically.
Releases the lock.
Removes a migration's record.
Replaces the lock's content.
Types
An index as get_indices/2 returns it: "mappings", "settings" (flat,
without the index. prefix) and "aliases" (names).
@type repo() :: Dowser.Repo.t()
@type result() :: :ok | {:error, term()}
Callbacks
Blocks writes to an index, once the writes in flight are done (the add-block API, not the setting).
The migrations recorded as run, in any order.
Creates an index from a create-index request body.
Deletes an index.
Whether the engine changes setting key (relative to index) on a live
index; anything else is changed by copying the documents.
Creates what tracking needs (its index) when missing.
@callback get_indices(repo(), names :: [String.t()]) :: {:ok, %{required(String.t()) => index()}} | {:error, term()}
The indices matching names — aliases, index names or patterns — keyed by
physical name; none for a name matching nothing.
The lock in place, or nil.
A background task's status, as the tasks API returns it: "completed",
then "response" (with "failures", "total", "created") or "error".
Takes the lock, creating it with lock; {:error, {:locked, lock}} with
the one in place when another migrator holds it.
Adds fields — and replaces _meta — with a put-mapping request body.
Updates settings; a nil value resets one.
Records a migration as run.
@callback reindex(repo(), source :: String.t(), dest :: String.t(), script :: map() | nil) :: {:ok, String.t()} | {:error, term()}
Starts copying source into dest in the background, through script
when not nil; returns the task's id.
Lifts an index's write block.
Moves alias name from index from to index to, atomically.
Releases the lock.
Removes a migration's record.
Replaces the lock's content.