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Deprecate LevelDB (#30213)

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* Deprecate LevelDB

In preparation of moving into the testing infra (or deleting it completely) at some distant future point in time

* Remove leveldb tests where there also is an inmem one

* More details in deprecation text, recommend inmem + journal proxy for testing etc.
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Johan Andrén 2021-06-02 13:37:52 +02:00 • committed by GitHub
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28
akka-docs/src/main/paradox/persistence-plugins.md
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@ -68,7 +68,10 @@ This plugin writes events to a local LevelDB instance.
@@@ warning
The LevelDB plugin cannot be used in an Akka Cluster since the storage is in a local file system.
@@@
@@@
The LevelDB journal is deprecated and it is not advised to build new applications with it.
As a replacement we recommend using [Akka Persistence JDBC](https://doc.akka.io/docs/akka-persistence-jdbc/current/index.html).
The LevelDB journal plugin config entry is `akka.persistence.journal.leveldb`. Enable this plugin by
defining config property:
@ -99,14 +102,8 @@ this end, LevelDB offers a special journal compaction function that is exposed v
### Shared LevelDB journal
For testing purposes a LevelDB instance can also be shared by multiple actor systems (on the same or on different nodes). This, for
example, allows persistent actors to failover to a backup node and continue using the shared journal instance from the
backup node.
@@@ warning
A shared LevelDB instance is a single point of failure and should therefore only be used for testing
purposes.
@@@
The LevelDB journal is deprecated and will be removed from a future Akka version, it is not advised to build new
applications with it. For testing in a multi node environment the "inmem" journal together with the @ref[proxy plugin](#persistence-plugin-proxy) can be used, but the actual journal used in production of applications is also a good choice.
@@@ note
This plugin has been supplanted by @ref:[Persistence Plugin Proxy](#persistence-plugin-proxy).
@ -165,20 +162,21 @@ you don't have to configure it.
### Persistence Plugin Proxy
For testing purposes a persistence plugin proxy allows sharing of journals and snapshot stores across multiple actor systems (on the same or
on different nodes). This, for example, allows persistent actors to failover to a backup node and continue using the
shared journal instance from the backup node. The proxy works by forwarding all the journal/snapshot store messages to a
single, shared, persistence plugin instance, and therefore supports any use case supported by the proxied plugin.
For testing purposes a persistence plugin proxy allows sharing of a journal and snapshot store on a single node across multiple
actor systems (on the same or on different nodes). This, for example, allows persistent actors to failover to a backup
node and continue using the shared journal instance from the backup node. The proxy works by forwarding all the
journal/snapshot store messages to a single, shared, persistence plugin instance, and therefore supports any use case
supported by the proxied plugin.
@@@ warning
A shared journal/snapshot store is a single point of failure and should therefore only be used for testing
A shared journal/snapshot store is a single point of failure and should only be used for testing
purposes.
@@@
The journal and snapshot store proxies are controlled via the `akka.persistence.journal.proxy` and
`akka.persistence.snapshot-store.proxy` configuration entries, respectively. Set the `target-journal-plugin` or
`target-snapshot-store-plugin` keys to the underlying plugin you wish to use (for example:
`akka.persistence.journal.leveldb`). The `start-target-journal` and `start-target-snapshot-store` keys should be
`akka.persistence.journal.inmem`). The `start-target-journal` and `start-target-snapshot-store` keys should be
set to `on` in exactly one actor system - this is the system that will instantiate the shared persistence plugin.
Next, the proxy needs to be told how to find the shared plugin. This can be done by setting the `target-journal-address`
and `target-snapshot-store-address` configuration keys, or programmatically by calling the

3
akka-docs/src/main/paradox/persistence-query-leveldb.md
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@ -1,5 +1,8 @@
# Persistence Query for LevelDB
The LevelDB journal and query plugin is deprecated and it is not advised to build new applications with it.
As a replacement we recommend using [Akka Persistence JDBC](https://doc.akka.io/docs/akka-persistence-jdbc/current/index.html).
## Dependency
To use Persistence Query, you must add the following dependency in your project:

2
akka-docs/src/main/paradox/persistence-query.md
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@ -266,8 +266,6 @@ used the next time this projection is started. This pattern is implemented in th
Query plugins are various (mostly community driven) `ReadJournal` implementations for all kinds
of available datastores. The complete list of available plugins is maintained on the Akka Persistence Query [Community Plugins](https://akka.io/community/#plugins-to-akka-persistence-query) page.
The plugin for LevelDB is described in @ref:[Persistence Query for LevelDB](persistence-query-leveldb.md).
This section aims to provide tips and guide plugin developers through implementing a custom query plugin.
Most users will not need to implement journals themselves, except if targeting a not yet supported datastore.

10
akka-docs/src/main/paradox/persistence.md
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@ -44,7 +44,7 @@ recover its state from these messages.
case of sender and receiver JVM crashes.
* `AsyncWriteJournal`: A journal stores the sequence of messages sent to a persistent actor. An application can control which messages
are journaled and which are received by the persistent actor without being journaled. Journal maintains `highestSequenceNr` that is increased on each message.
The storage backend of a journal is pluggable. The persistence extension comes with a "leveldb" journal plugin, which writes to the local filesystem.
The storage backend of a journal is pluggable.
Replicated journals are available as [Community plugins](https://akka.io/community/).
* *Snapshot store*: A snapshot store persists snapshots of a persistent actor's state. Snapshots are
used for optimizing recovery times. The storage backend of a snapshot store is pluggable.
@ -828,6 +828,10 @@ For more advanced schema evolution techniques refer to the @ref:[Persistence - S
## Testing with LevelDB journal
The LevelDB journal is deprecated and will be removed from a future Akka version, it is not advised to build new applications
with it. For testing the built in "inmem" journal or the actual journal that will be used in production of the application
is recommended. See @ref[Persistence Plugins](persistence-plugins.md) for some journal implementation choices.
When running tests with LevelDB default settings in `sbt`, make sure to set `fork := true` in your sbt project. Otherwise, you'll see an `UnsatisfiedLinkError`. Alternatively, you can switch to a LevelDB Java port by setting
@@snip [PersistencePluginDocSpec.scala](/akka-docs/src/test/scala/docs/persistence/PersistencePluginDocSpec.scala) { #native-config }
@ -836,9 +840,7 @@ or
@@snip [PersistencePluginDocSpec.scala](/akka-docs/src/test/scala/docs/persistence/PersistencePluginDocSpec.scala) { #shared-store-native-config }
in your Akka configuration. The LevelDB Java port is for testing purposes only.
Also note that for the LevelDB Java port, you will need the following dependencies:
in your Akka configuration. Also note that for the LevelDB Java port, you will need the following dependencies:
@@dependency[sbt,Maven,Gradle] {
group="org.iq80.leveldb"