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lambda-functions.ts
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lambda-functions.ts
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import { Writable } from 'stream';
import * as AWS from 'aws-sdk';
import { flatMap } from '../../util';
import { ISDK } from '../aws-auth';
import { CfnEvaluationException, EvaluateCloudFormationTemplate } from '../evaluate-cloudformation-template';
import { ChangeHotswapImpact, ChangeHotswapResult, HotswapOperation, HotswappableChangeCandidate } from './common';
// namespace object imports won't work in the bundle for function exports
// eslint-disable-next-line @typescript-eslint/no-require-imports
const archiver = require('archiver');
/**
* Returns `ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT` if the change cannot be short-circuited,
* `ChangeHotswapImpact.IRRELEVANT` if the change is irrelevant from a short-circuit perspective
* (like a change to CDKMetadata),
* or a LambdaFunctionResource if the change can be short-circuited.
*/
export async function isHotswappableLambdaFunctionChange(
logicalId: string, change: HotswappableChangeCandidate, evaluateCfnTemplate: EvaluateCloudFormationTemplate,
): Promise<ChangeHotswapResult> {
// if the change is for a Lambda Version,
// ignore it by returning an empty hotswap operation -
// we will publish a new version when we get to hotswapping the actual Function this Version points to, below
// (Versions can't be changed in CloudFormation anyway, they're immutable)
if (change.newValue.Type === 'AWS::Lambda::Version') {
return ChangeHotswapImpact.IRRELEVANT;
}
// we handle Aliases specially too
if (change.newValue.Type === 'AWS::Lambda::Alias') {
return checkAliasHasVersionOnlyChange(change);
}
const lambdaCodeChange = await isLambdaFunctionCodeOnlyChange(change, evaluateCfnTemplate);
if (typeof lambdaCodeChange === 'string') {
return lambdaCodeChange;
}
const functionName = await evaluateCfnTemplate.establishResourcePhysicalName(logicalId, change.newValue.Properties?.FunctionName);
if (!functionName) {
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
const functionArn = await evaluateCfnTemplate.evaluateCfnExpression({
'Fn::Sub': 'arn:${AWS::Partition}:lambda:${AWS::Region}:${AWS::AccountId}:function:' + functionName,
});
// find all Lambda Versions that reference this Function
const versionsReferencingFunction = evaluateCfnTemplate.findReferencesTo(logicalId)
.filter(r => r.Type === 'AWS::Lambda::Version');
// find all Lambda Aliases that reference the above Versions
const aliasesReferencingVersions = flatMap(versionsReferencingFunction, v =>
evaluateCfnTemplate.findReferencesTo(v.LogicalId));
const aliasesNames = await Promise.all(aliasesReferencingVersions.map(a =>
evaluateCfnTemplate.evaluateCfnExpression(a.Properties?.Name)));
return new LambdaFunctionHotswapOperation({
physicalName: functionName,
functionArn: functionArn,
resource: lambdaCodeChange,
publishVersion: versionsReferencingFunction.length > 0,
aliasesNames,
});
}
/**
* Returns is a given Alias change is only in the 'FunctionVersion' property,
* and `ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT` is the change is for any other property.
*/
function checkAliasHasVersionOnlyChange(change: HotswappableChangeCandidate): ChangeHotswapResult {
for (const updatedPropName in change.propertyUpdates) {
if (updatedPropName !== 'FunctionVersion') {
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
}
return ChangeHotswapImpact.IRRELEVANT;
}
/**
* Returns `ChangeHotswapImpact.IRRELEVANT` if the change is not for a AWS::Lambda::Function,
* but doesn't prevent short-circuiting
* (like a change to CDKMetadata resource),
* `ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT` if the change is to a AWS::Lambda::Function,
* but not only to its Code property,
* or a LambdaFunctionCode if the change is to a AWS::Lambda::Function,
* and only affects its Code property.
*/
async function isLambdaFunctionCodeOnlyChange(
change: HotswappableChangeCandidate, evaluateCfnTemplate: EvaluateCloudFormationTemplate,
): Promise<LambdaFunctionChange | ChangeHotswapImpact> {
const newResourceType = change.newValue.Type;
if (newResourceType !== 'AWS::Lambda::Function') {
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
/*
* At first glance, we would want to initialize these using the "previous" values (change.oldValue),
* in case only one of them changed, like the key, and the Bucket stayed the same.
* However, that actually fails for old-style synthesis, which uses CFN Parameters!
* Because the names of the Parameters depend on the hash of the Asset,
* the Parameters used for the "old" values no longer exist in `assetParams` at this point,
* which means we don't have the correct values available to evaluate the CFN expression with.
* Fortunately, the diff will always include both the s3Bucket and s3Key parts of the Lambda's Code property,
* even if only one of them was actually changed,
* which means we don't need the "old" values at all, and we can safely initialize these with just `''`.
