# collectd

*本节作者：crazw*

collectd 是一个守护(daemon)进程，用来收集系统性能和提供各种存储方式来存储不同值的机制。它会在系统运行和存储信息时周期性的统计系统的相关统计信息。利用这些信息有助于查找当前系统性能瓶颈（如作为性能分析 `performance analysis`）和预测系统未来的 load（如能力部署`capacity planning`）等

下面简单介绍一下: collectd的部署以及与logstash对接的相关配置实例

## collectd的安装

### 软件仓库安装(推荐)

collectd官方有一个的[软件仓库](https://collectd.org/download.shtml): <https://pkg.ci.collectd.org> ，构建有`RHEL/CentOS`(rpm)，`Debian/Ubuntu`(deb)的软件包，如果你使用的操作系统属于上述，那么推荐使用软件仓库安装。

目前collectd官方维护3个版本: `5.4`, `5.5`, `5.6`。根据需要选择合适的版本。

Debian/Ubuntu仓库安装(示例中使用`5.5`版本):

```bash
echo "deb http://pkg.ci.collectd.org/deb $(lsb_release -sc) collectd-5.5" | sudo tee /etc/apt/sources.list.d/collectd.list
curl -s https://pkg.ci.collectd.org/pubkey.asc | sudo apt-key add -
sudo apt-get update && sudo apt-get install -y collectd
```

> **NOTE**: Debian/Ubuntu软件仓库自带有`collectd`软件包，如果软件仓库自带的版本足够你使用，那么可以不用添加仓库，直接通过`apt-get install collectd`即可。

RHEL/CentOS仓库安装(示例中使用`5.5`版本):

```bash
cat > /etc/yum.repos.d/collectd.repo <<EOF
[collectd-5.5]
name=collectd-5.5
baseurl=http://pkg.ci.collectd.org/rpm/collectd-5.5/epel-\$releasever-\$basearch/
gpgcheck=1
gpgkey=http://pkg.ci.collectd.org/pubkey.asc
EOF

yum install -y collectd
# 其他collectd插件需要安装对应的collectd-xxxx软件包
```

### 源码安装collectd

```bash
# collectd目前维护3个版本, 5.4, 5.5, 5.6。根据自己需要选择版本
wget http://collectd.org/files/collectd-5.4.1.tar.gz
tar zxvf collectd-5.4.1.tar.gz
cd collectd-5.4.1
./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --libdir=/usr/lib --mandir=/usr/share/man --enable-all-plugins
make && make install
```

解决依赖(RH系列):

```bash
rpm -ivh "http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm"
yum -y install libcurl libcurl-devel rrdtool rrdtool-devel perl-rrdtool rrdtool-perl libgcrypt-devel gcc make gcc-c++ liboping liboping-devel perl-CPAN net-snmp net-snmp-devel
```

安装启动脚本

```bash
cp contrib/redhat/init.d-collectd /etc/init.d/collectd
chmod +x /etc/init.d/collectd
```

### 启动collectd

```
service collectd start
```

## collectd的配置

以下配置可以实现对服务器基本的**CPU、内存、网卡流量、磁盘 IO 以及磁盘空间占用**情况的监控:

```
Hostname "host.example.com"
LoadPlugin interface
LoadPlugin cpu
LoadPlugin memory
LoadPlugin network
LoadPlugin df
LoadPlugin disk
<Plugin interface>
    Interface "eth0"
    IgnoreSelected false
</Plugin>
<Plugin network>
    # logstash 的 IP 地址和 collectd 的数据接收端口号>
    # 如果logstash和collectd在同一台主机上也可以用环回地址127.0.0.1
    <Server "10.0.0.1" "25826">
    </Server>
</Plugin>
```

## logstash的配置

以下配置实现通过 logstash 监听 `25826` 端口，接收从 collectd 发送过来的各项检测数据。

logstash默认自带有`collectd`的codec插件，详见官方文档: <https://www.elastic.co/guide/en/logstash/current/plugins-codecs-collectd.html>

### 示例：

```ruby
input {
    udp {
        port => 25826
        buffer_size => 1452
        workers => 3          # Default is 2
        queue_size => 30000   # Default is 2000
        codec => collectd { }
        type => "collectd"
    }
}
```

## 运行结果

下面是简单的一个输出结果：

```javascript
{
  "_index": "logstash-2014.12.11",
  "_type": "collectd",
  "_id": "dS6vVz4aRtK5xS86kwjZnw",
  "_score": null,
  "_source": {
    "host": "host.example.com",
    "@timestamp": "2014-12-11T06:28:52.118Z",
    "plugin": "interface",
    "plugin_instance": "eth0",
    "collectd_type": "if_packets",
    "rx": 19147144,
    "tx": 3608629,
    "@version": "1",
    "type": "collectd",
    "tags": [
      "_grokparsefailure"
    ]
  },
  "sort": [
    1418279332118
  ]
}
```

## 参考资料

* collectd支持收集的数据类型： <http://git.verplant.org/?p=collectd.git;a=blob;hb=master;f=README>
* collectd收集各数据类型的配置参考资料： <http://collectd.org/documentation/manpages/collectd.conf.5.shtml>
* collectd简单配置文件示例： <https://gist.github.com/untergeek/ab85cb86a9bf39f1fc6d>


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