TCP scaler

This is a simple TCP proxy that starts an AWS EC2 instance when any number of clients exist, and then forward them to a backend instance when available.

Build

These instructions have been tested on Debian 10.

Installed the required packages:

apt-get install python3 python3-venv netcat

Set up a virtualenv environment:

python3 -m venv env
. env/bin/activate
pip install -r requirements.txt

Build the wheel:

pip install wheel
python setup.py bdist_wheel

Installing

Copy the wheel to the desired system, and run the following to install:

apt-get install python3 python3-pip
pip3 install <wheel>

The tcp-scaler and tcp-scaler-forwarder commands will now be available.

Systemd service

Use the following to set up tcp-scaler as a service (tested under Debian 10):

PORT=<frontend-port>
INSTANCE_ID=<instance-id>
BACKEND_PORT=<backend-port>
REGION=<aws-region>

cat > /lib/systemd/system/tcp-scaler-forwarder-${INSTANCE_ID}-${BACKEND_PORT}.socket <<EOF
[Unit]
Description=TCP forwarder component of tcp-scaler

[Socket]
ListenStream=0.0.0.0:${PORT}
Accept=yes

[Install]
WantedBy=sockets.target
EOF

cat > /lib/systemd/system/tcp-scaler-forwarder-${INSTANCE_ID}-${BACKEND_PORT}@.service <<EOF
[Unit]
Description=TCP forwarder component of tcp-scaler
Requires=tcp-scaler-forwarder-${INSTANCE_ID}-${BACKEND_PORT}.socket

[Service]
Type=simple
Environment="AWS_DEFAULT_REGION=${REGION}"
ExecStart=-tcp-scaler-forwarder -v ${INSTANCE_ID} /tmp/tcp-scaler-${INSTANCE_ID}-${BACKEND_PORT} ${BACKEND_PORT}
StandardInput=socket
StandardError=journal
TimeoutStopSec=5

[Install]
WantedBy=multi-user.target
EOF

cat > /lib/systemd/system/tcp-scaler-${INSTANCE_ID}-${BACKEND_PORT}.service <<EOF
[Unit]
Description=Instance manager for tcp-scaler

[Service]
Type=simple
Environment="AWS_DEFAULT_REGION=${REGION}"
ExecStart=tcp-scaler -v ${INSTANCE_ID} /tmp/tcp-scaler-${INSTANCE_ID}-${BACKEND_PORT}

[Install]
WantedBy=multi-user.target
EOF

systemctl daemon-reload
systemctl start tcp-scaler-${INSTANCE_ID}-${BACKEND_PORT}.service
systemctl start tcp-scaler-forwarder-${INSTANCE_ID}-${BACKEND_PORT}.socket