Consul 简明教程

Consul - Installation

为了演示的目的，我们将在开发人员模式中使用 Consul 代理，使用 -dev 模式。只针对本地计算机设置，我们将执行单一系统 Consul 设置。 Please do not use this single node consul cluster in your production 。正如 Hashicorp 在单节点 Consul 群集的情况场景中提到的， the data loss is inevitable 。

For demonstration purposes, we are going to use consul agent in the developer mode using the -dev mode. Just for the local machine setup, we are going to do a single system consul setup. Please do not use this single node consul cluster in your production. As Hashicorp already mentions it in the case scenario of a single node consul cluster, the data loss is inevitable.

Installing Consul

可以通过以下位置的“下载”页面安装 Consul： www.consul.io/downloads.html

Consul can be installed via the Downloads page at www.consul.io/downloads.html

installing consul

你可以将二进制包解压到计算机上的“下载”部分。

You can extract the binary package in your Downloads section of your machine.

$ cd Downloads
$ chmod +x consul
$ sudo mv consul /usr/bin/

现在，让我们开始使用以下内容使用 Consul -dev flag 。

Now let us start using consul using the -dev flag.

$ consul agent -dev -data-dir=/tmp/consul

输出将如以下屏幕截图所示。

The output would be as shown in the following screenshot.

dev flag

现在，你可以使用以下命令检查你的 Consul 成员。

Now you can check your consul members using the following command.

$ consul members

输出将如以下屏幕截图所示。

The output would be as shown in the following screenshot.

memebers

如果你想将其他节点加入这个节点 −

If you want to join other nodes to this node −

$ consul join <Node 2> <Node 3>

或者，你可以在节点 2 和 3 上运行以下命令 −

Alternatively, you can run the following command on Node 2 & 3 −

$ consul join <Node 1>

Using the Command Line

Consul 的命令行包含几个不同的选项，其中一些最常用的选项如下 −

The command line of consul consists of several different options, some of the most commonly used ones are as follows −

  1. agent − which runs a Consul agent.

  2. configtest − to validate a config file.

  3. event − to start up a new event.

  4. exec − to execute a command on Consul nodes.

  5. force-leave − forcing a member of the cluster to leave the cluster.

  6. info − it provides us the debugging information for operators.

  7. join − to make a Consul agent join the cluster.

  8. keygen − to generate a new encryption key.

  9. keyring − to manage gossip layer encryption keys.

  10. *kv * − to interact with the key-value store.

  11. leave − to leave the Consul cluster and shut it down without force.

  12. lock − to execute a command to hold down a lock.

  13. maint − to control node or service maintenance mode.

  14. members − it lists the members of a Consul cluster.

  15. monitor − it streams logs from a Consul agent.

  16. operator − it provides us a cluster of tools for Consul operators.

  17. reload − it triggers the agent to reload configuration files.

  18. rtt − it estimates network round trip time between nodes.

  19. snapshot − it saves, restores and inspects snapshots of Consul server state.

  20. version − to print the current Consul version.

  21. watch − to Watch out for changes in the Consul.

Consul Template

consul-template 为我们提供了一个守护程序，它会查询 Consul 实例并在文件系统上更新任何指定数目的模板。consul-template 可以选择在更新过程完成后运行任意的命令。此选项帮助我们设置 Consul 集群，而无需手动执行所有操作。

The consul-template provides us a daemon that queries the Consul instance and updates any number of specified templates on the file system. The consul-template can optionally run arbitrary commands when the update process completes. This option helps us to setup the consul cluster without manually doing everything on our own.

consul 模板将在 /tmp/<name-of-file>.conf.tmpfl 处形成。该模板所用语言根据 Hashicorp Configuration Language （HCL）编写。

The consul template is to be formed at /tmp/<name-of-file>.conf.tmpfl. The language in which the template is written according to Hashicorp Configuration Language (HCL).

你可以在此 page 处下载 consul-template。

You can download the consul-template from this page.

template

使用以下命令进行尝试 −

Try it out by using the following command −

$ ./consul-template -h

输出将如以下屏幕截图所示。

The output would be as shown in the following screenshot.

template output

如果你希望将此二进制文件移动到更加突出的空间，以便用户在任何时候都可以使用，则可以输入以下命令 −

If you wish to move this binary to a more prominent space, so that it is available for the user every time. You can type in the following commands −

$ chmod +x consul-template
$ sudo mv consul-template /usr/share/bin/

用于演示，我们将使用 nginx 的示例配置作为服务。你可以在 https://github.com/hashicorp/consul-template/tree/master/examples 处尝试更多演示，或更好地写下你自己的模板。

For demo purposes, we are going to use a sample configuration of nginx to be used as our service. You can try out more demos at https://github.com/hashicorp/consul-template/tree/master/examples or better write down your own template.

$ vim /tmp/nginx.conf.ctmpl

输出将如以下屏幕截图所示。

The output would be as shown in the following screenshot.

nginx

配置文件可能如下所示 −

The config file may look like −

{{range services}} {{$name := .Name}} {{$service := service .Name}}

upstream {{$name}} {
   zone upstream-{{$name}} 64k;
   {{range $service}}server {{.Address}}:{{.Port}} max_fails = 3 fail_timeout = 60
   weight = 1;
   {{else}}server 127.0.0.1:65535; # force a 502{{end}}
} {{end}}

server {
   listen 80 default_server;
   location / {
      root /usr/share/nginx/html/;
      index index.html;
   }
   location /stub_status {
      stub_status;
   }
   {{range services}} {{$name := .Name}}
   location /{{$name}} {
      proxy_pass http://{{$name}};
   }
   {{end}}
}

现在，使用 consul 模板二进制文件，请运行以下命令 −

Now using the consul template binary file, please run the following commands −

$ consul-template \
 -template = "/tmp/nginx.conf.ctmpl:/etc/nginx/conf.d/default.conf"

通过前一个命令，进程已经启动。你可以稍后打开另一个终端，并使用以下命令查看已经完全呈现的 nginx.conf 文件。

With the previous command the process has started. You can later open up another terminal and view the nginx.conf file being completely rendered using the following command.

$ cat /etc/nginx/conf.d/default.conf

输出将如以下屏幕截图所示。

The output would be as shown in the following screenshot.

output