feat: Have an ability to configure session name (#29)

* 1. Add 'role-session-name' variable to action.yml
2. Configure roleSessionName with role-session-name from action or default value (GitHubActions)

* Add description on README.md

* update README.md

* update dist/index.js

* add test code

* update context based on comments

Author: cychiang

Diff for: README.md

@@ -53,7 +53,8 @@ We recommend following [Amazon IAM best practices](https://docs.aws.amazon.com/I
 ## Assuming a role
 If you would like to use the credentials you provide to this action to assume a role, you can do so by specifying the role ARN in `role-to-assume`.
 The role credentials will then be output instead of the ones you have provided.
-The default session duration is 6 hours, but if you would like to adjust this you can pass a duration to `role-duration-seconds`.
+The default session duration is 6 hours, but if you would like to adjust this you can pass a duration to `role-duration-seconds`. 
+The default session name is GitHubActions, and you can modify it by specifying the desired name in `role-session-name`.
 
 Example:
 ```yaml
@@ -65,6 +66,7 @@ Example:
         aws-region: us-east-2
         role-to-assume: arn:aws:iam::123456789100:role/role-to-assume
         role-duration-seconds: 1200
+        role-session-name: MySessionName
 ```
 
 ### Session tagging

Diff for: action.yml

@@ -25,6 +25,9 @@ inputs:
   role-duration-seconds:
     description: "Role duration in seconds (default: 6 hours)"
     required: false
+  role-session-name:
+    description: 'Role session name (default: GitHubActions)'
+    required: false
 outputs:
   aws-account-id:
     description: 'The AWS account ID for the provided credentials'

Diff for: dist/index.js

@@ -8,15 +8,16 @@ const util = require('util');
 const MAX_ACTION_RUNTIME = 6 * 3600;
 const USER_AGENT = 'configure-aws-credentials-for-github-actions';
 const MAX_TAG_VALUE_LENGTH = 256;
-const SANITIZATION_CHARACTER = '_'
+const SANITIZATION_CHARACTER = '_';
+const ROLE_SESSION_NAME = 'GitHubActions';
 
 async function assumeRole(params) {
   // Assume a role to get short-lived credentials using longer-lived credentials.
   const isDefined = i => !!i;
 
-  const {roleToAssume, roleDurationSeconds, accessKeyId, secretAccessKey, sessionToken, region} = params;
+  const {roleToAssume, roleDurationSeconds, roleSessionName, accessKeyId, secretAccessKey, sessionToken, region} = params;
   assert(
-      [roleToAssume, roleDurationSeconds, accessKeyId, secretAccessKey, region].every(isDefined),
+      [roleToAssume, roleDurationSeconds, roleSessionName, accessKeyId, secretAccessKey, region].every(isDefined),
       "Missing required input when assuming a Role."
   );
 
@@ -33,7 +34,7 @@ async function assumeRole(params) {
   });
   return sts.assumeRole({
     RoleArn: roleToAssume,
-    RoleSessionName: 'GitHubActions',
+    RoleSessionName: roleSessionName,
     DurationSeconds: roleDurationSeconds,
     Tags: [
       {Key: 'GitHub', Value: 'Actions'},
@@ -121,11 +122,12 @@ async function run() {
     const maskAccountId = core.getInput('mask-aws-account-id', { required: false });
     const roleToAssume = core.getInput('role-to-assume', {required: false});
     const roleDurationSeconds = core.getInput('role-duration-seconds', {required: false}) || MAX_ACTION_RUNTIME;
+    const roleSessionName = core.getInput('role-session-name', { required: false }) || ROLE_SESSION_NAME;
 
     // Get role credentials if configured to do so
     if (roleToAssume) {
       const roleCredentials = await assumeRole(
-          {accessKeyId, secretAccessKey, sessionToken, region, roleToAssume, roleDurationSeconds}
+          {accessKeyId, secretAccessKey, sessionToken, region, roleToAssume, roleDurationSeconds, roleSessionName}
       );
       exportCredentials(roleCredentials);
     } else {

Diff for: index.js

@@ -238,6 +238,28 @@ describe('Configure AWS Credentials', () => {
         })
     });
 
+    test('role assumption session name provided', async () => {
+        core.getInput = jest
+            .fn()
+            .mockImplementation(mockGetInput({...ASSUME_ROLE_INPUTS, 'role-session-name': 'MySessionName'}));
+
+        await run();
+        expect(mockStsAssumeRole).toHaveBeenCalledWith({
+            RoleArn: ROLE_NAME,
+            RoleSessionName: 'MySessionName',
+            DurationSeconds: 6 * 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: 'Branch', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_REF},
+                {Key: 'Commit', Value: ENVIRONMENT_VARIABLE_OVERRIDES.GITHUB_SHA},
+            ]
+        })
+    });
+
     test('workflow name sanitized in role assumption tags', async () => {
         core.getInput = jest
             .fn()