Parameterising node relationships using Chef -

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i have group of servers perform specific roles dependencies between them i.e.

web server -> application server -> database server

i have chef cookbooks can build nodes roles. generating each node's hosts file using chef , using hosted chef server. far good. can't quite grips how flexibly represent relationships between nodes different roles.

by flexibly mean in development may have 1 node fulfils 3 roles, whereas in staging , production environments they'd separated out @ least 1 node per role.

it's not clear me how parameterise generation of hosts files accommodate requirement. how other people tackling issue?

thanks in advance.

do have chef-server setup/hosted chef?

chef runs tool called ohai on each converge collects information node (e.g. ip addresses, interfaces, storage, package data) , writes node object. when converge finished, chef-client upload node object data chef-server stored , available search other nodes/clients:

manual: http://docs.chef.io/chef_search.html

depending on how have split stages, e.g. using different chef environments, use tags or custom logic, can dynamically build /etc/hosts file, reconfigure load balancers , firewall rules using search. example: https://serverfault.com/questions/412127/chef-recipe-read-attributes-from-another-node

if not using chef-server based setup, not possible. have manually "describe" infrastructure/topology, e.g. inside data bag or attributes.


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