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Docker - 用Flannel跨主机
试了下比较流行的几种SDN,感觉flannel还是比较好用,这里简单记录一下。
用的是virtualbox,3个机器,分别为:
- genesis : inet 192.168.99.103/24 brd 192.168.99.255 scope global dynamic enp0s3
- exodus : inet 192.168.99.105/24 brd 192.168.99.255 scope global dynamic enp0s3
- leviticus : inet 192.168.99.106/24 brd 192.168.99.255 scope global dynamic enp0s3
虚机信息如下
[root@localhost yum.repos.d]# uname -mars Linux localhost.localdomain 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
[root@localhost yum.repos.d]# cat /etc/*-releaseCentOS Linux release 7.3.1611 (Core)NAME="CentOS Linux"VERSION="7 (Core)"ID="centos"ID_LIKE="rhel fedora"VERSION_ID="7"PRETTY_NAME="CentOS Linux 7 (Core)"ANSI_COLOR="0;31"CPE_NAME="cpe:/o:centos:centos:7"HOME_URL="https://www.centos.org/"BUG_REPORT_URL="https://bugs.centos.org/"CENTOS_MANTISBT_PROJECT="CentOS-7"CENTOS_MANTISBT_PROJECT_VERSION="7"REDHAT_SUPPORT_PRODUCT="centos"REDHAT_SUPPORT_PRODUCT_VERSION="7"CentOS Linux release 7.3.1611 (Core)CentOS Linux release 7.3.1611 (Core)[root@localhost yum.repos.d]# docker versionClient: Version: 1.12.5 API version: 1.24 Go version: go1.6.4 Git commit: 7392c3b Built: Fri Dec 16 02:23:59 2016 OS/Arch: linux/amd64
随便选择两台机器run一下,在容器中ifconfig:
[root@localhost ~]# docker run -it busybox/ # ifconfigeth0 Link encap:Ethernet HWaddr 02:42:AC:11:00:02 inet addr:172.17.0.2 Bcast:0.0.0.0 Mask:255.255.0.0 inet6 addr: fe80::42:acff:fe11:2/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:12 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1016 (1016.0 B) TX bytes:508 (508.0 B)lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
发现参数完全相同,单纯bridge模式下并没有跨主机互通,而host模式是并不建议使用的。
install
先yum install -y etcd flannel
,如果没问题是再好不过了。
etcd 3.x支持--config-file
参数,需要的话可以从源代码install(需要golang 1.6+)。
先从etcd开始,简单说就是"distributed key value store"。
etcd集群的3种方式:
- static
- etcd discovery
- DNS discovery
DNS discovery主要是用srv record,这里先不搞DNS服务,下面对static和etcd discovery两种方式简单说明一下。
static
参数可以在启动时置顶,或者写到配置文件中,默认配置文件为/etc/etcd/etcd.conf
。
genesis的配置如下:
ETCD_NAME=genesisETCD_DATA_DIR="/var/lib/etcd/genesis"ETCD_LISTEN_PEER_URLS="http://192.168.99.103:2380"ETCD_LISTEN_CLIENT_URLS="http://192.168.99.103:2379,http://127.0.0.1:2379"ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.99.103:2380"ETCD_ADVERTISE_CLIENT_URLS="http://192.168.99.103:2379"ETCD_INITIAL_CLUSTER_STATE="new"ETCD_INITIAL_CLUSTER_TOKEN="etct-fantasy"ETCD_INITIAL_CLUSTER="exodus=http://192.168.99.105:2380,genesis=http://192.168.99.103:2380"
exodus的配置如下:
ETCD_NAME=exodusETCD_DATA_DIR="/var/lib/etcd/exodus"ETCD_LISTEN_PEER_URLS="http://192.168.99.105:2380"ETCD_LISTEN_CLIENT_URLS="http://192.168.99.105:2379,http://127.0.0.1:2379"ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.99.105:2380"ETCD_ADVERTISE_CLIENT_URLS="http://192.168.99.105:2379"ETCD_INITIAL_CLUSTER_STATE="new"ETCD_INITIAL_CLUSTER_TOKEN="etct-fantasy"ETCD_INITIAL_CLUSTER="exodus=http://192.168.99.105:2380,genesis=http://192.168.99.103:2380"
启动方式看自己喜好,如果打算用systemctl
启动的话,注意/usr/lib/systemd/system/etcd.service
中的内容可能不会如你所愿。
启动后,检查一下集群状态,顺便也看看有哪些成员:
