Ansible — 编程 — Variables

2021/6/14 22:20:53

编程Tag： 编程变量 Ansible vars 01 variables 35 31

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Variables

Ansible 提供了 Variables（变量）机制，用于完成自动化的配置工作，变量定义的格式为 key=value，key 为变量名。

合法的变量名：变量名可以为字母、数字以及下划线，变量名始终应该以字母开头。

变量重载的优先级：

–extra-vars/-e 优先级最高。
在 inventory 中定义的连接变量（e.g. ansible_ssh_user）。
大多数的其它变量（e.g. 命令行转换、Play 中的变量、included 的变量、Role 中的变量等)。
在 inventory 定义的其它变量。
由系统发现的 Facts 变量。
Role 的默认变量优先级最低。

内置变量

Ansible 内置的预留变量名，例如：

hostvars：可以访问主机的变量，包括 Facts。

{{ hostvars['test.example.com']['ansible_distribution'] }}

group_names：当前 Host 所在所有 Groups 的列表。

{% if 'webserver' in group_names %}
   # some part of a configuration file that only applies to webservers
{% endif %}

groups：inventory 清单文件中所有的 Groups。

# 枚举群组中的所有主机。
{% for host in groups['app_servers'] %}
   # something that applies to all app servers.
{% endfor %}

# 找出该群组中的所有 IP 地址。
{% for host in groups['app_servers'] %}
   {{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}

在 Inventory 中定义变量

在 Inventory 中定义的变量类型有两种：

Group Vars

[atlanta]
host1
host2

[atlanta:vars]
ntp_server=ntp.atlanta.example.com
proxy=proxy.atlanta.example.com

Host Vars

[atlanta]
host1 http_port=80 maxRequestsPerChild=808
host2 http_port=303 maxRequestsPerChild=909

值得注意的是，若在 Inventory 清单文件中保存所有的变量并不明智，一个更好的方式是将变量保存在外部的若干个文件中，然后再 “关联” 到 Inventory。在 Ansible 1.4 及以上版本，支持了通过 group_vars 和 host_vars 变量文件来组织变量。

在 Playbook 中定义变量

在 Playbook YAML 文件中可以这样定义变量：

- hosts: webservers
  vars:
    http_port: 80

在 Role 中定义变量

NOTE：在 Role 中定义的变量会在 ansible-playbook CLI 中被使用，但不能给 ansible CLI 使用。

在 Role 中定义变量，只需要在 roles/{role_name}/vars/main.yml YAML 文件中定义即可，其中列出的 variables 将被添加到 play 中。

Role Default Variables

Role Default Variables（角色默认变量）允许你为 included roles 或者 dependent roles 设置默认变量。要创建默认变量，只需在 roles 目录下添加 defaults/main.yml 文件。这些变量在所有可用变量中拥有最低优先级。

在 group_vars 和 host_vars 文件中定义变量

NOTE：在文件中定义的变量会在 ansible-playbook CLI 中被使用，但不能给 ansible CLI 使用。
NOTE：Inventory 清单文件采用了 .ini 格式，而这些外部的变量文件采用 YAML 格式。

假设：一个 Host，hostname 为 foosball，同时属于 raleigh 和 webservers Group。那么，我们可以这么组织 foosball 的变量文件：

/etc/ansible/group_vars/raleigh
/etc/ansible/group_vars/webservers
/etc/ansible/host_vars/foosball

再假设：希望 raleigh Group 中的所有 Hosts 都使用同一个 NTP Server、DB Server。那么，我们可以这么编写 raleigh Group Vars：

---
ntp_server: acme.example.org
database_server: storage.example.org

更加一步的，我们可以为一个 Group 或一个 Host 创建同名的 Dir，再该 Dir 下再细分为不同的 files，以此更细粒度的组织 Vars：

/etc/ansible/group_vars/raleigh/db_settings
/etc/ansible/group_vars/raleigh/cluster_settings

可见，Inventory 清单文件与 group_vars、host_vars 变量文件/目录之间的 “关联” 是通过 “名称匹配” 来完成的。

注册变量

注册变量，即：在运行过程中，把 cmd/shell 结果存储到一个变量中。e.g.

