Add Get Workflow API to retrieve a stored template by workflow id

src/main/java/org/opensearch/flowframework/FlowFrameworkPlugin.java

@@ -28,11 +28,14 @@
 import org.opensearch.flowframework.common.FlowFrameworkFeatureEnabledSetting;
 import org.opensearch.flowframework.indices.FlowFrameworkIndicesHandler;
 import org.opensearch.flowframework.rest.RestCreateWorkflowAction;
+import org.opensearch.flowframework.rest.RestGetTemplateAction;
 import org.opensearch.flowframework.rest.RestGetWorkflowAction;
 import org.opensearch.flowframework.rest.RestProvisionWorkflowAction;
 import org.opensearch.flowframework.rest.RestSearchWorkflowAction;
 import org.opensearch.flowframework.transport.CreateWorkflowAction;
 import org.opensearch.flowframework.transport.CreateWorkflowTransportAction;
+import org.opensearch.flowframework.transport.GetTemplateAction;
+import org.opensearch.flowframework.transport.GetTemplateTransportAction;
 import org.opensearch.flowframework.transport.GetWorkflowAction;
 import org.opensearch.flowframework.transport.GetWorkflowTransportAction;
 import org.opensearch.flowframework.transport.ProvisionWorkflowAction;
@@ -125,7 +128,8 @@ public List<RestHandler> getRestHandlers(
             new RestCreateWorkflowAction(flowFrameworkFeatureEnabledSetting, settings, clusterService),
             new RestProvisionWorkflowAction(flowFrameworkFeatureEnabledSetting),
             new RestSearchWorkflowAction(flowFrameworkFeatureEnabledSetting),
-            new RestGetWorkflowAction(flowFrameworkFeatureEnabledSetting)
+            new RestGetWorkflowAction(flowFrameworkFeatureEnabledSetting),
+            new RestGetTemplateAction(flowFrameworkFeatureEnabledSetting)
         );
     }
 
@@ -135,7 +139,8 @@ public List<RestHandler> getRestHandlers(
             new ActionHandler<>(CreateWorkflowAction.INSTANCE, CreateWorkflowTransportAction.class),
             new ActionHandler<>(ProvisionWorkflowAction.INSTANCE, ProvisionWorkflowTransportAction.class),
             new ActionHandler<>(SearchWorkflowAction.INSTANCE, SearchWorkflowTransportAction.class),
-            new ActionHandler<>(GetWorkflowAction.INSTANCE, GetWorkflowTransportAction.class)
+            new ActionHandler<>(GetWorkflowAction.INSTANCE, GetWorkflowTransportAction.class),
+            new ActionHandler<>(GetTemplateAction.INSTANCE, GetTemplateTransportAction.class)
         );
     }
 

