Docker同一台宿主机容器通信-通过容器名称互联
作者：尹正杰
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一.通过容器名称互联概述
即在同一个宿主机上的容器之间可以通过自定义的容器名称相互访问,比如一个业务前端静态页面使用nginx,动态页面使用的是tomcat,由于容器在启动的时候其内部IP地址是DHCP随机分配的，所以如果通过内部访问的话,自定义名称是相对比较固定的，因此比较适合于此场景。
二.通过容器名称互联实战案例
1>.创建一个tomcat容器(镜像制作可参考我之前的笔记:https://www.cnblogs.com/yinzhengjie/p/12230043.html)
[root@docker101.yinzhengjie.org.cn ~]# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE centos-haproxy v1.8.20 1858fe05d96f 8 days ago 606MB registry latest 708bc6af7e5e 8 days ago 25.8MB tomcat-app01 v0.1 bf45c22f2d5b 8 days ago 983MB tomcat-base 8.5.50 9ff79f369094 10 days ago 968MB jdk-base 1.8.0_231 0f63a97ddc85 10 days ago 953MB centos-base 7.6.1810 b4931fd9ace2 10 days ago 551MB centos centos7.6.1810 f1cb7c7d58b7 10 months ago 202MB lorel/docker-stress-ng latest 1ae56ccafe55 3 years ago 8.1MB [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container run -it -d --name tomcat-app01 tomcat-app01:v0.1 36315d1b0cb52beecd474121ae697c551ff7a51468f9600c228be18c02fc336d [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container exec -it 36315d1b0cb52beecd474121ae697c551ff7a51468f9600c228be18c02fc336d bash [root@36315d1b0cb5 /]# [root@36315d1b0cb5 /]# cat /etc/hosts 127.0.0.1 localhost ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 172.17.0.2 36315d1b0cb5 [root@36315d1b0cb5 /]# [root@36315d1b0cb5 /]# ping 36315d1b0cb5 -c 2 PING 36315d1b0cb5 (172.17.0.2) 56(84) bytes of data. 64 bytes from 36315d1b0cb5 (172.17.0.2): icmp_seq=1 ttl=64 time=0.085 ms 64 bytes from 36315d1b0cb5 (172.17.0.2): icmp_seq=2 ttl=64 time=0.032 ms --- 36315d1b0cb5 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1000ms rtt min/avg/max/mdev = 0.032/0.058/0.085/0.027 ms [root@36315d1b0cb5 /]# [root@36315d1b0cb5 /]# exit exit [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 36315d1b0cb5 tomcat-app01:v0.1 "/yinzhengjie/softwa…" About a minute ago Up About a minute 8080/tcp, 8443/tcp tomcat-app01 [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]#
2>.创建一个nginx容器(镜像制作可参考我之前的笔记:https://www.cnblogs.com/yinzhengjie/p/12198878.html)时使用"--link"选项和上面创建的tomcat容器互联
[root@docker101.yinzhengjie.org.cn ~]# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE nginx v0.1-20200201 1a8b4f68e96a 22 minutes ago 449MB centos-haproxy v1.8.20 1858fe05d96f 8 days ago 606MB registry latest 708bc6af7e5e 8 days ago 25.8MB tomcat-app01 v0.1 bf45c22f2d5b 8 days ago 983MB tomcat-base 8.5.50 9ff79f369094 10 days ago 968MB jdk-base 1.8.0_231 0f63a97ddc85 10 days ago 953MB centos-base 7.6.1810 b4931fd9ace2 10 days ago 551MB centos centos7.6.1810 f1cb7c7d58b7 10 months ago 202MB lorel/docker-stress-ng latest 1ae56ccafe55 3 years ago 8.1MB [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container run -it -d --name nginx-web01 --link tomcat-app01 -p 80:80 nginx:v0.1-20200201 8e05fc399edd16fe5bde32bebba269c0a07a0a1a928b46421693dd7ee4943ebf [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8e05fc399edd nginx:v0.1-20200201 "nginx" 23 seconds ago Up 22 seconds 0.0.0.0:80->80/tcp, 443/tcp nginx-web01 36315d1b0cb5 tomcat-app01:v0.1 "/yinzhengjie/softwa…" 34 minutes ago Up 34 minutes 8080/tcp, 8443/tcp tomcat-app01 [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container