AWS SAM deployment (#91)

* Generate AWS SAM application
with the Poseidon Java 11 Executor Lambda Function.

* Extend AWS Lambda documentation.

* Apply suggestions from code review

Co-authored-by: Sebastian Serth <MrSerth@users.noreply.github.com>

* Parse dynamic AWS region

Co-authored-by: Sebastian Serth <MrSerth@users.noreply.github.com>

deploy/aws/java11Exec/src/main/java/poseidon/App.java

@@ -0,0 +1,152 @@
+package poseidon;
+
+import java.io.*;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.Base64;
+import java.util.Map;
+import java.util.Scanner;
+
+import com.amazonaws.client.builder.AwsClientBuilder;
+import com.amazonaws.regions.Regions;
+import com.amazonaws.services.apigatewaymanagementapi.AmazonApiGatewayManagementApi;
+import com.amazonaws.services.apigatewaymanagementapi.AmazonApiGatewayManagementApiClientBuilder;
+import com.amazonaws.services.apigatewaymanagementapi.model.PostToConnectionRequest;
+import com.amazonaws.services.lambda.runtime.Context;
+import com.amazonaws.services.lambda.runtime.RequestHandler;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayV2WebSocketEvent;
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+
+// AwsFunctionRequest contains the java files that needs to be executed.
+class AwsFunctionRequest {
+    String[] cmd;
+    Map<String, String> files;
+}
+
+// WebSocketMessageType are the types of messages that are being sent back over the WebSocket connection.
+enum WebSocketMessageType {
+    WebSocketOutputStdout("stdout"),
+    WebSocketOutputStderr("stderr"),
+    WebSocketOutputError("error"),
+    WebSocketExit("exit");
+
+    private final String typeName;
+
+    WebSocketMessageType(String name) {
+        this.typeName = name;
+    }
+
+    public String toString() {
+        return typeName;
+    }
+}
+
+/**
+ * Handler for requests to Lambda function.
+ * This Lambda function executes the passed command with the provided files in an isolated Java environment.
+ */
+public class App implements RequestHandler<APIGatewayV2WebSocketEvent, APIGatewayProxyResponseEvent> {
+
+    // gson helps parse the json objects.
+    private static final Gson gson = new Gson();
+
+    // gwClient is used to send messages back via the WebSocket connection.
+    private AmazonApiGatewayManagementApi gwClient;
+
+    // connectionID helps to identify the WebSocket connection that has called this function.
+    private String connectionID;
+
+    public static final String disableOutputHeaderKey = "disableOutput";
+
+    // disableOutput: If set to true, no output will be sent over the WebSocket connection.
+    private boolean disableOutput = false;
+
+    public APIGatewayProxyResponseEvent handleRequest(final APIGatewayV2WebSocketEvent input, final Context context) {
+        APIGatewayV2WebSocketEvent.RequestContext ctx = input.getRequestContext();
+        String[] domains = ctx.getDomainName().split("\\.");
+        String region = domains[domains.length-3];
+        this.gwClient = AmazonApiGatewayManagementApiClientBuilder.standard()
+                .withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration("https://" + ctx.getDomainName() + "/" + ctx.getStage(), region))
+                .build();
+        this.connectionID = ctx.getConnectionId();
+        this.disableOutput = input.getHeaders() != null && input.getHeaders().containsKey(disableOutputHeaderKey) && Boolean.parseBoolean(input.getHeaders().get(disableOutputHeaderKey));
+        AwsFunctionRequest execution = gson.fromJson(input.getBody(), AwsFunctionRequest.class);
+
+        try {
+            File workingDirectory = this.writeFS(execution.files);
+
+            ProcessBuilder pb = new ProcessBuilder(execution.cmd).redirectErrorStream(true);
+            pb.directory(workingDirectory);
+            Process p = pb.start();
+            InputStream stdout = p.getInputStream(), stderr = p.getErrorStream();
+            this.forwardOutput(p, stdout, stderr);
+            p.destroy();
+            return new APIGatewayProxyResponseEvent().withStatusCode(200);
+        } catch (Exception e) {
+            this.sendMessage(WebSocketMessageType.WebSocketOutputError, e.toString(), null);
+            return new APIGatewayProxyResponseEvent().withBody(e.toString()).withStatusCode(500);
+        }
+    }
+
+    // writeFS writes the files to the local filesystem.
+    private File writeFS(Map<String, String> files) throws IOException {
+        File workspace = Files.createTempDirectory("workspace").toFile();
+        for (Map.Entry<String, String> entry : files.entrySet()) {
+            File f = new File(workspace, entry.getKey());
+
+            f.getParentFile().mkdirs();
+            if (!f.getParentFile().exists()) {
+                throw new IOException("Cannot create parent directories.");
+            }
+
+            f.createNewFile();
+            if (!f.exists()) {
+                throw new IOException("Cannot create file.");
+            }
+
+            Files.write(f.toPath(), Base64.getDecoder().decode(entry.getValue()));
+        }
+        return workspace;
+    }
+
+    // forwardOutput sends the output of the process to the WebSocket connection.
+    private void forwardOutput(Process p, InputStream stdout, InputStream stderr) throws InterruptedException {
+        Thread output = new Thread(() -> scanForOutput(p, stdout, WebSocketMessageType.WebSocketOutputStdout));
+        Thread error = new Thread(() -> scanForOutput(p, stderr, WebSocketMessageType.WebSocketOutputStderr));
+        output.start();
+        error.start();
+
+        output.join();
+        error.join();
+        this.sendMessage(WebSocketMessageType.WebSocketExit, null, p.exitValue());
+    }
+
+    // scanForOutput reads the passed stream and forwards it via the WebSocket connection.
+    private void scanForOutput(Process p, InputStream stream, WebSocketMessageType type) {
+        Scanner outputScanner = new Scanner(stream);
+        while (p.isAlive() || outputScanner.hasNextLine()) {
+            this.sendMessage(type, outputScanner.nextLine(), null);
+        }
+    }
+
+    // sendMessage sends WebSocketMessage objects back to the requester of this Lambda function.
+    private void sendMessage(WebSocketMessageType type, String data, Integer exitCode) {
+        if (this.disableOutput) {
+            return;
+        }
+        JsonObject msg = new JsonObject();
+        msg.addProperty("type", type.toString());
+        if (type == WebSocketMessageType.WebSocketExit) {
+            msg.addProperty("data", exitCode);
+        } else {
+            msg.addProperty("data", data);
+        }
+
+        this.gwClient.postToConnection(new PostToConnectionRequest()
+                .withConnectionId(this.connectionID)
+                .withData(ByteBuffer.wrap(gson.toJson(msg).getBytes(StandardCharsets.UTF_8))));
+    }
+}

