try to ping the workers

roles/deploy_flask_app/tasks/setup_bastion.yaml

@@ -0,0 +1,30 @@
+---
+- name: Update ssh_config
+  ansible.builtin.lineinfile:
+    path: /etc/ssh/sshd_config
+    regex: "{{ item.regex }}"
+    line: "{{ item.line }}"
+  loop:
+    - regex: ^(# *)?ClientAliveInterval
+      line: ClientAliveInterval  1200
+    - regex: ^(# *)?ClientAliveCountMax
+      line: ClientAliveCountMax 3
+  become: true
+
+- name: Install required packages
+  ansible.builtin.yum:
+    name: "{{ deploy_flask_app_bastion_host_required_packages }}"
+    state: present
+  become: true
+
+- name: Generate ssh configuration for current user
+  ansible.builtin.user:
+    generate_ssh_key: true
+    state: present
+    name: "{{ deploy_flask_app_bastion_host_username }}"
+
+- name: Copy remote ssh private key file into bastion
+  ansible.builtin.copy:
+    src: "{{ deploy_flask_app_bastion_ssh_private_key }}"
+    dest: "{{ deploy_flask_app_workers_ssh_private_key }}"
+    mode: 0400

roles/deploy_flask_app/tasks/update_inventory.yaml

@@ -0,0 +1,21 @@
+---
+- name: Add bastion host into inventory
+  ansible.builtin.add_host:
+    hostname: bastion
+    ansible_ssh_user: "{{ deploy_flask_app_bastion_host_username }}"
+    ansible_host: "{{ deploy_flask_app__bastion_public_ip }}"
+    ansible_ssh_common_args: -o "UserKnownHostsFile=/dev/null" -o StrictHostKeyChecking=no -i {{ deploy_flask_app_bastion_ssh_private_key }}
+    ansible_python_interpreter: auto
+    ansible_host_name: "{{ deploy_flask_app__resource_prefix }}"
+    host_config:
+      public_subnet_id: "{{ deploy_flask_app__public_subnet_id }}"
+      private_subnet_id: "{{ deploy_flask_app__private_subnet_id }}"
+      image_id: "{{ deploy_flask_app__vm_image_id }}"
+      group_id: "{{ deploy_flask_app__group_id }}"
+      private_ip: "{{ deploy_flask_app__bastion_private_ip }}"
+      vpc_id: "{{ deploy_flask_app_vpc_id }}"
+      rds_info:
+        # host: "{{ deploy_flask_app__rds_host }}"
+        # name: "{{ deploy_flask_app__rds_dbname }}"
+        master_user_password: "{{ deploy_flask_app_rds_master_password }}"
+        master_username: "{{ deploy_flask_app_rds_master_username }}"

roles/deploy_flask_app/templates/inventory.yml.j2

@@ -0,0 +1,8 @@
+all:
+    hosts:
+        {{ item.instance_id }}:
+            ansible_host: "{{ item.private_ip_address }}"
+            workers_hosts: "{{ deploy_flask_app_workers_join }}"
+            ansible_ssh_user: "{{ deploy_flask_app_workers_user_name }}"
+            ansible_ssh_common_args: '-o "UserKnownHostsFile=/dev/null" -o StrictHostKeyChecking=no -i {{ deploy_flask_app_workers_ssh_private_key }}'
+            ansible_python_interpreter: auto