Introducing ansible's Ad-hoc and commands modules

Ad-Hoc 是指ansible下临时执行的一条命令，并且不需要保存的命令，对于复杂的命令后面会说playbook。讲到Ad-hoc 就要提到模块，所有的命令执行都要依赖于事先写好的模块，默认安装好的ansible 里面已经自带了很多模块，如：command、raw、shell、file、cron等，具体可以通过ansible-doc -l 进行查看 。

一、Ad-hoc

1、直接执行

这里还是先来一个上几篇幅经常用到的一个例子：

[root@361way ~]# ansible 10.212.52.252 -a 'uptime' -k
SSH password:
10.212.52.252 | success | rc=0 >>
10:10am up 27 days 19:33, 2 users, load average: 0.39, 0.34, 0.33

一个ad-hoc命令的执行，需要按以下格式进行执行：

1. ansible 主机或组 -m 模块名 -a '模块参数' ansible参数

• 主机和组，是在/etc/ansible/hosts 里进行指定的部分，当然动态Inventory 使用的是脚本从外部应用里获取的主机，这部分具体可以参考ansible小结（五）Dynamic Inventory ；
• 模块名，可以通过ansible-doc -l 查看目前安装的模块，默认不指定时，使用的是command模块，具体可以查看/etc/ansible/ansible.cfg 的“#module_name = command ” 部分，默认模块可以在该配置文件中进行修改；
• 模块参数，可以通过 “ansible-doc 模块名” 查看具体的用法及后面的参数；
• ansible参数，可以通过ansible命令的帮忙信息里查看到，这里有很多参数可以供选择，如是否需要输入密码、是否sudo等。

2、后台执行

当命令执行时间比较长时，也可以放到后台执行，这里会用到-B、-P参数，如下：

ansible all -B 3600 -a "/usr/bin/long_running_operation --do-stuff" 
\\后台执行命令 3600s，-B 表示后台执行的时间
ansible all -m async_status -a "jid=123456789" 
\\检查任务的状态
ansible all -B 1800 -P 60 -a "/usr/bin/long_running_operation --do-stuff" 
\\后台执行命令最大时间是 1800s 即 30 分钟，-P 每 60s 检查下状态默认 15s

示例如下：

[root@361way ~]# ansible 10.212.52.252 -B 3600 -P 0 -a 'watch ls'
background launch...
10.212.52.252 | success >> {
"ansible_job_id": "411650646689.13501",
"results_file": "/root/.ansible_async/411650646689.13501",
"started": 1
}
[root@361way ~]# ansible 10.212.52.252 -m async_status -a 'jid=411650646689.13501'
10.212.52.252 | success >> {
"ansible_job_id": "411650646689.13501",
"changed": false,
"finished": 0,
"results_file": "/root/.ansible_async/411650646689.13501",
"started": 1
}

不指定-P或-P参数为非0时，该任务就会按-P直接的参数一直刷新下去，直到超出-B参数指定的时间或命令执行完成：

[root@361way ~]# ansible 10.212.52.252 -B 3600 -a 'watch ls'
background launch...
10.212.52.252 | success >> {
"ansible_job_id": "397200656414.15008",
"results_file": "/root/.ansible_async/397200656414.15008",
"started": 1
}
10.212.52.252 | success >> {
"ansible_job_id": "397200656414.15008",
"changed": false,
"finished": 0,
"results_file": "/root/.ansible_async/397200656414.15008",
"started": 1
}
 polling on 10.212.52.252, 3585s remaining
…………………………………………略

二、commands模块

上面已经提到，ansbile自身已经自带了很多模块，可以通过ansible-doc -l 进行查看。这里就结合command、shell、raw、script模块了解下其用法。

上面四个模块都属于commands 类。

• command模块，该模块通过-a跟上要执行的命令可以直接执行，不过命令里如果有带有如下字符部分则执行不成功 “ so variables like $HOME and operations like "", "|", and "&" will not work (use the shell module if you need these features).”；
• shell 模块，用法其本和command一样，不过的是其是通过/bin/sh进行执行，所以shell 模块可以执行任何命令，就像在本机执行一样，“ It is almost exactly like the command module but runs the command through a shell (/bin/sh) on the remote node.”；
• raw模块，用法和shell 模块一样 ，其也可以执行任意命令，就像在本机执行一样，“Executes a low-down and dirty SSH command, not going through the module subsystem. There is no change handler support for this module. This module does not require python on the remote system”
• script模块，其是将管理端的shell 在被管理主机上执行，其原理是先将shell 复制到远程主机，再在远程主机上执行，原理类似于raw模块，“This module does not require python on the remote system, much like the raw module.” 。