- hosts: web_servers

  tasks:

     - shell: /usr/bin/foo
       register: foo_result
       ignore_errors: True

     - shell: /usr/bin/bar
       when: foo_result.rc == 5

使用 Facts 获取的变量

除了通过上述的方式来自定义变量之外，还可以通过 Facts 来自动获取变量。

例如：

$ ansible ubuntu_hostname -m setup

"ansible_all_ipv4_addresses": [
    "REDACTED IP ADDRESS"
],
"ansible_all_ipv6_addresses": [
    "REDACTED IPV6 ADDRESS"
],
"ansible_architecture": "x86_64",
"ansible_bios_date": "09/20/2012",
"ansible_bios_version": "6.00",
"ansible_cmdline": {
    "BOOT_IMAGE": "/boot/vmlinuz-3.5.0-23-generic",
    "quiet": true,
    "ro": true,
    "root": "UUID=4195bff4-e157-4e41-8701-e93f0aec9e22",
    "splash": true
},
"ansible_date_time": {
    "date": "2013-10-02",
    "day": "02",
    "epoch": "1380756810",
    "hour": "19",
    "iso8601": "2013-10-02T23:33:30Z",
    "iso8601_micro": "2013-10-02T23:33:30.036070Z",
    "minute": "33",
    "month": "10",
    "second": "30",
    "time": "19:33:30",
    "tz": "EDT",
    "year": "2013"
},
"ansible_default_ipv4": {
    "address": "REDACTED",
    "alias": "eth0",
    "gateway": "REDACTED",
    "interface": "eth0",
    "macaddress": "REDACTED",
    "mtu": 1500,
    "netmask": "255.255.255.0",
    "network": "REDACTED",
    "type": "ether"
},
"ansible_default_ipv6": {},
"ansible_devices": {
    "fd0": {
        "holders": [],
        "host": "",
        "model": null,
        "partitions": {},
        "removable": "1",
        "rotational": "1",
        "scheduler_mode": "deadline",
        "sectors": "0",
        "sectorsize": "512",
        "size": "0.00 Bytes",
        "support_discard": "0",
        "vendor": null
    },
    "sda": {
        "holders": [],
        "host": "SCSI storage controller: LSI Logic / Symbios Logic 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 01)",
        "model": "VMware Virtual S",
        "partitions": {
            "sda1": {
                "sectors": "39843840",
                "sectorsize": 512,
                "size": "19.00 GB",
                "start": "2048"
            },
            "sda2": {
                "sectors": "2",
                "sectorsize": 512,
                "size": "1.00 KB",
                "start": "39847934"
            },
            "sda5": {
                "sectors": "2093056",
                "sectorsize": 512,
                "size": "1022.00 MB",
                "start": "39847936"
            }
        },
        "removable": "0",
        "rotational": "1",
        "scheduler_mode": "deadline",
        "sectors": "41943040",
        "sectorsize": "512",
        "size": "20.00 GB",
        "support_discard": "0",
        "vendor": "VMware,"
    },
    "sr0": {
        "holders": [],
        "host": "IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)",
        "model": "VMware IDE CDR10",
        "partitions": {},
        "removable": "1",
        "rotational": "1",
        "scheduler_mode": "deadline",
        "sectors": "2097151",
        "sectorsize": "512",
        "size": "1024.00 MB",
        "support_discard": "0",
        "vendor": "NECVMWar"
    }
},
"ansible_distribution": "Ubuntu",
"ansible_distribution_release": "precise",
"ansible_distribution_version": "12.04",
"ansible_domain": "",
"ansible_env": {
    "COLORTERM": "gnome-terminal",
    "DISPLAY": ":0",
    "HOME": "/home/mdehaan",
    "LANG": "C",
    "LESSCLOSE": "/usr/bin/lesspipe %s %s",
    "LESSOPEN": "| /usr/bin/lesspipe %s",
    "LOGNAME": "root",
    "LS_COLORS": "rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lz=01;31:*.xz=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.axv=01;35:*.anx=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.axa=00;36:*.oga=00;36:*.spx=00;36:*.xspf=00;36:",
