add initContainer capabilities (#2820)

* set init container capabilities

* set init container capabilities

* correct parameter definition + change assertThat

Co-authored-by: Adnan Awan <adnan.awan@sap.com>
Co-authored-by: Thorsten Duda <thorsten.duda@sap.com>

test/groovy/DockerExecuteOnKubernetesTest.groovy

@@ -676,7 +676,6 @@ class DockerExecuteOnKubernetesTest extends BasePiperTest {
         def expectedSecurityContext = [runAsUser: 1000, fsGroup: 1000]
         nullScript.commonPipelineEnvironment.configuration = [general: [jenkinsKubernetes: [
             securityContext: expectedSecurityContext]]]
-
         stepRule.step.dockerExecuteOnKubernetes(
             script: nullScript,
             juStabUtils: utils,
@@ -803,11 +802,12 @@ class DockerExecuteOnKubernetesTest extends BasePiperTest {
             script: nullScript,
             juStabUtils: utils,
             containerName: 'mycontainer',
+            initContainerImage: 'ppiper/cf-cli',
             dockerImage: 'maven:3.5-jdk-8-alpine',
             containerMountPath: '/opt',
         ) { bodyExecuted = true }
-
         def containerSpec = podSpec.spec.containers.find{it.image == "maven:3.5-jdk-8-alpine"}
+        def initContainerSpec = podSpec.spec.initContainers[0]
         assertTrue(bodyExecuted)
         assertEquals(
             [[
@@ -819,6 +819,46 @@ class DockerExecuteOnKubernetesTest extends BasePiperTest {
                 "name"     : "volume",
                 "mountPath": "/opt"
             ]], containerSpec.volumeMounts)
+        assertEquals(
+            [[
+                 "name"     : "volume",
+                 "mountPath": "/opt"
+             ]], initContainerSpec.volumeMounts)
+    }
+
+    @Test
+    void testInitContainerDefaultWithParameters() {
+        stepRule.step.dockerExecuteOnKubernetes(
+            script: nullScript,
+            juStabUtils: utils,
+            containerName: 'mycontainer',
+            initContainerImage: 'ppiper/cf-cli@sha256:latest',
+            initContainerCommand: 'cp /usr/local/bin/cf7 /opt/bin/cf',
+            dockerImage: 'maven:3.5-jdk-8-alpine',
+            containerMountPath: '/opt',
+        ) { bodyExecuted = true }
+        def initContainer = podSpec.spec.initContainers[0]
+        def expectedCommandOutput = ["sh", "-c", "cp /usr/local/bin/cf7 /opt/bin/cf"]
+        assertTrue(bodyExecuted)
+        assertEquals("ppiper-cf-cli-sha256-latest", initContainer.name)
+        assertEquals("ppiper/cf-cli@sha256:latest", initContainer.image)
+        assertThat(initContainer.command, is(equalTo(expectedCommandOutput)))
+    }
+
+    @Test
+    void testInitContainerWithoutContainerCommand() {
+        stepRule.step.dockerExecuteOnKubernetes(
+            script: nullScript,
+            juStabUtils: utils,
+            containerName: 'mycontainer',
+            initContainerImage: 'ppiper/cf-cli@sha256:latest',
+            dockerImage: 'maven:3.5-jdk-8-alpine',
+            containerMountPath: '/opt',
+        ) { bodyExecuted = true }
+        def initContainer = podSpec.spec.initContainers[0]
+        def expectedCommandOutput = ["/usr/bin/tail", "-f", "/dev/null"]
+        assertTrue(bodyExecuted)
+        assertThat(initContainer.command, is(equalTo(expectedCommandOutput)))
     }
 
     private container(options, body) {

vars/dockerExecuteOnKubernetes.groovy

@@ -198,6 +198,15 @@ import hudson.AbortException
      * use this volume in an initContainer.
      */
     'containerMountPath',
+     /**
+     * The docker image to run as initContainer.
+     */
+    'initContainerImage',
+    /**
+     * Command executed inside the init container shell. Please enter command without providing any "sh -c" prefix. For example for an echo message, simply enter: echo `HelloWorld`
+     */
+    'initContainerCommand',
+
 ])
 @Field Set PARAMETER_KEYS = STEP_CONFIG_KEYS.minus([
     'stashIncludes',
@@ -336,6 +345,7 @@ private String generatePodSpec(Map config) {
         spec      : [:]
     ]
     podSpec.spec += getAdditionalPodProperties(config)
+    podSpec.spec.initContainers = getInitContainerList(config)
     podSpec.spec.containers = getContainerList(config)
     podSpec.spec.securityContext = getSecurityContext(config)
 
@@ -349,7 +359,6 @@ private String generatePodSpec(Map config) {
     return new JsonUtils().groovyObjectToPrettyJsonString(podSpec)
 }
 
-
 private String stashWorkspace(config, prefix, boolean chown = false, boolean stashBack = false) {
     def stashName = "${prefix}-${config.uniqueId}"
     try {
@@ -416,6 +425,36 @@ private void unstashWorkspace(config, prefix) {
     }
 }
 
+private List getInitContainerList(config){
+    def initContainerSpecList = []
+    if (config.initContainerImage && config.containerMountPath) {
+        // regex [\W_] matches any non-word character equivalent to [^a-zA-Z0-9_]
+        def initContainerName = config.initContainerImage.toLowerCase().replaceAll(/[\W_]/,"-" )
+        def initContainerSpec = [
+            name           : initContainerName,
+            image          : config.initContainerImage
+            ]
+        if (config.containerMountPath) {
+            initContainerSpec.volumeMounts = [[name: "volume", mountPath: config.containerMountPath]]
+        }
+        if (config.initContainerCommand == null) {
+            initContainerSpec['command'] = [
+                '/usr/bin/tail',
+                '-f',
+                '/dev/null'
+            ]
+        } else {
+            initContainerSpec['command'] = [
+                'sh',
+                '-c',
+                config.initContainerCommand
+            ]
+        }
+        initContainerSpecList.push(initContainerSpec)
+    }
+    return initContainerSpecList
+}
+
 private List getContainerList(config) {
 
     //If no custom jnlp agent provided as default jnlp agent (jenkins/jnlp-slave) as defined in the plugin, see https://github.com/jenkinsci/kubernetes-plugin#pipeline-support
@@ -497,7 +536,6 @@ private List getContainerList(config) {
             env            : getContainerEnvs(config, config.sidecarImage, config.sidecarEnvVars, config.sidecarWorkspace),
             command        : []
         ]
-
         def resources = getResources(sideCarContainerName, config)
         if(resources) {
             containerSpec.resources = resources