Rolling updates, zero downtime with just nginx and docker compose

rollout.sh

#!/bin/bash
set -e

docker-compose build

echo Update only secondary on 3333
docker-compose up -d cooked_secondary

echo Wait until secondary is live
curl --silent --include --retry-connrefused --retry 30 --retry-delay 1 --fail http://localhost:3333/health.txt

echo Start serving secondary instead of main
sed -i 's/localhost:3000/localhost:3333/g' /etc/nginx/sites-enabled/default
service nginx reload

echo Waiting a bit before updating main
sleep 60

echo Update main on 3000
docker-compose up -d cooked

echo Wait until main is live
curl --silent --include --retry-connrefused --retry 30 --retry-delay 1 --fail http://localhost:3000/health.txt

echo Start serving main again
sed -i 's/localhost:3333/localhost:3000/g' /etc/nginx/sites-enabled/default
service nginx reload

echo Update all the other services
docker-compose up -d

echo Waiting a bit before stopping secondary
sleep 60

echo Stop secondary
docker-compose stop cooked_secondary

echo Rollout completed