Can’t post inline (outlook bug).

kolla-kubernetes has no use-case for COPY_ALWAYS.

The kolla-kubernetes deliverable uses a construct called EmptyDir to store 
configuration files.

There is no way to hand-modify the configuration files in EmptyDir that I am 
aware of nor was any of the core team aware of during the review processes that 
have been taking place in the helm reviews.

Therefore, kolla-kubernetes has standardized on COPY_ONCE for immutability 
since hand-modification of config files is an impossibility.

Hope that clears things up.


From: Jeffrey Zhang <>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" 
Date: Thursday, December 1, 2016 at 5:53 AM
To: "OpenStack Development Mailing List (not for usage questions)" 
Subject: Re: [openstack-dev] [kolla] propose to remove COPY_ONCE feature

we can keep COPY_ONCE and COPY_ALWAY in docker images. But in
kolla-ansible side, only implement COPY_ALWAY.

And does kolla-k8s will only implement COPY_ONCE?

COPY_ALWAYS only affect the configuration file, like /etc/nova/nova.conf.
others are still immutable.

For the end-user, either COPY_ONCE or COPY_ALWAYS is transparent. When he
running kolla-ansible, there is no big difference.

On Thu, Dec 1, 2016 at 6:29 PM, Paul Bourke 
<<>> wrote:
While I would be interested to know how many people actually do use COPY_ONCE, 
I think if I was in charge of a production deployment I would use COPY_ONCE.

On 01/12/16 02:27, Jeffrey Zhang wrote:
Kolla has a config_strategy option during deployment. it supports
COPY_ALWAYS.  which means whether copy the configuration files defined in
config.json again during starting containers.

COPY_ALWAYS: copy all configuration files always during every start (
             value now )
COPY_ONCE: copy only once for the first start, then it
           won't copy even the configuration is changed

COPY_ALWAYS is more common for most users. change configuration, then
containers and it works. but COPY_ONCE is not. after changing the
should remove the container and start it again.

for COPY_ONCE, the pro is keeping immutability of the container.  the con is
making thing difficult. no matter for kolla code or end-user.

I am curiosity does end-user really care about the immutability cause by
configuration file? how many user really need such a feature?

So I propose to remove COPY_ONCE.

any idea is welcome ;)

Jeffrey Zhang
Blog: <>

OpenStack Development Mailing List (not for usage questions)

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Jeffrey Zhang
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