fix: Resolve AWS Region error in GitHub Actions

- Move sam validate after AWS credentials configuration
- Add explicit AWS_REGION environment variable to SAM steps
- Add AWS identity verification for debugging
- Fix 'AWS Region was not found' error in SAM execution
- Ensure proper execution order: credentials → validate → deploy

Author: Hirose-Sebastian-Taikai

.github/workflows/deploy.yml

@@ -32,16 +32,21 @@ jobs:
         python -m pip install --upgrade pip
         pip install -r requirements.txt
         
-    - name: Validate SAM template
-      run: |
-        sam validate
-        
     - name: Configure AWS credentials
       uses: aws-actions/configure-aws-credentials@v4
       with:
         role-to-assume: ${{ github.ref == 'refs/heads/main' && secrets.AWS_ROLE_ARN_PROD || secrets.AWS_ROLE_ARN_DEV }}
         aws-region: ${{ env.AWS_REGION }}
 
+    - name: Validate SAM template
+      run: |
+        # AWS認証情報の確認
+        aws sts get-caller-identity
+        echo "AWS Region: $AWS_REGION"
+        sam validate
+      env:
+        AWS_REGION: ${{ env.AWS_REGION }}
+        
     - name: Deploy with SAM
       run: |
         # ブランチに基づいて環境設定を決定
@@ -55,13 +60,15 @@ jobs:
         
         echo "Deploying to environment: $ENVIRONMENT"
         echo "Stack name: $STACK_NAME"
+        echo "AWS Region: $AWS_REGION"
         
         sam build
         sam deploy --no-confirm-changeset --no-fail-on-empty-changeset \
           --stack-name $STACK_NAME \
           --s3-bucket cn-seba-aws-sam-cli-managed-default-samclisourcebucket \
           --parameter-overrides ProjectName=${{ env.PROJECT_NAME }} Environment=$ENVIRONMENT
       env:
+        AWS_REGION: ${{ env.AWS_REGION }}
         SAM_CLI_TELEMETRY: 0
 
     - name: Deploy status