Jaeger preserves the trace data of router healthz endpoints
which is not so helpful for monitoring function metrics and
consumes storage to store such trace data.
This PR uses `GetStartOptions` to examine the request's path and
check if it's a request to healthz endpoint. If yes, skip and not
to trace it.
To follow 12-factor app rules, make jaeger collector endpoint
as an environment variable instead of CLI args. It's easier to
replace the value in different deployments. Also, we can utilize
valueFrom to get value from the configmap.
Encoded path means the URL path contains encoded string like "/foo%2Fbar".
Gorilla/Mux by default doesn't enable encoded path support, you need to enable
it when initializing the router.
This PR adds a new environment variable USE_ENCODED_PATH to the router
deployment to enable encoded path support.
ReplicaSet generated by Deployment distributes pods to nodes based
on nodes resource usage, which means in some cases the newly created
pods may be assigned to only a few nodes. The requests will go to the
same node if there multiple pods on it and may increase the node
resource usage and overall request latency.
To solve the problem mentioned above, this PR allows users to deploy
the router as DaemonSet so that we can distribute requests across all
nodes for better workload distribution and lower latency.
