高可用性部署与Ansible

Question

我正在使用ansible来部署nginx / tomcat实例对，我正在尝试在部署期间提高可用性。

逻辑实例是1 nginx + 1 tomcat：我有4个逻辑实例分布在2个遥远位置超过2个位置（请参阅主机文件波纹管）。

我启动一个名为deploy.xml的playbook，它看起来像这样：

- hosts: ngx-servers
  pre_tasks:
    - include: tasks/remove-server.yml
  roles:
    - role: ngx-server

- hosts: app-servers
  roles:
    - role: app-server

- hosts: ngx-servers
  tasks:
    - include: tasks/add-server.yml

.

我想要的是在部署其他人之前部署50％的逻辑实例（如果出现问题，则停止所有内容）。 一个解决方案可以首先定位Montigny-App-Server / Montigny-NGX服务器（而不是App-Server / NGX-Servers），然后是第二个位置，但我需要重复播放簿内容（如果我需要添加）其他服务器位置）。

任何想法使它正确？

这是我的主机文件：

#
# Serveurs d'application
#

# Montigny
[montigny-app-servers]
mo-app-server-1 ansible_ssh_host=1y.domain.fr ansible_ssh_user=devops
mo-app-server-2 ansible_ssh_host=2y.domain.fr ansible_ssh_user=devops

# Bievre
[bievre-app-servers]
bi-app-server-1 ansible_ssh_host=1b.domain.fr ansible_ssh_user=devops
bi-app-server-2 ansible_ssh_host=2b.domain.fr ansible_ssh_user=devops

# Tous
[app-servers:children]
montigny-app-servers
bievre-app-servers

#
# Serveurs NGinx
#

# Montigny
[montigny-ngx-servers]
mo-ngx-server-1 ansible_ssh_host=1y.domain.fr ansible_ssh_user=devops
mo-ngx-server-2 ansible_ssh_host=2y.domain.fr ansible_ssh_user=devops

# Bievre
[bievre-ngx-servers]
bi-ngx-server-1 ansible_ssh_host=1b.domain.fr ansible_ssh_user=devops
bi-ngx-server-2 ansible_ssh_host=2b.domain.fr ansible_ssh_user=devops

# Tous
[ngx-servers:children]
montigny-ngx-servers
bievre-ngx-servers

.

Answer 1

一个解决方案首先是针对montigny-app-server / montigny-ngx服务器的（而不是app-server / ngx-servers），然后是第二个位置

这是我们所做的，情侣改变：

添加Geolocated组：

[Montigny-servers:children]
montigny-app-servers
montigny-ngx-servers

[bievre-servers:children]
bievre-app-servers
bievre-ngx-servers

.

然后，您可以使用选项-l / - limnit

在子集上执行您的播放手册

$ ansible-playbooks -i inventory site.yml -l Montigny-servers && \
  ansible-playbooks -i inventory site.yml -l bievre-servers

.

这样它将首先从Montigny运行逻辑实例，如果一切顺利（0 exit 0），它将运行Bievre实例的PlayBook

找到更多的优势： http://docs.ansible.com/playbooks_best_practics.html#what-this-compannal-ewelate - 示例

Answer 2

I agree with the idea of putting your hosts in separate groups so that you can run commands on first one group and then the other.

You should be able to put that in one playbook though - if you create the fundamental actions in an include script, you can then create a playbook that will have multiple '- hosts' sections, each of which will call the include script.

That would look something like:

---
- hosts: firstgroupname
  tasks:
    - include: pathandnameofincludescript.yaml
- hosts: secondgroupname
  tasks:
    - include: pathandnameofincludescript.yaml

and your include script would look something like:

---
- name: action 1
  command: echo hello world
- name: action 2
  command: echo hello again

Note the indentation difference for include scripts - its very important! YAML can be annoying at times....

Answer 3

Okay, here is what I think you actually want.

You can use the serial keyword to say how many hosts ansible should manage at a single time in a play. So in the example below, ansible would only run the plays on two hosts at a time.

By default, anisble will keep running the plays even if the first two machines fail, so you can use the max_fail_percentage keyword to define the percentage of failures acceptable before stopping. In the example below, Ansible will stop if 1 percent of machines failed.

Source: http://docs.ansible.com/playbooks_delegation.html#rolling-update-batch-size

- hosts: app-servers`
  serial: 2 
  max_fail_percentage: 1
  roles: 
   - role: deploy-env

And then in your deploy-env role have:

- name: remove from LB
  include: remove-server.yml
  delegate_to: paired_nginx_box

  /* app-server tasks */

- name: add to LB
  include: add-server.yml
  delegate_to: paired_nginx_box