Start Redpanda only after its config is in place

packages/modules/redpanda/src/redpanda-container.test.ts

@@ -1,9 +1,30 @@
+import { setTimeout } from "node:timers/promises";
+import type { InspectResult, StartedTestContainer } from "testcontainers";
 import { getImage } from "../../../testcontainers/src/utils/test-helper";
 import { RedpandaContainer } from "./redpanda-container";
 import { assertMessageProducedAndConsumed } from "./test-helper";
 
 const IMAGE = getImage(__dirname);
 
+// Writes each copied file in two parts with a pause between them, as a busy Docker host can.
+class SlowCopyRedpandaContainer extends RedpandaContainer {
+  protected override async containerStarted(
+    container: StartedTestContainer,
+    inspectResult: InspectResult
+  ): Promise<void> {
+    const copyContentToContainer = container.copyContentToContainer.bind(container);
+    container.copyContentToContainer = async (contentsToCopy) => {
+      for (const { content, target, mode } of contentsToCopy) {
+        const [firstLine] = String(content).split("\n", 1);
+        await copyContentToContainer([{ content: `${firstLine}\n`, target, mode }]);
+        await setTimeout(1_000);
+        await copyContentToContainer([{ content, target, mode }]);
+      }
+    };
+    await super.containerStarted(container, inspectResult);
+  }
+}
+
 describe("RedpandaContainer", { timeout: 240_000 }, () => {
   it("should connect", async () => {
     // connectToKafka {
@@ -13,6 +34,12 @@ describe("RedpandaContainer", { timeout: 240_000 }, () => {
     // }
   });
 
+  it("should connect when the config reaches the container late and in parts", async () => {
+    await using container = await new SlowCopyRedpandaContainer(IMAGE).start();
+
+    await assertMessageProducedAndConsumed(container);
+  });
+
   it("should connect to schema registry", async () => {
     // connectToSchemaRegistry {
     await using container = await new RedpandaContainer(IMAGE).start();

packages/modules/redpanda/src/redpanda-container.ts

@@ -17,8 +17,10 @@ const REDPANDA_PORT = 9092;
 const REDPANDA_ADMIN_PORT = 9644;
 const SCHEMA_REGISTRY_PORT = 8081;
 const REST_PROXY_PORT = 8082;
-const STARTER_SCRIPT = "/testcontainers_start.sh";
-const WAIT_FOR_SCRIPT_MESSAGE = "Waiting for script...";
+const REDPANDA_CONFIG = "/etc/redpanda/redpanda.yaml";
+const REDPANDA_CONFIG_STAGING = `${REDPANDA_CONFIG}.testcontainers`;
+const REDPANDA_CONFIG_MARKER = "# Injected by testcontainers";
+const WAIT_FOR_CONFIG_MESSAGE = "Waiting for config...";
 
 export class RedpandaContainer extends GenericContainer {
   private originalWaitStrategy: WaitStrategy | undefined;
@@ -42,29 +44,34 @@ export class RedpandaContainer extends GenericContainer {
   }
 
   protected override async beforeContainerCreated(): Promise<void> {
-    // Change the wait strategy to wait for a log message from a fake starter script
-    // so that we can put a real starter script in place at that moment
+    // Change the wait strategy to wait for a log message from a fake starter,
+    // which starts Redpanda only once the config with the mapped Kafka port is in place
     this.originalWaitStrategy = this.waitStrategy;
-    this.waitStrategy = Wait.forLogMessage(WAIT_FOR_SCRIPT_MESSAGE);
+    this.waitStrategy = Wait.forLogMessage(WAIT_FOR_CONFIG_MESSAGE);
     this.withEntrypoint(["sh"]);
     this.withCommand([
       "-c",
-      `echo '${WAIT_FOR_SCRIPT_MESSAGE}'; while [ ! -f ${STARTER_SCRIPT} ]; do sleep 0.1; done; ${STARTER_SCRIPT}`,
+      `echo '${WAIT_FOR_CONFIG_MESSAGE}'; until grep -q '${REDPANDA_CONFIG_MARKER}' ${REDPANDA_CONFIG}; do sleep 0.1; done; exec rpk redpanda start --mode dev-container --smp=1 --memory=1G`,
     ]);
   }
 
   protected override async containerStarted(
     container: StartedTestContainer,
     inspectResult: InspectResult
   ): Promise<void> {
-    const command = "#!/bin/bash\nrpk redpanda start --mode dev-container --smp=1 --memory=1G";
-    await container.copyContentToContainer([{ content: command, target: STARTER_SCRIPT, mode: 0o777 }]);
+    // Docker writes a copied file in place, so the starter could read the marker before the rest.
+    // A rename on the same filesystem publishes the whole file at once.
     await container.copyContentToContainer([
       {
         content: this.renderRedpandaFile(container.getHost(), container.getMappedPort(REDPANDA_PORT)),
-        target: "/etc/redpanda/redpanda.yaml",
+        target: REDPANDA_CONFIG_STAGING,
       },
     ]);
+    const { exitCode, output } = await container.exec(["mv", REDPANDA_CONFIG_STAGING, REDPANDA_CONFIG]);
+
+    if (exitCode !== 0) {
+      throw new Error(`Redpanda container configuration failed with exit code ${exitCode}: ${output}`);
+    }
 
     const client = await getContainerRuntimeClient();
     const dockerContainer = client.container.getById(container.getId());