问题说明：

docker网桥地址：172.17.0.1
nginx容器地址：172.17.0.2

nginx容器 apt-get update 想更新源然后发现国外的源很慢，换为阿里的源，还是没有成功。
然后就ping 172.17.0.1发现可以通，接着ping172.17.0.2发现通不了
docker info 查看状态

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Build with BuildKit (Docker Inc., v0.5.1-docker)

Server:
 Containers: 2
  Running: 1
  Paused: 0
  Stopped: 1
 Images: 3
 Server Version: 20.10.5
 Storage Driver: overlay2
  Backing Filesystem: xfs
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 05f951a3781f4f2c1911b05e61c160e9c30eaa8e
 runc version: 12644e614e25b05da6fd08a38ffa0cfe1903fdec
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 3.10.0-1160.21.1.el7.x86_64
 Operating System: CentOS Linux 7 (Core)
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 3.7GiB
 Name: docker-seata.xd.local
 ID: FQRG:XBJ5:K5CW:A7KU:KQQJ:OEWC:HHAO:FCLN:DFVU:Q42Q:VNJ7:32GT
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  nexus:8082
  nexus:8084
  127.0.0.0/8
 Registry Mirrors:
  http://nexus:8084/
 Live Restore Enabled: false

WARNING: IPv4 forwarding is disabled
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

最后三行warning

解决的办法

vim /etc/sysctl.conf

net.bridge.bridge-nf-call-ip6tables=1
net.bridge.bridge-nf-call-iptables=1
net.bridge.bridge-nf-call-arptables=1
net.ipv4.ip_forward=1

然后重启网络

systemctl restart network

最后成功解决问题