couchbase: allow to configure bucket replicas and default to 0.

This change allows the user to configure the number of bucket replicas
and defaults it to 0 since most of the time the user ever only needs
no replicas since it is a single container.

Note: technically this is a behavioral change since before the number
of replicas was 1 (if not defined) but this causes issues when
testing transactions (as seen in testcontainers#5835).

Fixes testcontainers#5835

modules/couchbase/src/main/java/org/testcontainers/couchbase/BucketDefinition.java

@@ -29,10 +29,32 @@ public class BucketDefinition {
 
     private int quota = 100;
 
+    private int numReplicas = 0;
+
     public BucketDefinition(final String name) {
         this.name = name;
     }
 
+    /**
+     * Allows to configure the number of replicas on a bucket (defaults to 0).
+     * <p>
+     * By default the bucket is initialized with 0 replicas since only a single container is launched. Modifying
+     * this value can still be useful in some test scenarios (i.e. to test failures with the wrong number of replicas
+     * and durability requirements on operations).
+     * <p>
+     * Couchbase buckets can have a maximum of three replicas configured.
+     *
+     * @param numReplicas the number of replicas to configure.
+     * @return this {@link BucketDefinition} for chaining purposes.
+     */
+    public BucketDefinition withReplicas(final int numReplicas) {
+        if (numReplicas < 0 || numReplicas > 3) {
+            throw new IllegalArgumentException("The number of replicas must be between 0 and 3 (inclusive)");
+        }
+        this.numReplicas = numReplicas;
+        return this;
+    }
+
     /**
      * Enables flush for this bucket (disabled by default).
      *
@@ -45,9 +67,9 @@ public BucketDefinition withFlushEnabled(final boolean flushEnabled) {
     }
 
     /**
-     * Sets a custom bucket quota (100MB by default).
+     * Sets a custom bucket quota (100MiB by default).
      *
-     * @param quota the quota to set for the bucket.
+     * @param quota the quota to set for the bucket in mebibytes.
      * @return this {@link BucketDefinition} for chaining purposes.
      */
     public BucketDefinition withQuota(final int quota) {
@@ -84,4 +106,8 @@ public boolean hasPrimaryIndex() {
     public int getQuota() {
         return quota;
     }
+
+    public int getNumReplicas() {
+        return numReplicas;
+    }
 }

modules/couchbase/src/main/java/org/testcontainers/couchbase/CouchbaseContainer.java

@@ -573,6 +573,7 @@ private void createBuckets() {
                     .add("name", bucket.getName())
                     .add("ramQuotaMB", Integer.toString(bucket.getQuota()))
                     .add("flushEnabled", bucket.hasFlushEnabled() ? "1" : "0")
+                    .add("replicaNumber", Integer.toString(bucket.getNumReplicas()))
                     .build(),
                 true
             );