To build debug images run

make debug

You can use the docker-compose.yaml in this directory to launch the debug versions of the image in docker

If you want to debug Promtail in kubernetes, I have done so with the ksonnet setup:

ks init promtail
cd promtail
ks env add promtail
jb init
jb install github.com/grafana/loki/production/ksonnet/promtail
vi environments/promtail/main.jsonnet

Replace the contents with:

local promtail = import 'promtail/promtail.libsonnet';


promtail + {
  _images+:: {
    promtail: 'grafana/promtail-debug:latest',
  },
  _config+:: {
    namespace: 'default',

    promtail_config+: {
      external_labels+: {
        cluster: 'some_cluster_name',
      },
      scheme: 'https',
      hostname: 'hostname',
      username: 'username',
      password: 'password',
    },
  },
}

change the some_cluster_name to anything meaningful to help find your logs in Loki

also update the hostname, username, and password for your Loki instance.

Haven't tried this yet, it works from docker-compose so it should run in kubernetes just fine also.