More Examples

This section includes some larger examples which use multiple packages.

Data Storage in Elasticsearch

Uses:

import {AwsHttps} from "@sailplane/aws-https";
import {ElasticsearchClient} from "@sailplane/elasticsearch-client";
import {Injector} from "@sailplane/injector";
import {Logger} from "@sailplane/logger";
import {Ticket} from "./ticket";

const logger = new Logger('ticket-storage');
const ES_TICKET_PATH_PREFIX = "/ticket/local/";

// TODO: Ideally, put this in central place so it only runs once.
Injector.register(ElasticsearchClient, () => {
    const endpoint: string = process.env.ES_ENDPOINT!;
    logger.info('Connecting to Elasticsearch @ ' + endpoint);
    return new ElasticsearchClient(new AwsHttps(), endpoint);
});

/**
 * Storage of service tickets in Elasticsearch on AWS.
 */
export class TicketStorage {

    static readonly $inject = [ElasticsearchClient];
    constructor(private readonly es: ElasticsearchClient) {
    }

    /**
     * Fetch a previously stored ticket by its ID
     * @param {string} id
     * @returns {Promise<Ticket>} if not found, returns undefined
     */
    get(id: string): Promise<Ticket> {
        return this.es.request('GET', ES_TICKET_PATH_PREFIX + id)
            .then((esDoc: ElasticsearchResult) => esDoc._source as Ticket);
    }

    /**
     * Store a ticket. Creates or replaces automatically.
     *
     * @param {Ticket} ticket
     * @returns {Promise<Ticket>} data stored (should match 'ticket')
     */
    put(ticket: Ticket): Promise<Ticket> {
        const path = ES_TICKET_PATH_PREFIX + ticket.id;
        return this.es.request('PUT', path, ticket)
            .then(() => ticket);
    }

    /**
     * Query for tickets that are not closed.
     *
     * @param {string} company
     * @param {number} maxResults Maximum number of results to return
     * @returns {Promise<Ticket[]>}
     * @throws Forbidden if no company value provided
     */
    queryOpen(company: string, maxResults: number): Promise<Ticket[]> {
        let query = {
            bool: {
                must_not: [
                    exists: {
                        field: "resolution"
                    }
                ]
            }
        };

        return this.es.request('GET', ES_TICKET_PATH_PREFIX + '_search', {
            size: maxResults,
            query: query
        })
        .then((esResults: ElasticsearchResult) => {
            if (esResults.timed_out) {
                throw new Error("Query of TicketStorage timed out");
            }
            else if (esResults.hits && esResults.hits.hits && esResults.hits.total) {
                return esResults.hits.hits.map(esDoc => esDoc._source as Ticket);
            }
            else {
                return [] as Ticket[];
            }
        });
    }

}

Injector.register(TicketStorage);

Serverless Framework Lambda

This example shows how to:

# serverless.yml
service:
name: serverless-demo

plugins:
  - serverless-webpack
  - serverless-offline
  - serverless-plugin-export-endpoints

provider:
  name: aws
  runtime: nodejs8.10

  environment:
    STATE_STORAGE_PREFIX: /${opt:stage}/myapp

  iamRoleStatements:
    - Effect: Allow
      Action:
        - ssm:GetParameter
        - ssm:PutParameter
      Resource: "arn:aws:ssm:${opt:region}:*:parameter${self:provider.environment.STATE_STORAGE_PREFIX}/*"

functions:
  getChatHistory:
    description: Retrieve some (more) history of the user's chat channel.
    handler: src/handlers.getChatHistory
    events:
      - http:
          method: get
          path: chat/history
          cors: true
          request:
            parameters:
              querystrings:
                channel: true
                cursor: false

import 'source-map-support/register';
import {APIGatewayEvent} from 'aws-lambda';
import {Injector} from "@sailplane/injector";
import * as LambdaUtils from "@sailplane/lambda-utils";
import {ChatService} from "./chat-service";
import * as createHttpError from "http-errors";

Injector.register(StateStorage, () => new StateStorage(process.env.STATE_STORAGE_PREFIX));

/**
 * Fetch history of chat on the user's channel
 */
export const getChatHistory = LambdaUtils.wrapApiHandler(async (event: LambdaUtils.APIGatewayProxyEvent) => {
    const channel = event.queryStringParameters.channel;
    const cursor = event.queryStringParameters.cursor;

    return Injector.get(ChatService)!.getHistory(channel, cursor);
});

// chat-service.ts
import {AwsHttps} from "@sailplane/aws-https";
import {ExpiringValue} from "@sailplane/expiring-value";
import {Injector} from "@sailplane/injector";
import {Logger} from "@sailplane/logger";
import {URL} from "url";
import * as createHttpError from "http-errors";

const logger = new Logger('chat-service');

const CONFIG_REFRESH_PERIOD = 15*60*1000; // 15 minutes

//// Define Data Structures
interface ChatConfig {
    url: string;
    authToken: string;
}

interface ChatMessage {
    from: string;
    when: number;
    text: string;
}

interface ChatHistory {
    messages: ChatMessage[];
    cursor: string;
}

/**
 * Service to interface with the external chat provider.
 */
export class ChatService {
    private config = new ExpiringValue<ChatConfig>(
            () => this.stateStorage.get('ChatService', 'config') as ChatConfig,
            CONFIG_REFRESH_PERIOD);
    private readonly awsHttps = new AwsHttps();

    /** Construct */
    constructor(private readonly stateStorage: StateStorage) {
    }

    /**
     * Fetch history of a chat channel.
     */
    async getHistory(channelId: string, cursor?: string): Promise<ChatHistory> {
        logger.debug(`getHistory(${channelId}, ${cursor})`);
        const config = await this.config.get();

        // Fetch history from external chat provider
        let options = this.awsHttp.buildOptions('POST' new URL(config.url));
        options.headers = { authorization: 'TOKEN ' + config.authToken };
        options.body = JSON.stringify({
            channel: channelId
            cursor: cursor
        });

        const response = await this.awsHttp.request(options);

        // Check for error
        if (!response.ok) {
            logger.info("External history request returned error: ", response);
            throw new createHttpError.InternalServerError(response.error);
        }

        // Prepare results
        const history: ChatHistory =  {
            messages: [],
            cursor: response.next_cursor
        };

        // Process each message
        for (let msg of response.messages) {
            history.messages.push({
                from: msg.username,
                when: msg.ts
                text: msg.text
            });
        }

        return history;
    }
}

Injector.register(ChatService, [StateStorage]);