@agiledigital/serverless-parameter-subscriber/lambda/handler.js

serverless plugin to make allow Lambdas to included dynamically updated parameters from the paramter store.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const aws_sdk_1 = require("aws-sdk");
const ssm = new aws_sdk_1.SSM();
const lambda = new aws_sdk_1.Lambda();
const subscriptions = (JSON.parse(process.env.PARAMETER_SUBSCRIPTIONS || '{}'));
/**
 * Updates the Lambda Functions environment variables value to the updated
 * parameter value. The environment variable to update is specified in the
 * subscriber parameter value.
 *
 * @param func the name of the function
 * @param envVar the name environment variable to update
 * @param value the value to set the environment variable to
 */
const updateLambdaFunctions = async (func, envVar, value) => {
    console.log(`Updating Lambda Function [${func}] environment variable [${envVar}] to [${value}].`);
    const lambdaFunctionConfig = await lambda
        .getFunctionConfiguration({
        FunctionName: func,
    })
        .promise();
    await lambda
        .updateFunctionConfiguration({
        FunctionName: func,
        Environment: {
            Variables: Object.assign(Object.assign({}, (lambdaFunctionConfig.Environment &&
                lambdaFunctionConfig.Environment.Variables)), { [envVar]: value }),
        },
    })
        .promise();
    return `Lambda Function [${func}] has been updated.`;
};
/**
 * Receives event from CloudWatch for SSM parameter change event, e.g. update,
 * create. Processes the change event so that the dependent Lambda Function
 * will get the updated/new SSM parameter value. The Lambda Function that is
 * depending on the SSM parameter value will have an environment variable
 * referencing the SSM parameter value. For example setup:
 *
 * Function Name: myFunction
 * Function ENV: MY_ENV
 * SSM Parameter Key: myParam
 *
 * For the above example setup, the MY_ENV value will be the value of myParam,
 * and this Lambda will update the MY_ENV environment variable based on the
 * change event from myParam.
 *
 * @param event the CloudWatch Parameter update event
 * @returns promise resolving when all environment variables have updated
 */
module.exports.handler = async (event) => {
    var _a, _b;
    const updatedParamName = event.detail.name;
    const operation = event.detail.operation;
    const subscription = subscriptions[updatedParamName];
    if ((operation === 'Update' || operation === 'Create') &&
        subscription !== undefined) {
        const updatedParamValueResult = await ssm
            .getParameter({
            Name: updatedParamName,
        })
            .promise();
        const updatedParamValue = (_b = (_a = updatedParamValueResult.Parameter) === null || _a === void 0 ? void 0 : _a.Value, (_b !== null && _b !== void 0 ? _b : ''));
        const updateResults = await subscription.reduce(async (promise, { func, env }) => {
            const results = await promise;
            const newResult = await updateLambdaFunctions(func, env, updatedParamValue);
            return [...results, newResult];
        }, Promise.resolve([]));
        console.log(updateResults.join('\n'));
    }
    return { message: 'success' };
};
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