[root@localhost etcd]# etcdctl cluster-healthmember 7a4f27f78a05e755 is healthy: got healthy result from http://192.168.99.103:2379failed to check the health of member 8e8718b335c6c9a2 on http://192.168.99.105:2379: Get http://192.168.99.105:2379/health: dial tcp 192.168.99.105:2379: i/o timeoutmember 8e8718b335c6c9a2 is unreachable: [http://192.168.99.105:2379] are all unreachablecluster is healthy
提示"member unreachable",看来是被exodus的防火墙拦住了,我们先粗暴一点。
[root@localhost etcd]# systemctl stop firewalld[root@localhost etcd]# etcdctl cluster-healthmember 7a4f27f78a05e755 is healthy: got healthy result from http://192.168.99.103:2379member 8e8718b335c6c9a2 is healthy: got healthy result from http://192.168.99.105:2379cluster is healthy
etcd discovery
当然,这样配置的前提是已经知道各个节点的信息。
但实际场景中可能无法预知各个member,所以我们需要让etcd自己去发现(discovery)。
首先,etcd提供了一个public discovery service - discovery.etcd.io,我们用它来生成一个discovery token,并在genesis创建目录:
[root@localhost etcd]# curl https://discovery.etcd.io/new?size=3https://discovery.etcd.io/6321c0706046c91f2b2598206ffa3272[root@localhost etcd]# etcdctl set /discovery/6321c0706046c91f2b2598206ffa3272/_config/size 3
修改exodus的配置,用discovery代替之前的cluster:
ETCD_NAME=exodusETCD_DATA_DIR="/var/lib/etcd/exodus"ETCD_LISTEN_PEER_URLS="http://192.168.99.105:2380"ETCD_LISTEN_CLIENT_URLS="http://192.168.99.105:2379,http://127.0.0.1:2379"ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.99.105:2380"ETCD_ADVERTISE_CLIENT_URLS="http://192.168.99.105:2379"ETCD_DISCOVERY=http://192.168.99.103:2379/v2/keys/discovery/98a976dac265a218f1a1959eb8dde57f
如果启动后一直显示如下错误(参考: raft election):
rafthttp: the clock difference against peer ?????? is too high [??????s > 1s]
简单的解决方法是通过ntp:
[root@localhost etcd]yum install ntp -y[root@localhost etcd]# systemctl enable ntpdCreated symlink from /etc/systemd/system/multi-user.target.wants/ntpd.service to /usr/lib/systemd/system/ntpd.service.[root@localhost etcd]# systemctl start ntpd
flannel
set一个路径给flannel用:
etcdctl set /coreos.com/network/config ‘{ "Network": "10.1.0.0/16" }‘
以systemctl start flanneld
方式启动时,如果出现以下错误
network.go:53] Failed to retrieve network config: 100: Key not found (/coreos.net) [9]
注意/etc/sysconfig/flanneld
中的内容,FLANNEL_ETCD_PREFIX很可能是/atomic.io/network
,将其改为/coreos.com/network
。
或者也可以通过-etcd-prefix指定。
启动成功后,查看subnet:
[root@localhost etcd]# etcdctl ls /coreos.com/network/subnets/coreos.com/network/subnets/10.1.90.0-24/coreos.com/network/subnets/10.1.30.0-24/coreos.com/network/subnets/10.1.18.0-24
flannel启动成功后会生成/run/flannel/docker
,内容如下:
DOCKER_OPT_BIP="--bip=10.1.30.1/24"DOCKER_OPT_IPMASQ="--ip-masq=true"DOCKER_OPT_MTU="--mtu=1450"DOCKER_NETWORK_OPTIONS=" --bip=10.1.30.1/24 --ip-masq=true --mtu=1450 "
用以下方式启动docker:
[root@localhost etcd]# source /run/flannel/docker[root@localhost etcd]# docker daemon ${DOCKER_NETWORK_OPTIONS} >> /dev/null 2>&1 &
/run/flannel/docker
是怎么来的?
参考flanneld的两个启动参数,-subnet-dir和-subnet-file。
在genesis进入容器看看效果:
[root@localhost etcd]# docker run -it busybox/ # ifconfigeth0 Link encap:Ethernet HWaddr 02:42:0A:01:5A:02 inet addr:10.1.90.2 Bcast:0.0.0.0 Mask:255.255.255.0 inet6 addr: fe80::42:aff:fe01:5a02/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1 RX packets:6 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:508 (508.0 B) TX bytes:508 (508.0 B)lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
在exodus也做类似操作,在exodus中ping一下10.1.90.2,发现是通的。
并在各自容器中也ping一下,检查是否跨主机互通。
Docker - 用Flannel跨主机