feat: Enable auto-purge and set defaults

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+### Added
+
+- BREAKING: Enable auto-purge feature for data directory cleanup ([#1068]).
+
 ### Changed
 
 - Internal operator refactoring: introduce a build() step in the reconciler that
@@ -24,6 +28,7 @@ All notable changes to this project will be documented in this file.
 [#1053]: https://github.com/stackabletech/zookeeper-operator/pull/1053
 [#1060]: https://github.com/stackabletech/zookeeper-operator/pull/1060
 [#1063]: https://github.com/stackabletech/zookeeper-operator/pull/1063
+[#1068]: https://github.com/stackabletech/zookeeper-operator/pull/1068
 [#1070]: https://github.com/stackabletech/zookeeper-operator/pull/1070
 
 ## [26.7.0] - 2026-07-21

deploy/helm/chart_testing.yaml

@@ -1,3 +1,4 @@
+---
 remote: origin
 target-branch: main
 chart-dirs:

docs/modules/zookeeper/pages/data_directory.adoc

@@ -0,0 +1,39 @@
+= Data directory
+:description: How ZooKeeper manages its data directory and which zoo.cfg properties control it.
+:zk-admin-advanced: https://zookeeper.apache.org/doc/r3.9.5/zookeeperAdmin.html#sc_advancedConfiguration
+
+This page is meant as a general explanation of how ZooKeeper manages the files in its data directory over time.
+To see a simple list of the properties the operator sets in relation to that and their defaults, see xref:reference/zoo_cfg_properties.adoc#data-dir-props[`zoo.cfg` properties reference].
+
+== Data directory files
+
+The data directory is located at the path specified by `dataDir` in `zoo.cfg`.
+The operator sets this to `/stackable/data` by default.
+This directory contains two types of files, which together persist the ZNode data:
+
+* Transaction log files: An append-only write-ahead log. Every change to the ZNodes is appended here first.
+* Snapshot files: A full dump of the current state of all ZNodes. Snapshots let ZooKeeper recover quickly after a restart.
+
+ZooKeeper can write the transaction logs to a separate directory, configured with `dataLogDir`.
+The operator does not set this property, so both file types share `dataDir` and therefore the same volume.
+
+ZooKeeper pre-allocates its transaction log file in fixed-size blocks of a certain size (`preAllocSize`) so it does not have to grow the file with every write, which keeps writes fast.
+
+== Snapshot creation and auto-purge
+
+A snapshot is written and the transaction log rolled to a fresh file when either of two independent limits is reached:
+
+`snapCount`:: Create snapshot after roughly this many transactions. The operator does not set this property, consult the {zk-admin-advanced}[ZooKeeper Administrator's Guide{external-link-icon}^] for its default.
+`snapSizeLimitInKb`:: Create snapshot after the transaction log reaches roughly this size.
+
+Snapshots and their logs accumulate indefinitely unless the auto-purge feature is enabled.
+The operator enables this feature by default.
+
+There are two settings to control auto-purge:
+
+`autopurge.purgeInterval`:: Time between cleanup runs, in hours.
+`autopurge.snapRetainCount`:: How many of the most recent snapshots to keep, together with the transaction logs belonging to them. The rest are deleted during the cleanup.
+
+Together these two settings control how large the data directory can grow.
+`autopurge.snapRetainCount` sets how much history a cleanup keeps, while `autopurge.purgeInterval` sets how long it takes until the next cleanup, during which new snapshots and logs keep accumulating.
+The volume needs to be sized accordingly, see xref:usage_guide/resource_configuration.adoc[].

docs/modules/zookeeper/pages/reference/index.adoc

@@ -5,3 +5,4 @@ Consult the reference documentation section to find exhaustive information on:
 * Descriptions and default values of all properties in the CRDs used by this operator in the xref:reference/crds.adoc[].
 * The properties in the xref:reference/discovery.adoc[].
 * The xref:reference/commandline-parameters.adoc[] and xref:reference/environment-variables.adoc[] accepted by the operator.
+* The default settings for `zoo.cfg` properties in xref:reference/zoo_cfg_properties.adoc[].

