Get exit code from pod to manage OOM in k8s

plugins/nf-k8s/src/main/nextflow/k8s/K8sTaskHandler.groovy

@@ -424,7 +424,15 @@ class K8sTaskHandler extends TaskHandler implements FusionAwareTask {
             }
             else {
                 // finalize the task
-                task.exitStatus = readExitFile()
+                // read the exit code from the K8s container terminated state, if 0 (successful) or missing
+                // take the exit code from the `.exitcode` file created by nextflow
+                // the rationale is that in case of error (e.g. OOMKilled, pod eviction), the exit code from
+                // the K8s API is more reliable because the container may terminate before the exit file is written
+                // See https://github.com/nextflow-io/nextflow/issues/6436
+                // https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.30/#containerstateterminated-v1-core
+                log.trace("[k8s] Container Terminated state ${state.terminated}")
+                final k8sExitCode = (state.terminated as Map)?.exitCode as Integer
+                task.exitStatus = k8sExitCode ?: readExitFile()
                 task.stdout = outputFile
                 task.stderr = errorFile
             }

plugins/nf-k8s/src/test/nextflow/k8s/K8sTaskHandlerTest.groovy

@@ -509,6 +509,32 @@ class K8sTaskHandlerTest extends Specification {
 
     }
 
+    def 'should use K8s exit code when available' () {
+        given:
+        def ERR_FILE = Paths.get('err.file')
+        def OUT_FILE = Paths.get('out.file')
+        def POD_NAME = 'pod-xyz'
+        def client = Mock(K8sClient)
+        def termState = [ reason: "Error",
+                          startedAt: "2018-01-13T10:09:36Z",
+                          finishedAt: "2018-01-13T10:19:36Z",
+                          exitCode: 137 ]
+        def task = new TaskRun()
+        def handler = Spy(new K8sTaskHandler(task: task, client:client, podName: POD_NAME, outputFile: OUT_FILE, errorFile: ERR_FILE))
+
+        when:
+        def result = handler.checkIfCompleted()
+        then:
+        1 * handler.getState() >> [terminated: termState]
+        1 * handler.updateTimestamps(termState)
+        0 * handler.readExitFile()
+        1 * handler.deletePodIfSuccessful(task) >> null
+        1 * handler.savePodLogOnError(task) >> null
+        handler.task.exitStatus == 137
+        handler.status == TaskStatus.COMPLETED
+        result == true
+    }
+
     def 'should kill a pod' () {
         given:
         def POD_NAME = 'pod-xyz'