3 ms·

Presumably you'll need to iterate over hosts anyway, so why not move directly towards your automation tools' (ansible, chef, puppet, etc) host inventory and not

• e_proxus 12y ago
  Just started out with Ansible. How do you efficiently SSH into all these hosts by name instead of IP?
  • thezilch 12y ago
    At the low level, Ansible has the ability to execute ad-hoc [0] modules [1] against any combination of hosts defined. In my host(s) inventory above, you can execute ad-hoc modules against just nyc-web, lax-web, web(against nyc and lax), or whatever suites your needs or you've defined a host group for in your inventory. Report, using the "command" module, free memory on all "nyc-web" hosts in our "prod-hosts": ansible -i prod-hosts nyc-web -m command -a 'free -m' More often, we'll want to have Ansible playbooks [2] that take our hosts and assign roles. Briefly on the topic, we might have a "common" role that deals with updating our package manager, checking/upgrading packages that every machine should have (eg. ssh, ntp, etc), and ensuring certain processes are running. Second, we might have a "web" role that is similar to "common" but dealing with web-server specific packages, configs, etc. As to keep it brief, we'll skip how the roles are setup, but here's our "web" playbook (web.yml), and find that we've defined the hosts [group] to execute against -- all hosts under our "web" group in the hosts inventory. --- - hosts: web remote_user: web-user roles: - common - web Which we'll execute with: ansible-playbook -i prod-hosts web.yml Maybe you only want to hit nyc-web and not all web hosts? The following will take the intersection of the playbook's hosts "web" and the "limit" hosts "nyc". ansible-playbook -i prod-hosts web.yml --limit nyc Or maybe you know the one IP you want to hit. The ":&" syntax is a logic AND to find only the nyc 10.0.2.21, because we also have one in LAX. If your IP layout, then simply a "--limit 10.0.2.21" would do. ansible-playbook -i prod-hosts web.yml --limit 'nyc:&10.0.2.21' [0] http://docs.ansible.com/intro_adhoc.html http://docs.ansible.com/intro_adhoc.html [1] http://docs.ansible.com/modules.html http://docs.ansible.com/modules.html [2] http://docs.ansible.com/playbooks_intro.html http://docs.ansible.com/playbooks_intro.html
    • e_proxus 12y ago
      Ah, cool. That clarifies things. I take it there is no way of smoothly combining Ansible host lists with being able to use pure, old SSH?
      • thezilch 12y ago
        Ansible will use the native OpenSSH on your box, which does enable you to use whatever is in your .ssh/config -- jump hosts, controlpersist, kerberos, etc