# Amazon OpenSearch Service Construct Library


Amazon OpenSearch Service is the successor to Amazon Elasticsearch Service.

See [Migrating to OpenSearch](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-elasticsearch-readme.html#migrating-to-opensearch) for migration instructions from `@aws-cdk/aws-elasticsearch` to this module, `@aws-cdk/aws-opensearchservice`.

## Quick start

Create a development cluster by simply specifying the version:

```ts
const devDomain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
});
```

To perform version upgrades without replacing the entire domain, specify the `enableVersionUpgrade` property.

```ts
const devDomain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  enableVersionUpgrade: true, // defaults to false
});
```

Create a production grade cluster by also specifying things like capacity and az distribution

```ts
const prodDomain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  capacity: {
    masterNodes: 5,
    dataNodes: 20,
  },
  ebs: {
    volumeSize: 20,
  },
  zoneAwareness: {
    availabilityZoneCount: 3,
  },
  logging: {
    slowSearchLogEnabled: true,
    appLogEnabled: true,
    slowIndexLogEnabled: true,
  },
});
```

This creates an Amazon OpenSearch Service cluster and automatically sets up log groups for
logging the domain logs and slow search logs.

## A note about SLR

Some cluster configurations (e.g VPC access) require the existence of the [`AWSServiceRoleForAmazonElasticsearchService`](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/slr.html) Service-Linked Role.

When performing such operations via the AWS Console, this SLR is created automatically when needed. However, this is not the behavior when using CloudFormation. If an SLR is needed, but doesn't exist, you will encounter a failure message simlar to:

```console
Before you can proceed, you must enable a service-linked role to give Amazon OpenSearch Service...
```

To resolve this, you need to [create](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html#create-service-linked-role) the SLR. We recommend using the AWS CLI:

```console
aws iam create-service-linked-role --aws-service-name es.amazonaws.com
```

You can also create it using the CDK, **but note that only the first application deploying this will succeed**:

```ts
const slr = new iam.CfnServiceLinkedRole(this, 'Service Linked Role', {
  awsServiceName: 'es.amazonaws.com',
});
```

## Importing existing domains

To import an existing domain into your CDK application, use the `Domain.fromDomainEndpoint` factory method.
This method accepts a domain endpoint of an already existing domain:

```ts
const domainEndpoint = 'https://my-domain-jcjotrt6f7otem4sqcwbch3c4u.us-east-1.es.amazonaws.com';
const domain = opensearch.Domain.fromDomainEndpoint(this, 'ImportedDomain', domainEndpoint);
```

## Permissions

### IAM

Helper methods also exist for managing access to the domain.

```ts
declare const fn: lambda.Function;
declare const domain: opensearch.Domain;

// Grant write access to the app-search index
domain.grantIndexWrite('app-search', fn);

// Grant read access to the 'app-search/_search' path
domain.grantPathRead('app-search/_search', fn);
```

## Encryption

The domain can also be created with encryption enabled:

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  ebs: {
    volumeSize: 100,
    volumeType: ec2.EbsDeviceVolumeType.GENERAL_PURPOSE_SSD,
  },
  nodeToNodeEncryption: true,
  encryptionAtRest: {
    enabled: true,
  },
});
```

This sets up the domain with node to node encryption and encryption at
rest. You can also choose to supply your own KMS key to use for encryption at
rest.

## VPC Support

Domains can be placed inside a VPC, providing a secure communication between Amazon OpenSearch Service and other services within the VPC without the need for an internet gateway, NAT device, or VPN connection.

> Visit [VPC Support for Amazon OpenSearch Service Domains](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/vpc.html) for more details.

```ts
const vpc = new ec2.Vpc(this, 'Vpc');
const domainProps: opensearch.DomainProps = {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  removalPolicy: RemovalPolicy.DESTROY,
  vpc,
  // must be enabled since our VPC contains multiple private subnets.
  zoneAwareness: {
    enabled: true,
  },
  capacity: {
    // must be an even number since the default az count is 2.
    dataNodes: 2,
  },
};
new opensearch.Domain(this, 'Domain', domainProps);
```

In addition, you can use the `vpcSubnets` property to control which specific subnets will be used, and the `securityGroups` property to control
which security groups will be attached to the domain. By default, CDK will select all *private* subnets in the VPC, and create one dedicated security group.

## Metrics

Helper methods exist to access common domain metrics for example:

```ts
declare const domain: opensearch.Domain;
const freeStorageSpace = domain.metricFreeStorageSpace();
const masterSysMemoryUtilization = domain.metric('MasterSysMemoryUtilization');
```

This module is part of the [AWS Cloud Development Kit](https://github.com/aws/aws-cdk) project.

## Fine grained access control

The domain can also be created with a master user configured. The password can
be supplied or dynamically created if not supplied.

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  enforceHttps: true,
  nodeToNodeEncryption: true,
  encryptionAtRest: {
    enabled: true,
  },
  fineGrainedAccessControl: {
    masterUserName: 'master-user',
  },
});

const masterUserPassword = domain.masterUserPassword;
```

## Using unsigned basic auth

For convenience, the domain can be configured to allow unsigned HTTP requests
that use basic auth. Unless the domain is configured to be part of a VPC this
means anyone can access the domain using the configured master username and
password.