src/main/java/org/opensearch/flowframework/rest/RestGetTemplateAction.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.rest;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.opensearch.ExceptionsHelper;
+import org.opensearch.client.node.NodeClient;
+import org.opensearch.core.action.ActionListener;
+import org.opensearch.core.rest.RestStatus;
+import org.opensearch.core.xcontent.ToXContent;
+import org.opensearch.core.xcontent.XContentBuilder;
+import org.opensearch.flowframework.common.FlowFrameworkFeatureEnabledSetting;
+import org.opensearch.flowframework.exception.FlowFrameworkException;
+import org.opensearch.flowframework.transport.GetTemplateAction;
+import org.opensearch.flowframework.transport.WorkflowRequest;
+import org.opensearch.rest.BaseRestHandler;
+import org.opensearch.rest.BytesRestResponse;
+import org.opensearch.rest.RestRequest;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Locale;
+
+import static org.opensearch.flowframework.common.CommonValue.WORKFLOW_ID;
+import static org.opensearch.flowframework.common.CommonValue.WORKFLOW_URI;
+import static org.opensearch.flowframework.common.FlowFrameworkSettings.FLOW_FRAMEWORK_ENABLED;
+
+/**
+ * Rest Action to facilitate requests to get a stored template
+ */
+public class RestGetTemplateAction extends BaseRestHandler {
+
+    private static final String GET_TEMPLATE_ACTION = "get_template";
+    private static final Logger logger = LogManager.getLogger(RestGetTemplateAction.class);
+    private FlowFrameworkFeatureEnabledSetting flowFrameworkFeatureEnabledSetting;
+
+    /**
+     * Instantiates a new RestGetWorkflowAction
+     * @param flowFrameworkFeatureEnabledSetting Whether this API is enabled
+     */
+    public RestGetTemplateAction(FlowFrameworkFeatureEnabledSetting flowFrameworkFeatureEnabledSetting) {
+        this.flowFrameworkFeatureEnabledSetting = flowFrameworkFeatureEnabledSetting;
+    }
+
+    @Override
+    public String getName() {
+        return GET_TEMPLATE_ACTION;
+    }
+
+    @Override
+    public List<Route> routes() {
+        return ImmutableList.of(new Route(RestRequest.Method.GET, String.format(Locale.ROOT, "%s/{%s}", WORKFLOW_URI, WORKFLOW_ID)));
+    }
+
+    @Override
+    protected BaseRestHandler.RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
+
+        try {
+            if (!flowFrameworkFeatureEnabledSetting.isFlowFrameworkEnabled()) {
+                throw new FlowFrameworkException(
+                    "This API is disabled. To enable it, update the setting [" + FLOW_FRAMEWORK_ENABLED.getKey() + "] to true.",
+                    RestStatus.FORBIDDEN
+                );
+            }
+
+            // Validate content
+            if (request.hasContent()) {
+                throw new FlowFrameworkException("Invalid request format", RestStatus.BAD_REQUEST);
+            }
+            // Validate params
+            String workflowId = request.param(WORKFLOW_ID);
+            if (workflowId == null) {
+                throw new FlowFrameworkException("workflow_id cannot be null", RestStatus.BAD_REQUEST);
+            }
+
+            WorkflowRequest workflowRequest = new WorkflowRequest(workflowId, null);
+            return channel -> client.execute(GetTemplateAction.INSTANCE, workflowRequest, ActionListener.wrap(response -> {
+                XContentBuilder builder = response.toXContent(channel.newBuilder(), ToXContent.EMPTY_PARAMS);
+                channel.sendResponse(new BytesRestResponse(RestStatus.OK, builder));
+            }, exception -> {
+                try {
+                    FlowFrameworkException ex = new FlowFrameworkException(exception.getMessage(), ExceptionsHelper.status(exception));
+                    XContentBuilder exceptionBuilder = ex.toXContent(channel.newErrorBuilder(), ToXContent.EMPTY_PARAMS);
+                    channel.sendResponse(new BytesRestResponse(ex.getRestStatus(), exceptionBuilder));
+
+                } catch (IOException e) {
+                    logger.error("Failed to send back get template exception", e);
+                    channel.sendResponse(new BytesRestResponse(ExceptionsHelper.status(e), e.getMessage()));
+                }
+            }));
+
+        } catch (FlowFrameworkException ex) {
+            return channel -> channel.sendResponse(
+                new BytesRestResponse(ex.getRestStatus(), ex.toXContent(channel.newErrorBuilder(), ToXContent.EMPTY_PARAMS))
+            );
+        }
+    }
+}

src/main/java/org/opensearch/flowframework/transport/GetTemplateAction.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.transport;
+
+import org.opensearch.action.ActionType;
+
+import static org.opensearch.flowframework.common.CommonValue.TRANSPORT_ACTION_NAME_PREFIX;
+
+/**
+ * External Action for public facing RestGetTemplateAction
+ */
+public class GetTemplateAction extends ActionType<GetTemplateResponse> {
+    /** The name of this action */
+    public static final String NAME = TRANSPORT_ACTION_NAME_PREFIX + "template/get";
+    /** An instance of this action */
+    public static final GetTemplateAction INSTANCE = new GetTemplateAction();
+
+    private GetTemplateAction() {
+        super(NAME, GetTemplateResponse::new);
+    }
+}

src/main/java/org/opensearch/flowframework/transport/GetTemplateResponse.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.transport;
+
+import org.opensearch.core.action.ActionResponse;
+import org.opensearch.core.common.io.stream.StreamInput;
+import org.opensearch.core.common.io.stream.StreamOutput;
+import org.opensearch.core.xcontent.ToXContentObject;
+import org.opensearch.core.xcontent.XContentBuilder;
+import org.opensearch.flowframework.model.Template;
+
+import java.io.IOException;
+
+/**
+ * Transport Response from getting a template
+ */
+public class GetTemplateResponse extends ActionResponse implements ToXContentObject {
+
+    /** The template */
+    private Template template;
+
+    /**
+     * Instantiates a new GetTemplateResponse from an input stream
+     * @param in the input stream to read from
+     * @throws IOException if the template json cannot be read from the input stream
+     */
+    public GetTemplateResponse(StreamInput in) throws IOException {
+        super(in);
+        this.template = Template.parse(in.readString());
+    }
+
+    /**
+     * Instantiates a new GetTemplateResponse
+     * @param template the template
+     */
+    public GetTemplateResponse(Template template) {
+        this.template = template;
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        out.writeString(template.toJson());
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder xContentBuilder, Params params) throws IOException {
+        return this.template.toXContent(xContentBuilder, params);
+    }
+
+    /**
+     * Gets the template
+     * @return the template
+     */
+    public Template getTemplate() {
+        return this.template;
+    }
+
+}

