Based on Bitnami WordPress Multi-Tier solution for AWS:

Run a stack on AWS:

Read the official doc on Bitnami

Build SSH tunnel over Bastion Host to App Instance

Reference: Connect To An Application Instance Using An SSH Tunnel

I am tired of ssh to Bastion Host and then ssh to App Instance, so, build a ssh tunnel.

1. Get 'Elastic IP 1 for Bastion' in CloudFormation
2. Get 'Private IP' of app instance in EC2
3. sudo chmod 600 KEYFILE_PATH
4. ssh -i ec2-user@BASTION_IP
5. Do in Bastion Host:

sudo sed -i -e 's/AllowTcpForwarding no/AllowTcpForwarding yes/g' /etc/ssh/sshd_config
sudo /etc/init.d/sshd restart
exit

1. Do in local:

cat >> ~/.ssh/config <<'EOF'
Host bastionHost
 Hostname BASTION_IP
 User ec2-user
 ForwardAgent yes
 IdentityFile KEYFILE_PATH

Host YOUR_APP_NAME
 Hostname APP_INSTANCE_PRIVATE_IP
 User bitnami
 ForwardAgent yes
 IdentityFile KEYFILE_PATH
 ProxyCommand ssh -A -W %h:22 bastionHost
EOF

1. Connect to App: ssh YOUR_APP_NAME