index.js

'use strict';

const AWS = require('aws-sdk');
const BbPromise = require('bluebird');
const crypto = require('crypto');
const fs = require('fs');
const _ = require('lodash');
const path = require('path');

class AwsCompileFunctions {
  constructor(serverless, options) {
    this.serverless = serverless;
    this.options = options;
    const servicePath = this.serverless.config.servicePath || '';
    this.packagePath =
      this.serverless.service.package.path || path.join(servicePath || '.', '.serverless');

    this.provider = this.serverless.getProvider('aws');

    this.ensureTargetExecutionPermission = _.memoize(this.ensureTargetExecutionPermission);
    if (
      this.serverless.service.provider.name === 'aws' &&
      this.serverless.service.provider.versionFunctions == null
    ) {
      this.serverless.service.provider.versionFunctions = true;
    }

    this.hooks = {
      'package:compileFunctions': () =>
        BbPromise.bind(this)
          .then(this.downloadPackageArtifacts)
          .then(this.compileFunctions),
    };
  }

  compileRole(newFunction, role) {
    const compiledFunction = newFunction;
    if (typeof role === 'string') {
      if (role.startsWith('arn:aws')) {
        // role is a statically defined iam arn
        compiledFunction.Properties.Role = role;
      } else if (role === 'IamRoleLambdaExecution') {
        // role is the default role generated by the framework
        compiledFunction.Properties.Role = { 'Fn::GetAtt': [role, 'Arn'] };
      } else {
        // role is a Logical Role Name
        compiledFunction.Properties.Role = { 'Fn::GetAtt': [role, 'Arn'] };
        compiledFunction.DependsOn = (compiledFunction.DependsOn || []).concat(role);
      }
    } else if ('Fn::GetAtt' in role) {
      // role is an "Fn::GetAtt" object
      compiledFunction.Properties.Role = role;
      compiledFunction.DependsOn = (compiledFunction.DependsOn || []).concat(role['Fn::GetAtt'][0]);
    } else {
      // role is an "Fn::ImportValue" object
      compiledFunction.Properties.Role = role;
    }
  }

  downloadPackageArtifact(functionName) {
    const { region } = this.options;
    const S3 = new AWS.S3({ region });

    const functionObject = this.serverless.service.getFunction(functionName);
    const artifactFilePath =
      _.get(functionObject, 'package.artifact') ||
      _.get(this, 'serverless.service.package.artifact');

    const regex = new RegExp('s3\\.amazonaws\\.com/(.+)/(.+)');
    const match = artifactFilePath.match(regex);

    if (match) {
      return new BbPromise((resolve, reject) => {
        const tmpDir = this.serverless.utils.getTmpDirPath();
        const filePath = path.join(tmpDir, match[2]);

        const readStream = S3.getObject({
          Bucket: match[1],
          Key: match[2],
        }).createReadStream();

        const writeStream = fs.createWriteStream(filePath);

        readStream.on('error', error => reject(error));
        readStream
          .pipe(writeStream)
          .on('error', reject)
          .on('close', () => {
            if (functionObject.package.artifact) {
              functionObject.package.artifact = filePath;
            } else {
              this.serverless.service.package.artifact = filePath;
            }
            return resolve(filePath);
          });
      });
    }

    return BbPromise.resolve();
  }

  compileFunction(functionName) {
    return BbPromise.try(() => {
      const cfTemplate = this.serverless.service.provider.compiledCloudFormationTemplate;
      const functionResource = this.cfLambdaFunctionTemplate();
      const functionObject = this.serverless.service.getFunction(functionName);
      functionObject.package = functionObject.package || {};

      const serviceArtifactFileName = this.provider.naming.getServiceArtifactName();
      const functionArtifactFileName = this.provider.naming.getFunctionArtifactName(functionName);

      let artifactFilePath =
        functionObject.package.artifact || this.serverless.service.package.artifact;

      if (
        !artifactFilePath ||
        (this.serverless.service.artifact && !functionObject.package.artifact)
      ) {
        let artifactFileName = serviceArtifactFileName;
        if (this.serverless.service.package.individually || functionObject.package.individually) {
          artifactFileName = functionArtifactFileName;
        }

        artifactFilePath = path.join(
          this.serverless.config.servicePath,
          '.serverless',
          artifactFileName
        );
      }

      if (this.serverless.service.package.deploymentBucket) {
        functionResource.Properties.Code.S3Bucket = this.serverless.service.package.deploymentBucket;
      }