src/main/java/org/opensearch/flowframework/transport/GetTemplateTransportAction.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.transport;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.opensearch.ExceptionsHelper;
+import org.opensearch.action.get.GetRequest;
+import org.opensearch.action.support.ActionFilters;
+import org.opensearch.action.support.HandledTransportAction;
+import org.opensearch.client.Client;
+import org.opensearch.common.inject.Inject;
+import org.opensearch.common.util.concurrent.ThreadContext;
+import org.opensearch.core.action.ActionListener;
+import org.opensearch.core.rest.RestStatus;
+import org.opensearch.flowframework.exception.FlowFrameworkException;
+import org.opensearch.flowframework.indices.FlowFrameworkIndicesHandler;
+import org.opensearch.flowframework.model.Template;
+import org.opensearch.tasks.Task;
+import org.opensearch.transport.TransportService;
+
+import static org.opensearch.flowframework.common.CommonValue.GLOBAL_CONTEXT_INDEX;
+
+/**
+ * Transport action to retrieve a use case template within the Global Context
+ */
+public class GetTemplateTransportAction extends HandledTransportAction<WorkflowRequest, GetTemplateResponse> {
+
+    private final Logger logger = LogManager.getLogger(GetTemplateTransportAction.class);
+    private final FlowFrameworkIndicesHandler flowFrameworkIndicesHandler;
+    private final Client client;
+
+    /**
+     * Instantiates a new GetTempltateTransportAction instance
+     * @param transportService the transport service
+     * @param actionFilters action filters
+     * @param flowFrameworkIndicesHandler The Flow Framework indices handler
+     * @param client the Opensearch Client
+     */
+    @Inject
+    public GetTemplateTransportAction(
+        TransportService transportService,
+        ActionFilters actionFilters,
+        FlowFrameworkIndicesHandler flowFrameworkIndicesHandler,
+        Client client
+    ) {
+        super(GetTemplateAction.NAME, transportService, actionFilters, WorkflowRequest::new);
+        this.flowFrameworkIndicesHandler = flowFrameworkIndicesHandler;
+        this.client = client;
+    }
+
+    @Override
+    protected void doExecute(Task task, WorkflowRequest request, ActionListener<GetTemplateResponse> listener) {
+        if (flowFrameworkIndicesHandler.doesIndexExist(GLOBAL_CONTEXT_INDEX)) {
+
+            String workflowId = request.getWorkflowId();
+            GetRequest getRequest = new GetRequest(GLOBAL_CONTEXT_INDEX, workflowId);
+
+            // Retrieve workflow by ID
+            try (ThreadContext.StoredContext context = client.threadPool().getThreadContext().stashContext()) {
+                client.get(getRequest, ActionListener.wrap(response -> {
+                    context.restore();
+
+                    if (!response.isExists()) {
+                        listener.onFailure(
+                            new FlowFrameworkException(
+                                "Failed to retrieve template (" + workflowId + ") from global context.",
+                                RestStatus.NOT_FOUND
+                            )
+                        );
+                    } else {
+                        listener.onResponse(new GetTemplateResponse(Template.parse(response.getSourceAsString())));
+                    }
+                }, exception -> {
+                    logger.error("Failed to retrieve template from global context.", exception);
+                    listener.onFailure(new FlowFrameworkException(exception.getMessage(), ExceptionsHelper.status(exception)));
+                }));
+            } catch (Exception e) {
+                logger.error("Failed to retrieve template from global context.", e);
+                listener.onFailure(new FlowFrameworkException(e.getMessage(), ExceptionsHelper.status(e)));
+            }
+
+        } else {
+            listener.onFailure(new FlowFrameworkException("There are no templates in the global_context", RestStatus.NOT_FOUND));
+        }
+
+    }
+}

src/test/java/org/opensearch/flowframework/FlowFrameworkPluginTests.java

@@ -81,8 +81,8 @@ public void testPlugin() throws IOException {
                 4,
                 ffp.createComponents(client, clusterService, threadPool, null, null, null, environment, null, null, null, null).size()
             );
-            assertEquals(4, ffp.getRestHandlers(settings, null, null, null, null, null, null).size());
-            assertEquals(4, ffp.getActions().size());
+            assertEquals(5, ffp.getRestHandlers(settings, null, null, null, null, null, null).size());
+            assertEquals(5, ffp.getActions().size());
             assertEquals(1, ffp.getExecutorBuilders(settings).size());
             assertEquals(4, ffp.getSettings().size());
         }