avoiding unnecessarily entering "upgrade mode"

[Dimiter Naydenov]

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This SGTM as well, however (see below)...

On  6.08.2014 04:10, Menno Smits wrote:
> Right now, a Juju machine agent is in "upgrade mode" from the 
> moment it starts until the upgrade-steps worker is finished.
> During this period API logins are heavily restricted and most of
> the agent's workers don't start until upgrade mode stops.
> 
> This happens even when there is no upgrade to perform. The 
> upgrade-steps worker always runs at machine agent startup and 
> upgrade mode is in force until it finishes.
> 
> Upgrade mode is typically short-lived (say 10 seconds) but if 
> something is wrong (e.g. mongo issues) the upgrade-steps worker
> may take longer or not finish resulting in the user seeing lots of 
> "upgrade in progress" messages from the client and in the logs. 
> This is particularly confusing when a user hasn't even requested an
> upgrade themselves.
> 
> I would like to change the machine agent so that upgrade mode is 
> only entered if the version in agent.conf is different from the 
> running software version. This would mean that upgrade mode is
> only entered if there is an actual upgrade to perform.
If you are referring to Upgraded-To version field in agent config, I
think this is set after the upgrade completes, so it might be
unavailable before that.

> 
> The version in agent.conf is only updated after a successful 
> upgrade so it is the right thing to use to determine if upgrade 
> mode should be entered.
> 
> The current behaviour means that the (idempotent) upgrade steps
> for the current version are always run each time the machine agent 
> starts. If the change I'm proposing is implemented this will no 
> longer happen. Does this seem like a problem to anyone? For 
> instance, do we rely on the upgrade steps for the current version 
> being run after bootstrap?
> 
> The ticket for this work is 
> at:https://bugs.launchpad.net/bugs/1350111 
> <https://bugs.launchpad.net/bugs/1350111>
> 
> Cheers, Menno
> 
> 
> 
> 


- -- 
Dimiter Naydenov <dimiter.naydenov at canonical.com>
juju-core team
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