CI Pipeline Compatibility

- Add "strictMode" functionality
  - "strictMode" is on by default
  - When enabled, an error is thrown when no Rust builds are found
  - When disabled, the error is suppressed
  - "strictMode" can be disabled with custom.rust.strictMode: false
- Fix validation warning
  - serverless does not accept "rust" as a runtime
  - a function can be marked as "rust" the old way, or by adding tags.language: "rust"
- Support predefined artifacts and skip recompile
  - This allows an artifact to be built in one CI-step and deployed in another
  - When artifact is defined, the artifact zip is uploaded and compile is skipped

Author: TravisCalder

index.js

@@ -47,6 +47,7 @@ class RustPlugin {
         dockerTag: DEFAULT_DOCKER_TAG,
         dockerImage: DEFAULT_DOCKER_IMAGE,
         dockerless: false,
+        strictMode: true,
       },
       (this.serverless.service.custom && this.serverless.service.custom.rust) ||
         {}
@@ -281,6 +282,7 @@ class RustPlugin {
 
   /** the entry point for building functions */
   build() {
+    const strictMode = this.custom.strictMode !== false;
     const service = this.serverless.service;
     if (service.provider.name != "aws") {
       return;
@@ -289,51 +291,59 @@ class RustPlugin {
     this.functions().forEach((funcName) => {
       const func = service.getFunction(funcName);
       const runtime = func.runtime || service.provider.runtime;
-      if (runtime != RUST_RUNTIME) {
+
+      func.tags = func.tags || {};
+      if (!(runtime === RUST_RUNTIME || func.tags.language === "rust")) {
         // skip functions which don't apply to rust
         return;
       }
       rustFunctionsFound = true;
-      const { cargoPackage, binary } = this.cargoBinary(func);
-
-      this.serverless.cli.log(`Building Rust ${func.handler} func...`);
-      let profile = (func.rust || {}).profile || this.custom.profile;
 
-      const res = this.buildLocally(func)
-        ? this.localBuild(func.rust, cargoPackage, binary, profile)
-        : this.dockerBuild(func.rust, cargoPackage, binary, profile);
-      if (res.error || res.status > 0) {
-        this.serverless.cli.log(
-          `Rust build encountered an error: ${res.error} ${res.status}.`
-        );
-        throw new Error(res.error);
-      }
-      // If all went well, we should now have find a packaged compiled binary under `target/lambda/release`.
-      //
-      // The AWS "provided" lambda runtime requires executables to be named
-      // "bootstrap" -- https://docs.aws.amazon.com/lambda/latest/dg/runtimes-custom.html
-      //
-      // To avoid artifact naming conflicts when we potentially have more than one function
-      // we leverage the ability to declare a package artifact directly
-      // see https://serverless.com/framework/docs/providers/aws/guide/packaging/
-      // for more information
-      const artifactPath = path.join(
-        this.srcPath,
-        `target/lambda/${"dev" === profile ? "debug" : "release"}`,
-        `${binary}.zip`
-      );
       func.package = func.package || {};
-      func.package.artifact = artifactPath;
+      if (func.package.artifact && func.package.artifact !== "") {
+        this.serverless.cli.log(`Artifact defined for ${func.handler}, skipping build...`);
+      } else {
+        const {cargoPackage, binary} = this.cargoBinary(func);
+
+        this.serverless.cli.log(`Building Rust ${func.handler} func...`);
+        let profile = (func.rust || {}).profile || this.custom.profile;
+
+        const res = this.buildLocally(func)
+            ? this.localBuild(func.rust, cargoPackage, binary, profile)
+            : this.dockerBuild(func.rust, cargoPackage, binary, profile);
+        if (res.error || res.status > 0) {
+          this.serverless.cli.log(
+              `Rust build encountered an error: ${res.error} ${res.status}.`
+          );
+          throw new Error(res.error);
+        }
+        // If all went well, we should now have find a packaged compiled binary under `target/lambda/release`.
+        //
+        // The AWS "provided" lambda runtime requires executables to be named
+        // "bootstrap" -- https://docs.aws.amazon.com/lambda/latest/dg/runtimes-custom.html
+        //
+        // To avoid artifact naming conflicts when we potentially have more than one function
+        // we leverage the ability to declare a package artifact directly
+        // see https://serverless.com/framework/docs/providers/aws/guide/packaging/
+        // for more information
+        const artifactPath = path.join(
+            this.srcPath,
+            `target/lambda/${"dev" === profile ? "debug" : "release"}`,
+            `${binary}.zip`
+        );
+        func.package = func.package || {};
+        func.package.artifact = artifactPath;
 
-      // Ensure the runtime is set to a sane value for other plugins
-      if (func.runtime == RUST_RUNTIME) {
-        func.runtime = BASE_RUNTIME;
+        // Ensure the runtime is set to a sane value for other plugins
+        if (func.runtime == RUST_RUNTIME) {
+          func.runtime = BASE_RUNTIME;
+        }
       }
     });
     if (service.provider.runtime === RUST_RUNTIME) {
       service.provider.runtime = BASE_RUNTIME;
     }
-    if (!rustFunctionsFound) {
+    if (!rustFunctionsFound && strictMode) {
       throw new Error(
         `Error: no Rust functions found. ` +
           `Use 'runtime: ${RUST_RUNTIME}' in global or ` +