Add Use Arm Architecture Rule

Author: gozineb

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 UseArm from "./rules/best_practices/use-arm";
 import {
   getAWSCredentials,
   getStackResources,
@@ -43,6 +44,7 @@ class GuardianCI {
       NoMaximumMemory,
       NoIdenticalCode,
       NoSharedRoles,
+      UseArm,
     ];
     this.failingChecks = [];
 

src/guardian/rules/best_practices/use-arm/index.js

@@ -0,0 +1,48 @@
+class UseArm {
+  constructor(AWS, stackName, stackFunctions, SLS) {
+    this.name = "use-arm";
+    this.AWS = AWS;
+    this.stackName = stackName;
+    this.stackFunctions = stackFunctions;
+    this.result = false;
+    this.failingResources = [];
+    this.armArchitecture = "arm64";
+    this.SLS = SLS;
+    this.failureMessage =
+      "The following functions do not use an arm64 architecture.";
+    this.rulePage =
+      "See (https://theodo-uk.github.io/sls-dev-tools/docs/no-default-memory) for impact and how to to resolve.";
+  }
+
+  hasArmArchitecture(lambdaFunction) {
+    return lambdaFunction.Architectures[0] === this.armArchitecture;
+  }
+
+  async run() {
+    console.log(this.stackFunctions);
+    try {
+      const notArmFunctions = this.stackFunctions.reduce(
+        (acc, current) =>
+          this.hasArmArchitecture(current) ? acc : [...acc, current],
+        []
+      );
+
+      this.failingResources = notArmFunctions.map((lambda) => ({
+        arn: lambda.FunctionArn,
+        architecture: lambda.Architectures[0],
+      }));
+
+      if (notArmFunctions.length > 0) {
+        this.result = false;
+      } else {
+        this.result = true;
+      }
+    } catch (e) {
+      console.error(e);
+      this.result = false;
+    }
+    return this.result;
+  }
+}
+
+export default UseArm;

src/guardian/rules/best_practices/use-arm/use-arm.MD

@@ -0,0 +1,10 @@
+# All functions have an arm64 architecture
+
+Lambdas Functions default architecture is x86_64 but should be configure to arm64.
+Lambda functions that use arm64 architecture (AWS Graviton2 processor) can achieve significantly better price and performance than the equivalent function running on x86_64 architecture.
+
+---
+
+## Suggested Actions:
+
+- Look into your function in your Lambda service to find `Architectures` in the code tab Runtime Settings. [more information](https://docs.aws.amazon.com/lambda/latest/dg/foundation-arch.html#foundation-arch-adv)