During a switchover (eqiad -> codfw) we want to have services running in an active/passive setup, with codfw pooled, and eqiad depooled. But when switching back (codfw -> eqiad), we want to be active/active, with both DCs pooled.

The cookbook currently forces one DC to be pooled and the other depooled. This means to go active/active, you have to manually pool it with conftool, switching traffic again.

Ideally the cookbook would have a flag that lets us go to an active/active state.

snippets from IRC today:

08:52:41 <legoktm> the only two notes I have are: 1) have the cookbook allow keeping the (now) passive DC pooled, 2) fix the !log line splitting
08:53:44 <volans> for (1) seems that a simple option might do wit
08:53:48 <volans> *do it
08:55:41 <rzl> yeah, either something like `sre.switchdc.services --pool-both` to indicate what it does, or something like `sre.switchdc.services --switchback` to indicate why you'd want it

Personally I like --pool-both.