exec -it nginx-web01 bash [root@8e05fc399edd /]# [root@8e05fc399edd /]# cat /etc/hosts 127.0.0.1 localhost ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 172.17.0.2 tomcat-app01 36315d1b0cb5 172.17.0.3 8e05fc399edd [root@8e05fc399edd /]# [root@8e05fc399edd /]# ping tomcat-app01 -c 1 PING tomcat-app01 (172.17.0.2) 56(84) bytes of data. 64 bytes from tomcat-app01 (172.17.0.2): icmp_seq=1 ttl=64 time=0.051 ms --- tomcat-app01 ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 0.051/0.051/0.051/0.000 ms [root@8e05fc399edd /]# [root@8e05fc399edd /]# exit exit [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]#
3>.进入nginx容器编辑nginx的配置文件反向代理tomcat服务
[root@docker101.yinzhengjie.org.cn ~]# docker container ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8e05fc399edd nginx:v0.1-20200201 "nginx" About a minute ago Up About a minute 0.0.0.0:80->80/tcp, 443/tcp nginx-web01 36315d1b0cb5 tomcat-app01:v0.1 "/yinzhengjie/softwa…" 35 minutes ago Up 35 minutes 8080/tcp, 8443/tcp tomcat-app01 [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container exec -it nginx-web01 bash [root@8e05fc399edd /]# [root@8e05fc399edd /]# vim /etc/nginx/nginx.conf [root@8e05fc399edd /]# [root@8e05fc399edd /]# cat /etc/nginx/nginx.conf user nginx; worker_processes auto; error_log /var/log/nginx/error.log; pid /run/nginx.pid; daemon off; include /usr/share/nginx/modules/*.conf; events { worker_connections 1024; } http { log_format my_access_json '{"@timestamp":"$time_iso8601",' '"host":"$server_addr",' '"clientip":"$remote_addr",' '"size":$body_bytes_sent,' '"responsetime":$request_time,' '"upstreamtime":"$upstream_response_time",' '"upstreamhost":"$upstream_addr",' '"http_host":"$host",' '"uri":"$uri",' '"domain":"$host",' '"xff":"$http_x_forwarded_for",' '"referer":"$http_referer",' '"tcp_xff":"$proxy_protocol_addr",' '"http_user_agent":"$http_user_agent",' '"status":"$status"}'; access_log /var/log/nginx/access_json.log my_access_json; sendfile on; keepalive_timeout 65; include mime.types; default_type text/html; charset utf-8; upstream tomcat { server 172.17.0.2:8080; } server { listen 80 default_server; listen [::]:80 default_server; server_name _; root /usr/share/nginx/html; include /etc/nginx/default.d/*.conf; location / { } location /app01 { proxy_pass http://tomcat; proxy_set_header Host $host; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Real-IP $remote_addr; } error_page 404 /404.html; location = /40x.html { } error_page 500 502 503 504 /50x.html; location = /50x.html { } } } [root@8e05fc399edd /]# [root@8e05fc399edd /]# nginx -t nginx: the configuration file /etc/nginx/nginx.conf syntax is ok nginx: configuration file /etc/nginx/nginx.conf test is successful [root@8e05fc399edd /]# [root@8e05fc399edd /]# nginx -s reload [root@8e05fc399edd /]#
4>.浏览器访问Nginx的web页面(http://docker101.yinzhengjie.org.cn/)
5>.浏览器访问Tomcat的web页面(http://docker101.yinzhengjie.org.cn/app01/)
三.通过容器名称互联的注意事项
1>.思考第二步存在的问题
先不要往下看，请闭眼10秒钟思考上面的配置可能会存在哪些故障问题,经过激烈的思考后再往下看咱们是否想到一起去了?
问题一:
nginx的配置文件中在upstream中写死了后端容器的IP地址.
问题剖析:
这样有一个致命的缺陷就是可移植性差,我们将该容器提交为镜像后再其它节点上运行很可能分配的容器IP地址不同会导致后端服务无法正常访问.
解决方案:
在配置文件中写后端服务器的主机名称,这样不管IP地址怎么变动都不用修改nginx的配置文件，只需要修改"/etc/hosts"文件将后端服务器主机的IP地址改成对应的IP地址即可(在新启动的容器这个操作是自动完成的).
