[Fix #936] Adding Python implementation

impl/core/src/main/java/io/serverlessworkflow/impl/WorkflowMutableInstance.java

@@ -34,6 +34,7 @@
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Supplier;
 
 public class WorkflowMutableInstance implements WorkflowInstance {
 
@@ -44,6 +45,8 @@ public class WorkflowMutableInstance implements WorkflowInstance {
   protected final WorkflowContext workflowContext;
   protected Instant startedAt;
 
+  protected final Map<String, Object> additionalObjects = new ConcurrentHashMap<String, Object>();
+
   protected AtomicReference<CompletableFuture<WorkflowModel>> futureRef = new AtomicReference<>();
   protected Instant completedAt;
 
@@ -279,4 +282,8 @@ public boolean cancel() {
   }
 
   public void restoreContext(WorkflowContext workflow, TaskContext context) {}
+
+  public <T> T additionalObject(String key, Supplier<T> supplier) {
+    return (T) additionalObjects.computeIfAbsent(key, k -> supplier.get());
+  }
 }

impl/core/src/main/java/io/serverlessworkflow/impl/config/AbstractConfigManager.java

@@ -17,6 +17,9 @@
 
 import java.time.Instant;
 import java.time.OffsetDateTime;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.Optional;
 
 public abstract class AbstractConfigManager implements ConfigManager {
@@ -56,5 +59,19 @@ protected <T> T convert(String value, Class<T> propClass) {
     return propClass.cast(result);
   }
 
+  @Override
+  public <T> Collection<T> multiConfig(String propName, Class<T> propClass) {
+    String multiValue = get(propName);
+    if (multiValue != null) {
+      Collection<T> result = new ArrayList<>();
+      for (String value : multiValue.split(",")) {
+        result.add(convert(value, propClass));
+      }
+      return result;
+    } else {
+      return Collections.emptyList();
+    }
+  }
+
   protected abstract <T> T convertComplex(String value, Class<T> propClass);
 }

impl/core/src/main/java/io/serverlessworkflow/impl/config/ConfigManager.java

@@ -16,11 +16,14 @@
 package io.serverlessworkflow.impl.config;
 
 import io.serverlessworkflow.impl.ServicePriority;
+import java.util.Collection;
 import java.util.Optional;
 
 public interface ConfigManager extends ServicePriority {
 
   <T> Optional<T> config(String propName, Class<T> propClass);
 
+  <T> Collection<T> multiConfig(String propName, Class<T> propClass);
+
   Iterable<String> names();
 }

impl/core/src/main/java/io/serverlessworkflow/impl/scripts/AbstractScriptRunner.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.scripts;
+
+import io.serverlessworkflow.api.types.RunTaskConfiguration;
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowContext;
+import io.serverlessworkflow.impl.WorkflowError;
+import io.serverlessworkflow.impl.WorkflowException;
+import io.serverlessworkflow.impl.WorkflowModel;
+import io.serverlessworkflow.impl.WorkflowModelFactory;
+import io.serverlessworkflow.impl.executors.ProcessResult;
+import java.io.ByteArrayOutputStream;
+
+public abstract class AbstractScriptRunner implements ScriptRunner {
+
+  @Override
+  public WorkflowModel runScript(
+      ScriptContext scriptContext,
+      WorkflowContext workflowContext,
+      TaskContext taskContext,
+      WorkflowModel input) {
+    ByteArrayOutputStream stderr = new ByteArrayOutputStream();
+    ByteArrayOutputStream stdout = new ByteArrayOutputStream();
+    try {
+      runScript(scriptContext, stdout, stderr, workflowContext, taskContext);
+      return scriptContext
+          .returnType()
+          .map(
+              type ->
+                  modelFromOutput(
+                      type,
+                      workflowContext.definition().application().modelFactory(),
+                      stdout,
+                      stderr))
+          .orElse(input);
+    } catch (Exception ex) {
+      throw new WorkflowException(WorkflowError.runtime(taskContext, ex).build());
+    }
+  }
+
+  protected abstract void runScript(
+      ScriptContext scriptContext,
+      ByteArrayOutputStream stdout,
+      ByteArrayOutputStream stderr,
+      WorkflowContext workflowContext,
+      TaskContext taskContext);
+
+  protected WorkflowModel modelFromOutput(
+      RunTaskConfiguration.ProcessReturnType returnType,
+      WorkflowModelFactory modelFactory,
+      ByteArrayOutputStream stdout,
+      ByteArrayOutputStream stderr) {
+    return switch (returnType) {
+      case ALL -> modelFactory.fromAny(new ProcessResult(0, toString(stdout), toString(stderr)));
+      case NONE -> modelFactory.fromNull();
+      case CODE -> modelFactory.from(0);
+      case STDOUT -> modelFactory.from(toString(stdout));
+      case STDERR -> modelFactory.from(toString(stderr));
+    };
+  }
+
+  private String toString(ByteArrayOutputStream stream) {
+    return stream.toString().trim();
+  }
+}