deploy/aws/java11Exec/src/test/java/poseidon/AppTest.java

@@ -0,0 +1,28 @@
+package poseidon;
+
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayV2WebSocketEvent;
+import org.junit.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class AppTest {
+  @Test
+  public void successfulResponse() {
+    App app = new App();
+    APIGatewayV2WebSocketEvent input = new APIGatewayV2WebSocketEvent();
+    APIGatewayV2WebSocketEvent.RequestContext ctx = new APIGatewayV2WebSocketEvent.RequestContext();
+    ctx.setDomainName("abcdef1234.execute-api.eu-central-1.amazonaws.com");
+    ctx.setConnectionId("myUUID");
+    input.setRequestContext(ctx);
+    Map<String, String> headers = new HashMap<>();
+    headers.put(App.disableOutputHeaderKey, "True");
+    input.setHeaders(headers);
+    input.setBody("{\n    \"action\": \"java11Exec\",\n    \"cmd\": [\n        \"sh\",\n        \"-c\",\n        \"javac org/example/RecursiveMath.java && java org/example/RecursiveMath\"\n    ],\n    \"files\": {\n        \"org/example/RecursiveMath.java\": \"cGFja2FnZSBvcmcuZXhhbXBsZTsKCnB1YmxpYyBjbGFzcyBSZWN1cnNpdmVNYXRoIHsKCiAgICBwdWJsaWMgc3RhdGljIHZvaWQgbWFpbihTdHJpbmdbXSBhcmdzKSB7CiAgICAgICAgU3lzdGVtLm91dC5wcmludGxuKCJNZWluIFRleHQiKTsKICAgIH0KCiAgICBwdWJsaWMgc3RhdGljIGRvdWJsZSBwb3dlcihpbnQgYmFzZSwgaW50IGV4cG9uZW50KSB7CiAgICAgICAgcmV0dXJuIDQyOwogICAgfQp9Cgo=\"\n    }\n}");
+    APIGatewayProxyResponseEvent result = app.handleRequest(input, null);
+    assertEquals(200, result.getStatusCode().intValue());
+  }
+}