Dockerfile of Influxdb's kapacitor (https://influxdb.com/docs/kapacitor/v0.1/introduction/index.html).
Either map your kapacitor.conf to /etc/kapacitor/kapacitor.conf using volume mapping or you can substitute configuration properties using KAPACITOR_KEY=value. If KEY is formatted as SECTION_KEY (environment variable is KAPACITOR_SECTION_KEY) then value for key is modified/added in section named SECTION.
For example:
docker run -e KAPACITOR_influxdb_urls='["http://influxdb:8086"]' lomo/kapacitor
Don't forget the kapacitor's hostname must be resolvable from InfluxDB host. If you need to override hostname in kapacitor:
docker run -e KAPACITOR_influxdb_urls='["http://influxdb:8086"]' -e HOSTNAME=kapacitor lomo/kapacitor