      const s3Folder = this.serverless.service.package.artifactDirectoryName;
      const s3FileName = artifactFilePath.split(path.sep).pop();
      functionResource.Properties.Code.S3Key = `${s3Folder}/${s3FileName}`;

      if (!functionObject.handler) {
        const errorMessage = [
          `Missing "handler" property in function "${functionName}".`,
          ' Please make sure you point to the correct lambda handler.',
          ' For example: handler.hello.',
          ' Please check the docs for more info',
        ].join('');
        throw new this.serverless.classes.Error(errorMessage);
      }

      const Handler = functionObject.handler;
      const FunctionName = functionObject.name;
      const MemorySize =
        functionObject.memorySize || this.serverless.service.provider.memorySize || 1024;
      const Timeout = functionObject.timeout || this.serverless.service.provider.timeout || 6;
      const Runtime = this.provider.getRuntime(functionObject.runtime);

      functionResource.Properties.Handler = Handler;
      functionResource.Properties.FunctionName = FunctionName;
      functionResource.Properties.MemorySize = MemorySize;
      functionResource.Properties.Timeout = Timeout;
      functionResource.Properties.Runtime = Runtime;

      // publish these properties to the platform
      this.serverless.service.functions[functionName].memory = MemorySize;
      this.serverless.service.functions[functionName].timeout = Timeout;
      this.serverless.service.functions[functionName].runtime = Runtime;

      if (functionObject.description) {
        functionResource.Properties.Description = functionObject.description;
      }

      if (functionObject.condition) {
        functionResource.Condition = functionObject.condition;
      }

      if (functionObject.dependsOn) {
        functionResource.DependsOn = (functionResource.DependsOn || []).concat(
          functionObject.dependsOn
        );
      }

      if (functionObject.tags || this.serverless.service.provider.tags) {
        const tags = Object.assign({}, this.serverless.service.provider.tags, functionObject.tags);
        functionResource.Properties.Tags = [];
        Object.entries(tags).forEach(([Key, Value]) => {
          functionResource.Properties.Tags.push({ Key, Value });
        });
      }

      if (functionObject.onError) {
        const arn = functionObject.onError;

        if (typeof arn === 'string') {
          const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;
          functionResource.Properties.DeadLetterConfig = {
            TargetArn: arn,
          };

          // update the PolicyDocument statements (if default policy is used)
          if (iamRoleLambdaExecution) {
            iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement.push({
              Effect: 'Allow',
              Action: ['sns:Publish'],
              Resource: [arn],
            });
          }
        } else {
          functionResource.Properties.DeadLetterConfig = {
            TargetArn: arn,
          };
        }
      }

      const serviceObj = this.serverless.service.serviceObject;
      if (functionObject.awsKmsKeyArn || (serviceObj && serviceObj.awsKmsKeyArn)) {
        const arn = functionObject.awsKmsKeyArn || (serviceObj && serviceObj.awsKmsKeyArn);

        if (typeof arn === 'string') {
          functionResource.Properties.KmsKeyArn = arn;

          // update the PolicyDocument statements (if default policy is used)
          const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;
          if (iamRoleLambdaExecution) {
            iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement = _.unionWith(
              iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement,
              [
                {
                  Effect: 'Allow',
                  Action: ['kms:Decrypt'],
                  Resource: [arn],
                },
              ],
              _.isEqual
            );
          }
        } else {
          functionResource.Properties.KmsKeyArn = arn;
        }
      }

      const tracing =
        functionObject.tracing ||
        (this.serverless.service.provider.tracing &&
          this.serverless.service.provider.tracing.lambda);

      if (tracing) {
        let mode = tracing;

        if (typeof tracing === 'boolean') {
          mode = 'Active';
        }

        const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;

        functionResource.Properties.TracingConfig = {
          Mode: mode,
        };

        const stmt = {
          Effect: 'Allow',
          Action: ['xray:PutTraceSegments', 'xray:PutTelemetryRecords'],
          Resource: ['*'],
        };

        // update the PolicyDocument statements (if default policy is used)
        if (iamRoleLambdaExecution) {
          iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement = _.unionWith(
            iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement,
            [stmt],
            _.isEqual
          );
        }
      }

      if (functionObject.environment || this.serverless.service.provider.environment) {
        functionResource.Properties.Environment = {};
        functionResource.Properties.Environment.Variables = Object.assign(
          {},
          this.serverless.service.provider.environment,
          functionObject.environment
        );
      }

      this.compileRole(
        functionResource,
        functionObject.role || this.serverless.service.provider.role || 'IamRoleLambdaExecution'
      );

      if (!functionObject.vpc) functionObject.vpc = {};
      if (!this.serverless.service.provider.vpc) this.serverless.service.provider.vpc = {};

