String interpolation for kubectl (#59)

Author: Alex Stockinger

src/main/java/com/dajudge/kindcontainer/kubectl/ApplyFluent.java

@@ -3,13 +3,22 @@
 import com.dajudge.kindcontainer.BaseSidecarContainer.ExecInContainer;
 import com.dajudge.kindcontainer.BaseSidecarContainer.FileTarget;
 import com.dajudge.kindcontainer.exception.ExecutionException;
-import org.testcontainers.utility.MountableFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testcontainers.images.builder.Transferable;
+import org.testcontainers.shaded.org.apache.commons.io.IOUtils;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Function;
+
+import static java.lang.Thread.currentThread;
+import static java.util.Arrays.asList;
+import static java.util.function.Function.identity;
 
 public class ApplyFluent<P> {
+    private static final Logger LOG = LoggerFactory.getLogger(ApplyFluent.class);
     private final ExecInContainer exec;
     private final FileTarget fileTarget;
     private final P parent;
@@ -29,17 +38,36 @@ public ApplyFluent<P> namespace(final String namespace) {
     }
 
     public ApplyFluent<P> fileFromClasspath(final String resourceName) {
+        return fileFromClasspath(resourceName, identity());
+    }
+
+    public ApplyFluent<P> fileFromClasspath(final String resourceName, final Function<byte[], byte[]> transform) {
         final String path = "/tmp/classpath:" + resourceName
                 .replaceAll("_", "__")
                 .replaceAll("[^a-zA-Z0-9.]", "_");
         files.add(path);
-        preExecutionRunnables.add(() -> fileTarget.copyFileToContainer(
-                MountableFile.forClasspathResource(resourceName),
-                path
-        ));
+        final byte[] bytes = transform.apply(resourceToByteArray(resourceName));
+        final Transferable transferable = Transferable.of(bytes);
+        preExecutionRunnables.add(() -> fileTarget.copyFileToContainer(transferable, path));
         return this;
     }
 
+    private byte[] resourceToByteArray(final String resourceName) {
+        final List<ClassLoader> classloaders = asList(
+                ApplyFluent.class.getClassLoader(),
+                currentThread().getContextClassLoader(),
+                ClassLoader.getSystemClassLoader()
+        );
+        for (final ClassLoader classloader : classloaders) {
+            try {
+                return IOUtils.resourceToByteArray(resourceName, ApplyFluent.class.getClassLoader());
+            } catch (final IOException e) {
+                LOG.debug("Failed to read classpath resource '{}' via classloader '{}'", resourceName, classloader, e);
+            }
+        }
+        throw new IllegalArgumentException("Unable to locate resource: " + resourceName);
+    }
+
     public P run() throws IOException, ExecutionException, InterruptedException {
         final List<String> cmdline = new ArrayList<>();
         cmdline.add("kubectl");

src/test/java/com/dajudge/kindcontainer/KubectlTest.java

@@ -1,24 +1,39 @@
 package com.dajudge.kindcontainer;
 
+import io.fabric8.kubernetes.api.model.ConfigMap;
 import org.junit.ClassRule;
 import org.junit.Test;
 
+import java.util.Objects;
+import java.util.function.Function;
+
 import static com.dajudge.kindcontainer.TestUtils.runWithClient;
-import static org.junit.Assert.assertNotNull;
-import static org.testcontainers.utility.MountableFile.forClasspathResource;
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.junit.Assert.assertEquals;
+import static org.testcontainers.shaded.org.awaitility.Awaitility.await;
 
 public class KubectlTest {
 
+    private static final Function<byte[], byte[]> APPLY_PLACEHOLDERS = bytes -> new String(bytes, UTF_8)
+            .replace("{{ my-value }}", "Hello, world!")
+            .getBytes(UTF_8);
     @ClassRule
     public static ApiServerContainer<?> K8S = new ApiServerContainer<>()
             .withKubectl(kubectl -> kubectl.apply
-                    .fileFromClasspath("manifests/config_map_1.yaml")
+                    .fileFromClasspath("manifests/config_map_1.yaml", APPLY_PLACEHOLDERS)
                     .run());
 
     @Test
-    public void can_apply_manifest() throws Exception {
+    public void can_apply_manifest() {
         runWithClient(K8S, client -> {
-            assertNotNull(client.configMaps().inNamespace("configmap1").withName("configmap1").get());
+            final ConfigMap configMap = await()
+                    .timeout(10, SECONDS)
+                    .until(
+                            () -> client.configMaps().inNamespace("configmap1").withName("configmap1").get(),
+                            Objects::nonNull
+                    );
+            assertEquals("Hello, world!", configMap.getData().get("my-key"));
         });
     }
 }

src/test/resources/manifests/config_map_1.yaml

@@ -8,3 +8,5 @@ kind: ConfigMap
 metadata:
   name: configmap1
   namespace: configmap1
+data:
+  my-key: {{ my-value }}