注：raw模块和comand、shell 模块不同的是其没有chdir、creates、removes参数，chdir参数的作用就是先切到chdir指定的目录后，再执行后面的命令，这在后面很多模块里都会有该参数 。

command模块包含如下选项：

• creates：一个文件名，当该文件存在，则该命令不执行
• free_form：要执行的linux指令
• chdir：在执行指令之前，先切换到该指定的目录
• removes：一个文件名，当该文件不存在，则该选项不执行
• executable：切换shell来执行指令，该执行路径必须是一个绝对路径

command模块、raw模块、shell模块示例：

[root@361way ~]# ansible 10.212.52.252 -m command -a 'ps auxf|grep snmp'
10.212.52.252 | FAILED | rc=1 >>
ERROR: Unsupported option (BSD syntax)
********* simple selection ********* ********* selection by list *********
-A all processes -C by command name
-N negate selection -G by real group ID (supports names)
-a all w/ tty except session leaders -U by real user ID (supports names)
-d all except session leaders -g by session OR by effective group name
-e all processes -p by process ID
T all processes on this terminal -s processes in the sessions given
a all w/ tty, including other users -t by tty
g OBSOLETE -- DO NOT USE -u by effective user ID (supports names)
r only running processes U processes for specified users
x processes w/o controlling ttys t by tty
*********** output format ********** *********** long options ***********
-o,o user-defined -f full --Group --User --pid --cols --ppid
-j,j job control s signal --group --user --sid --rows --info
-O,O preloaded -o v virtual memory --cumulative --format --deselect
-l,l long u user-oriented --sort --tty --forest --version
-F extra full X registers --heading --no-heading --context
********* misc options *********
-V,V show version L list format codes f ASCII art forest
-m,m,-L,-T,H threads S children in sum -y change -l format
-M,Z security data c true command name -c scheduling class
-w,w wide output n numeric WCHAN,UID -H process hierarchy
[root@361way ~]# ansible 10.212.52.252 -m raw -a 'ps auxf|grep snmp'
10.212.52.252 | success | rc=0 >>
root 5580 25.0 0.0 12876 1792 pts/2 Ss+ 12:36 0:00 \_ bash -c ps auxf|grep snmp
root 5607 0.0 0.0 5720 832 pts/2 S+ 12:36 0:00 \_ grep snmp
root 24364 0.0 0.0 70416 6696 ? SNl May15 0:22 /usr/sbin/snmpd -r -A -LF i /var/log/net-snmpd.log
 -p /var/run/snmpd.pid
[root@361way ~]# ansible 10.212.52.252 -m shell -a 'ps auxf|grep snmp'
10.212.52.252 | success | rc=0 >>
root 5803 0.0 0.0 11308 1308 pts/2 S+ 12:36 0:00 \_ /bin/sh -c ps auxf|grep snmp
root 5805 0.0 0.0 4260 572 pts/2 S+ 12:36 0:00 \_ grep snmp
root 24364 0.0 0.0 70416 6696 ? SNl May15 0:22 /usr/sbin/snmpd -r -A -LF i /var/log/net-snmpd.log
 -p /var/run/snmpd.pid

上面的执行结果可以看到，我这里加了管道，command模块执行时出错，而使用raw模块和shell 模块都正常。

使用chdir的示例：

[root@361way ~]# ansible 10.212.52.252 -m command -a 'chdir=/tmp/361way touch test.file'
10.212.52.252 | success | rc=0 >>
[root@361way ~]# ansible 10.212.52.252 -m shell -a 'chdir=/tmp/361way touch test2.file'
10.212.52.252 | success | rc=0 >>
[root@361way ~]# ansible 10.212.52.252 -m raw -a 'chdir=/tmp/361way touch test3.file'
10.212.52.252 | success | rc=0 >>

从上面执行结果来看，三个命令都执行成功了。不过通过在远程主机上查看，前两个文件被成功创建：

linux-wdh1:/tmp/361way # ls /tmp/361way
test.file test2.file

使用raw模块的执行的结果文件也被正常创建了，不过不是在chdir 指定的目录，而是在当前执行用户的家目录。

linux-wdh1:~ # ls ~/test3.file
/root/test3.file

creates与removes示例：

这里我在测试主机上创建/tmp/361way/server.txt文件，执行结果如下：

[root@361way ~]# ansible 10.212.52.252 -a 'creates=/tmp/361way/server.txt uptime'
10.212.52.252 | success | rc=0 >>
skipped, since /tmp/361way/server.txt exists
[root@361way ~]# ansible 10.212.52.252 -a 'removes=/tmp/361way/server.txt uptime'
10.212.52.252 | success | rc=0 >>
15:11pm up 28 days 0:34, 2 users, load average: 0.75, 0.46, 0.39