docs/modules/zookeeper/pages/reference/zoo_cfg_properties.adoc

@@ -0,0 +1,40 @@
+= `zoo.cfg` properties
+:description: Reference for the zoo.cfg properties set by the Stackable Operator for Apache ZooKeeper.
+
+This is a reference page for `zoo.cfg` properties set by the operator.
+
+[[data-dir-props]]
+== Data directory properties
+
+The following `zoo.cfg` properties control how ZooKeeper manages the files in its data directory.
+You can override them using xref:usage_guide/overrides.adoc[configOverrides].
+
+[cols="2,1,2,3",options="header"]
+|===
+| Property | Unit | Default set by the operator | Description
+
+| `dataDir`
+| path
+| `/stackable/data`
+| The location where ZooKeeper stores the snapshots of its in-memory database and the transaction log of updates to that database.
+
+| `autopurge.purgeInterval`
+| hours
+| `6`
+| Time between cleanup runs. `0` disables auto-purge.
+
+| `autopurge.snapRetainCount`
+| count
+| `3`
+| Number of recent snapshots (and their transaction logs) to keep. Minimum `3`.
+
+| `snapSizeLimitInKb`
+| KiB
+| `102400` (= 100 MiB)
+| Take a snapshot after the log reaches roughly this size. A non-positive value disables this trigger.
+
+| `preAllocSize`
+| KiB
+| `16384` (= 16 MiB)
+| Block size in which the transaction log file is pre-allocated.
+|===

docs/modules/zookeeper/pages/usage_guide/resource_configuration.adoc

@@ -22,6 +22,9 @@ In the above example, all ZooKeeper nodes in the default group will store data (
 
 You can also configure which StorageClass to use, consult the xref:concepts:resources.adoc#storageclass[resources docs] to learn more.
 
+ZooKeeper stores both its snapshots and transaction logs on this volume.
+See the xref:data_directory.adoc[data directory docs] for how that data grows and is reclaimed over time.
+
 == Resource requests
 
 include::home:concepts:stackable_resource_requests.adoc[]

docs/modules/zookeeper/partials/nav.adoc

@@ -3,6 +3,7 @@
 ** xref:zookeeper:getting_started/first_steps.adoc[]
 * Concepts
 ** xref:zookeeper:znodes.adoc[]
+** xref:zookeeper:data_directory.adoc[]
 * xref:zookeeper:usage_guide/index.adoc[]
 ** xref:zookeeper:usage_guide/listenerclass.adoc[]
 ** xref:zookeeper:usage_guide/encryption.adoc[]
@@ -25,3 +26,4 @@
 ** xref:zookeeper:reference/discovery.adoc[]
 ** xref:zookeeper:reference/commandline-parameters.adoc[]
 ** xref:zookeeper:reference/environment-variables.adoc[]
+** xref:zookeeper:reference/zoo_cfg_properties.adoc[]

rust/operator-binary/src/zk_controller/build/properties/zoo_cfg.rs

@@ -22,6 +22,15 @@ const DEFAULT_INIT_LIMIT: &str = "5";
 const DEFAULT_SYNC_LIMIT: &str = "2";
 const DEFAULT_TICK_TIME: &str = "3000";
 
