wallaby inventory is a useful command for quickly checking up on the health of your pool and answering certain kinds of questions: Which nodes have checked in recently? Which nodes have checked in without being explicitly configured? Which nodes have never checked in?

Recently, I added constraint support to wallaby inventory. That is, instead of listing all nodes, you can choose to list only nodes for which a given Ruby expression is true. These constraints can be simple, like last_checkin < 1.hour_ago (which will find all nodes that have checked in more than one hour ago), or more complex. They are only limited by Ruby's $SAFE execution: among other things, they cannot modify running classes, perform file I/O, fork new processes, or, because of how QMF is implemented, invoke QMF methods on the node object. However, every QMF property of the node object is available to wallaby inventory constraints. The transcript below provides some examples running against a wallaby agent loaded up with test data.

Some examples of the new constraint support in the Wallaby inventory tool

Constraints can make use of simple syntactic sugar for specifying times.

wallaby:master!? % wallaby inventory -c “not last_checkin.is_never && last_checkin < 2.hours_ago” node name is provisioned? last checkin ——— ————— ———— Aldridge-Brownhills provisioned Mon Oct 18 11:23:47 -0500 2010

Constraints can be defined over any property of a node.

wallaby:master!? % wallaby inventory -c “memberships.size == 0”
node name is provisioned? last checkin ——— ————— ———— betty unprovisioned never bigpool-7b6379dc unprovisioned never fred provisioned never test-dev-winxp unprovisioned never test31.lab.bigpool-domain unprovisioned never wilma unprovisioned never

wallaby:master!? % wallaby inventory -c “name =~ /yel/” node name is provisioned? last checkin ——— ————— ———— cystopyelonephritis provisioned never encephalomyelopathy provisioned never meningomyelorrhaphy provisioned never polioencephalomyelitis provisioned never yellow-complexioned provisioned never yellowish-red-yellow provisioned never

Constraints can be arbitrarily complex, but they run under Ruby $SAFE level 4,

which means that they cannot call QMF methods.

wallaby:master!? % wallaby inventory -c “last_checkin.is_never && (name =~ /wa/ || name =~ /lla/ || name =~ /by/)” node name is provisioned? last checkin ——— ————— ———— Boulogne-Billancourt provisioned never Mentor-on-the-Lake-Villag provisioned never Pseudo-presbyterian provisioned never alto-cumulus-castellatus provisioned never by-doingby-drinking provisioned never east-northeastwardly provisioned never hyperpolysyllabically provisioned never labyrinthibranchiate provisioned never main-topgallantmast provisioned never maxillopremaxillary provisioned never milk-and-wateriness provisioned never miscellaneousnesses provisioned never north-northeastward provisioned never north-northeastwardly provisioned never north-northeastwards provisioned never north-northwestward provisioned never north-northwestwardly provisioned never north-northwestwards provisioned never pseudo-Presbyterian provisioned never south-southeastward provisioned never straightforwardness provisioned never unstraightforwardness provisioned never west-southwestwardly provisioned never westnorthwestwardly provisioned never zygomaticomaxillary provisioned never

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