feature(rules): limit the Lambda number of versions

package.json

@@ -4,7 +4,7 @@
     "sls-dev-tools": "./lib/index.js"
   },
   "dependencies": {
-    "aws-sdk": "^2.655.0",
+    "aws-sdk": "2.1124.0",
     "blessed": "^0.1.81",
     "blessed-contrib": "^4.8.17",
     "chalk": "^4.0.0",

src/guardian/index.js

@@ -7,6 +7,7 @@ import NoMaximumTimeout from "./rules/best_practices/no-max-timeout";
 import NoMaximumMemory from "./rules/best_practices/no-max-memory";
 import NoIdenticalCode from "./rules/best_practices/no-identical-code";
 import NoSharedRoles from "./rules/best_practices/no-shared-roles";
+import LimitedNumberOfVersions from "./rules/best_practices/limited-number-of-versions";
 import {
   getAWSCredentials,
   getStackResources,
@@ -43,6 +44,7 @@ class GuardianCI {
       NoMaximumMemory,
       NoIdenticalCode,
       NoSharedRoles,
+      LimitedNumberOfVersions,
     ];
     this.failingChecks = [];
 

src/guardian/rules/best_practices/limited-number-of-versions/index.js

@@ -0,0 +1,66 @@
+class LimitedNumberOfVersions {
+  constructor(AWS, stackName, stackFunctions) {
+    this.name = "limited-number-of-versions";
+    this.AWS = AWS;
+    this.stackName = stackName;
+    this.stackFunctions = stackFunctions;
+    this.result = false;
+    this.failingResources = [];
+    this.failureMessage =
+      "The following functions have a number of deployed versions greater than 3";
+    this.rulePage =
+      "See (https://m33.notion.site/Serverless-Sustainability-Audit-a36847289fd64339a60e40bc5aa63092) for impact.";
+    this.lambda = new AWS.Lambda();
+  }
+
+  // Given the name of a lambda, returns its number of versions (excluding $Latest)
+  async getNumberOfLambdaVersions(FunctionName) {
+    const lambdaVersions = await this.lambda
+      .listVersionsByFunction({
+        FunctionName,
+      })
+      .promise();
+    return lambdaVersions.Versions.length - 1;
+  }
+
+  async run() {
+    try {
+      const functionsWithCount = await Promise.all(
+        this.stackFunctions.map(async (lambda) => {
+          const numberOfVersions = await this.getNumberOfLambdaVersions(
+            lambda.FunctionName
+          );
+          return {
+            functionArn: lambda.FunctionArn,
+            numberOfVersions,
+          };
+        })
+      );
+
+      const functionsWithTooManyVersions = functionsWithCount.reduce(
+        (acc, current) =>
+          current.numberOfVersions > 3 ? [...acc, current] : acc,
+        []
+      );
+
+      this.failingResources = functionsWithTooManyVersions.map(
+        (lambdaWithCount) => ({
+          arn: lambdaWithCount.functionArn,
+          numberOfVersions: lambdaWithCount.numberOfVersions,
+        })
+      );
+
+      if (functionsWithTooManyVersions.length > 0) {
+        this.result = false;
+      } else {
+        this.result = true;
+      }
+    } catch (e) {
+      console.error(e);
+      this.result = false;
+    }
+    return this.result;
+  }
+}
+
+export default LimitedNumberOfVersions;

src/guardian/rules/best_practices/limited-number-of-versions/limited-number-of-versions.MD

@@ -0,0 +1,12 @@
+# Functions should have less than 3 versions
+
+It is most of the time useless to keep more than 3 online versions for your lambdas.
+Storing useless data has a negative impact on teh environment. (For more info, see https://www.notion.so/m33/Serverless-Sustainability-Audit-a36847289fd64339a60e40bc5aa63092?p=a0471b2c407144fe839150326ed804d8)
+
+AWS Lambda service furthermore has limited storage space, which can be easily reached if you keep every single version of your lambdas.
+
+---
+
+## Suggested Actions
+
+- Use [serverless-prune-versions](https://github.com/manwaring/serverless-prune-versions) to regularly prune the versions of the affected lambdas

yarn.lock

@@ -1689,15 +1689,15 @@ atob@^2.1.2:
   resolved "https://registry.yarnpkg.com/atob/-/atob-2.1.2.tgz#6d9517eb9e030d2436666651e86bd9f6f13533c9"
   integrity sha512-Wm6ukoaOGJi/73p/cl2GvLjTI5JM1k/O14isD73YML8StrH/7/lRFgmg8nICZgD3bZZvjwCGxtMOD3wWNAu8cg==
 
-aws-sdk@^2.655.0:
-  version "2.855.0"
-  resolved "https://registry.yarnpkg.com/aws-sdk/-/aws-sdk-2.855.0.tgz#2788e2655d8e2eecfc9d86acafd13d872725e73a"
-  integrity sha512-u1lO75V82E4REeu0Pt3RE1Kg2CdtUoMgMnyR02cUxdWnoTBpdSlwvz2X2U0VEGW2oYzeJJYp0N0H1sgSRnv8vg==
+aws-sdk@2.1124.0:
+  version "2.1124.0"
+  resolved "https://registry.yarnpkg.com/aws-sdk/-/aws-sdk-2.1124.0.tgz#350550b973f210b092a45184036659251d7cbd1e"
+  integrity sha512-LIj2EmvduQmyjpSLoDPe2TvRBrGWhJKlCuC7lungN4f+qYPOfVWg6/c9GdP99W0q5p2IqhDkCmQ/ZZBpO1Z/Fg==
   dependencies:
     buffer "4.9.2"
     events "1.1.1"
     ieee754 "1.1.13"
-    jmespath "0.15.0"
+    jmespath "0.16.0"
     querystring "0.2.0"
     sax "1.2.1"
     url "0.10.3"
@@ -4382,10 +4382,10 @@ jest@^26.6.3:
     import-local "^3.0.2"
     jest-cli "^26.6.3"
 
-jmespath@0.15.0:
-  version "0.15.0"
-  resolved "https://registry.yarnpkg.com/jmespath/-/jmespath-0.15.0.tgz#a3f222a9aae9f966f5d27c796510e28091764217"
-  integrity sha1-o/Iiqarp+Wb10nx5ZRDigJF2Qhc=
+jmespath@0.16.0:
+  version "0.16.0"
+  resolved "https://registry.yarnpkg.com/jmespath/-/jmespath-0.16.0.tgz#b15b0a85dfd4d930d43e69ed605943c802785076"
+  integrity sha512-9FzQjJ7MATs1tSpnco1K6ayiYE3figslrXA72G2HQ/n76RzvYlofyi5QM+iX4YRs/pu3yzxlVQSST23+dMDknw==
 
 "js-tokens@^3.0.0 || ^4.0.0", js-tokens@^4.0.0:
   version "4.0.0"