fix: Implemented output truncation and suppression on Github comments (…

…#221)

.projenrc.ts

@@ -89,6 +89,12 @@ const inputs = {
     required: false,
     type: "string",
   },
+  suppressOutput: {
+    description: "Whether to suppress the output of the action in PR comments",
+    default: "false",
+    required: false,
+    type: "boolean",
+  },
 };
 
 const repoName = "terraform-cdk-action";

README.md

@@ -18,6 +18,7 @@ The Terraform CDK GitHub Action allows you to run CDKTF as part of your CI/CD wo
 | updateComment | Whether to update the last comment on the PR rather than adding a new comment | `false` | true |
 | customNpxArgs | The additional CLI arguments to pass to npx as part of the cdktf-cli execution. | `false` |  |
 | cdktfArgs | The additional CLI arguments to pass to cdktf as part of the cdktf-cli execution. | `false` |  |
+| suppressOutput | Whether to suppress the output of the action in PR comments | `false` | false |
 <!-- action-docs-inputs -->
 
 ## Example Configurations

src/action.ts

@@ -25,6 +25,7 @@ function postComment(
   output: string | undefined,
   outputTitle: Error | string
 ): Promise<void> {
+  output = output ? commentController.truncateOutput(output) : undefined;
   return commentController.postCommentOnPr(
     `### ${title}
 
@@ -129,6 +130,7 @@ export async function run(): Promise<void> {
     updateComment: input.updateComment,
     customNpxArgs: input.customNpxArgs,
     cdktfArgs: input.cdktfArgs,
+    suppressOutput: input.suppressOutput,
   };
   const octokit = github.getOctokit(inputs.githubToken);
   const commentController = new CommentController({
@@ -159,7 +161,7 @@ export async function run(): Promise<void> {
             commentController,
             "❌ Error synthesizing the Terraform CDK Application",
             undefined,
-            output,
+            inputs.suppressOutput ? undefined : output,
             error
           )
       );
@@ -180,22 +182,22 @@ export async function run(): Promise<void> {
                 commentController,
                 `✅ Successfully planned Terraform CDK Stack '${inputs.stackName}'`,
                 runUrl,
-                output,
+                inputs.suppressOutput ? undefined : output,
                 "Show Plan"
               )
             : postComment(
                 commentController,
                 `🟰 No changes in Terraform CDK Stack '${inputs.stackName}'`,
                 runUrl,
-                output,
+                inputs.suppressOutput ? undefined : output,
                 "Show Plan"
               ),
         (error, output, runUrl) =>
           postComment(
             commentController,
             `❌ Error planning Terraform CDK Stack '${inputs.stackName}'`,
             runUrl,
-            output,
+            inputs.suppressOutput ? undefined : output,
             error
           )
       );
@@ -216,22 +218,22 @@ export async function run(): Promise<void> {
                 commentController,
                 `✅ Successfully applied Terraform CDK Stack '${inputs.stackName}'`,
                 runUrl,
-                output,
+                inputs.suppressOutput ? undefined : output,
                 "Show Run"
               )
             : postComment(
                 commentController,
                 `🟰 No changes to apply in Terraform CDK Stack '${inputs.stackName}'`,
                 runUrl,
-                output,
+                inputs.suppressOutput ? undefined : output,
                 "Show Run"
               ),
         (error, output, runUrl) =>
           postComment(
             commentController,
             `❌ Error applying Terraform CDK Stack '${inputs.stackName}'`,
             runUrl,
-            output,
+            inputs.suppressOutput ? undefined : output,
             error
           )
       );
@@ -259,7 +261,7 @@ export async function run(): Promise<void> {
             commentController,
             `❌ Error destroying the Terraform CDK Application '${inputs.stackName}'`,
             undefined,
-            output,
+            inputs.suppressOutput ? undefined : output,
             error
           )
       );

src/comment.ts

@@ -130,6 +130,17 @@ export class CommentController {
 
     return !previousComment ? null : previousComment;
   }
+
+  public truncateOutput(output: string): string {
+    // Github max comment length is 65536, but we want to leave room for the rest of the comment content
+    const maxOutputLength = 65000;
+    if (output.length > maxOutputLength) {
+      return `... Output truncated to the last ${maxOutputLength} characters ...\n\n${output.substring(
+        output.length - maxOutputLength
+      )}`;
+    }
+    return output;
+  }
 }
 const hashString = (str: string) => {
   return crypto.createHash("md5").update(str).digest("hex");

src/models.ts

@@ -16,4 +16,5 @@ export interface Inputs {
   updateComment: boolean;
   customNpxArgs: string;
   cdktfArgs: string;
+  suppressOutput: boolean;
 }

test/comment.test.ts

@@ -42,6 +42,7 @@ describe("comment", () => {
     updateComment: true,
     customNpxArgs: "",
     cdktfArgs: "",
+    suppressOutput: false,
   };
 
   const pullRequestData = {
@@ -179,6 +180,60 @@ describe("comment", () => {
       expect(createComment).not.toBeCalled();
     });
 
+    it("should successfully truncate comment if it exceeds the limit", async () => {
+      const maxOutputLength = 65536;
+      const commentController = new CommentController({
+        inputs: defaultInput,
+        context,
+        octokit,
+      });
+      const commentBody = `${"a".repeat(maxOutputLength + 1)}\nlong-message`;
+      const truncatedBody = commentController.truncateOutput(commentBody);
+      const expectedBody = `<!-- terraform cdk action for options with hash ${hash} -->\n${truncatedBody}`;
+      const actual = await commentController.postCommentOnPr(truncatedBody);
+      expect(actual).toBeUndefined();
+      expect(createComment).not.toBeCalled();
+      expect(updateComment).toBeCalledWith({
+        body: expectedBody,
+        comment_id: "comment_id_2",
+      });
+      expect(expectedBody.length).toBeLessThanOrEqual(65536);
+    });
+
+    it("should not truncate comment if it does not exceed the limit", async () => {
+      const commentController = new CommentController({
+        inputs: defaultInput,
+        context,
+        octokit,
+      });
+      const commentBody = "short-message";
+      const truncatedBody = commentController.truncateOutput(commentBody);
+      const expectedBody = `<!-- terraform cdk action for options with hash ${hash} -->\n${truncatedBody}`;
+      const actual = await commentController.postCommentOnPr(truncatedBody);
+      expect(actual).toBeUndefined();
+      expect(createComment).not.toBeCalled();
+      expect(updateComment).toBeCalledWith({
+        body: expectedBody,
+        comment_id: "comment_id_2",
+      });
+      expect(expectedBody.length).toBeLessThanOrEqual(65536);
+    });
+
+    it("should omit output in comment if suppressOutput is true", async () => {
+      const commentController = new CommentController({
+        inputs: { ...defaultInput, suppressOutput: true },
+        context,
+        octokit,
+      });
+      const actual = await commentController.postCommentOnPr("some-message");
+      expect(actual).toBeUndefined();
+      expect(createComment).not.toBeCalled();
+      expect(updateComment).toBeCalledWith({
+        body: `<!-- terraform cdk action for options with hash ${hash} -->\nsome-message`,
+        comment_id: "comment_id_2",
+      });
+    });
+
     it("should get pull_number via API if not running on PR", async () => {
       issuesAndPullRequests.mockResolvedValueOnce(pullRequestData);
       paginate.mockResolvedValueOnce(commentDataWithTag);