      functionResource.Properties.VpcConfig = {
        SecurityGroupIds:
          functionObject.vpc.securityGroupIds ||
          this.serverless.service.provider.vpc.securityGroupIds,
        SubnetIds: functionObject.vpc.subnetIds || this.serverless.service.provider.vpc.subnetIds,
      };

      if (
        !functionResource.Properties.VpcConfig.SecurityGroupIds ||
        !functionResource.Properties.VpcConfig.SubnetIds
      ) {
        delete functionResource.Properties.VpcConfig;
      }

      const fileSystemConfig = functionObject.fileSystemConfig;

      if (fileSystemConfig) {
        if (!functionResource.Properties.VpcConfig) {
          const errorMessage = [
            `Function "${functionName}": when using fileSystemConfig, `,
            'ensure that function has vpc configured ',
            'on function or provider level',
          ].join('');
          throw new this.serverless.classes.Error(
            errorMessage,
            'LAMBDA_FILE_SYSTEM_CONFIG_MISSING_VPC'
          );
        }

        const iamRoleLambdaExecution = cfTemplate.Resources.IamRoleLambdaExecution;

        const stmt = {
          Effect: 'Allow',
          Action: ['elasticfilesystem:ClientMount', 'elasticfilesystem:ClientWrite'],
          Resource: [fileSystemConfig.arn],
        };

        // update the PolicyDocument statements (if default policy is used)
        if (iamRoleLambdaExecution) {
          iamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement.push(stmt);
        }

        const cfFileSystemConfig = {
          Arn: fileSystemConfig.arn,
          LocalMountPath: fileSystemConfig.localMountPath,
        };

        functionResource.Properties.FileSystemConfigs = [cfFileSystemConfig];
      }

      if (functionObject.reservedConcurrency || functionObject.reservedConcurrency === 0) {
        functionResource.Properties.ReservedConcurrentExecutions =
          functionObject.reservedConcurrency;
      }

      if (!functionObject.disableLogs) {
        functionResource.DependsOn = [
          this.provider.naming.getLogGroupLogicalId(functionName),
        ].concat(functionResource.DependsOn || []);
      }

      if (functionObject.layers) {
        functionResource.Properties.Layers = functionObject.layers;
      } else if (this.serverless.service.provider.layers) {
        functionResource.Properties.Layers = this.serverless.service.provider.layers;
      }

      const functionLogicalId = this.provider.naming.getLambdaLogicalId(functionName);
      const newFunctionObject = {
        [functionLogicalId]: functionResource,
      };

      Object.assign(cfTemplate.Resources, newFunctionObject);

      const shouldVersionFunction =
        functionObject.versionFunction != null
          ? functionObject.versionFunction
          : this.serverless.service.provider.versionFunctions;

      let versionCompilationPromise;

      if (shouldVersionFunction || functionObject.provisionedConcurrency) {
        // Create hashes for the artifact and the logical id of the version resource
        // The one for the version resource must include the function configuration
        // to make sure that a new version is created on configuration changes and
        // not only on source changes.
        const fileHash = crypto.createHash('sha256');
        const versionHash = crypto.createHash('sha256');
        fileHash.setEncoding('base64');
        versionHash.setEncoding('base64');
        const layerConfigurations = _.cloneDeep(
          extractLayerConfigurationsFromFunction(functionResource.Properties, cfTemplate)
        );

        // Include function and layer configuration in version id hash (without the Code part)
        versionCompilationPromise = addFileContentsToHashes(artifactFilePath, [
          fileHash,
          versionHash,
        ])
          .then(async () => {
            // Include all referenced layer code in the version id hash
            const layerArtifactPaths = [];
            layerConfigurations.forEach(layer => {
              const layerArtifactPath = this.provider.resolveLayerArtifactName(layer.name);
              layerArtifactPaths.push(layerArtifactPath);
            });

            for (const layerArtifactPath of layerArtifactPaths.sort()) {
              await addFileContentsToHashes(layerArtifactPath, [versionHash]);
            }
          })
          .then(() => {
            // Include function and layer configuration details in the version id hash
            for (const layerConfig of layerConfigurations) {
              delete layerConfig.properties.Content.S3Key;
            }