script模块示例：
[root@361way ~]# cat script.sh<br> #!/bin/bash<br> df -hl<br> ifconfig<br> ps auxf|grep snmp<br> [root@361way ~]# ansible 10.212.52.252 -m script -a 'scrip.sh'<br> 10.212.52.252 | FAILED => file or module does not exist: /root/scrip.sh<br> [root@361way ~]# ansible 10.212.52.252 -m script -a 'script.sh'<br> 10.212.52.252 | success >> {<br> "changed": true,<br> "rc": 0,<br> "stderr": "OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013\ndebug1: Reading configuration data /etc/ssh/ssh_config\r\ndebug1: Applying options for *\r\ndebug1: auto-mux: Trying existing master\r\nControl socket connect(/root/.ansible/cp/ansible-ssh-10.212.52.252-22-root): Connection refused\r\ndebug1: Connecting to 10.212.52.252 [10.212.52.252] port 22.\r\ndebug1: fd 3 clearing O_NONBLOCK\r\ndebug1: Connection established.\r\ndebug1: permanently_set_uid: 0/0\r\ndebug1: identity file /root/.ssh/identity type -1\r\ndebug1: identity file /root/.ssh/identity-cert type -1\r\ndebug1: identity file /root/.ssh/id_rsa type -1\r\ndebug1: identity file /root/.ssh/id_rsa-cert type -1\r\ndebug1: identity file /root/.ssh/id_dsa type -1\r\ndebug1: identity file /root/.ssh/id_dsa-cert type -1\r\ndebug1: identity file /root/.ssh/id_ecdsa type -1\r\ndebug1: identity file /root/.ssh/id_ecdsa-cert type -1\r\ndebug1: Remote protocol version 2.0, remote software version OpenSSH_6.2\r\ndebug1: match: OpenSSH_6.2 pat OpenSSH*\r\ndebug1: Enabling compatibility mode for protocol 2.0\r\ndebug1: Local version string SSH-2.0-OpenSSH_5.3\r\ndebug1: SSH2_MSG_KEXINIT sent\r\ndebug1: SSH2_MSG_KEXINIT received\r\ndebug1: kex: server->client aes128-ctr hmac-md5 zlib@openssh.com\r\ndebug1: kex: client->server aes128-ctr hmac-md5 zlib@openssh.com\r\ndebug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024 "stdout": "Filesystem Size Used Avail Use% Mounted on\r\n/dev/sda2 9.9G 872M 8.5G 10% /\r\nudev 3.9G 128K 3.9G 1% /dev\r\ntmpfs 3.9G 76K 3.9G 1% /dev/shm\r\n/dev/sda3 5.0G 219M 4.5G 5% /boot\r\n/dev/sda8 40G 15G 23G 40% /home\r\n/dev/sda9 9.9G 5.2G 4.3G 55% /opt\r\n/dev/sda6 5.0G 2.7G 2.1G 57% /tmp\r\n/dev/sda5 9.9G 3.4G 6.0G 36% /usr\r\n/dev/sda7 9.9G 823M 8.6G 9% /var\r\neth0 Link encap:Ethernet HWaddr 00:50:56:A8:65:7E \r\n inet addr:10.212.52.252 Bcast:10.212.52.255 Mask:255.255.255.0\r\n inet6 addr: fe80::250:56ff:fea8:657e/64 Scope:Link\r\n UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1\r\n RX packets:24112135 errors:0 dropped:792372 overruns:0 frame:0\r\n TX packets:10697339 errors:0 dropped:0 overruns:0 carrier:0\r\n collisions:0 txqueuelen:1000 \r\n RX bytes:17137233328 (16343.3 Mb) TX bytes:13390377826 (12770.0 Mb)\r\n\r\nlo Link encap:Local Loopback \r\n inet addr:127.0.0.1 Mask:255.0.0.0\r\n inet6 addr: ::1/128 Scope:Host\r\n UP LOOPBACK RUNNING MTU:16436 Metric:1\r\n RX packets:3407332 errors:0 dropped:0 overruns:0 frame:0\r\n TX packets:3407332 errors:0 dropped:0 overruns:0 carrier:0\r\n collisions:0 txqueuelen:0 \r\n RX bytes:262675450 (250.5 Mb) TX bytes:262675450 (250.5 Mb)\r\n\r\nroot 25332 0.0 0.0 4260 568 pts/2 S+ 12:54 0:00 \\_ grep snmp\r\nroot 24364 0.0 0.0 70416 6696 ? SNl May15 0:22 /usr/sbin/snmpd -r -A -LF i /var/log/net-snmpd.log -p /var/run/snmpd.pid\r\n"<br> }<br>
输出结果很多，看起来也很乱，不过查下stdout部分，这个部分是实际上执行后的结果。这里可以配合管道一起使用，可以如下使用：

[root@361way ~]# ansible 10.212.52.252 -m script -a 'script.sh' |egrep '>>|stdout'

篇幅所限，本来想把常用模块都放在该篇来写，感觉太冗长，后面再单独分开相应的篇幅做模块的介绍。

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