CODEWITHSUNDEEP
amazon-ec2ansibleansible-inventory
chacd
chacd

Reputation: 161

How to exclude instances of the EC2 inventory in Ansible?

We have an Ansible server using EC2 dynamic inventory:

However, with the number of instances we have, running ./ec2.py --list or ./ec2.py --refresh-cache returns a 28,000 line JSON response.

This I assume, causes it to randomly fail (returns a Python stack trace) as it only receives a partial response when sending a call to AWS, but is then fine if ran again.

Which is why I want to know if there's a way to cut this down.

I know there is a way to include specific instances by tag in the ec2.ini (i.e. # instance_filters = tag:env=staging), but with the way our instances are tagged, is there a way to exclude instances instead (something that would look similar to: # instance_filters = tag:name=!dev)?

Upvotes: 2

Views: 1321

Answers (2)

Nadia
Nadia

Reputation: 108

I use the option pattern_exclude in ec2.ini:

# If you want to exclude any hosts that match a certain regular expression
pattern_exclude = staging-*

and 

hostname_variable = tag_Name

Upvotes: 0

mdaniel
mdaniel

Reputation: 33203

is there a way to exclude instances instead

Just for completeness, I wanted to point out that the "inventory protocol" for ansible is super straightforward to implement, and they even have a JSON Schema for it.

You can see an example of the output it is expecting by running the newly included ansible-inventory script with --list to see the output it generates from one of the .ini style inventories, and then use that to emit your own:

$ printf 'somehost ansible_user=bob\n\n[some_group]\nsomehost\n' > sample
$ ansible-inventory -i ./sample --list

What I am suggesting is that you might have better luck making a custom inventory script, that does know your local business practices, rather than trying to force ec2.py into running a negation query (which, as best I can tell, it will not do).

To generate dynamic inventory, just make an executable -- as far as I know it can be in any language at all -- and then point the -i at the executable script instead of a "normal" file. Ansible will invoke that program, and operate on the JSON output as the inventory. There are several examples people have posted as gists, in all kinds of languages.

I would still love it if you would file an issue with ansible about ec2.py, because you have the situation that can make the bug report concrete for them in ways that a simple "it doesn't work for large inventories" doesn't capture. But in the mean time, writing your own inventory provider is actually less work than it sounds.

Upvotes: 0

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