Serverless Frameworkの開発でDynamoDB Localを使う

$ yarn add -D serverless-dynamodb-local

plugins:
  - serverless-dynamodb-local #追加

$ npx sls dynamodb install

projectRoot/
  .dynamodb/
    DynamoDBLocal_lib/
    third_party_licenses/
    DynamoDBLocal.jar
    ・・・
  package.json
  serverless.yml

.dynamodb

custom:
  dynamodb:
    stages: #stagesについては後述
      - dev
    start:
      inMemory: true

--port                    -p  Port to listen on. Default: 8000
--cors                    -c  Enable CORS support (cross-origin resource sharing) for JavaScript. You must provide a comma-separated "allow" list of specific domains. The default setting for -cors is an asterisk (*), which allows public access.
--inMemory                -i  DynamoDB; will run in memory, instead of using a database file. When you stop DynamoDB;, none of the data will be saved. Note that you cannot specify both -dbPath and -inMemory at once.
--dbPath                  -d  The directory where DynamoDB will write its database file. If you do not specify this option, the file will be written to the current directory. Note that you cannot specify both -dbPath and -inMemory at once. For the path, current working directory is <projectroot>/node_modules/serverless-dynamodb-local/dynamob. For example to create <projectroot>/node_modules/serverless-dynamodb-local/dynamob/<mypath> you should specify -d <mypath>/ or --dbPath <mypath>/ with a forwardslash at the end.
--sharedDb                -h  DynamoDB will use a single database file, instead of using separate files for each credential and region. If you specify -sharedDb, all DynamoDB clients will interact with the same set of tables regardless of their region and credential configuration.
--delayTransientStatuses  -t  Causes DynamoDB to introduce delays for certain operations. DynamoDB can perform some tasks almost instantaneously, such as create/update/delete operations on tables and indexes; however, the actual DynamoDB service requires more time for these tasks. Setting this parameter helps DynamoDB simulate the behavior of the Amazon DynamoDB web service more closely. (Currently, this parameter introduces delays only for global secondary indexes that are in either CREATING or DELETING status.)
--optimizeDbBeforeStartup -o  Optimizes the underlying database tables before starting up DynamoDB on your computer. You must also specify -dbPath when you use this parameter.
--migration               -m  After starting dynamodb local, run dynamodb migrations.

$ npx sls dynamodb start
Dynamodb Local Started, Visit: http://localhost:8000/shell
2021-01-11 16:21:21.519:INFO::main: Logging initialized @1156ms to org.eclipse.jetty.util.log.StdErrLog

custom:
  dynamodb:
    stages:
      - dev

$ npx sls dynamodb start
Serverless: Skipping start: DynamoDB Local is not available for stage: dev

resources: # CloudFormation template syntax
  Resources:
    usersTable:
      Type: AWS::DynamoDB::Table
      Properties:
        TableName: users
        AttributeDefinitions:
          - AttributeName: email
            AttributeType: S
        KeySchema:
          - AttributeName: email
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1

custom:
  dynamodb:
    stages:
      - dev
    start:
      inMemory: true
      migrate: true

$ npx sls dynamodb start
Dynamodb Local Started, Visit: http://localhost:8000/shell
2021-01-11 16:59:46.987:INFO::main: Logging initialized @1019ms to org.eclipse.jetty.util.log.StdErrLog
Serverless: DynamoDB - created table users

var params = {
    TableName: 'users',
};
dynamodb.scan(params, function(err, data) {
    if (err) ppJson(err);
    else ppJson(data);
});

projectRoot/
  migrations/
    users.json

[
  {
    "id": 1,
    "email": "hoge@example.com"
  },
  {
    "id": 2,
    "email": "fuga@example.com"
  }
]

custom:
  dynamodb:
    stages:
      - dev
    start:
      inMemory: true
      migrate: true
      seed: true
    seed:
      development:
        sources:
          - table: users
            sources: [ ./migrations/users.json ]

$ npx sls dynamodb start
Dynamodb Local Started, Visit: http://localhost:8000/shell
2021-01-11 19:53:38.178:INFO::main: Logging initialized @868ms to org.eclipse.jetty.util.log.StdErrLog
Serverless: DynamoDB - created table users
Seed running complete for table: users

# slsコマンドで `sls dynamodb install` などを実行する上でも必要
plugins:
  - serverless-dynamodb-local
 
custom:
  dynamodb:
    # dymanodb start時に起動が出来ないため記載、起動が出来るのであれば書かなくて問題ない
    stages:
      - dev
    # dymanodb start実行時の設定
    # 以下の場合
    # - データの永続化はしない（inMemory: true）
    # - migration実行とseedデータの投入をstart時に実行
    start:
      inMemory: true
      migrate: true
      seed: true
    seed:
      development:
        sources:
          - table: programs
            sources: [ ./migrations/users.json ]
 
# usersテーブルの定義
# migrationを実行した際にこの定義を元にテーブルを作る
resources:
  Resources:
    usersTable:
      Type: AWS::DynamoDB::Table
      Properties:
        TableName: users
        AttributeDefinitions:
          - AttributeName: email
            AttributeType: S
        KeySchema:
          - AttributeName: email
            KeyType: HASH
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1