Summary of Docker Consul container service updates and issues found

docker run -d \
--name=registrator \
--net=host \
-v /var/run/docker.sock:/tmp/docker.sock \
--restart=always \
gliderlabs/registrator:latest \
-ip=192.168.80.20 \
consul://192.168.80.10:8500

1. Container service update and discovery of Docker consul

1. What is service registration and discovery?
2. What is consul?
3. Some key features provided by consul

2. Consul deployment

Step 1: The operations on the consul server are as follows

1. Establish consul service
2. Set up the proxy and start the consul server in the background

Step 2: Registrator deployment 192.168.80.20 The operation is as follows:

4. Container service automatically joins the Nginx cluster
5. Install Nginx and httpd test images
6. Check whether the image is registered in the consul server
7. Check in a web browser to see if the registry has discovered these services.

3. Configure template to update automatically

1. Prepare template nginx template file

2. Consul multi-node configuration

1. Container service update and discovery of Docker consul

1. What is service registration and discovery?

Service registration and discovery are important components that are indispensable in microservice architecture. Initially, all services were single-node, with no guarantee of high availability and no consideration of service pressure. Service calls were simply made through interface access. It was not until the emergence of a distributed architecture with multiple nodes that the initial solution was to load balance the service front-end. In this way, the front-end must know the network location of all back-end services and configure them in the configuration file. There are several problems here:

If you need to call the backend service AN, you need to configure the network location of N services, which is very troublesome.
Changes in the network location of the backend service require changes to the configuration of each caller

Since there are these problems, service registration and discovery are the solutions to these problems. Backend services A–N can register their current network locations to the service discovery module, and the service discovery is recorded in the form of Kv, where K is generally the service name and v is IP:PORT. The service discovery module performs health checks regularly and polls to see whether these backend services are accessible. When the front end calls the backend service AN, it goes to the service discovery module to ask about their network location, and then calls their services. This approach can solve the above problems. The front-end does not need to record the network location of these back-end services at all, and the front-end and back-end are completely decoupled.

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2. What is consul?

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Consul is an open source service management software developed by Google using the Go language. Supports multiple data centers, distributed high availability, service discovery, and configuration sharing. The Raft algorithm is used to ensure high availability of services. It has built-in service registration and discovery framework, distributed consistency protocol implementation, health check, Key/Value storage, and multi-data center solutions, and no longer needs to rely on other tools (such as ZooKeeper, etc.). The service is easy to deploy, with only one executable binary package. Each node needs to run the agent, which has two operating modes: server and client. The official recommendation is to have 3 or 5 server nodes per data center to ensure data security and ensure that the server-leader election can be carried out correctly.
In client mode, all services registered with the current node will be forwarded to the server node, and this information is not persisted.
In server mode, the functions are similar to those in client mode. The only difference is that it persists all information locally so that the information can be retained in case of failure.
The server-leader is the leader of all server nodes. Unlike other server nodes, it is responsible for synchronizing registration information to other server nodes and is also responsible for health monitoring of each node.

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3. Some key features provided by consul

Service Registration and Discovery

Consul makes service registration and service discovery easy through DNS or HTTP interfaces. Some external services, such as those provided by SaaS, can also be registered in the same way.

Health Check:

Health checks allow Consul to quickly alert on operations in the cluster. Integration with service discovery can prevent services from being forwarded to failed services.

Key/Value Storage:

A system for storing dynamic configuration. Provides a simple HTTP interface that can be operated anywhere. Multi-datacenter, supporting any number of regions without complex configuration.
Installing consul is used for service registration, that is, some information of the container itself is registered in consul, and other programs can obtain the relevant registered service information through consul. This is service registration and discovery.

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2. Consul deployment

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Environment Preparation

Server Type	system	IP address	Components to be installed
consul server	CentOS7.4(64 bit)	192.168.80.10	Run consul service, nginx service, consul-template daemon
Registrator server	CentOS7.4(64 bit)	192.168.80.20	Run the registrator container and nginx service

Disable firewall and SElinux on all servers

systemctl stop firewalld
setenforce 0

Step 1: The operations on the consul server are as follows

1. Establish consul service

mkdir /opt/consul/
cd /opt/consul/
rz -E #Import the following compressed package consul_0.9.2_linux_amd64.zip
unzip consul_0.9.2_linux_amd64.zip 
mv consul /usr/local/bin/

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2. Set up the proxy and start the consul server in the background

consul agent \
-server \
-bootstrap \
-ui \
-data-dir=/var/lib/consul-data \
-bind=192.168.80.10 \
-client=0.0.0.0 \
-node=consul-server01 &> /var/log/consul.log &

netstat -napt | grep consul
consul members
consul info | grep leader

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The related options are described as follows:

Options	illustrate
-Start as server	The default is client.
-bootstrap	Used to control whether a server is in bootstrap mode. There can only be one server in bootstrap mode in a data center. When a server is in bootstrap mode, it can elect itself as a server-leader.
-bootstrap-expect=2	The minimum number of servers required by the cluster. If the number is lower than this, the cluster will fail.
-ui	Specify to open the UI interface, so that you can access the web UI interface of consul through the address such as http://localhost:8500/ui.
-data-dir	Specifies the data storage journal.
-bind	Specifies the communication address used within the cluster. All nodes in the cluster must be reachable to this address. The default is 0.0.0.0.
-client	Specifies the client address that consul is bound to. This address provides HTTP, DNS, RPC and other services. The default is 127.0.0.1.
-node	The name of the node in the cluster must be unique in a cluster. The default is the host name of the node.
-datacenter	Specify the data center name. The default is dc1.