*/
const propertyUpdates = change.propertyUpdates;
let code: LambdaFunctionCode | undefined = undefined;
let tags: LambdaFunctionTags | undefined = undefined;
for (const updatedPropName in propertyUpdates) {
const updatedProp = propertyUpdates[updatedPropName];
switch (updatedPropName) {
case 'Code':
let foundCodeDifference = false;
let s3Bucket, s3Key, imageUri, functionCodeZip;
for (const newPropName in updatedProp.newValue) {
switch (newPropName) {
case 'S3Bucket':
foundCodeDifference = true;
s3Bucket = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
break;
case 'S3Key':
foundCodeDifference = true;
s3Key = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
break;
case 'ImageUri':
foundCodeDifference = true;
imageUri = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
break;
case 'ZipFile':
foundCodeDifference = true;
// We must create a zip package containing a file with the inline code
const functionCode = await evaluateCfnTemplate.evaluateCfnExpression(updatedProp.newValue[newPropName]);
const functionRuntime = await evaluateCfnTemplate.evaluateCfnExpression(change.newValue.Properties?.Runtime);
if (!functionRuntime) {
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
// file extension must be chosen depending on the runtime
const codeFileExt = determineCodeFileExtFromRuntime(functionRuntime);
functionCodeZip = await zipString(`index.${codeFileExt}`, functionCode);
break;
default:
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
}
if (foundCodeDifference) {
code = {
s3Bucket,
s3Key,
imageUri,
functionCodeZip,
};
}
break;
case 'Tags':
/*
* Tag updates are a bit odd; they manifest as two lists, are flagged only as
* `isDifferent`, and we have to reconcile them.
*/
const tagUpdates: { [tag: string]: string | TagDeletion } = {};
if (updatedProp?.isDifferent) {
updatedProp.newValue.forEach((tag: CfnDiffTagValue) => {
tagUpdates[tag.Key] = tag.Value;
});
updatedProp.oldValue.forEach((tag: CfnDiffTagValue) => {
if (tagUpdates[tag.Key] === undefined) {
tagUpdates[tag.Key] = TagDeletion.DELETE;
}
});
tags = { tagUpdates };
}
break;
default:
return ChangeHotswapImpact.REQUIRES_FULL_DEPLOYMENT;
}
}
return code || tags ? { code, tags } : ChangeHotswapImpact.IRRELEVANT;
}
interface CfnDiffTagValue {
readonly Key: string;
readonly Value: string;
}
interface LambdaFunctionCode {
readonly s3Bucket?: string;
readonly s3Key?: string;
readonly imageUri?: string;
readonly functionCodeZip?: Buffer;
}
enum TagDeletion {
DELETE = -1,
}
interface LambdaFunctionTags {
readonly tagUpdates: { [tag : string] : string | TagDeletion };
}
interface LambdaFunctionChange {
readonly code?: LambdaFunctionCode;
readonly tags?: LambdaFunctionTags;
}
interface LambdaFunctionResource {
readonly physicalName: string;
readonly functionArn: string;
readonly resource: LambdaFunctionChange;
readonly publishVersion: boolean;
readonly aliasesNames: string[];
}
class LambdaFunctionHotswapOperation implements HotswapOperation {
public readonly service = 'lambda-function';
public readonly resourceNames: string[];
constructor(private readonly lambdaFunctionResource: LambdaFunctionResource) {
this.resourceNames = [
`Lambda Function '${lambdaFunctionResource.physicalName}'`,
// add Version here if we're publishing a new one
...(lambdaFunctionResource.publishVersion ? [`Lambda Version for Function '${lambdaFunctionResource.physicalName}'`] : []),
// add any Aliases that we are hotswapping here
...lambdaFunctionResource.aliasesNames.map(alias => `Lambda Alias '${alias}' for Function '${lambdaFunctionResource.physicalName}'`),
];
}
public async apply(sdk: ISDK): Promise<any> {
const lambda = sdk.lambda();
const resource = this.lambdaFunctionResource.resource;
const operations: Promise<any>[] = [];
if (resource.code !== undefined) {
const updateFunctionCodeResponse = await lambda.updateFunctionCode({
FunctionName: this.lambdaFunctionResource.physicalName,
S3Bucket: resource.code.s3Bucket,
S3Key: resource.code.s3Key,
ImageUri: resource.code.imageUri,
ZipFile: resource.code.functionCodeZip,
}).promise();
await this.waitForLambdasCodeUpdateToFinish(updateFunctionCodeResponse, lambda);
// only if the code changed is there any point in publishing a new Version
if (this.lambdaFunctionResource.publishVersion) {
const publishVersionPromise = lambda.publishVersion({
FunctionName: this.lambdaFunctionResource.physicalName,
}).promise();
if (this.lambdaFunctionResource.aliasesNames.length > 0) {
// we need to wait for the Version to finish publishing