impl/pom.xml

@@ -17,6 +17,7 @@
         <version.com.cronutils>9.2.1</version.com.cronutils>
         <version.docker.java>3.7.0</version.docker.java>
         <version.org.graalvm.polyglot>25.0.1</version.org.graalvm.polyglot>
+        <version.black.ninia>4.2.0</version.black.ninia>
     </properties>
     <dependencyManagement>
         <dependencies>
@@ -142,6 +143,11 @@
                 <artifactId>serverlessworkflow-impl-script-js</artifactId>
                 <version>${project.version}</version>
             </dependency>
+            <dependency>
+                <groupId>io.serverlessworkflow</groupId>
+                <artifactId>serverlessworkflow-impl-script-python</artifactId>
+                <version>${project.version}</version>
+            </dependency>
             <dependency>
                <groupId>com.cronutils</groupId>
                <artifactId>cron-utils</artifactId>
@@ -168,6 +174,11 @@
                 <artifactId>polyglot</artifactId>
                 <version>${version.org.graalvm.polyglot}</version>
             </dependency>
+            <dependency>
+              <groupId>black.ninia</groupId>
+              <artifactId>jep</artifactId>
+              <version>${version.black.ninia}</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>
     <modules>
@@ -187,5 +198,6 @@
         <module>container</module>
         <module>test</module>
         <module>script-js</module>
+        <module>python</module>
     </modules>
 </project>

impl/python/pom.xml

@@ -0,0 +1,20 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>io.serverlessworkflow</groupId>
+        <artifactId>serverlessworkflow-impl</artifactId>
+        <version>8.0.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>serverlessworkflow-impl-script-python</artifactId>
+    <name>Serverless Workflow :: Impl :: Script Python</name>
+    <dependencies>
+        <dependency>
+            <groupId>io.serverlessworkflow</groupId>
+            <artifactId>serverlessworkflow-impl-core</artifactId>
+        </dependency>
+      <dependency>
+         <groupId>black.ninia</groupId>
+          <artifactId>jep</artifactId>
+    </dependency>
+    </dependencies>
+</project>

impl/python/src/main/java/io/serverlessworkflow/impl/executors/script/python/PythonScriptTaskRunner.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.executors.script.python;
+
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowContext;
+import io.serverlessworkflow.impl.config.ConfigManager;
+import io.serverlessworkflow.impl.scripts.AbstractScriptRunner;
+import io.serverlessworkflow.impl.scripts.ScriptContext;
+import io.serverlessworkflow.impl.scripts.ScriptLanguageId;
+import java.io.ByteArrayOutputStream;
+import java.util.Collection;
+import jep.Interpreter;
+import jep.SharedInterpreter;
+
+public class PythonScriptTaskRunner extends AbstractScriptRunner {
+
+  @Override
+  public ScriptLanguageId identifier() {
+    return ScriptLanguageId.PYTHON;
+  }
+
+  private static final String PYTHON_SYS_PATH = "sys.path.append('%s')\n";
+  private static final String SEARCH_PATH_PROPERTY = "io.serverlessworkflow.impl.";
+
+  @Override
+  protected void runScript(
+      ScriptContext scriptContext,
+      ByteArrayOutputStream stdout,
+      ByteArrayOutputStream stderr,
+      WorkflowContext workflowContext,
+      TaskContext taskContext) {
+    Interpreter py =
+        workflowContext
+            .instance()
+            .additionalObject(
+                "pyInterpreter",
+                () -> interpreter(workflowContext.definition().application().configManager()));
+    scriptContext.args().forEach(py::set);
+    py.exec(scriptContext.code());
+  }
+
+  protected Interpreter interpreter(ConfigManager configManager) {
+    Interpreter py = new SharedInterpreter();
+    Collection<String> searchPaths = configManager.multiConfig(SEARCH_PATH_PROPERTY, String.class);
+    if (!searchPaths.isEmpty()) {
+      StringBuilder sb = new StringBuilder("import sys\n");
+      searchPaths.forEach(path -> sb.append(String.format(PYTHON_SYS_PATH, path)));
+      py.exec(sb.toString());
+    }
+    return py;
+  }
+}

impl/python/src/main/resources/META-INF/services/io.serverlessworkflow.impl.scripts.ScriptRunner

@@ -0,0 +1 @@
+io.serverlessworkflow.impl.executors.script.python.PythonScriptTaskRunner