Docker Consul Overview and Cluster Environment Construction Steps (Graphical Explanation)

Docker Consul Overview and Cluster Environment Construction Steps (Graphical Explanation)

1. Overview of Docker consul

Container service update and discovery: Discover first and then update. What is discovered is the change of the container on the backend node (registrator), and what is updated is the nginx configuration file (agent)

Registrator: It is the spy installed by Consul in the Docker container. It is used to monitor the changes of containers on the monitoring node (increase or decrease, or downtime). Once there is a change, it will tell this information and register it on the Consul server (using callbacks and coroutines, so its delay and resource consumption will be very small). Once the registration list changes, the Consul server will tell the agent the registration information

Agent: used to control consul template, use template component to connect with nginx.conf, the template is full of variables, use variables to load the backend after registering with consul server, the server will tell the agent the information, the agent and template are connected, write to the template, the template has a mirror, after the update, it will be recognized as a sub-configuration file of nginx.conf by the front-end nginx, consul agent will control the reload and identify the changes in the nginx.conf configuration file, which is equivalent to identifying the back-end node, and can dynamically adjust its own back-end resources in the address pool.

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Features of Consul

  • Support health checks and allow storage of key-value pairs
  • Based on Golong language, highly portable
  • Support ACL access control

2. Build an automatic discovery and highly available Docker service architecture based on nginx and consul

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1. Project requirements

  • Use Docker to combine Consul, Consul template, Registrator and Nginx into a worthy and scalable service architecture
  • When adding or removing services from this architecture, there is no need to rewrite any configuration or restart any services. Everything can run normally to achieve automated operation and maintenance.

2. Environmental Preparation

Host IP address Software that needs to be installed
Master Node 192.168.126.11 docker-ce, consul, consul-template, nginx
nginx 192.168.126.12 doker-ce

3. Deployment steps

#Install Docker-ce on both nodes. Remember to turn off the firewall systemctl stop firewalld && systemctl disable firewalld
setenforce 0 && sed -i "s/SELINUX=*/SELINUX=disabled/g" /etc/selinux/config

①Deploy consul on the master node

[root@xjj ~]# mkdir /consul
[root@xjj ~]# cd /consul/
[root@xjj consul]# rz 
[root@xjj consul]# ls
consul_0.9.2_linux_amd64.zip
[root@xjj consul]# unzip consul_0.9.2_linux_amd64.zip -d /usr/bin/
Archive: consul_0.9.2_linux_amd64.zip
  inflating: /usr/bin/consul         
[root@xjj consul]# consul agent \
> -server \
> -bootstrap \
> -ui \
> -data-dir=/var/lib/consul-data \
> -bind=192.168.126.11 \
> -client=0.0.0.0 \
> -node=consul-server01 &> /var/log/consul.log &
[1] 100683
[root@xjj consul]# jobs -l
[1]+ 100683 Running consul agent -server -bootstrap -ui -data-dir=/var/lib/consul-data -bind=192.168.126.11 -client=0.0.0.0 -node=consul-server01 &>/var/log/consul.log &
[root@xjj consul]# consul members
Node Address Status Type Build Protocol DC
consul-server01 192.168.126.11:8301 alive server 0.9.2 2 dc1
[root@xjj consul]# consul info|grep leader
        leader = true
        leader_addr = 192.168.126.11:8300
[root@xjj consul]# netstat -natp|grep 8500
tcp 0 0 127.0.0.1:34120 127.0.0.1:8500 TIME_WAIT -                   
tcp 0 0 127.0.0.1:34118 127.0.0.1:8500 TIME_WAIT -                   
tcp6 0 0 :::8500 :::* LISTEN 100683/consul

Parameters

[root@xjj consul]# consul agent \ #Set up the agent> -server \ #Service function> -bootstrap \ #Participate in the election leader> -ui \ #Provide web access interface> -data-dir=/var/lib/consul-data \ #Provide a proxy storage data directory> -bind=192.168.126.16 \ #Bind local address> -client=0.0.0.0 \ #Client address facing (all)
> -node=consul-server01 &> /var/log/consul.log & #Define the node name, output the logs to the log, and run them in the background jobs -l #View the work put into the background by the current terminal and list the PID number of the process consul members #View cluster information consul info|grep leader #View management information, leader is the leader #Cluster information can be obtained through HTTP API:

curl 127.0.0.1:8500/v1/status/peers '//View cluster server members'
curl 127.0.0.1:8500/v1/status/leader '//Cluster Raf leader'
curl 127.0.0.1:8500/v1/catalog/services '//All registered services'
curl 127.0.0.1:8500/v1/catalog/nginx '//View (nginx) service information'
curl 127.0.0.1:8500/v1/catalog/nodes '//Cluster node details'

②The nginx server connects to consul and creates the nginx container service

[root@localhost ~]# docker run -d \
> --name=registrator \
> --net=host \
> -v /var/run/docker.sock:/tmp/docker.sock \
> --restart=always \
> gliderlabs/registrator:latest \
> -ip=192.168.126.12 \
> consul://192.168.126.11:8500
-----
Digest: sha256:6e708681dd52e28f4f39d048ac75376c9a762c44b3d75b2824173f8364e52c10
Status: Downloaded newer image for gliderlabs/registrator:latest
db4cb9d6a56ce8b9a2155b1113e48e6c974889cd4cca363b410c116b75be5d59
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
db4cb9d6a56c gliderlabs/registrator:latest "/bin/registrator -i…" 5 seconds ago Up 5 seconds registrator

#Create a container to test whether the service discovery function is normal:

