example docker update.sh

#!/bin/bash

echo "Updating server: ${HOSTNAME}"
echo ""

# pull latest image
docker pull float/auth:${CODE_BRANCH}

# get image id
NEW_IMAGE_ID=$(docker images | grep -E "^float\/auth.*?${CODE_BRANCH}" | awk -e '{print $3}')
NEW_CONTAINER_NAME="auth_${NEW_IMAGE_ID}"

# get running container name
RUNNING_CONTAINER_NAME=$(docker ps | grep -E "auth_.*?$" | awk -e '{print $NF}')

if [ "${RUNNING_CONTAINER_NAME}" == "${NEW_CONTAINER_NAME}" ]
then
    echo "WARNING: Attempt to deploy already-running verion: ${NEW_IMAGE_ID}"
    exit 1
fi

echo "Updating to image id: ${NEW_IMAGE_ID}"
echo "  New container name: ${NEW_CONTAINER_NAME}"
# create new container

docker run -d \
    --name ${NEW_CONTAINER_NAME} \
    --volumes-from=data \
    --link rethinkdb_proxy:rethinkdb \
    --restart=always \
    -P \
    -e "EPICENTER_HTTPS_CERT=/data/auth/certs/server.crt" \
    -e "EPICENTER_HTTPS_KEY=/data/auth/certs/server.key" \
    -e "EPICENTER_HTTPS_REDIRECT=1" \
    float/auth:${CODE_BRANCH}

if [ "${RUNNING_CONTAINER_NAME}" != "" ]
then
    RUNNING_CONTAINER_IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' ${RUNNING_CONTAINER_NAME})
fi

# get new container mapped ports
NEW_CONTAINER_IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' ${NEW_CONTAINER_NAME})
echo "  Networking info:"
echo "    New container ip: ${NEW_CONTAINER_IP}"
if [ "${RUNNING_CONTAINER_NAME}" != "" ]
then
    echo "    Running container ip: ${RUNNING_CONTAINER_IP}"
fi

#HTTPS_PORT=$(docker port ${NEW_CONTAINER_NAME} 4443/tcp | sed 's/.*:\([0-9]*\)/\1/')
#HTTP_PORT=$(docker port ${NEW_CONTAINER_NAME} 8000/tcp | sed 's/.*:\([0-9]*\)/\1/')

# test container

echo "  Waiting for new container to be ready..."

until $(curl -ks https://${NEW_CONTAINER_IP}:4443/__epicenter | grep -q '"ready":true'); do
    printf '.'
    sleep 1
done

# point iptables to new container
echo "  Switching networking to new container..."
iptables -t nat -A DOCKER ! -i docker0 -p tcp --dport 443 -j DNAT --to-destination ${NEW_CONTAINER_IP}:4443
iptables -t nat -A DOCKER ! -i docker0 -p tcp --dport 80 -j DNAT --to-destination ${NEW_CONTAINER_IP}:8000

# shut down old container
if [ "${RUNNING_CONTAINER_NAME}" != "" ]
then
    echo "  Removing previous container networking forwards..."
    iptables -t nat -D DOCKER ! -i docker0 -p tcp --dport 443 -j DNAT --to-destination ${RUNNING_CONTAINER_IP}:4443
    iptables -t nat -D DOCKER ! -i docker0 -p tcp --dport 80 -j DNAT --to-destination ${RUNNING_CONTAINER_IP}:8000

    # wait for connections to drop on old container

    echo "  Waiting for old container to be finished serving requests..."

    # single active connection is the request for status itself (vs. 0 active)
    until $(curl -ks https://${RUNNING_CONTAINER_IP}:4443/__epicenter | grep -q '"active":1,'); do
        printf '.'
        sleep 1
    done

    # stop old container
    echo "  Stopping old container: ${RUNNING_CONTAINER_NAME}"
    docker stop ${RUNNING_CONTAINER_NAME}

    # remove old container
    echo "  Removing old container: ${RUNNING_CONTAINER_NAME}"
    docker rm ${RUNNING_CONTAINER_NAME}
fi

echo "Done"