[Security Solution + Fleet] Add FleetFilesClient to fleet and refac…

…tor endpoint actions to use it (#157658)

## Summary

PR introduces a new Files service client to the Fleet server-side code
that will enable integration to work with Files received/sent to Hosts
without having to access `.fleet-*` indexes directly.

### Fleet changes

- Adds `FleetFilesClient` to Fleet's server-side code. Supports both
files that are received from the host as well as files that can be sent
to the host.
- exposes new `createFilesClient()` method from `FleetStartContract`
that enables fleet dependents to get a files client.


### Security Solution changes

- Refactors API routes to use new `FleetFilesClient`
- Deletes all file related services from server code

src/plugins/files/server/mocks.ts

@@ -10,7 +10,7 @@ import { KibanaRequest } from '@kbn/core/server';
 import { DeeplyMockedKeys } from '@kbn/utility-types-jest';
 import * as stream from 'stream';
 import { clone } from 'lodash';
-import { File } from '../common';
+import { File, FileJSON } from '../common';
 import { FileClient, FileServiceFactory, FileServiceStart, FilesSetup } from '.';
 
 export const createFileServiceMock = (): DeeplyMockedKeys<FileServiceStart> => ({
@@ -34,7 +34,9 @@ export const createFileServiceFactoryMock = (): DeeplyMockedKeys<FileServiceFact
   asScoped: jest.fn((_: KibanaRequest) => createFileServiceMock()),
 });
 
-export const createFileMock = (): DeeplyMockedKeys<File> => {
+export const createFileMock = <Meta = unknown>(
+  fileDataOverride: Partial<FileJSON<Meta>> = {}
+): DeeplyMockedKeys<File> => {
   const fileMock: DeeplyMockedKeys<File> = {
     id: '123',
     data: {
@@ -49,6 +51,8 @@ export const createFileMock = (): DeeplyMockedKeys<File> => {
       alt: undefined,
       fileKind: 'none',
       status: 'READY',
+
+      ...fileDataOverride,
     },
     update: jest.fn(),
     uploadContent: jest.fn(),
@@ -68,8 +72,10 @@ export const createFileMock = (): DeeplyMockedKeys<File> => {
   return fileMock;
 };
 
-export const createFileClientMock = (): DeeplyMockedKeys<FileClient> => {
-  const fileMock = createFileMock();
+export const createFileClientMock = <Meta = unknown>(
+  fileDataOverride: Partial<FileJSON<Meta>> = {}
+): DeeplyMockedKeys<FileClient> => {
+  const fileMock = createFileMock(fileDataOverride);
 
   return {
     fileKind: 'none',

x-pack/plugins/fleet/server/errors/index.ts

@@ -110,3 +110,6 @@ export class ArtifactsElasticsearchError extends FleetError {
     }
   }
 }
+
+export class FleetFilesClientError extends FleetError {}
+export class FleetFileNotFound extends FleetFilesClientError {}

x-pack/plugins/fleet/server/index.ts

@@ -42,6 +42,14 @@ export type { PackagePolicyClient } from './services/package_policy_service';
 
 export { relativeDownloadUrlFromArtifact } from './services/artifacts/mappings';
 
+export type {
+  FleetFileTransferDirection,
+  FleetFileClientInterface,
+  FleetFile,
+  HapiReadableStream,
+  FleetFileUpdatableFields,
+} from './services/files/types';
+
 export const plugin = (initializerContext: PluginInitializerContext) => {
   return new FleetPlugin(initializerContext);
 };

x-pack/plugins/fleet/server/mocks/index.ts

@@ -32,6 +32,9 @@ import { packageServiceMock } from '../services/epm/package_service.mock';
 // Export all mocks from artifacts
 export * from '../services/artifacts/mocks';
 
+// export all mocks from fleet files client
+export * from '../services/files/mocks';
+
 export interface MockedFleetAppContext extends FleetAppContext {
   elasticsearch: ReturnType<typeof elasticsearchServiceMock.createStart>;
   data: ReturnType<typeof dataPluginMock.createStartContract>;

x-pack/plugins/fleet/server/plugin.ts

@@ -65,6 +65,10 @@ import {
 } from '../common';
 import { parseExperimentalConfigValue } from '../common/experimental_features';
 
+import { FleetFilesClient } from './services/files/client';
+
+import type { FleetFileClientInterface, FleetFileTransferDirection } from './services/files/types';
+
 import type { MessageSigningServiceInterface } from './services/security';
 import {
   getRouteRequiredAuthz,
@@ -217,6 +221,21 @@ export interface FleetStartContract {
    */
   createArtifactsClient: (packageName: string) => FleetArtifactsClient;
 
+  /**
+   * Create a Fleet Files client instance
+   * @param packageName
+   * @param type
+   * @param maxSizeBytes
+   */
+  createFilesClient: (
+    /** The integration package name */
+    packageName: string,
+    /** Type of file */
+    type: FleetFileTransferDirection,
+    /** Max size for files created when `type` is `to-host` */
+    maxSizeBytes?: number
+  ) => FleetFileClientInterface;
+
   messageSigningService: MessageSigningServiceInterface;
   uninstallTokenService: UninstallTokenServiceInterface;
 }
@@ -567,6 +586,15 @@ export class FleetPlugin
       createArtifactsClient(packageName: string) {
         return new FleetArtifactsClient(core.elasticsearch.client.asInternalUser, packageName);
       },
+      createFilesClient: (packageName, type, maxFileBytes) => {
+        return new FleetFilesClient(
+          core.elasticsearch.client.asInternalUser,
+          this.initializerContext.logger.get('fleetFiles', packageName),
+          packageName,
+          type,
+          maxFileBytes
+        );
+      },
       messageSigningService,
       uninstallTokenService,
     };