            // sort the layer conifigurations for hash consistency
            const sortedLayerConfigurations = {};
            const byKey = ([key1], [key2]) => key1.localeCompare(key2);
            for (const { name, properties: layerProperties } of layerConfigurations) {
              sortedLayerConfigurations[name] = _.fromPairs(
                Object.entries(layerProperties).sort(byKey)
              );
            }

            const functionProperties = _.cloneDeep(functionResource.Properties);
            delete functionProperties.Code;
            // Properties applied to function globally (not specific to version or alias)
            delete functionProperties.ReservedConcurrentExecutions;
            delete functionProperties.Tags;
            functionProperties.layerConfigurations = sortedLayerConfigurations;

            const sortedFunctionProperties = _.fromPairs(
              Object.entries(functionProperties).sort(byKey)
            );
            versionHash.write(JSON.stringify(sortedFunctionProperties));

            // Finalize hashes
            fileHash.end();
            versionHash.end();

            const fileDigest = fileHash.read();
            const versionDigest = versionHash.read();

            const versionResource = this.cfLambdaVersionTemplate();

            versionResource.Properties.CodeSha256 = fileDigest;
            versionResource.Properties.FunctionName = { Ref: functionLogicalId };
            if (functionObject.description) {
              versionResource.Properties.Description = functionObject.description;
            }

            // use the version SHA in the logical resource ID of the version because
            // AWS::Lambda::Version resource will not support updates
            const versionLogicalId = this.provider.naming.getLambdaVersionLogicalId(
              functionName,
              versionDigest
            );
            functionObject.versionLogicalId = versionLogicalId;
            const newVersionObject = {
              [versionLogicalId]: versionResource,
            };

            Object.assign(cfTemplate.Resources, newVersionObject);

            // Add function versions to Outputs section
            const functionVersionOutputLogicalId = this.provider.naming.getLambdaVersionOutputLogicalId(
              functionName
            );
            const newVersionOutput = this.cfOutputLatestVersionTemplate();

            newVersionOutput.Value = { Ref: versionLogicalId };

            Object.assign(cfTemplate.Outputs, {
              [functionVersionOutputLogicalId]: newVersionOutput,
            });

            if (!functionObject.provisionedConcurrency) return;
            if (!shouldVersionFunction) delete versionResource.DeletionPolicy;

            const provisionedConcurrency = Number(functionObject.provisionedConcurrency);
            const aliasLogicalId = this.provider.naming.getLambdaProvisionedConcurrencyAliasLogicalId(
              functionName
            );
            const aliasName = this.provider.naming.getLambdaProvisionedConcurrencyAliasName();

            functionObject.targetAlias = { name: aliasName, logicalId: aliasLogicalId };

            const aliasResource = {
              Type: 'AWS::Lambda::Alias',
              Properties: {
                FunctionName: { Ref: functionLogicalId },
                FunctionVersion: { 'Fn::GetAtt': [versionLogicalId, 'Version'] },
                Name: aliasName,
                ProvisionedConcurrencyConfig: {
                  ProvisionedConcurrentExecutions: provisionedConcurrency,
                },
              },
              DependsOn: functionLogicalId,
            };

            cfTemplate.Resources[aliasLogicalId] = aliasResource;
          });
      } else {
        versionCompilationPromise = BbPromise.resolve();
      }

      return versionCompilationPromise.then(() =>
        this.compileFunctionEventInvokeConfig(functionName)
      );
    });
  }

  compileFunctionEventInvokeConfig(functionName) {
    const functionObject = this.serverless.service.getFunction(functionName);
    const { destinations, maximumEventAge, maximumRetryAttempts } = functionObject;

    if (!destinations && !maximumEventAge && maximumRetryAttempts == null) {
      return;
    }

    const destinationConfig = {};

    if (destinations) {
      const hasAccessPoliciesHandledExternally = Boolean(
        functionObject.role || this.serverless.service.provider.role
      );

      if (destinations.onSuccess) {
        if (!hasAccessPoliciesHandledExternally) {
          this.ensureTargetExecutionPermission(destinations.onSuccess);
        }
        destinationConfig.OnSuccess = {
          Destination: destinations.onSuccess.startsWith('arn:')
            ? destinations.onSuccess
            : this.provider.resolveFunctionArn(destinations.onSuccess),
        };
      }

      if (destinations.onFailure) {
        if (!hasAccessPoliciesHandledExternally) {
          this.ensureTargetExecutionPermission(destinations.onFailure);
        }
        destinationConfig.OnFailure = {
          Destination: destinations.onFailure.startsWith('arn:')
            ? destinations.onFailure
            : this.provider.resolveFunctionArn(destinations.onFailure),
        };
      }
    }

    const cfResources = this.serverless.service.provider.compiledCloudFormationTemplate.Resources;
    const functionLogicalId = this.provider.naming.getLambdaLogicalId(functionName);

    const resource = {
      Type: 'AWS::Lambda::EventInvokeConfig',
      Properties: {
        FunctionName: { Ref: functionLogicalId },
        DestinationConfig: destinationConfig,
        Qualifier: functionObject.targetAlias ? functionObject.targetAlias.name : '$LATEST',
      },
    };

    if (maximumEventAge) {
      resource.Properties.MaximumEventAgeInSeconds = maximumEventAge;
    }

    if (maximumRetryAttempts != null) {
      resource.Properties.MaximumRetryAttempts = maximumRetryAttempts;
    }

    cfResources[this.provider.naming.getLambdaEventConfigLogicalId(functionName)] = resource;
  }

