Update nf-azure: Add Azure Batch node communication mode option

docs/azure.mdx

@@ -619,6 +619,16 @@ Nextflow can submit tasks to existing pools that are already attached to a virtu
 Virtual networks require Microsoft Entra authentication (service principal or managed identity).
 :::
 
+**Node communication mode**
+
+Pools can be configured to use [simplified compute node communication](https://learn.microsoft.com/en-us/azure/batch/simplified-compute-node-communication), which changes how the Batch service communicates with the compute nodes and reduces the outbound network access required by the nodes.
+
+```groovy
+azure.batch.pools.<pool-name>.targetCommunicationMode = 'simplified'  // 'simplified' or 'classic'
+```
+
+When this option is not set, the Azure Batch service selects the communication mode.
+
 **Start tasks**
 
 Start tasks are optional commands that run when a node joins the pool. They are useful for setting up the node environment or for running other commands that need to be executed when the node is created.

docs/reference/config.mdx

@@ -577,6 +577,10 @@ Enable the `startTask` to run with elevated access (default`false`).
 
 The `startTask` that is executed as the node joins the Azure Batch node pool.
 
+##### `azure.batch.pools.<name>.targetCommunicationMode`
+
+The node communication mode used by the pool. Can be either `classic` or `simplified`. When not set, the Azure Batch service selects the mode. In `simplified` mode the Batch service initiates communication with the compute nodes, reducing the outbound network access required by the nodes.
+
 ##### `azure.batch.pools.<name>.virtualNetwork`
 
 <AddedInVersion version="23.04" />

plugins/nf-azure/src/main/nextflow/cloud/azure/batch/AzBatchService.groovy

@@ -952,6 +952,10 @@ class AzBatchService implements Closeable {
             poolParams.setTaskSchedulingPolicy( new BatchTaskSchedulingPolicy(pol) )
         }
 
+        // node communication mode
+        if( spec.opts.targetCommunicationMode )
+            poolParams.setTargetNodeCommunicationMode( spec.opts.targetCommunicationMode )
+
         // mount points
         if ( config.storage().fileShares ) {
             List<MountConfiguration> mountConfigs = new ArrayList(config.storage().fileShares.size())

plugins/nf-azure/src/main/nextflow/cloud/azure/config/AzPoolOpts.groovy

@@ -16,6 +16,7 @@
 
 package nextflow.cloud.azure.config
 
+import com.azure.compute.batch.models.BatchNodeCommunicationMode
 import com.azure.compute.batch.models.ImageVerificationType
 import com.azure.compute.batch.models.OSType
 import com.google.common.hash.Hasher
@@ -144,6 +145,12 @@ class AzPoolOpts implements CacheFunnel, ConfigScope {
     """)
     final String vmType
 
+    @ConfigOption
+    @Description("""
+        The node communication mode used by the pool. Can be either `classic` or `simplified`. When not set, the Azure Batch service selects the mode. In `simplified` mode the Batch service initiates communication with the compute nodes, reducing the outbound network access required by the nodes.
+    """)
+    final BatchNodeCommunicationMode targetCommunicationMode
+
     OSType osType = DEFAULT_OS_TYPE
     ImageVerificationType verification = ImageVerificationType.VERIFIED
 
@@ -175,6 +182,18 @@ class AzPoolOpts implements CacheFunnel, ConfigScope {
         this.password = opts.password
         this.virtualNetwork = opts.virtualNetwork
         this.lowPriority = opts.lowPriority as boolean
+        this.targetCommunicationMode = parseCommunicationMode(opts.targetCommunicationMode)
+    }
+
+    protected static BatchNodeCommunicationMode parseCommunicationMode(value) {
+        if( value == null )
+            return null
+        if( value instanceof BatchNodeCommunicationMode )
+            return value
+        final str = value.toString().toLowerCase()
+        if( str == 'simplified' ) return BatchNodeCommunicationMode.SIMPLIFIED
+        if( str == 'classic' ) return BatchNodeCommunicationMode.CLASSIC
+        throw new IllegalArgumentException("Invalid azure.batch.pools.<name>.targetCommunicationMode value: '$value' - expected 'simplified' or 'classic'")
     }
 
     @Override
@@ -195,6 +214,7 @@ class AzPoolOpts implements CacheFunnel, ConfigScope {
         hasher.putUnencodedChars(schedulePolicy ?: '')
         hasher.putUnencodedChars(virtualNetwork ?: '')
         hasher.putBoolean(lowPriority)
+        hasher.putUnencodedChars(targetCommunicationMode?.toString() ?: '')
         hasher.putUnencodedChars(startTask.script ?: '')
         hasher.putBoolean(startTask.privileged)
         return hasher

plugins/nf-azure/src/test/nextflow/cloud/azure/config/AzPoolOptsTest.groovy

@@ -16,6 +16,9 @@
 
 package nextflow.cloud.azure.config
 
+import com.azure.compute.batch.models.BatchNodeCommunicationMode
+import com.google.common.hash.Hashing
+import nextflow.util.CacheHelper
 import nextflow.util.Duration
 import spock.lang.Specification
 /**
@@ -48,6 +51,39 @@ class AzPoolOptsTest extends Specification {
         !opts.lowPriority
         !opts.startTask.script
         !opts.startTask.privileged
+        opts.targetCommunicationMode == null
+    }
+
+    def 'should parse the target communication mode' () {
+        expect:
+        new AzPoolOpts([targetCommunicationMode: VALUE]).targetCommunicationMode == EXPECTED
+        where:
+        VALUE         | EXPECTED
+        null          | null
+        'simplified'  | BatchNodeCommunicationMode.SIMPLIFIED
+        'classic'     | BatchNodeCommunicationMode.CLASSIC
+        'SIMPLIFIED'  | BatchNodeCommunicationMode.SIMPLIFIED
+        'CLASSIC'     | BatchNodeCommunicationMode.CLASSIC
+    }
+
+    def 'should reject an invalid target communication mode' () {
+        when:
+        new AzPoolOpts([targetCommunicationMode: 'bogus'])
+        then:
+        def e = thrown(IllegalArgumentException)
+        e.message.contains('targetCommunicationMode')
+    }
+
+    private static String hash(AzPoolOpts opts) {
+        opts.funnel(Hashing.murmur3_128().newHasher(), CacheHelper.HashMode.STANDARD).hash().toString()
+    }
+
+    def 'pool hash should differ when communication mode differs' () {
+        given:
+        def base = new AzPoolOpts()
+        def classic = new AzPoolOpts([targetCommunicationMode: 'classic'])
+        expect:
+        hash(base) != hash(classic)
     }
 
     def 'should create pool with custom options' () {