MINOR: fix docs upgrade instructions fro 3.9 and 3.8 (apache#17447)

* MINOR: Fix upgrade instructions for 3.8 and 3.9

Signed-off-by: Josep Prat <[email protected]>

Reviewers: Chia-Ping Tsai <[email protected]>, Colin McCabe <[email protected]>

Author: jlprat

docs/upgrade.html

@@ -20,6 +20,68 @@
 <script id="upgrade-template" type="text/x-handlebars-template">
 
 <h4><a id="upgrade_3_9_0" href="#upgrade_3_9_0">Upgrading to 3.9.0 from any version 0.8.x through 3.8.x</a></h4>
+
+    <h5><a id="upgrade_390_zk" href="#upgrade_390_zk">Upgrading ZooKeeper-based clusters</a></h5>
+    <p><b>If you are upgrading from a version prior to 2.1.x, please see the note in step 5 below about the change to the schema used to store consumer offsets.
+        Once you have changed the inter.broker.protocol.version to the latest version, it will not be possible to downgrade to a version prior to 2.1.</b></p>
+
+    <p><b>For a rolling upgrade:</b></p>
+
+    <ol>
+        <li>Update server.properties on all brokers and add the following properties. CURRENT_KAFKA_VERSION refers to the version you
+            are upgrading from. CURRENT_MESSAGE_FORMAT_VERSION refers to the message format version currently in use. If you have previously
+            overridden the message format version, you should keep its current value. Alternatively, if you are upgrading from a version prior
+            to 0.11.0.x, then CURRENT_MESSAGE_FORMAT_VERSION should be set to match CURRENT_KAFKA_VERSION.
+            <ul>
+                <li>inter.broker.protocol.version=CURRENT_KAFKA_VERSION (e.g. <code>3.8</code>, <code>3.7</code>, etc.)</li>
+                <li>log.message.format.version=CURRENT_MESSAGE_FORMAT_VERSION  (See <a href="#upgrade_10_performance_impact">potential performance impact
+                    following the upgrade</a> for the details on what this configuration does.)</li>
+            </ul>
+            If you are upgrading from version 2.4.0 or above, and you have not overridden the message format, then you only need to override
+            the inter-broker protocol version. However, before doing this, make sure ZooKeeper is upgraded to version 3.8.3 or higher.
+            <ul>
+                <li>inter.broker.protocol.version=CURRENT_KAFKA_VERSION (e.g. <code>3.8</code>, <code>3.7</code>, etc.)</li>
+            </ul>
+        </li>
+        <li>Upgrade the brokers one at a time: shut down the broker, update the code, and restart it. Once you have done so, the
+            brokers will be running the latest version and you can verify that the cluster's behavior and performance meets expectations.
+            It is still possible to downgrade at this point if there are any problems.
+        </li>
+        <li>Once the cluster's behavior and performance has been verified, bump the protocol version by editing
+            <code>inter.broker.protocol.version</code> and setting it to <code>3.9</code>.
+        </li>
+        <li>Restart the brokers one by one for the new protocol version to take effect. Once the brokers begin using the latest
+            protocol version, it will no longer be possible to downgrade the cluster to an older version.
+        </li>
+        <li>If you have overridden the message format version as instructed above, then you need to do one more rolling restart to
+            upgrade it to its latest version. Once all (or most) consumers have been upgraded to 0.11.0 or later,
+            change log.message.format.version to 3.8 on each broker and restart them one by one. Note that the older Scala clients,
+            which are no longer maintained, do not support the message format introduced in 0.11, so to avoid conversion costs
+            (or to take advantage of <a href="#upgrade_11_exactly_once_semantics">exactly once semantics</a>),
+            the newer Java clients must be used.
+        </li>
+    </ol>
+
+    <h5><a id="upgrade_390_kraft" href="#upgrade_390_kraft">Upgrading KRaft-based clusters</a></h5>
+    <p><b>If you are upgrading from a version prior to 3.3.0, please see the note in step 3 below. Once you have changed the metadata.version to the latest version, it will not be possible to downgrade to a version prior to 3.3-IV0.</b></p>
+
+    <p><b>For a rolling upgrade:</b></p>
+
+    <ol>
+        <li>Upgrade the brokers one at a time: shut down the broker, update the code, and restart it. Once you have done so, the
+            brokers will be running the latest version and you can verify that the cluster's behavior and performance meets expectations.
+        </li>
+        <li>Once the cluster's behavior and performance has been verified, bump the metadata.version by running
+            <code>
+                bin/kafka-features.sh upgrade --metadata 3.9
+            </code>
+        </li>
+        <li>Note that cluster metadata downgrade is not supported in this software version.
+            Every <a href="https://github.com/apache/kafka/blob/trunk/server-common/src/main/java/org/apache/kafka/server/common/MetadataVersion.java">MetadataVersion</a>
+            after 3.2.x has a boolean parameter that indicates if there are metadata changes (i.e. <code>IBP_3_3_IV3(7, "3.3", "IV3", true)</code> means this version has metadata changes).
+            Given your current and target versions, a downgrade is only possible if there are no metadata changes in the versions between.</li>
+    </ol>
+
     <h5><a id="upgrade_390_notable" href="#upgrade_390_notable">Notable changes in 3.9.0</a></h5>
     <ul>
         <li>In case you run your Kafka clusters with no execution permission for the <code>/tmp</code> partition, Kafka will not work properly. It might either refuse to start or fail
@@ -123,6 +185,67 @@ <h5><a id="upgrade_381_notable" href="#upgrade_381_notable">Notable changes in 3
 
