In Krill Manager when we refer to logs we primarily refer to a series of (mainly) unstructured messages, not to metrics such as counters and guages exposed by Prometheus endpoints.

On a Krill Manager host journald is the primary log subystem and Docker container logs are routed to the journal via the Docker journald logging driver.

Log Viewing

  • Host logs can be viewed in the usual way with journalctl and via files stored in /var/log/.
  • Primary Krill Manager logs can be viewed with the krillmanager logs command.
  • Other Krill Manager logs can be viewed with the docker service logs command.


In cluster mode krillmanager logs and docker service logs can be used to view logs even if the source container is on a slave cluster node.

Log Aggregation, Upload & Analysis

Using FluentD Krill Manager can:
  • aggregate journal logs across all cluster nodes together.
  • stream journal logs to an AWS S3 compatible storage service.
  • stream journal logs to one of many 3rd party services for external processing and analysis.
Using s3cmd Krill Manager can:
  • upload Krill RFC audit log files to an AWS S3 compatible storage service.


FluentD and s3cmd related Krill Manager Docker services are only created if log uploading was enabled during Initial Setup.

Upload Frequency

RFC protocol exchange logs are uploaded hourly. All other logs are uploaded at least every 10 minutes, more frequently if there is a lot of logging activity.

Force Flush

If needed you can force FluentD to flush its buffers which should cause it to stream any data it has pending to the destination, e.g. S3 compatible storage or a custom destination that you have configured:

  1. Use docker service ps krill_log_uploader to find the server running the log upload container.
  2. SSH to the server running the log upload container.
  3. Use docker ps to find the the container ID or name of the krill_log_uploader container.
  4. Use docker kill -s USR1 <container PID/name> to send the flush signal to FluentD.
  5. Use docker logs <container PID/name> to see that the flush was received and if it caused any upload activity, e.g.:
# docker service logs --raw z1c6ksk6zvdx | fgrep flush
2020-04-21 08:44:25 +0000 [info]: #0 force flushing buffered events
2020-04-21 08:44:25 +0000 [info]: #0 flushing all buffer forcedly

Log Retention

When log upload is enabled, local copies of Krill RFC audit logs are deleted after two days as these logs can become quite large. All other logs are rotated according to the default journald behaviour and logrotate configuration.

Log Bucket Structure

When using the default s3.conf fluentd config file, uploaded logs are structured like so:

/<Bucket Directory>/rfc_trail
/<Bucket Directory>/YYYY/MM/DD/HH/<hostname>/<service>.<N>.gz
/<Bucket Directory>/YYYY/MM/DD/HH/<hostname>/<container>/<instance id>.<N>.gz

Where <Bucket Directory> is the value you provided to the wizard.

Log File format

The format of the files is dependent on the type of log file:

  • rfc_trail log files are in a Krill internal binary format.
  • <service> log files are in JSON format.
  • <container> log file are in JSON format with additional fields.

This SSHD log message shows a <service> log line example:

  "hostname": "demomaster",
  "source": "syslog",
  "syslog_id": "sshd",
  "ts_epoch_ms": "1586277165425045",
  "message": "Invalid user test from port 49112"

This NGINX access log message shows a <container> log line example:

  "hostname": "demomaster",
  "source": "journal",
  "syslog_id": "6ef2bbf3eba9",
  "ts_epoch_ms": "1586278786997270",
  "container": "krill_nginx.w2ia8pd3b2kxqm77uwyepooqh.o3lv5trgdnykegaeo9ylhs9d5",
  "message": "::ffff: - - [07/Apr/2020:16:59:46 +0000] \"GET / HTTP/1.1\" 404 153 \"-\" \"https://gdnplus.com:Gather Analyze Provide.\" \"-\"",
  "image": "krillmanager/http-server:v0.1.0@sha256:f88c52b73abf86c3223dcf4c0cc3ff8351f61e74ee307aa8c420c9e0856678f7"

Custom Behaviour


When providing custom configuration files you should use the krillmanager edit command to create and edit configuration files so that the changes are properly replicated across all cluster nodes.

Customising Log Streaming

Files in /fluentd-conf/*.conf can be edited with krillmanager edit to configure fluentd according to your own design, streaming logs to any of the many 3rd party services that fluentd supports. Configuration elemnents should be placed inside a label stanza like so:

<label @ready>
  <match **>
    @type s3

When working with Fluentd configuration files note the following useful commands:

# Reload the Fluentd configuration:
docker service restart krill_log_uploader --force

# Flush Fluentd output buffers:
docker kill -s SIGUSR1 <krill_log_uploader container name/id>

Diagnosing Streaming Problems

Krill Manager v0.2.2 added a Fluentd Prometheus metrics endpoint on port 24231 at /metrics. The statistics published at this endpoint can help identify whether events are being received and handled by the expected Fluentd output plugins.

