fix: Change role duration behavior

When a session token provided, use 1hr as role duration
Otherwise, use the max duration of GitHub action (6hr)

Author: amancevice

index.js

@@ -4,9 +4,10 @@ const assert = require('assert');
 const fs = require('fs');
 const path = require('path');
 
-// The max time that a GitHub action is allowed to run is 6 hours.
-// That seems like a reasonable default to use if no role duration is defined.
+// When a session token provided, use 1hr as role duration
+// Otherwise, use the max duration of GitHub action (6hr)
 const MAX_ACTION_RUNTIME = 6 * 3600;
+const SESSION_ROLE_DURATION = 3600;
 const DEFAULT_ROLE_DURATION_FOR_OIDC_ROLES = 3600;
 const USER_AGENT = 'configure-aws-credentials-for-github-actions';
 const MAX_TAG_VALUE_LENGTH = 256;
@@ -85,7 +86,7 @@ async function assumeRole(params) {
   }
 
   let assumeFunction = sts.assumeRole.bind(sts);
-  
+
   // These are customizations needed for the GH OIDC Provider
   if(isDefined(webIdentityToken)) {
     delete assumeRoleRequest.Tags;
@@ -110,8 +111,8 @@ async function assumeRole(params) {
     } catch(error) {
       throw new Error(`Web identity token file could not be read: ${error.message}`);
     }
-    
-  } 
+
+  }
 
   return assumeFunction(assumeRoleRequest)
     .promise()
@@ -270,7 +271,9 @@ async function run() {
     const maskAccountId = core.getInput('mask-aws-account-id', { required: false });
     const roleToAssume = core.getInput('role-to-assume', {required: false});
     const roleExternalId = core.getInput('role-external-id', { required: false });
-    let roleDurationSeconds = core.getInput('role-duration-seconds', {required: false}) || MAX_ACTION_RUNTIME;
+    let roleDurationSeconds = core.getInput('role-duration-seconds', {required: false})
+    || (sessionToken && SESSION_ROLE_DURATION)
+    || MAX_ACTION_RUNTIME;
     const roleSessionName = core.getInput('role-session-name', { required: false }) || ROLE_SESSION_NAME;
     const roleSkipSessionTaggingInput = core.getInput('role-skip-session-tagging', { required: false })|| 'false';
     const roleSkipSessionTagging = roleSkipSessionTaggingInput.toLowerCase() === 'true';
@@ -304,7 +307,7 @@ async function run() {
 
       exportCredentials({accessKeyId, secretAccessKey, sessionToken});
     }
-    
+
     // Attempt to load credentials from the GitHub OIDC provider.
     // If a user provides an IAM Role Arn and DOESN'T provide an Access Key Id
     // The only way to assume the role is via GitHub's OIDC provider.

index.test.js

@@ -527,6 +527,28 @@ describe('Configure AWS Credentials', () => {
         })
     });
 
+    test('role assumption session token provided, no role assumption duration provided', async () => {
+        core.getInput = jest
+            .fn()
+            .mockImplementation(mockGetInput({...ASSUME_ROLE_INPUTS, 'aws-session-token': FAKE_SESSION_TOKEN}));
+
+        await run();
+        expect(mockStsAssumeRole).toHaveBeenCalledWith({
+            RoleArn: ROLE_ARN,
+            RoleSessionName: 'GitHubActions',
+            DurationSeconds: 3600,
+            Tags: [
+                {Key: 'GitHub', Value: 'Actions'},
+                {Key: 'Repository', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REPOSITORY},
+                {Key: 'Workflow', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_WORKFLOW},
+                {Key: 'Action', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_ACTION},
+                {Key: 'Actor', Value: GITHUB_ACTOR_SANITIZED},
+                {Key: 'Commit', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_SHA},
+                {Key: 'Branch', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REF},
+            ]
+        })
+    });
+
     test('role name provided instead of ARN', async () => {
         core.getInput = jest
             .fn()