+const AUTOPURGE_SNAP_RETAIN_COUNT_KEY: &str = "autopurge.snapRetainCount";
+const DEFAULT_AUTOPURGE_SNAP_RETAIN_COUNT: &str = "3";
+const AUTOPURGE_PURGE_INTERVAL_KEY: &str = "autopurge.purgeInterval";
+const DEFAULT_AUTOPURGE_PURGE_INTERVAL: &str = "6"; // in hours
+const SNAP_SIZE_LIMIT_IN_KB_KEY: &str = "snapSizeLimitInKb";
+const DEFAULT_SNAP_SIZE_LIMIT_IN_KB: &str = "102400"; // 100MiB
+const PRE_ALLOC_SIZE_KEY: &str = "preAllocSize";
+const DEFAULT_PRE_ALLOC_SIZE: &str = "16384"; // 16MiB
+
 /// Builds the `server.<myid>` quorum entries for `zoo.cfg` from the expected pods.
 ///
 /// The pods are predicted from the validated role-group configs (`replicas` + `myidOffset`)
@@ -114,6 +123,22 @@ fn build_base(
         METRICS_PROVIDER_HTTP_PORT_KEY.to_string(),
         METRICS_PROVIDER_HTTP_PORT.to_string(),
     );
+    zoo_cfg.insert(
+        AUTOPURGE_SNAP_RETAIN_COUNT_KEY.to_string(),
+        DEFAULT_AUTOPURGE_SNAP_RETAIN_COUNT.to_string(),
+    );
+    zoo_cfg.insert(
+        AUTOPURGE_PURGE_INTERVAL_KEY.to_string(),
+        DEFAULT_AUTOPURGE_PURGE_INTERVAL.to_string(),
+    );
+    zoo_cfg.insert(
+        SNAP_SIZE_LIMIT_IN_KB_KEY.to_string(),
+        DEFAULT_SNAP_SIZE_LIMIT_IN_KB.to_string(),
+    );
+    zoo_cfg.insert(
+        PRE_ALLOC_SIZE_KEY.to_string(),
+        DEFAULT_PRE_ALLOC_SIZE.to_string(),
+    );
 
     // 2. TLS / quorum settings.
     zoo_cfg.extend(security.config_settings());

tests/templates/kuttl/smoke/10-assert.yaml

@@ -6,3 +6,4 @@ metadata:
 timeout: 300
 commands:
   - script: kubectl -n $NAMESPACE wait --for=condition=available=true zookeeperclusters.zookeeper.stackable.tech/test-zk --timeout 301s
+  - script: kubectl -n $NAMESPACE wait --for=create configmap/test-znode --timeout 301s

tests/templates/kuttl/smoke/14-assert.yaml.j2

@@ -322,6 +322,8 @@ commands:
       zoo.cfg: |
         admin.serverPort=8080
         authProvider.x509=org.apache.zookeeper.server.auth.X509AuthenticationProvider
+        autopurge.purgeInterval=6
+        autopurge.snapRetainCount=3
 {% if use_client_tls %}
         client.portUnification=true
 {% endif %}
@@ -330,13 +332,15 @@ commands:
         initLimit=5
         metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
         metricsProvider.httpPort=7000
+        preAllocSize=16384
         prop.common=group
         prop.group=group
         prop.role=role
         server.10=test-zk-server-primary-0.test-zk-server-primary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         server.11=test-zk-server-primary-1.test-zk-server-primary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         server.20=test-zk-server-secondary-0.test-zk-server-secondary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         serverCnxnFactory=org.apache.zookeeper.server.NettyServerCnxnFactory
+        snapSizeLimitInKb=102400
 {% if use_client_auth %}
         ssl.clientAuth=need
 {% endif %}
@@ -601,6 +605,8 @@ commands:
       zoo.cfg: |
         admin.serverPort=8080
         authProvider.x509=org.apache.zookeeper.server.auth.X509AuthenticationProvider
+        autopurge.purgeInterval=6
+        autopurge.snapRetainCount=3
 {% if use_client_tls %}
         client.portUnification=true
 {% endif %}
@@ -609,12 +615,14 @@ commands:
         initLimit=5
         metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
         metricsProvider.httpPort=7000
+        preAllocSize=16384
         prop.common=role
         prop.role=role
         server.10=test-zk-server-primary-0.test-zk-server-primary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         server.11=test-zk-server-primary-1.test-zk-server-primary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         server.20=test-zk-server-secondary-0.test-zk-server-secondary-headless.__NAMESPACE__.svc.cluster.local\:2888\:3888;{{ zk_client_port }}
         serverCnxnFactory=org.apache.zookeeper.server.NettyServerCnxnFactory
+        snapSizeLimitInKb=102400
 {% if use_client_auth %}
         ssl.clientAuth=need
 {% endif %}