CODEWITHSUNDEEP
chef-infra
A-letubby
A-letubby

Reputation: 9152

What is the difference between the default run_list and '_default' environment run_list in chef?

I am a bit confused about how to use environment runlist in chef. As you can see following role.json. In env_run_lists, you have _default and then we already have the default run_list one. What is the difference? and will the default one run everytime before running the environment run_list?

{
  "name": "webserver",
  "default_attributes": {
  },
  "json_class": "Chef::Role",
  "env_run_lists": {
    "_default": [

    ],
    "production": [

    ],
    "dev": [
      "role[base]",
      "recipe[apache]",
      "recipe[apache::copy_dev_configs]"
    ]
  },
  "run_list": [
    "role[base]",
    "recipe[apache]"
  ],
  "description": "The webserver role",
  "chef_type": "role",
  "override_attributes": {
  }
}

Upvotes: 4

Views: 4842

Answers (2)

fletchowns
fletchowns

Reputation: 573

What this means in practice is that if you specify a run_list attribute then you do not need to include the _default environment in the env_run_list attribute.

I don't have 50 reputation so I can't comment on Jared Russell's answer, but if I have this in my role definition:

common_run_list = ["recipe[something]", "recipe[something_else]"]

run_list(common_run_list)

env_run_lists(
    "dev" => common_run_list + ["recipe[another_thing]"]
)

Then I get the following error:

[2014-02-04T16:38:57-08:00] ERROR: _default key is required in env_run_lists.

So I had to specify the _default key in the env_run_lists even though my run_list is specified.

Upvotes: 2

Jared Russell
Jared Russell

Reputation: 11372

I agree that this is quite confusing, especially so since the documentation seems to be incorrect with regards to the behaviour I can see by looking at the source.

From reading the source we can see that when the Role object is constructed it keys the content of the run_list attribute against the _default environment, and then merges the hash with the contents of the env_run_lists attribute (overwriting the value for the _default key).

What this means in practice is that if you specify a run_list attribute then you do not need to include the _default environment in the env_run_list attribute. If you choose to include the _default environment in the env_run_list attribute then it will overwrite anything defined in the run_list attribute.

The one other obvious thing to point out is that if your node is not part of any of the environments defined in the role (_default or otherwise) it will fall back to using the run_list for the _default environment.

Upvotes: 3

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