    "MAIL": "/var/mail/root",
    "OLDPWD": "/root/ansible/docsite",
    "PATH": "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
    "PWD": "/root/ansible",
    "SHELL": "/bin/bash",
    "SHLVL": "1",
    "SUDO_COMMAND": "/bin/bash",
    "SUDO_GID": "1000",
    "SUDO_UID": "1000",
    "SUDO_USER": "mdehaan",
    "TERM": "xterm",
    "USER": "root",
    "USERNAME": "root",
    "XAUTHORITY": "/home/mdehaan/.Xauthority",
    "_": "/usr/local/bin/ansible"
},
"ansible_eth0": {
    "active": true,
    "device": "eth0",
    "ipv4": {
        "address": "REDACTED",
        "netmask": "255.255.255.0",
        "network": "REDACTED"
    },
    "ipv6": [
        {
            "address": "REDACTED",
            "prefix": "64",
            "scope": "link"
        }
    ],
    "macaddress": "REDACTED",
    "module": "e1000",
    "mtu": 1500,
    "type": "ether"
},
"ansible_form_factor": "Other",
"ansible_fqdn": "ubuntu2.example.com",
"ansible_hostname": "ubuntu2",
"ansible_interfaces": [
    "lo",
    "eth0"
],
"ansible_kernel": "3.5.0-23-generic",
"ansible_lo": {
    "active": true,
    "device": "lo",
    "ipv4": {
        "address": "127.0.0.1",
        "netmask": "255.0.0.0",
        "network": "127.0.0.0"
    },
    "ipv6": [
        {
            "address": "::1",
            "prefix": "128",
            "scope": "host"
        }
    ],
    "mtu": 16436,
    "type": "loopback"
},
"ansible_lsb": {
    "codename": "precise",
    "description": "Ubuntu 12.04.2 LTS",
    "id": "Ubuntu",
    "major_release": "12",
    "release": "12.04"
},
"ansible_machine": "x86_64",
"ansible_memfree_mb": 74,
"ansible_memtotal_mb": 991,
"ansible_mounts": [
    {
        "device": "/dev/sda1",
        "fstype": "ext4",
        "mount": "/",
        "options": "rw,errors=remount-ro",
        "size_available": 15032406016,
        "size_total": 20079898624
    }
],
"ansible_nodename": "ubuntu2.example.com",
"ansible_os_family": "Debian",
"ansible_pkg_mgr": "apt",
"ansible_processor": [
    "Intel(R) Core(TM) i7 CPU         860  @ 2.80GHz"
],
"ansible_processor_cores": 1,
"ansible_processor_count": 1,
"ansible_processor_threads_per_core": 1,
"ansible_processor_vcpus": 1,
"ansible_product_name": "VMware Virtual Platform",
"ansible_product_serial": "REDACTED",
"ansible_product_uuid": "REDACTED",
"ansible_product_version": "None",
"ansible_python_version": "2.7.3",
"ansible_selinux": false,
"ansible_ssh_host_key_dsa_public": "REDACTED KEY VALUE"
"ansible_ssh_host_key_ecdsa_public": "REDACTED KEY VALUE"
"ansible_ssh_host_key_rsa_public": "REDACTED KEY VALUE"
"ansible_swapfree_mb": 665,
"ansible_swaptotal_mb": 1021,
"ansible_system": "Linux",
"ansible_system_vendor": "VMware, Inc.",
"ansible_user_id": "root",
"ansible_userspace_architecture": "x86_64",
"ansible_userspace_bits": "64",
"ansible_virtualization_role": "guest",
"ansible_virtualization_type": "VMware"

Facts 获取到远程主机的信息之后，可以通过下述方式来引用：

# 获取 Dosk Model
{{ ansible_devices.sda.model }}

# 获取 hostname
{{ ansible_nodename }}

NOTE：Facts 是可以关闭的。

- hosts: whatever
  gather_facts: no

引入变量文件

当你可能会想把 Playbook 源码公开之余，还想保持某些重要的变量私有，此时可以把某些变量信息放置在不同的文件中。然后在 Playbook 中引入外部的变量文件：

---

- hosts: all
  remote_user: root
  vars:
    favcolor: blue
  vars_files:
    - /vars/external_vars.yml

  tasks:

  - name: this is just a placeholder
    command: /bin/echo foo

变量文件的内容是一个简单的 YAML 文件：

---
# in the above example, this would be vars/external_vars.yml
somevar: somevalue
password: magic

在命令行中传递变量

ansible-playbook release.yml --extra-vars "version=1.23.45 other_variable=foo"

# 支持 JSON 格式
--extra-vars '{"pacman":"mrs","ghosts":["inky","pinky","clyde","sue"]}'
# 支持 JSON 文件
--extra-vars "@some_file.json"

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