This guarantees that the output won't contain bare nodes containing
just an id and topology, as produced by ipToNode. Previously this was
ensured by calling convention, now it's ensured by construction.
This map function isn't actually needed.
Children are only populated from mapping to parents during rendering,
so there's no pre-existing replicasets to map.
Simply having the Map2Parent function map pods to deployments has it do the right thing.
Use a special kind of selector renderer to elide replica sets from pod nodes
and directly reference deployment parents instead.
Do the inverse (replace replica sets with pods) during the mapping from pod to deployment.
Note we can no longer use renderParents since we're using a non-standard Selector
* Maps metrics if there is a single pod in the controller, as per all other views.
* Also added heavy commenting on the increasingly-complex render chain
The existing technique of "reducing" the two rendered graphs for daemonsets and deployments
had a glaring issue that no connections would ever be made between nodes of different types,
since that information would've been discarded earlier in the process.
It also makes it hard to identify "parentless" pods.
This commit extends the Map2Parent function, teaching it:
* To check multiple topologies for parents
* To pass through nodes with no parents found without modification
Since we already had two 'modes' for what to do with nodes without parents,
and it would've been clunky to try to encode the third option into the existing PseudoNodeID
arg in some way, we instead split it into two args, with the first being an enum specifying
either the old pseudo node behaviour, the old drop behaviour, or the new keep behaviour.
We then use the new Map2Parent to map pods to:
* A replica set, if it has one
* A daemonset, if it has one
* Itself, if neither of the above
and then map again from the results to any deployment, leaving as-is any nodes that
don't map to a deployment. Hence we are left with:
* Deployments
* Daemonsets
* Replica sets, but only if they map to no deployment
* Pods, but only if they map to none of the above
and connections between all these will be calculated correctly.
Squash of:
* We have to keep all the container hostnames until the end so we can
count how many we've filtered
* Adding tests for ContainerHostnameRenderer and PodServiceRenderer with
filters
* Because we filter on image name we need the image name before
filtering
* Alternative approach to passing decorators.
* Refactor out some of the decorator capture
* Don't memoise decorated calls to Render
* Fixing filtered counts on containers topology
Tricky, because we need the filters to be silent sometimes (when they're
in the middle), but not when they're at the top, so we take the "top"
filter's stats. However, this means we have to compose all
user-specified filters into a single Filter layer, so we can get all
stats.
There are no more Silent filters, as all filters are silent (unless they
are at the top).
Additionally, I clarified some of the filters as their usage/terminology
was inconsistent and confused. Now Filter(IsFoo, ...) *keeps* only nodes
where IsFoo is true.