[root@localhost ~]# docker run -itd -p 81:80 --name xjj01 -h xcf01 nginx #-h option indicates the specified host host name [root@localhost ~]# docker run -itd -p 82:80 --name xjj02 -h xcf02 nginx
[root@localhost ~]# docker run -itd -p 83:80 --name xjj03 -h xcf03 httpd
[root@localhost ~]# docker run -itd -p 84:80 --name xjj0 -h xcf04 httpd
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8940a9b03dbb httpd "httpd-foreground" 4 seconds ago Up 3 seconds 0.0.0.0:84->80/tcp, :::84->80/tcp xjj0
9ac4d089eb14 httpd "httpd-foreground" 39 seconds ago Up 38 seconds 0.0.0.0:83->80/tcp, :::83->80/tcp xjj03
3d626fd61639 nginx "/docker-entrypoint.…" 25 minutes ago Created xjj02
263aa9deb346 nginx "/docker-entrypoint.…" 26 minutes ago Up 26 minutes 0.0.0.0:81->80/tcp, :::81->80/tcp xjj01
db4cb9d6a56c gliderlabs/registrator:latest "/bin/registrator -i…" 29 minutes ago Up 29 minutes registrator


Browser access test: `192.168.126.11:8500`

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[root@xjj consul]# curl 127.0.0.1:8500/v1/catalog/services
{"consul":[],"httpd":[],"nginx":[]}[root@xjj consul]#

③Consul cluster adds consul-template to enable automatic container joining

Consul-Template is a daemon that queries Consul cluster information in real time, updates any number of specified templates on the file system, generates configuration files, and after the update is complete, you can query the service directory, Key, Key-values, etc. in Consul

cd consul/
vim nginx.ctmpl

upstream http_backend {
 {{range service "nginx"}}
  server {{.Address}}:{{.Port}};
  {{end}}
}

server {
 listen 100;
 server_name localhost 192.168.126.11;
 access_log /var/log/nginx/lic.com-access.log;
 index index.html index.php;
 location / {
        proxy_set_header HOST $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Client-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://http_backend;
  }     
}

yum -y install gcc pcre-devel zlib-devel
rz nginx-1.12.2.tar.gz
tar zxvf nginx-1.12.2.tar.gz -C /opt
cd /opt/nginx-1.12.10

./configure --prefix=/usr/local/nginx

make && make install

--
vim /usr/local/nginx/conf/nginx.conf
No. 19 include vhost/*.conf; #19 line add, virtual host directory [root@xjj nginx-1.12.2]# mkdir /usr/local/nginx/conf/vhost
'//Create a virtual host directory'
[root@xjj nginx-1.12.2]# mkdir /var/log/nginx
'//Create a log file directory'
[root@xjj nginx-1.12.2]# /usr/local/nginx/sbin/nginx 
'//Start nginx'
[root@xjj nginx-1.12.2]# netstat -natp|grep nginx
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 104348/nginx: maste

--

#Start template, specify template file and generation path:
[root@xjj consul]# consul-template -consul-addr 192.168.126.16:8500 -template "/consul/nginx.ctmpl:/usr/local/nginx/conf/vhost/xjj.conf:/usr/local/nginx/sbin/nginx -s reload" --log-level=info
#Specify the template path /consul/nginx.ctmpl, generate it to /usr/locla/nginx/conf/vhost/xjj.conf, then reload nginx -s reload, then define the log level and enter the monitoring state--
#The master node opens a new terminal to view the configuration file:
[root@xjj ~]# cat /usr/local/nginx/conf/vhost/xjj.conf
#To access the web page in this pool, you have to access 192.168.126.11:8080, and it is a polling mechanism. If you can't access it here, you can reload nginx and try again upstream http_backend {
  
   server 192.168.126.12:81;
  
   server 192.168.126.12:82;
  
}

server {
  listen 8080;
  server_name localhost 192.168.126.11;
  access_log /var/log/nginx/xjj.cn-access.log;
  index index.html index.php;
  location / {
    proxy_set_header HOST $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Client-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_pass http://http_backend;
	}
}

④Add a new nginx container node to test automatic updates

[root@localhost ~]# docker run -itd -p 85:80 --name xjj05 -h xcf05 nginx #Add an nginx container node to test service discovery and configuration update functions [root@xjj ~]# cat /usr/local/nginx/conf/vhost/xcf.conf 
upstream http_backend { 
        
        server 192.168.126.12:81;
          
        server 192.168.126.12:82;
          
        server 192.168.126.12:85;
          
}

server {
  listen 8080;
  server_name localhost 192.168.126.11;
  access_log /var/log/nginx/xcf.cn-access.log;
  index index.html index.php;
  location / {
    proxy_set_header HOST $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header Client-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; }       
}

⑤ Test whether access to the proxy server can complete proxy access polling

http://192.168.126.11:80/

docker logs -f xjj01
docker logs -f xjj02
docker logs -f xjj05

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⑥consul multi-node configuration

#Add a server with an existing Docker environment to the existing cluster:

consul agent \
-server \
-bootstrap \
-ui \
-data-dir=/var/ib/consul-data \
-bind=192.168.126.11 \
-client=0.0.0.0 \
-node=consul-server02 \
-enable-script-checks=true \
-datacenter=dc1 \
-join 192.168.126.15 &> /var/log/consul.log &


--explain--
-enable-script-checks=true: Set the check service to be available -datacenter: data center name -join: Join an existing cluster

This is the end of this article about the overview of Docker-Consul and the steps to build a cluster environment (with pictures and text). For more information about building a Docker-Consul cluster environment, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope you will support 123WORDPRESS.COM in the future!

You may also be interested in:
  • Example of using docker compose to build a consul cluster environment

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