#!/bin/bash
set -e

# Note above that we run dumb-init as PID 1 in order to reap zombie processes
# as well as forward signals to all processes in its session. Normally, sh
# wouldn't do either of these functions so we'd leak zombies as well as do
# unclean termination of all our sub-processes.

# You can set CONSUL_BIND_INTERFACE to the name of the interface you'd like to
# bind to and this will look up the IP and pass the proper -bind= option along
# to Consul.
CONSUL_BIND=
if [ -n "$CONSUL_BIND_INTERFACE" ]; then
  CONSUL_BIND_ADDRESS=$(ip -o -4 addr list $CONSUL_BIND_INTERFACE | head -n1 | awk '{print $4}' | cut -d/ -f1)
  if [ -z "$CONSUL_BIND_ADDRESS" ]; then
    echo "Could not find IP for interface '$CONSUL_BIND_INTERFACE', exiting"
    exit 1
  fi

  CONSUL_BIND="-bind=$CONSUL_BIND_ADDRESS"
  echo "==> Found address '$CONSUL_BIND_ADDRESS' for interface '$CONSUL_BIND_INTERFACE', setting bind option..."
fi

# You can set CONSUL_CLIENT_INTERFACE to the name of the interface you'd like to
# bind client intefaces (HTTP, DNS, and RPC) to and this will look up the IP and
# pass the proper -client= option along to Consul.
CONSUL_CLIENT=
if [ -n "$CONSUL_CLIENT_INTERFACE" ]; then
  CONSUL_CLIENT_ADDRESS=$(ip -o -4 addr list $CONSUL_CLIENT_INTERFACE | head -n1 | awk '{print $4}' | cut -d/ -f1)
  if [ -z "$CONSUL_CLIENT_ADDRESS" ]; then
    echo "Could not find IP for interface '$CONSUL_CLIENT_INTERFACE', exiting"
    exit 1
  fi

  CONSUL_CLIENT="-client=$CONSUL_CLIENT_ADDRESS"
  echo "==> Found address '$CONSUL_CLIENT_ADDRESS' for interface '$CONSUL_CLIENT_INTERFACE', setting client option..."
fi

# CONSUL_DATA_DIR is exposed as a volume for possible persistent storage. The
# CONSUL_CONFIG_DIR isn't exposed as a volume but you can compose additional
# config files in there if you use this image as a base, or use CONSUL_LOCAL_CONFIG
# below.
CONSUL_DATA_DIR=/consul/data
CONSUL_CONFIG_DIR=/consul/config

# You can also set the CONSUL_LOCAL_CONFIG environemnt variable to pass some
# Consul configuration JSON without having to bind any volumes.
if [ -n "$CONSUL_LOCAL_CONFIG" ]; then
	echo "$CONSUL_LOCAL_CONFIG" > "$CONSUL_CONFIG_DIR/local.json"
fi

# If the user is trying to run Consul directly with some arguments, then
# pass them to Consul.
if [ "${1:0:1}" = '-' ]; then
    set -- consul "$@"
fi

# Look for Consul subcommands.
if [ "$1" = 'agent' ]; then
    shift
    set -- consul agent \
        -data-dir="$CONSUL_DATA_DIR" \
        -config-dir="$CONSUL_CONFIG_DIR" \
        $CONSUL_BIND \
        $CONSUL_CLIENT \
        "$@"
elif [ "$1" = 'version' ]; then
    # This needs a special case because there's no help output.
    set -- consul "$@"
elif consul --help "$1" 2>&1 | grep -q "consul $1"; then
    # We can't use the return code to check for the existence of a subcommand, so
    # we have to use grep to look for a pattern in the help output.
    set -- consul "$@"
fi

# If we are running Consul, make sure it executes as the proper user.
if [ "$1" = 'consul' ]; then
    # If the data or config dirs are bind mounted then chown them.
    # Note: This checks for root ownership as that's the most common case.
    if [ "$(stat -c %u /consul/data)" != "$(id -u consul)" ]; then
        chown consul:consul /consul/data
    fi
    if [ "$(stat -c %u /consul/config)" != "$(id -u consul)" ]; then
        chown consul:consul /consul/config
    fi

    # If requested, set the capability to bind to privileged ports before
    # we drop to the non-root user. Note that this doesn't work with all
    # storage drivers (it won't work with AUFS).
    if [ ! -z ${CONSUL_ALLOW_PRIVILEGED_PORTS+x} ]; then
        setcap "cap_net_bind_service=+ep" /bin/consul
    fi

    set -- gosu consul "$@"
fi

exec "$@"