 <h4><a id="upgrade_3_8_0" href="#upgrade_3_8_0">Upgrading to 3.8.0 from any version 0.8.x through 3.7.x</a></h4>
 
+    <h5><a id="upgrade_380_zk" href="#upgrade_380_zk">Upgrading ZooKeeper-based clusters</a></h5>
+    <p><b>If you are upgrading from a version prior to 2.1.x, please see the note in step 5 below about the change to the schema used to store consumer offsets.
+        Once you have changed the inter.broker.protocol.version to the latest version, it will not be possible to downgrade to a version prior to 2.1.</b></p>
+
+    <p><b>For a rolling upgrade:</b></p>
+
+    <ol>
+        <li>Update server.properties on all brokers and add the following properties. CURRENT_KAFKA_VERSION refers to the version you
+            are upgrading from. CURRENT_MESSAGE_FORMAT_VERSION refers to the message format version currently in use. If you have previously
+            overridden the message format version, you should keep its current value. Alternatively, if you are upgrading from a version prior
+            to 0.11.0.x, then CURRENT_MESSAGE_FORMAT_VERSION should be set to match CURRENT_KAFKA_VERSION.
+            <ul>
+                <li>inter.broker.protocol.version=CURRENT_KAFKA_VERSION (e.g. <code>3.7</code>, <code>3.6</code>, etc.)</li>
+                <li>log.message.format.version=CURRENT_MESSAGE_FORMAT_VERSION  (See <a href="#upgrade_10_performance_impact">potential performance impact
+                    following the upgrade</a> for the details on what this configuration does.)</li>
+            </ul>
+            If you are upgrading from version 2.4.0 or above, and you have not overridden the message format, then you only need to override
+            the inter-broker protocol version. However, before doing this, make sure ZooKeeper is upgraded to version 3.8.3 or higher.
+            <ul>
+                <li>inter.broker.protocol.version=CURRENT_KAFKA_VERSION (e.g. <code>3.7</code>, <code>3.6</code>, etc.)</li>
+            </ul>
+        </li>
+        <li>Upgrade the brokers one at a time: shut down the broker, update the code, and restart it. Once you have done so, the
+            brokers will be running the latest version and you can verify that the cluster's behavior and performance meets expectations.
+            It is still possible to downgrade at this point if there are any problems.
+        </li>
+        <li>Once the cluster's behavior and performance has been verified, bump the protocol version by editing
+            <code>inter.broker.protocol.version</code> and setting it to <code>3.8</code>.
+        </li>
+        <li>Restart the brokers one by one for the new protocol version to take effect. Once the brokers begin using the latest
+            protocol version, it will no longer be possible to downgrade the cluster to an older version.
+        </li>
+        <li>If you have overridden the message format version as instructed above, then you need to do one more rolling restart to
+            upgrade it to its latest version. Once all (or most) consumers have been upgraded to 0.11.0 or later,
+            change log.message.format.version to 3.8 on each broker and restart them one by one. Note that the older Scala clients,
+            which are no longer maintained, do not support the message format introduced in 0.11, so to avoid conversion costs
+            (or to take advantage of <a href="#upgrade_11_exactly_once_semantics">exactly once semantics</a>),
+            the newer Java clients must be used.
+        </li>
+    </ol>
+
+    <h5><a id="upgrade_380_kraft" href="#upgrade_380_kraft">Upgrading KRaft-based clusters</a></h5>
+    <p><b>If you are upgrading from a version prior to 3.3.0, please see the note in step 3 below. Once you have changed the metadata.version to the latest version, it will not be possible to downgrade to a version prior to 3.3-IV0.</b></p>
+
+    <p><b>For a rolling upgrade:</b></p>
+
+    <ol>
+        <li>Upgrade the brokers one at a time: shut down the broker, update the code, and restart it. Once you have done so, the
+            brokers will be running the latest version and you can verify that the cluster's behavior and performance meets expectations.
+        </li>
+        <li>Once the cluster's behavior and performance has been verified, bump the metadata.version by running
+            <code>
+                bin/kafka-features.sh upgrade --metadata 3.8
+            </code>
+        </li>
+        <li>Note that cluster metadata downgrade is not supported in this software version.
+            Every <a href="https://github.com/apache/kafka/blob/trunk/server-common/src/main/java/org/apache/kafka/server/common/MetadataVersion.java">MetadataVersion</a>
+            after 3.2.x has a boolean parameter that indicates if there are metadata changes (i.e. <code>IBP_3_3_IV3(7, "3.3", "IV3", true)</code> means this version has metadata changes).
+            Given your current and target versions, a downgrade is only possible if there are no metadata changes in the versions between.</li>
+    </ol>
+
     <h5><a id="upgrade_380_notable" href="#upgrade_380_notable">Notable changes in 3.8.0</a></h5>
     <ul>
         <li>MirrorMaker 2 can now emit checkpoints for offsets mirrored before the start of the Checkpoint task for improved offset translation.