NestJS Config AWS Parameter Store

!Package License
!Build Status

This package allows you to configure your NestJS application by loading the configuration from AWS SSM Parameter Store.

Installation

``bash
npm install nestjs-param-store @aws-sdk/client-ssm
`

Configuration

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`typescript
import { Module } from '@nestjs/common';
import { PSConfigModule } from 'nestjs-param-store';

@Module({
imports: [
PSConfigModule.register({
ssmParamStorePath: '/production/services/my-service',
ssmDecryptParams: true,
ssmRecursive: false,
ssmClientOptions: {
region: 'us-east-1',
},
}),
],
})
export class AppModule {}
`

By calling PSConfigModule.register, you configure the module to load all the parameters under the path ssmParamStorePath.

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The following example shows how to retrieve the configuration before registering the module.

`typescript
import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { PSConfigModule } from 'nestjs-param-store';

@Module({
imports: [
PSConfigModule.registerAsync({
imports: [ConfigModule],
useFactory: async (config: ConfigService) => ({
ssmParamStorePath: config.get('APP_CONFIG_PATH'),
ssmDecryptParams: true,
ssmRecursive: false,
ssmClientOptions: {
region: config.get('AWS_REGION'),
},
}),
inject: [ConfigService],
}),
],
})
export class AppModule {}
`

Options

| Option | Required | Default | Description |
|------------------- |---------- |------------- |------------------------------------------------------------------- |
| ssmParamStorePath | Yes | | The hierarchy for the parameter |
| ssmDecryptParams | No | false | Retrieve all parameters in a hierarchy with their value decrypted |
| ssmRecursive | No | false | Retrieve all parameters within a hierarchy |
| ssmClientOptions | No | undefined | Options to pass to the underlying SSM client |

Services

This module exposes the following services.

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The PSConfigService service allows you to access the configuration loaded from Parameter Store. Use its own class name as the injection token.

Let's assume the following parameters were previously registered:

- /production/services/my-service/pagination-limit: '25'
- /production/services/my-service/post-table: 'ProductionPostTable'

Configure the module with ssmParamStorePath pointing to /production/services/my-service to access all the parameters register for the service in production.

Then, access the configuration as follows:

`typescript
import { Injectable } from '@nestjs/common';
import { PSConfigService } from 'nestjs-param-store';
import { DynamoDBClient, QueryCommand, GetItemCommand } from '@aws-sdk/client-dynamodb';

@Injectable()
export class PostRepository {
// Some common initialization.
public constructor(
private readonly dynamodbClient: DynamoDBClient,
private readonly psConfigService: PSConfigService,
) {}

public getPostsByUser(userId: string) {
// Here: Note how to retrieve the configuration.
const table = await this.psConfigService.get('post-table');
const limit = await this.psConfigService.get('pagination-limit');

const queryCommand = new QueryCommand({
TableName: table, // <- use
KeyConditionExpression: 'PK = :pk',
ExpressionAttributeValues: {
':pk': { S: USER#${userId} },
},
Limit: limit, // <- use
});

const { Items = [] } = await this.dynamodbClient.send(queryCommand);
// .... snip ....
}
}
`

The PSConfigService service exposes the following methods:

- get(name, defaultValue): To retrieve a string configuration.
- getBool(name, defaultValue): To retrieve a boolean configuration. The following values as considered truly: true, True, 1, y, yes, and Yes.
- getNumber(name, defaultValue): To retrieve a numeric configuration.

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When calling get, getBool, or getNumber, the service will look up a parameter whose name ends with the name specified. This means that the match is partial.

Given the following parameter:

- /production/services/my-service/pagination-limit: '25'

It can be retrieved using one of these alternatives:

- get('pagination-limit')
- get('my-service/pagination-limit')
- get('services/my-service/pagination-limit')
- get('production/services/my-service/pagination-limit')

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You can access the raw parameters loaded from the Parameter Store.

`typescript
import { Inject, Injectable } from '@nestjs/common';
import { PS_CONFIG_PARAMETERS, PSConfigParameters } from 'nestjs-param-store';

@Injectable()
export class SophisticatedService {
public constructor(
@Inject(PS_CONFIG_PARAMETERS) parameters: PSConfigParameters,
) {
console.log(parameters);
}
}
`

Example of output:

`json
[
{
"Name": "/production/services/my-service/pagination-limit",
"Type": "String",
"Value": "25",
"Version": 1,
"LastModifiedDate": "2022-09-03T02:55:00.389000-04:00",
"ARN": "arn:aws:ssm:us-east-1:000000000000:parameter/production/services/my-service/pagination-limit",
"DataType": "text"
},
{
"Name": "/production/services/my-service/post-table",
"Type": "String",
"Value": "ProductionPostTable",
"Version": 1,
"LastModifiedDate": "2022-09-03T03:15:15.032000-04:00",
"ARN": "arn:aws:ssm:us-east-1:000000000000:parameter/production/services/my-service/post-table",
"DataType": "text"
}
]
`

Troubleshooting

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This happens when recursive is false and the specified path does not resolve the final level in the hierarchy.

Reference: GetParametersByPath

`typescript
import { Module } from '@nestjs/common';
import { PSConfigModule } from 'nestjs-param-store';

@Module({
imports: [
PSConfigModule.register({
ssmParamStorePath: '/production',
ssmRecursive: true, // <-- specify recursively
}),
],
})
export class AppModule {}
``