1) Check member status and cluster status

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

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Step 2: Registrator deployment 192.168.80.20 The operation is as follows:

4. Container service automatically joins the Nginx cluster

Gliderlabs/Registrator can check the running status of the container and automatically register it, and can also unregister the docker container service to the service configuration center.
Currently supports Consul, Etcd and SkyDNS2.

–net=host	Set the running Docker container to host network mode.
-v /var/run/docker.sock:/tmp/docker.sock	Mount the Unix domain socket that the host's Docker daemon listens on by default into the container.
--restart=always	Set the container to always restart when it exits.
–ip	We just specified the network to host mode, so we specify the ip as the host machine's ip.
consul	Specify the IP and port of the consul server.

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5. Install Nginx and httpd test images

docker run -itd -p:81:80 --name test-01 -h test01 nginx
docker run -itd -p:82:80 --name test-02 -h test02 nginx
docker run -itd -p:83:80 --name test-03 -h test03 httpd
docker run -itd -p:84:80 --name test-04 -h test04 httpd

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6. Check whether the image is registered in the consul server

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7. Check in a web browser to see if the registry has discovered these services.

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3. Configure template to update automatically

Consul-Template is an application based on Consul that automatically replaces configuration files. Consul-Template is a daemon process that queries Consul cluster information in real time and updates any number of specified templates on the file system to generate configuration files. After the update is complete, you can choose to run the shell command to perform the update operation and reload Nginx.
Consul-Template can query the service catalog, Key, Key-values, etc. in Consul. This powerful abstraction and query language templates make Consul-Template particularly suitable for dynamically creating configuration files. For example: create Apache/Nginx Proxy Balancers, Haproxy Backends, etc.

1. Prepare template nginx template file

Perform operations on the consul server
1) Add the nginx.ctmpl configuration file

[root@consul consul]# pwd #Currently in the /opt/consul directory /opt/consul
[root@consul consul]# vim nginx.ctmpl

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

server {
 listen 8000;
 server_name localhost 192.168.80.10;
 access_log /var/log/nginx/clj.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://nginx_slb;
  }     
}

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2) Import the nginx installation package and decompress it

cd ..
rz -E #Upload the nginx compressed package as follows:
nginx-1.12.0.tar.gz
tar zxvf nginx-1.12.0.tar.gz #Decompress

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3) Create nginx program user and install dependent packages

useradd -M -s /sbin/nologin nginx
yum -y install gcc pcre-devel zlib-devel gcc-c++ make

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4) Optimize the path after compiling and installing

cd nginx-1.12.0/
 ./configure --prefix=/usr/local/nginx --user=nginx --group=nginx && make && make install
ln -s /usr/local/nginx/sbin/nginx /usr/local/sbin/

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5) Modify the nginx configuration file

cd /usr/local/nginx/conf/
vim nginx.conf
http {
    include vhost/*.conf; #Add this configuration in line 19

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6) Create vhost and log directory for nginx service

mkdir vhost
mkdir /var/log/nginx
nginx #Start nginx
netstat -natp | grep :80
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 59892/nginx: master

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7) Pass in the consul-template_0.19.3_linux_amd64.zip compressed package and decompress it

cd /opt/
rz -E # Pass in the template file, as follows consul-template_0.19.3_linux_amd64.zip
unzip consul-template_0.19.3_linux_amd64.zip
mv consul-template /usr/local/bin/

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8) Start consul-template in the foreground (or in the background)

consul-template --consul-addr 192.168.80.10:8500 \
--template "/opt/consul/nginx.ctmpl:/usr/local/nginx/conf/vhost/clj.conf:/usr/local/nginx/sbin/nginx -s reload" \
--log-level=info

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9) Open a new terminal to check whether the configuration file is generated

cd /usr/local/nginx/conf/vhost/
vim clj.conf

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10) Add an nginx container with port 85 on the registrator server

docker run -itd -p:85:80 --name test-05 -h test05 nginx

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11) Check that the template service page of the consul server has changed

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12) Check the configuration file again (you can see that a port 85 is added. If you stop a container using docker stop, the configuration file will change accordingly)

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13) Modify the default html.index file in the container nginx site directory

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14) Access test in browser

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2. Consul multi-node configuration

1) Establish the consul service first

rz -y #Import the consul compression package consul_0.9.2_linux_amd64.zip             
mv consul /usr/local/bin/

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2) Add a server with an existing Docker environment to the existing cluster

consul agent \
-server \
--bootstrap \
-ui \
-data-dir=/var/lib/consul-data \
-bind=192.168.80.30 \
-client=0.0.0.0 \
-node=consul-server02 \
-enable-script-checks=true \
-datacenter=dc1 \
-join 192.168.80.10 &> /var/log/consul.log &

--enable-script-ckecks=true	Set the check service to be available
-datacenter	Data Center Name
-join	Join an existing cluster

--enable-script-ckecks=true Set the check service to available -datacenter data center name -join to join the existing cluster

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3) View on the consul server

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This is the end of this article about Docker consul container service updates and discoveries. For more relevant Docker consul container content, please search 123WORDPRESS.COM's previous articles or continue to browse the following related articles. I hope everyone will support 123WORDPRESS.COM in the future!

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