  // Memoized in a construtor
  ensureTargetExecutionPermission(functionAddress) {
    const iamPolicyStatements = this.serverless.service.provider.compiledCloudFormationTemplate
      .Resources.IamRoleLambdaExecution.Properties.Policies[0].PolicyDocument.Statement;

    const action = (() => {
      if (!functionAddress.startsWith('arn:') || functionAddress.includes(':function:')) {
        return 'lambda:InvokeFunction';
      }
      if (functionAddress.includes(':sqs:')) return 'sqs:SendMessage';
      if (functionAddress.includes(':sns:')) return 'sns:Publish';
      if (functionAddress.includes(':event-bus/')) return 'events:PutEvents';
      throw new this.serverless.classes.Error(`Unsupported destination target ${functionAddress}`);
    })();
    iamPolicyStatements.push({
      Effect: 'Allow',
      Action: action,
      // Note: Cannot address function via { 'Fn::GetAtt': [targetLogicalId, 'Arn'] }
      // as same IAM settings are used for target function and that will introduce
      // circular dependency error. Relying on Fn::Sub as a workaround
      Resource: functionAddress.startsWith('arn:')
        ? functionAddress
        : {
            'Fn::Sub': `arn:\${AWS::Partition}:lambda:\${AWS::Region}:\${AWS::AccountId}:function:${
              this.serverless.service.getFunction(functionAddress).name
            }`,
          },
    });
  }

  downloadPackageArtifacts() {
    const allFunctions = this.serverless.service.getAllFunctions();
    return BbPromise.each(allFunctions, functionName => this.downloadPackageArtifact(functionName));
  }

  compileFunctions() {
    const allFunctions = this.serverless.service.getAllFunctions();
    return BbPromise.each(allFunctions, functionName => this.compileFunction(functionName));
  }

  cfLambdaFunctionTemplate() {
    return {
      Type: 'AWS::Lambda::Function',
      Properties: {
        Code: {
          S3Bucket: {
            Ref: 'ServerlessDeploymentBucket',
          },
          S3Key: 'S3Key',
        },
        FunctionName: 'FunctionName',
        Handler: 'Handler',
        MemorySize: 'MemorySize',
        Role: 'Role',
        Runtime: 'Runtime',
        Timeout: 'Timeout',
      },
    };
  }

  cfLambdaVersionTemplate() {
    return {
      Type: 'AWS::Lambda::Version',
      // Retain old versions even though they will not be in future
      // CloudFormation stacks. On stack delete, these will be removed when
      // their associated function is removed.
      DeletionPolicy: 'Retain',
      Properties: {
        FunctionName: 'FunctionName',
        CodeSha256: 'CodeSha256',
      },
    };
  }

  cfOutputLatestVersionTemplate() {
    return {
      Description: 'Current Lambda function version',
      Value: 'Value',
    };
  }
}

function addFileContentsToHashes(filePath, hashes) {
  return new Promise((resolve, reject) => {
    const readStream = fs.createReadStream(filePath);
    readStream
      .on('data', chunk => {
        hashes.forEach(hash => {
          hash.write(chunk);
        });
      })
      .on('close', () => {
        resolve();
      })
      .on('error', error => {
        reject(new Error(`Could not add file content to hash: ${error}`));
      });
  });
}

function extractLayerConfigurationsFromFunction(functionProperties, cfTemplate) {
  const layerConfigurations = [];
  if (!functionProperties.Layers) return layerConfigurations;
  functionProperties.Layers.forEach(potentialLocalLayerObject => {
    if (potentialLocalLayerObject.Ref) {
      const configuration = cfTemplate.Resources[potentialLocalLayerObject.Ref];
      layerConfigurations.push({
        name: configuration._serverlessLayerName,
        ref: potentialLocalLayerObject.Ref,
        properties: configuration.Properties,
      });
    }
  });
  return layerConfigurations;
}

module.exports = AwsCompileFunctions;