const versionUpdate = await publishVersionPromise;
for (const alias of this.lambdaFunctionResource.aliasesNames) {
operations.push(lambda.updateAlias({
FunctionName: this.lambdaFunctionResource.physicalName,
Name: alias,
FunctionVersion: versionUpdate.Version,
}).promise());
}
} else {
operations.push(publishVersionPromise);
}
}
}
if (resource.tags !== undefined) {
const tagsToDelete: string[] = Object.entries(resource.tags.tagUpdates)
.filter(([_key, val]) => val === TagDeletion.DELETE)
.map(([key, _val]) => key);
const tagsToSet: { [tag: string]: string } = {};
Object.entries(resource.tags!.tagUpdates)
.filter(([_key, val]) => val !== TagDeletion.DELETE)
.forEach(([tagName, tagValue]) => {
tagsToSet[tagName] = tagValue as string;
});
if (tagsToDelete.length > 0) {
operations.push(lambda.untagResource({
Resource: this.lambdaFunctionResource.functionArn,
TagKeys: tagsToDelete,
}).promise());
}
if (Object.keys(tagsToSet).length > 0) {
operations.push(lambda.tagResource({
Resource: this.lambdaFunctionResource.functionArn,
Tags: tagsToSet,
}).promise());
}
}
// run all of our updates in parallel
return Promise.all(operations);
}
/**
* After a Lambda Function is updated, it cannot be updated again until the
* `State=Active` and the `LastUpdateStatus=Successful`.
*
* Depending on the configuration of the Lambda Function this could happen relatively quickly
* or very slowly. For example, Zip based functions _not_ in a VPC can take ~1 second whereas VPC
* or Container functions can take ~25 seconds (and 'idle' VPC functions can take minutes).
*/
private async waitForLambdasCodeUpdateToFinish(currentFunctionConfiguration: AWS.Lambda.FunctionConfiguration, lambda: AWS.Lambda): Promise<void> {
const functionIsInVpcOrUsesDockerForCode = currentFunctionConfiguration.VpcConfig?.VpcId ||
currentFunctionConfiguration.PackageType === 'Image';
// if the function is deployed in a VPC or if it is a container image function
// then the update will take much longer and we can wait longer between checks
// otherwise, the update will be quick, so a 1-second delay is fine
const delaySeconds = functionIsInVpcOrUsesDockerForCode ? 5 : 1;
// configure a custom waiter to wait for the function update to complete
(lambda as any).api.waiters.updateFunctionCodeToFinish = {
name: 'UpdateFunctionCodeToFinish',
operation: 'getFunction',
// equates to 1 minute for zip function not in a VPC and
// 5 minutes for container functions or function in a VPC
maxAttempts: 60,
delay: delaySeconds,
acceptors: [
{
matcher: 'path',
argument: "Configuration.LastUpdateStatus == 'Successful' && Configuration.State == 'Active'",
expected: true,
state: 'success',
},
{
matcher: 'path',
argument: 'Configuration.LastUpdateStatus',
expected: 'Failed',
state: 'failure',
},
],
};
const updateFunctionCodeWaiter = new (AWS as any).ResourceWaiter(lambda, 'updateFunctionCodeToFinish');
await updateFunctionCodeWaiter.wait({
FunctionName: this.lambdaFunctionResource.physicalName,
}).promise();
}
}
/**
* Compress a string as a file, returning a promise for the zip buffer
* https://github.com/archiverjs/node-archiver/issues/342
*/
function zipString(fileName: string, rawString: string): Promise<Buffer> {
return new Promise((resolve, reject) => {
const buffers: Buffer[] = [];
const converter = new Writable();
converter._write = (chunk: Buffer, _: string, callback: () => void) => {
buffers.push(chunk);
process.nextTick(callback);
};
converter.on('finish', () => {
resolve(Buffer.concat(buffers));
});
const archive = archiver('zip');
archive.on('error', (err: any) => {
reject(err);
});
archive.pipe(converter);
archive.append(rawString, {
name: fileName,
date: new Date('1980-01-01T00:00:00.000Z'), // Add date to make resulting zip file deterministic
});
void archive.finalize();
});
}
/**
* Get file extension from Lambda runtime string.
* We use this extension to create a deployment package from Lambda inline code.
*/
function determineCodeFileExtFromRuntime(runtime: string): string {
if (runtime.startsWith('node')) {
return 'js';
}
if (runtime.startsWith('python')) {
return 'py';
}
// Currently inline code only supports Node.js and Python, ignoring other runtimes.
// https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-lambda-function-code.html#aws-properties-lambda-function-code-properties
throw new CfnEvaluationException(`runtime ${runtime} is unsupported, only node.js and python runtimes are currently supported.`);
}