Backup and Restore container

# Set the container name here
INSTANCE_NAME="bluedata-400"
# Extract the device num from the instance name
INSTANCE_DEV_ID=$(echo $INSTANCE_NAME | cut -d"-" -f2)
# device name to use for the snapshot
SNAP_NAME=$INSTANCE_NAME-snap


# To create a snapshot device, we need to specify a unique device id. This has to be 24-bit number
# Going to start from 16484 as the base
UNIQUE_DEVICE_BASE_ID="16384"

# Setup unique device id
UNIQUE_DEVICE_ID="$(( $UNIQUE_DEVICE_BASE_ID+$INSTANCE_DEV_ID ))"

# Get the docker device mapper pool information.
POOL=$(docker info | grep pool | awk '{print $3}')
DEVMAPPER_POOL="/dev/mapper/$POOL"

# Extract the container id.
CONT_ID=$(docker inspect -f {{.Id}} $INSTANCE_NAME)

# Get the size and the device id for this container
METADATA_FILE="/var/lib/docker/devicemapper/metadata/$CONT_ID"
SIZE=$(cat $METADATA_FILE | python -c "import json,sys;obj=json.load(sys.stdin);print obj['size']")
DEVICE_ID=$(cat $METADATA_FILE | python -c "import json,sys;obj=json.load(sys.stdin);print obj['device_id']")

# Temporarily suspend the pool to take snapshot and resume it
dmsetup suspend $DEVMAPPER_POOL
dmsetup message $DEVMAPPER_POOL 0 "create_snap $UNIQUE_DEVICE_ID $DEVICE_ID"
dmsetup resume $DEVMAPPER_POOL

dmsetup create $SNAP_NAME --table "0 $(($SIZE / 512)) thin $DEVMAPPER_POOL $UNIQUE_DEVICE_ID"

# We can do dd now, using 1M block size
time dd if=/dev/mapper/$SNAP_NAME conv=sync,noerror bs=128M | gzip -c  > ~/$INSTANCE_NAME.tgz

# We can remove the snapshot now
dmsetup remove $INSTANCE_NAME-snap
dmsetup message $DEVMAPPER_POOL 0 "delete $UNIQUE_DEVICE_ID"

# For debug
ls -l ~/$INSTANCE_NANE.tgz




# For RESTORE
# Set the container name here
INSTANCE_NAME="bluedata-400"
# Extract the container id.
CONT_ID=$(docker inspect -f {{.Id}} $INSTANCE_NAME)
SNAP_NAME=$INSTANCE_NAME-snap

# Get the docker device mapper pool information.
POOL=$(docker info | grep pool | awk '{print $3}')
DEVMAPPER_POOL="/dev/mapper/$POOL"

# Get the size and the device id for this container
METADATA_FILE="/var/lib/docker/devicemapper/metadata/$CONT_ID"
SIZE=$(cat $METADATA_FILE | python -c "import json,sys;obj=json.load(sys.stdin);print obj['size']")
DEVICE_ID=$(cat $METADATA_FILE | python -c "import json,sys;obj=json.load(sys.stdin);print obj['device_id']")

# Stop the container
docker stop $INSTANCE_NAME

# Create a device using the same device_id
dmsetup create "$SNAP_NAME" --table "0 $(($SIZE / 512)) thin $DEVMAPPER_POOL $DEVICE_ID"

gunzip -c ~/$INSTANCE_NAME.tgz | dd of=/dev/mapper/$SNAP_NAME

dmsetup remove $SNAP_NAME


# Use instance_reboot function to restart the container
docker start $INSTANCE_NAME