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zalando-stups / senza

Deploy immutable application stacks and create and execute AWS CloudFormation templates in a sane way

Home Page:https://pypi.python.org/pypi/stups-senza

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Strange behaviour: Senza scales up to 100 instances....

kanuku opened this issue · comments

commented

While trying to scale down the old version of our application, we received the notification that alll versions of the stack are being increased with 100 instances.... This was found by mistakingly using the scale option. See the details below:

First I request the versions deployed

→ senza traffic hecate-live.yml
Stack Name │Version│Identifier       │Weight%
hecate-live 0462    hecate-live-0462      0.0
hecate-live R0471   hecate-live-R0471   100.0

Result
When I use the scale option and a non existing version (0462), senza understands that it should scale up everything to 100 instances.

→ senza scale hecate-live.yml 0460
Scaling hecate-live-R0471-AppServer-xxxxxxxxxxxxxxxx from 2 to 100 instances.. OK
Scaling hecate-live-0462-AppServer-xxxxxxxxxxxxxxxx from 2 to 100 instances.. OK

Expectation
Senza should not scale up nor down any of the versions, because no valid options were passed.

commented

I am not sure how to fix it because I am not sure what is allowed and what is not with this command.

First

For senza scale last argument is always a number of instances to scale up/down. In you case 0460 but there is a limit to 100 instances. That's why it was scaled only to 100 instances. It does not matter what number will be. If the number is more than 100 then it will be 100.

Second

senza scale hecate-live.yml 0460 is a valid command because stack can have no version at all.
Also available commands are:

  • senza scale hecate-live.yml v10123sdfs 0460
    Scale stack <stack_name>-v10123sdfs to 100 instances. Instead of <stack_name> will be value from hecate-live.yml from attribute SenzaInfo/StackName.

  • senza scale stack1 v1 stack2 v2 10
    Scale two stacks stack1-v1 and stack2-v2 to 10 instances.

  • senza scale stack1 v1 stack2 10
    Scale two stacks stack1-v1 and stack2-<no version> to 10 instances.

My questions are

  • Is it allowed to scale stack without specifying stack version?
  • Is it allowed to scale several stacks in one command?
commented

Hello @jmcs! Could you help me with that?

commented

Hi, as @vadeg said the version is optional, and the last argument is always the number of instances capped to 100.

Regarding your questions:

Is it allowed to scale stack without specifying stack version?

Yes, this will scale all versions.

Is it allowed to scale several stacks in one command?

Yes, scale accepts the same stack references format as other senza commands.