AzureBackend: Add Azure MediaBackend

Add @azure/storage-blob dependency
This is the relevant part of the official azure sdk.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/media/backends/azure-backend.ts

@@ -0,0 +1,85 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Inject, Injectable } from '@nestjs/common';
+import mediaConfiguration, { MediaConfig } from '../../config/media.config';
+import { ConsoleLoggerService } from '../../logger/console-logger.service';
+import { MediaBackend } from '../media-backend.interface';
+import { BackendData } from '../media-upload.entity';
+import {
+  BlobServiceClient,
+  BlockBlobClient,
+  ContainerClient,
+} from '@azure/storage-blob';
+import { BackendType } from './backend-type.enum';
+import { MediaBackendError } from '../../errors/errors';
+
+@Injectable()
+export class AzureBackend implements MediaBackend {
+  private config: MediaConfig['backend']['azure'];
+  private client: ContainerClient;
+
+  constructor(
+    private readonly logger: ConsoleLoggerService,
+    @Inject(mediaConfiguration.KEY)
+    private mediaConfig: MediaConfig,
+  ) {
+    this.logger.setContext(AzureBackend.name);
+    this.config = mediaConfig.backend.azure;
+    if (mediaConfig.backend.use === BackendType.AZURE) {
+      // only create the client if the backend is configured to azure
+      const blobServiceClient = BlobServiceClient.fromConnectionString(
+        this.config.connectionString,
+      );
+      this.client = blobServiceClient.getContainerClient(this.config.container);
+    }
+  }
+
+  async saveFile(
+    buffer: Buffer,
+    fileName: string,
+  ): Promise<[string, BackendData]> {
+    const blockBlobClient: BlockBlobClient = this.client.getBlockBlobClient(
+      fileName,
+    );
+    try {
+      await blockBlobClient.upload(buffer, buffer.length);
+      const url = this.getUrl(fileName);
+      this.logger.log(`Uploaded ${url}`, 'saveFile');
+      return [url, null];
+    } catch (e) {
+      this.logger.error(
+        `error: ${(e as Error).message}`,
+        (e as Error).stack,
+        'saveFile',
+      );
+      throw new MediaBackendError(`Could not save '${fileName}' on Azure`);
+    }
+  }
+
+  async deleteFile(fileName: string, _: BackendData): Promise<void> {
+    const blockBlobClient: BlockBlobClient = this.client.getBlockBlobClient(
+      fileName,
+    );
+    try {
+      await blockBlobClient.delete();
+      const url = this.getUrl(fileName);
+      this.logger.log(`Deleted ${url}`, 'deleteFile');
+      return;
+    } catch (e) {
+      this.logger.error(
+        `error: ${(e as Error).message}`,
+        (e as Error).stack,
+        'deleteFile',
+      );
+      throw new MediaBackendError(`Could not delete '${fileName}' on Azure`);
+    }
+  }
+
+  private getUrl(fileName: string): string {
+    return `${this.client.url}/${fileName}`;
+  }
+}

src/media/media.module.ts

@@ -14,6 +14,7 @@ import { FilesystemBackend } from './backends/filesystem-backend';
 import { MediaUpload } from './media-upload.entity';
 import { MediaService } from './media.service';
 import { ImgurBackend } from './backends/imgur-backend';
+import { AzureBackend } from './backends/azure-backend';
 
 @Module({
   imports: [
@@ -23,7 +24,7 @@ import { ImgurBackend } from './backends/imgur-backend';
     LoggerModule,
     ConfigModule,
   ],
-  providers: [MediaService, FilesystemBackend, ImgurBackend],
+  providers: [MediaService, FilesystemBackend, AzureBackend, ImgurBackend],
   exports: [MediaService],
 })
 export class MediaModule {}

src/media/media.service.ts

@@ -19,6 +19,7 @@ import { FilesystemBackend } from './backends/filesystem-backend';
 import { MediaBackend } from './media-backend.interface';
 import { MediaUpload } from './media-upload.entity';
 import { MediaUploadUrlDto } from './media-upload-url.dto';
+import { AzureBackend } from './backends/azure-backend';
 import { ImgurBackend } from './backends/imgur-backend';
 
 @Injectable()
@@ -159,6 +160,8 @@ export class MediaService {
     switch (this.mediaConfig.backend.use) {
       case 'filesystem':
         return BackendType.FILESYSTEM;
+      case 'azure':
+        return BackendType.AZURE;
       case 'imgur':
         return BackendType.IMGUR;
     }
@@ -168,6 +171,8 @@ export class MediaService {
     switch (type) {
       case BackendType.FILESYSTEM:
         return this.moduleRef.get(FilesystemBackend);
+      case BackendType.AZURE:
+        return this.moduleRef.get(AzureBackend);
       case BackendType.IMGUR:
         return this.moduleRef.get(ImgurBackend);
     }