NestJs TypeORM configuration using AWS Parameter Store

Question

new to NestJS and have come across an issue. For our deployments we need to get our configuration from AWS Parameter Store (Systems Manager), including the database connection string. I have a ConfigModule and ConfigService which retrieves all the parameter store entries for my environment based on the param store path:

Here is my config service:

import * as dotenv from 'dotenv';
import * as fs from 'fs';
import * as AWS from 'aws-sdk';

export class ConfigService {
    private readonly envConfig: { [key: string]: string };
    private awsParamStoreEntries: { [key: string]: string }[];

    constructor(awsParamStorePath: string, filePath: string) {
        this.envConfig = dotenv.parse(fs.readFileSync(filePath));

        this.loadAwsParameterStoreEntries(awsParamStorePath).then((data) => {
            this.awsParamStoreEntries = data;
        });
    }

    loadAwsParameterStoreEntries(pathPrefix: string) {
        const credentials = new AWS.SharedIniFileCredentials({ profile: 'grasshopper-parameter' });
        AWS.config.credentials = credentials;
        const ssm = new AWS.SSM({ region: 'us-west-2' });
        var params: { [key: string]: string }[] = [];

        return getParams({
            Path: '/app/v3/development/',
            Recursive: true,
            WithDecryption: true,
            MaxResults: 10,
        }).then(() => {
            return params;
        });

        function getParams(options) {
            return new Promise((resolve, reject) => {
                ssm.getParametersByPath(options, processParams(options, (err, data) => {
                    if (err) {
                        return reject(err);
                    }
                    resolve(data);
                }));
            });
        }

        function processParams(options, cb) {
            return function (err, data) {
                if (err) {
                    return cb(err)
                };
                data.Parameters.forEach(element => {
                    let key = element.Name.split('/').join(':')
                    params.push({ key: key, value: element.Value });
                });
                if (data.NextToken) {
                    const nextOptions = Object.assign({}, options);
                    nextOptions.NextToken = data.NextToken;
                    return ssm.getParametersByPath(nextOptions, processParams(options, cb));
                }
                return cb(null);
            };
        }
    }

    get(key: string): string {
        return this.envConfig[key];
    }

    getParamStoreValue(key: string): string {
        return this.awsParamStoreEntries.find(element => element.key === key)['value'];
    }

    getDatabase(): string {
        return this.awsParamStoreEntries.find(element => element.key === 'ConnectionStrings:CoreDb')['value'];
    }
}

Here is the main app module declaration block:

@Module({
  imports: [ConfigModule, TypeOrmModule.forRootAsync({
    imports: [ConfigModule],
    useFactory: async (configService: ConfigService) => ({
      url: configService.getDatabase()
    }),
    inject: [ConfigService]
  }),
    CoreModule, AuthModule],
  controllers: [AppController],
  providers: [AppService],
})

As you can see I am telling TypeORM to call the getDatabase() method in the ConfigService but the problem is that it takes about 3-4 seconds for the parameter store entries to load so an "undefined" error occurs because "this.awsParamStoreEntries" is still undefined when TypeORM tries to load the connection string.

Have scoured the web to see if this has been done but could not find anything that uses NestJS / TypeORM / AWS Parameter Store in this way. There is an existing (unanswered) question here on StackOverflow as well.

Thanks!

Answer 1

Can you do something like this.

import { TypeOrmOptionsFactory, TypeOrmModuleOptions } from '@nestjs/typeorm';
import { ConfigService } from './config.service';
import { Injectable } from '@nestjs/common';

@Injectable()
export class TypeOrmConfigService implements TypeOrmOptionsFactory {
    constructor(private readonly configService: ConfigService) {
    }

    async createTypeOrmOptions(): Promise<TypeOrmModuleOptions> {
        this.configService.awsParamStoreEntries = await this.configService.loadAwsParameterStoreEntries(this.configService.awsParamStorePath);

        return {
            url: this.configService.getDatabase(),
        };
    }
}

@Module({
  imports: [
    ConfigModule, 
    TypeOrmModule.forRootAsync({
      imports: [ConfigModule],
      useClass: TypeOrmConfigService,
    }),
    CoreModule, 
    AuthModule
  ],
  controllers: [AppController],
  providers: [AppService],
})

import * as dotenv from 'dotenv';
import * as fs from 'fs';
import * as AWS from 'aws-sdk';
import { Injectable } from '@nestjs/common';

@Injectable()
export class ConfigService {
    private readonly envConfig: { [key: string]: string };
    awsParamStoreEntries: { [key: string]: string }[];
    private readonly awsParamStorePath: string;

    constructor(awsParamStorePath: string, filePath: string) {
        this.envConfig = dotenv.parse(fs.readFileSync(filePath));
        this.awsParamStorePath = awsParamStorePath;
    }

    loadAwsParameterStoreEntries(pathPrefix: string) {...

https://docs.nestjs.com/techniques/database