feat(Kubernetes): Support init containers

Allow additional containers to be declared as init containers. Handle
them correctly when setting up the Kubernetes manifest.

This makes it possible to run some initialization tasks before an ORT
Server worker gets active.

Signed-off-by: Oliver Heger <oliver.heger@bosch.com>

Author: oheger-bosch

transport/kubernetes/src/main/kotlin/Container.kt

@@ -65,7 +65,13 @@ data class Container(
      * A list with the names of volume mounts to add to this container. The strings in the list reference the names of
      * declared volume mounts. In addition, volume mounts without a name are added to all containers.
      */
-    val volumeMounts: List<String> = emptyList()
+    val volumeMounts: List<String> = emptyList(),
+
+    /**
+     * A flag whether this container is an init container.
+     * See https://kubernetes.io/docs/concepts/workloads/pods/init-containers/
+     */
+    val isInitContainer: Boolean = false
 ) {
     /**
      * Return an optional [V1ResourceRequirements] object based on the properties related to resource requests and

transport/kubernetes/src/main/kotlin/KubernetesMessageSender.kt

@@ -20,6 +20,7 @@
 package org.eclipse.apoapsis.ortserver.transport.kubernetes
 
 import io.kubernetes.client.openapi.apis.BatchV1Api
+import io.kubernetes.client.openapi.models.V1ContainerFluent
 import io.kubernetes.client.openapi.models.V1EnvVar
 import io.kubernetes.client.openapi.models.V1EnvVarBuilder
 import io.kubernetes.client.openapi.models.V1JobBuilder
@@ -189,14 +190,34 @@ private fun <A : V1PodSpecFluent<A>> A.addContainers(
     namedMounts: Map<String, V1VolumeMount>
 ): A =
     (listOf(config.mainContainer) + config.additionalContainers).fold(this) { pod, container ->
-        pod.addNewContainer()
-            .withName(container.name)
-            .withImage(container.imageName.substituteVariables(variables))
-            .withImagePullPolicy(container.imagePullPolicy)
-            .withCommand(container.commands)
-            .withArgs(container.args)
-            .withEnv(environment)
-            .withResources(container.createResources(variables))
-            .withVolumeMounts(globalMounts + container.volumeMounts.mapNotNull { namedMounts[it] })
-            .endContainer()
+        if (container.isInitContainer) {
+            pod.addNewInitContainer()
+                .configureContainer(container, environment, variables, globalMounts, namedMounts)
+                .endInitContainer()
+        } else {
+            pod.addNewContainer()
+                .configureContainer(container, environment, variables, globalMounts, namedMounts)
+                .endContainer()
+        }
     }
+
+/**
+ * Configure this container fluent builder with all properties from the given [container]. The [environment] is set
+ * as env vars. Variable substitution is done based on the provided [variables]. Volume mounts are generated from
+ * [globalMounts] (added to all containers) and [namedMounts] (explicitly referenced by single containers).
+ */
+private fun <F : V1ContainerFluent<F>> F.configureContainer(
+    container: Container,
+    environment: List<V1EnvVar>,
+    variables: Map<String, String>,
+    globalMounts: List<V1VolumeMount>,
+    namedMounts: Map<String, V1VolumeMount>
+): F =
+    withName(container.name)
+        .withImage(container.imageName.substituteVariables(variables))
+        .withImagePullPolicy(container.imagePullPolicy)
+        .withCommand(container.commands)
+        .withArgs(container.args)
+        .withEnv(environment)
+        .withResources(container.createResources(variables))
+        .withVolumeMounts(globalMounts + container.volumeMounts.mapNotNull { namedMounts[it] })

transport/kubernetes/src/main/kotlin/KubernetesSenderConfig.kt

@@ -323,7 +323,8 @@ data class KubernetesSenderConfig(
                 cpuRequest = System.getenv("${prefix}CPU_REQUEST"),
                 memoryLimit = System.getenv("${prefix}MEMORY_LIMIT"),
                 memoryRequest = System.getenv("${prefix}MEMORY_REQUEST"),
-                volumeMounts = System.getenv("${prefix}VOLUME_MOUNTS").splitAt(splitCommaListRegex)
+                volumeMounts = System.getenv("${prefix}VOLUME_MOUNTS").splitAt(splitCommaListRegex),
+                isInitContainer = System.getenv("${prefix}INIT_CONTAINER")?.toBoolean() ?: false
             )
         }
 

transport/kubernetes/src/test/kotlin/KubernetesMessageSenderTest.kt

@@ -289,6 +289,41 @@ class KubernetesMessageSenderTest : StringSpec({
             expectMounts("dir1", "dir2", "secret-volume-1", "pvc-volume-2")
         }
     }
+
+    "Init containers can be created" {
+        val containerVariables = mapOf(
+            "INIT_INIT_CONTAINER" to "true",
+            "INIT_IMAGE_NAME" to "init-image:1.0",
+            "INIT_COMMANDS" to "initialize.sh",
+            "INIT_MEMORY_REQUEST" to "128",
+            "INIT_VOLUME_MOUNTS" to "secretMount"
+        )
+
+        val config = createConfig(
+            mapOf(
+                "additionalContainers" to "INIT",
+                "mountPvcs" to "",
+                "mountSecrets" to "secretMount=topSecret->/mnt/top/secret|sub-secret",
+                "mountEmptyDirs" to "dir1->/mnt/dir1"
+            ),
+            containerVariables
+        )
+
+        val job = createJob(config, message)
+
+        job.spec?.template?.spec?.containers.orEmpty() shouldHaveSize 1
+
+        job.spec?.template?.spec?.initContainers.orEmpty().single().shouldNotBeNull {
+            image shouldBe "init-image:1.0"
+            command shouldBe listOf("initialize.sh")
+            args shouldBe config.mainContainer.args
+            resources shouldNotBeNull {
+                limits?.keys.orEmpty() should beEmpty()
+                requests shouldBe mapOf("memory" to Quantity("128"))
+            }
+            expectMounts("secret-volume-1", "dir1")
+        }
+    }
 })
 
 private val annotations = mapOf(