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#!/bin/bash
# Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
set -e
source "${0%/*}/common.sh"
declare -r HOSTS_FILE=/etc/hosts
declare -r HOSTS_LINE_SUFFIX=" # Managed by etc-hosts.sh"
function Usage {
UsageHelper "$@" <<EOF
Usage: $SCRIPT_NAME <command> [--num-nodes <num-nodes>]
Manage Docker container DNS<->IP resolution ($HOSTS_FILE).
Commands:
start Add Docker containers to $HOSTS_FILE
stop Remove Docker containers from $HOSTS_FILE (not implemented)
restart Stop, then start
Options:
--num-nodes <num-nodes>
Add <num-nodes> hosts instead of the default $DEFAULT_NUM_APP_CONTAINERS.
EOF
}
function IsInHostsAlready {
local ip="$1"
local hostname="$2"
local file="$3"
# TODO: Escape $ip to make sure it's matched as a literal in the regex.
local matching_ip_line
matching_ip_line=$(grep -E "^$ip[ \\t]" "$file")
local -i num_ip_lines=0
# This 'if' is needed because wc -l <<< "" is 1.
if [ -n "$matching_ip_line" ]
then
num_ip_lines=$(wc -l <<< "$matching_ip_line")
fi
local matching_hostname_line
matching_hostname_line=$(grep -E "^[^#]*[ \\t]$hostname(\$|[ \\t])" "$file")
local -i num_hostname_lines=0
# This 'if' is needed because wc -l <<< "" is 1.
if [ -n "$matching_hostname_line" ]
then
num_hostname_lines=$(wc -l <<< "$matching_hostname_line")
fi
if ((num_ip_lines == 1)) && ((num_hostname_lines == 1)) &&
[ "$matching_ip_line" == "$matching_hostname_line" ]
then
return 0
elif ((num_ip_lines == 0)) && ((num_hostname_lines == 0))
then
return 1
else
Fail "$file contains a conflicting host specification for $hostname/$ip"
fi
}
function AddHost {
local ip="$1"
local hostname="$2"
local file="$3"
if IsInHostsAlready "$ip" "$hostname" "$file"
then
return
fi
echo -n "Adding host $hostname ($ip) to $file... "
printf "%-11s %s%s\n" "$ip" "$hostname" "$HOSTS_LINE_SUFFIX" >> "$file"
echo done
}
function Stop {
# TODO: Remove entries.
:
}
function StartAsRoot {
if (($# != 0))
then
Usage
fi
# May need sudo
if [ ! -w "$HOSTS_FILE" ]
then
Fail "$HOSTS_FILE is not writeable (run script with sudo)"
fi
AddHost "$CONFIG_SERVER_IP" "$CONFIG_SERVER_HOSTNAME" "$HOSTS_FILE"
local -i index=1
for ((; index <= NUM_APP_CONTAINERS; ++index))
do
local ip="$APP_NETWORK_PREFIX.$index"
local container_name="$APP_HOSTNAME_PREFIX$index"
AddHost "$ip" "$container_name" "$HOSTS_FILE"
done
}
function Start {
if [ "$(id -u)" != 0 ]
then
sudo "$0" "$@"
else
StartAsRoot "$@"
fi
}
Main "$@"
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