To enable unsigned basic auth access the domain is configured with an access
policy that allows anyonmous requests, HTTPS required, node to node encryption,
encryption at rest and fine grained access control.

If the above settings are not set they will be configured as part of enabling
unsigned basic auth. If they are set with conflicting values, an error will be
thrown.

If no master user is configured a default master user is created with the
username `admin`.

If no password is configured a default master user password is created and
stored in the AWS Secrets Manager as secret. The secret has the prefix
`<domain id>MasterUser`.

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  useUnsignedBasicAuth: true,
});

const masterUserPassword = domain.masterUserPassword;
```

## Custom access policies

If the domain requires custom access control it can be configured either as a
constructor property, or later by means of a helper method.

For simple permissions the `accessPolicies` constructor may be sufficient:

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  accessPolicies: [
    new iam.PolicyStatement({
      actions: ['es:*ESHttpPost', 'es:ESHttpPut*'],
      effect: iam.Effect.ALLOW,
      principals: [new iam.AccountPrincipal('123456789012')],
      resources: ['*'],
    }),
  ]
});
```

For more complex use-cases, for example, to set the domain up to receive data from a
[cross-account Kinesis Firehose](https://aws.amazon.com/premiumsupport/knowledge-center/kinesis-firehose-cross-account-streaming/) the `addAccessPolicies` helper method
allows for policies that include the explicit domain ARN.

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
});
domain.addAccessPolicies(
  new iam.PolicyStatement({
    actions: ['es:ESHttpPost', 'es:ESHttpPut'],
    effect: iam.Effect.ALLOW,
    principals: [new iam.AccountPrincipal('123456789012')],
    resources: [domain.domainArn, `${domain.domainArn}/*`],
  }),
  new iam.PolicyStatement({
    actions: ['es:ESHttpGet'],
    effect: iam.Effect.ALLOW,
    principals: [new iam.AccountPrincipal('123456789012')],
    resources: [
      `${domain.domainArn}/_all/_settings`,
      `${domain.domainArn}/_cluster/stats`,
      `${domain.domainArn}/index-name*/_mapping/type-name`,
      `${domain.domainArn}/roletest*/_mapping/roletest`,
      `${domain.domainArn}/_nodes`,
      `${domain.domainArn}/_nodes/stats`,
      `${domain.domainArn}/_nodes/*/stats`,
      `${domain.domainArn}/_stats`,
      `${domain.domainArn}/index-name*/_stats`,
      `${domain.domainArn}/roletest*/_stat`,
    ],
  }),
);
```


## Audit logs

Audit logs can be enabled for a domain, but only when fine grained access control is enabled.

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  enforceHttps: true,
  nodeToNodeEncryption: true,
  encryptionAtRest: {
    enabled: true,
  },
  fineGrainedAccessControl: {
    masterUserName: 'master-user',
  },
  logging: {
    auditLogEnabled: true,
    slowSearchLogEnabled: true,
    appLogEnabled: true,
    slowIndexLogEnabled: true,
  },
});
```

## UltraWarm

UltraWarm nodes can be enabled to provide a cost-effective way to store large amounts of read-only data.

```ts
const domain = new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  capacity: {
    masterNodes: 2,
    warmNodes: 2,
    warmInstanceType: 'ultrawarm1.medium.search',
  },
});
```

## Custom endpoint

Custom endpoints can be configured to reach the domain under a custom domain name.

```ts
new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  customEndpoint: {
    domainName: 'search.example.com',
  },
});
```

It is also possible to specify a custom certificate instead of the auto-generated one.

Additionally, an automatic CNAME-Record is created if a hosted zone is provided for the custom endpoint

## Advanced options

[Advanced options](https://docs.aws.amazon.com/opensearch-service/latest/developerguide/createupdatedomains.html#createdomain-configure-advanced-options) can used to configure additional options.

```ts
new opensearch.Domain(this, 'Domain', {
  version: opensearch.EngineVersion.OPENSEARCH_1_0,
  advancedOptions: {
    'rest.action.multi.allow_explicit_index': 'false',
    'indices.fielddata.cache.size': '25',
    'indices.query.bool.max_clause_count': '2048',
  },
});
```