问题二:
代码升级时可能后端容器的名称发生变动.
问题刨析:
这是一个让人和头疼的问题，尽管我们上面解决了写死IP地址的问题，但是后端的主机名一直频繁的改动那意味这我们依旧得重新nginx的配置文件.
解决方案:
在使用"--link"通过容器名称互联时我们可以自定义容器别名,使用容器别名在"/etc/hosts"文件中解析的后端服务器主机名是咱们自定义的后端主机名.
2>.通过自定义容器别名互联案例
[root@docker101.yinzhengjie.org.cn ~]# docker container run -it -d --name nginx-web02 --link tomcat-app01:www.yinzhengjie.org.cn -p 81:80 nginx:v0.1-20200201 d5d2b409cc0c20486a1d454d6b26fdc398dae93df9c128577c95fdbbc617d868 [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES d5d2b409cc0c nginx:v0.1-20200201 "nginx" 8 seconds ago Up 7 seconds 443/tcp, 0.0.0.0:81->80/tcp nginx-web02 8e05fc399edd nginx:v0.1-20200201 "nginx" 51 minutes ago Up 51 minutes 0.0.0.0:80->80/tcp, 443/tcp nginx-web01 36315d1b0cb5 tomcat-app01:v0.1 "/yinzhengjie/softwa…" About an hour ago Up About an hour 8080/tcp, 8443/tcp tomcat-app01 [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]# docker container exec -it nginx-web02 bash [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# cat /etc/hosts 127.0.0.1 localhost ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 172.17.0.2 www.yinzhengjie.org.cn 36315d1b0cb5 tomcat-app01 172.17.0.4 d5d2b409cc0c [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# ping www.yinzhengjie.org.cn -c 3 PING www.yinzhengjie.org.cn (172.17.0.2) 56(84) bytes of data. 64 bytes from www.yinzhengjie.org.cn (172.17.0.2): icmp_seq=1 ttl=64 time=0.059 ms 64 bytes from www.yinzhengjie.org.cn (172.17.0.2): icmp_seq=2 ttl=64 time=0.100 ms 64 bytes from www.yinzhengjie.org.cn (172.17.0.2): icmp_seq=3 ttl=64 time=0.040 ms --- www.yinzhengjie.org.cn ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2000ms rtt min/avg/max/mdev = 0.040/0.066/0.100/0.025 ms [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# exit exit [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]#
3>.修改nginx的配置文件
[root@docker101.yinzhengjie.org.cn ~]# docker container exec -it nginx-web02 bash [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# vim /etc/nginx/nginx.conf [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# cat /etc/nginx/nginx.conf user nginx; worker_processes auto; error_log /var/log/nginx/error.log; pid /run/nginx.pid; daemon off; include /usr/share/nginx/modules/*.conf; events { worker_connections 1024; } http { log_format my_access_json '{"@timestamp":"$time_iso8601",' '"host":"$server_addr",' '"clientip":"$remote_addr",' '"size":$body_bytes_sent,' '"responsetime":$request_time,' '"upstreamtime":"$upstream_response_time",' '"upstreamhost":"$upstream_addr",' '"http_host":"$host",' '"uri":"$uri",' '"domain":"$host",' '"xff":"$http_x_forwarded_for",' '"referer":"$http_referer",' '"tcp_xff":"$proxy_protocol_addr",' '"http_user_agent":"$http_user_agent",' '"status":"$status"}'; access_log /var/log/nginx/access_json.log my_access_json; sendfile on; keepalive_timeout 65; include mime.types; default_type text/html; charset utf-8; upstream tomcat { server www.yinzhengjie.org.cn:8080; } server { listen 80 default_server; listen [::]:80 default_server; server_name _; root /usr/share/nginx/html; include /etc/nginx/default.d/*.conf; location / { } location /app01 { proxy_pass http://tomcat; proxy_set_header Host $host; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Real-IP $remote_addr; } error_page 404 /404.html; location = /40x.html { } error_page 500 502 503 504 /50x.html; location = /50x.html { } } } [root@d5d2b409cc0c /]# [root@d5d2b409cc0c /]# exit exit [root@docker101.yinzhengjie.org.cn ~]# [root@docker101.yinzhengjie.org.cn ~]#