ah, thanks phillippe. I think in my case this won't work since i DO care about doing it one more time. The thing i'm doing is creating vms. But i don't want to create 1 more if i already have my desired N.
k On Thu, May 1, 2014 at 2:17 PM, Philippe Eveque <[email protected]>wrote: > The link references a previous exchange similar to yours > > The specific case was about using the lineinfile module and with_sequence > to add a parameter to all the kernel liles in grub.conf > > here is a copy of what I wrote: > > " > tasks 1: count the number of lines to replace (via shell module using and > grep -E <regexp> | wc -l ) > using register to remember the linecounted > > task 2: using lineinfile and with_sequence: linecounted > > one caveat is that with sequence does not accept a 0 count ( a potential > future improvement ?) > > so just add 1 to the count (you do not care about doing it one more time) > > then you can run those 2 tasks multiples times > > works for me on grub.conf > " > > > Phil > > > 2014-05-01 15:34 GMT+02:00 kesten broughton <[email protected]>: > >> Phil, the link doesn't work for me. >> >> >> On Thursday, May 1, 2014 2:32:23 AM UTC-5, Philippe Eveque wrote: >> >>> In similar case A workaround I used is to add 1 to your sequence count >>> see https://mail.google.com/mail/#search/label%3Aansible+with_ >>> sequence/1435e13b34e3a0e1 >>> >>> Phil >>> >>> >>> 2014-04-30 23:51 GMT+02:00 kesten broughton <[email protected]>: >>> >>>> The error is >>>> fatal: [localhost] => can't count backwards >>>> >>>> This occurs whenever count=0 or start=M end=M >>>> >>>> If with_sequence is used for the purpose of bringing a system to a >>>> state = HAS N of something >>>> then there should be a way of running the playbook twice and not having >>>> anything new created. >>>> That's what i meant by idempotent. >>>> >>>> "with sequence can't traverse a zero length list" accurately describes >>>> my concern >>>> >>>> kesten >>>> >>>> On Wednesday, April 30, 2014 3:03:56 PM UTC-5, Michael DeHaan wrote: >>>> >>>>> You are throwing two words together that have nothing to do with each >>>>> other. >>>>> >>>>> with_sequence is a loop. >>>>> >>>>> Idempotency is a mathematical statement that says "F(X) = F(F(X))" for >>>>> how many times X is applied. >>>>> >>>>> "This will work if M is strictly less than N, but if M=N (the >>>>> idempotent case) then ansible gives an error." >>>>> >>>>> What you have here is Ansible giving an error. It has nothing to do >>>>> with idempotency. >>>>> >>>>> It may imply "with sequence can't traverse a zero length list", which >>>>> more accurately describes the problem. >>>>> >>>>> So, the best thing to do here is to share what the error is and we can >>>>> go from there. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Wed, Apr 30, 2014 at 9:34 AM, Kesten Broughton < >>>>> [email protected]> wrote: >>>>> >>>>>> >>>>>> I recently had a need for with_sequence, but it doesn't seem possible >>>>>> to do a zero count of actions. >>>>>> >>>>>> Suppose i have a local action to create N things, perhaps vms or >>>>>> floating ips. Some number M < N may already be present. >>>>>> >>>>>> I'd like to do >>>>>> >>>>>> hosts: localhost >>>>>> vars: >>>>>> expected_foo_count: 10 >>>>>> >>>>>> - name: Get the number of foos >>>>>> shell: echo M >>>>>> register: foo_count >>>>>> >>>>>> - name: Create the missing number of foos >>>>>> shell: make_new_foos >>>>>> with_sequence: start=0 end="{{expected_foo_count -foo_count.stdout >>>>>> }}" >>>>>> >>>>>> or with_sequence: count="{{expected_foo_count - foo_count.stdout}}" >>>>>> >>>>>> This will work if M is strictly less than N, but if M=N (the >>>>>> idempotent case) then ansible gives an error. >>>>>> >>>>>> fatal: [localhost] => can't count backwards >>>>>> I tried putting a "when" guard such as >>>>>> when: "{{ expected_foo_count - foo_count.stdout > 0 }}" >>>>>> >>>>>> But it appears "when" gets evaluated after the with_sequence >>>>>> conditional. That in itself poses problems, since in branching code the >>>>>> register variables may not be defined and you have to litter code with >>>>>> when: "{{ (register_var or '') | conditional }}". >>>>>> >>>>>> The problem with the with_sequence is in the >>>>>> lib/ansible/runner/lookup_plugins/sequence.py >>>>>> >>>>>> def generate_sequence(self): >>>>>> numbers = xrange(self.start, self.end+1, self.stride) >>>>>> >>>>>> which means that contrary to conventional python such as >>>>>> range(a,b) which gives a sequence starting at 'a' and ending at >>>>>> 'b-1', ie. [a,b) >>>>>> >>>>>> with_sequence: start=n end=m >>>>>> >>>>>> runs over the sequence [n,m]. If n=m with_sequence still executes >>>>>> once, so there is no possible way to have a with_sequence that runs zero >>>>>> times. >>>>>> >>>>>> changing the generate_sequence code to >>>>>> >>>>>> def generate_sequence(self): >>>>>> numbers = xrange(self.start, self.end, self.stride) >>>>>> >>>>>> Fixes the problem. >>>>>> >>>>>> Is there a design reason behind not allowing for zero count >>>>>> sequences? If so, how can a playbook including with_sequence be made >>>>>> idempotent? >>>>>> >>>>>> kesten >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Ansible Project" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to [email protected]. >>>>>> To post to this group, send email to [email protected]. >>>>>> >>>>>> To view this discussion on the web visit https://groups.google.com/d/ >>>>>> msgid/ansible-project/CAO2fFsVLwC6qoVKReu--zjyfOwUA1KUJQWy2cG3 >>>>>> 6nmHRietk0g%40mail.gmail.com<https://groups.google.com/d/msgid/ansible-project/CAO2fFsVLwC6qoVKReu--zjyfOwUA1KUJQWy2cG36nmHRietk0g%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Ansible Project" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> To view this discussion on the web visit https://groups.google.com/d/ >>>> msgid/ansible-project/263df645-0b20-419b-ae3f- >>>> 2cdff75280f5%40googlegroups.com<https://groups.google.com/d/msgid/ansible-project/263df645-0b20-419b-ae3f-2cdff75280f5%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "Ansible Project" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> >> To post to this group, send email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/ansible-project/361bfbdc-5ba1-4bcc-bde5-603c633cf4fa%40googlegroups.com<https://groups.google.com/d/msgid/ansible-project/361bfbdc-5ba1-4bcc-bde5-603c633cf4fa%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to a topic in the > Google Groups "Ansible Project" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/ansible-project/swkbKGLio1g/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/ansible-project/CAB1FMuSeAVaMDXKUfNRPz6pphRKNE8LV-PaXhqUGhK92ORTX8A%40mail.gmail.com<https://groups.google.com/d/msgid/ansible-project/CAB1FMuSeAVaMDXKUfNRPz6pphRKNE8LV-PaXhqUGhK92ORTX8A%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Ansible Project" group. 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