This removes fluentd in favor of using fluentbit, which is lighter (in
memory usage) and seems to be more actively maintained.
Fluentbit's config file format is different from fluentd's. It also
doesn't support the same record modification stuff that fluentd
supports, so we have to change the influxdb query slightly. This
means that after an upgrade, the new CLI may won't work for querying older
logs. Hopefully, this slight breakage is acceptable; if users
really need older logs they can use the older CLI.
Remove the `logger` container from the logging daemonset.
Remove the outgoing call from the poolmgr to the logger. Use Fluentd's Kubernetes filter to add function name and UID to influx metadata.
This means fluentd now figures out when to start collecting function logs on its own, without being informed by poolmgr. This is great for other execution strategies, and for autoscaling, where fission isn't in direct control of function pod creation.
Also adds an integration test to make sure logging keeps working.
Add function log aggregation and persistence using Fluentd and InfluxDB.
Fluentd and a helper sidecar run as a daemonset. The poolmgr sets up logging for each function pod, using the helper sidecar. Fluentd forwards logs to InfluxDB, which is run as a deployment and service. The client CLI directly queries InfluxDB for logs.
Fluentd supports many outputs besides InfluxDB, so we aren't very tied to InfluxDB.
The setup is somewhat manual, which we should be able to improve by integrating this into the helm chart.
Diagram of component interactions: https://cloud.githubusercontent.com/assets/202578/23100399/b0e3ea00-f6ba-11e6-8f2f-6588cfef2e84.png
