dnsdocker_使用DNS缓存修复Docker中的DNS超时[教程]

$ tcpdump -n -i eth1 port 53
11:35:59.474735 IP 172.16.0.131.54264 > 172.16.0.119.domain: 64859&＃43; AAAA? registry-1.docker.io. (38)
11:35:59.474854 IP 172.16.0.131.49631 > 172.16.0.119.domain: 43524&＃43; A? registry-1.docker.io. (38)
11:35:59.476871 IP 172.16.0.119.domain > 172.16.0.131.49631: 43524 8/0/1 A 34.197.189.129, A 34.199.40.84, A 34.199.77.19, A 34.201.196.144, A 34.228.211.243, A 34.232.31.24, A 52.2.186.244, A 52.55.198.220 (177)
11:35:59.476957 IP 172.16.0.119.domain > 172.16.0.131.54264: 64859 0/1/1 (133)


#!/usr/bin/env bash: " ${IMAGE:&＃61;andyshinn/dnsmasq:2.76} "
: " ${NAME:&＃61;dnsmasq} "
: " ${ADAPT_DNS_IP_FILE:&＃61;/tmp/adapt_dns_ip} "# Get IP address for an interface, as visible from inside a container
# connected to the host network
interfaceIP () {# Run a container and get ifconfig output from inside# We need the ifconfig that will be visible from inside the dnsmaq# containerdocker run --rm --net&＃61;host busybox ifconfig " $1 " 2>/dev/null | \awk &＃39;/inet /{print(gensub(/^.*inet (addr:)?([0-9.]&＃43;)\s.*$/, "\\2", 1))}&＃39;
}if docker inspect -- type container " ${NAME} " >& /dev/null ; thenif [ -f " ${ADAPT_DNS_IP_FILE} " ]; then# dnsmasq is already startedcat " ${ADAPT_DNS_IP_FILE} "exit 0elseecho DNS cache container running but file ${ADAPT_DNS_IP_FILE} does not exist. >&2exit 1fi
fi# We only support attaching to the default (host) bridge named "bridge".
DOCKER_HOST_NETWORK&＃61;bridge# Confirm that "bridge" is the default bridge
IS_DEFAULT&＃61;$(docker network inspect " ${DOCKER_HOST_NETWORK} " --format &＃39;{{(index .Options "com.docker.network.bridge.default_bridge")}}&＃39; )
if [ " ${IS_DEFAULT} " !&＃61; "true" ]; thenecho Cannot start DNS cache. The Docker network named \ " ${DOCKER_HOST_NETWORK} \" does not exist or is not the default bridge. >&2exit 1
fi# Get the Linux interface name for the bridge, typically " docker0 "
INTF_NAME&＃61; $(docker network inspect "${DOCKER_HOST_NETWORK}" --format &＃39;{{(index .Options "com.docker.network.bridge.name") }}&＃39;)
if [ -z " ${INTF_NAME} " ]; thenecho Cannot start DNS cache. Unable to determine default bridge interface name. >&2exit 1
fi# Get the IP address of the bridge interface. This is the address that
# dnsmasq will listen on and other containers will send DNS requests to.
IP_ADDR&＃61; $(interfaceIP "${INTF_NAME}")
if [ -z " ${IP_ADDR} " ]; thenecho Cannot start DNS cache. Docker bridge interface ${INTF_NAME} does not exist. >&2exit 1
fi# Run the dnsmasq container. The hosts&＃39;s /etc/resolv.conf configuration will
# be used by dnsmasq to resolve requests.
docker run --rm -d --cap-add&＃61;NET_ADMIN --name " ${NAME} " --net&＃61;host -v/etc/resolv.conf:/etc/resolv.conf " ${IMAGE} " --bind-interfaces --listen-address&＃61;" ${IP_ADDR} " --log-facility&＃61;- > /dev/null
if [ $? -ne 0 ]; thenecho Cannot start DNS cache. Docker run failed.exit 1
fi# Remember what IP address to use as DNS server, then output it.
echo ${IP_ADDR} > " ${ADAPT_DNS_IP_FILE} "
echo ${IP_ADDR}


$ DNS_IP&＃61;$(dns_cache)
$ docker run --dns ${DNS_IP} --rm busybox ping -c1 adaptjs.org

$ docker kill -s USR1 dnsmasq
$ docker logs dnsmasq
dnsmasq[1]: cache size 150, 1085/4664 cache insertions re-used unexpired cache entries.
dnsmasq[1]: queries forwarded 1712, queries answered locally 3940
dnsmasq[1]: queries for authoritative zones 0
dnsmasq[1]: server 172.16.0.119#53: queries sent 1172, retried or failed 0
dnsmasq[1]: server 172.16.1.65#53: queries sent 252, retried or failed 0
dnsmasq[1]: server 172.16.0.2#53: queries sent 608, retried or failed 0