Logs from the log streaming and audit trail upload processes can be checked with the following commands:

docker service logs --since=2h krill_log_forwarder
docker service logs --since=2h krill_log_uploader
docker service logs --since=2h krill_rfc_trail_uploader

If you have configured log uploading to an S3 bucket look for permission errors in these logs. For AWS S3 a sample IAM policy that grants sufficient access for Krill Manager is:

    "Version": "2012-10-17",
    "Statement": [
            "Sid": "KrillManagerLogUpload",
            "Effect": "Allow",
            "Action": [
            "Resource": [

Remember to replace <bucket_name> with the name of the actual S3 bucket.

Customising Audit Log Upload

The /s3cmd-conf/s3cmd.conf file can be edited with krillmanager edit to take advantage of any additional features of your S3-like service provider that s3cmd supports.

Analysis Examples

Manual Log Analysis


Upload to an AWS S3 compatible service is primarily intended for archival and root cause analysis after an incident. If your intention is to extract interesting metrics or you would like a more visual way to interact with your logs we suggest feeding tools like Grafana Loki or Elastic Search from FluentD.

Assuming that you have configured Krill Manager to store logs in a DigitalOcean Space, you can generate a report of RRDP clients visiting your Krill Manager instance on a particular date like so:

532 RIPE NCC RPKI Validator/3.1-2020.
515 reqwest/0.9.19
190 Jetty/9.4.15.v20190215
101 RIPE NCC RPKI Validator/3.1-2019.
 81 Routinator/0.7.0

Such a report can be produced using comands like those below:

$ DATE_OF_INTEREST="2020/05/11"
$ S3_BUCKET_NAME="my-bucket-name"
$ export AWS_ACCESS_KEY_ID="your-access-key"
$ export AWS_SECRET_ACCESS_KEY="your-secret-access-key"
$ docker run -it --rm \
   -v /tmp/logs:/mnt/logs \
   --entrypoint=s3cmd \
   krillmanager/log-uploader:v0.1.1 \
     get \
       -r \
       --host-bucket="%(bucket)s.ams3.digitaloceanspaces.com" \
       --rexclude=".*" \
       --rinclude=".*${DATE_OF_INTEREST}.*/krill_nginx/.*" \
       s3://${S3_BUCKET_NAME}/logs/ /mnt/logs/
$ find /tmp/logs/ \
    -name '*.gz' \
    -exec zcat {} \; | \
      jq -r '.message | select(contains("/rrdp/"))' | \
        grep -oP '[0-9]+ [0-9]+ "-" \K"[^"]+"' | \
          cut -d '"' -f 2 | \
            sort | \
              uniq -c | \
                sort -rn

Streaming to Elasticsearch


The examples below require Krill Manager v0.2.2 or higher.

Using the Fluentd support integrated into Krill Manager you can stream logs to 3rd party log analysis tools such as EFK (Elasticsearch, Fluentd and Kibana).

When streaming to an external service you can either do that:

  • Instead of streaming to an S3 storage backend: replace s3.conf.
  • In addition to streaming to an S3 storage backend: modify s3.conf and add additional Fluentd config files.

Below is an example configuration for sending rsync access logs to Elasticsearch:

# elastic-search.conf
<label @ready>
  <filter **>
    @type grep
      key container
      pattern /krill_rsyncd..+/

  <filter **>
    # Given a log record with a message field whose value is like:
    #   2020/05/11 23:59:59 [31881] connect from UNDETERMINED (
    @type parser
    key_name message
    reserve_data true
      @type regexp
      expression /^(?<datetime>d+/d+/d+ d+:d+:d+) [(?<unknown>[^]]*)] connect from (?<client_host>[^ ]+) ((?<client_ip>[^)]*))$/

  <match **>
    @type elasticsearch
    host elasticsearch.mydomain.com
    port 9200
    logstash_format true

A similar technique can be used to stream NGINX access logs, using the built-in nginx parser in Fluentd. However, if you use a CDN (content delivery network) in front of your Krill Manager instance(s) you’ll want to analzye the CDN provider logs, not the NGINX logs.

To stream rsync access logs to Elasticsearch but also still upload all logs to an S3 compatible storage target, use a copy configuration like so:

# copy.conf
<label @ready>
  <match **>
    @type copy
      @type relabel
      @label @s3
      @type relabel
      @label @elastic-search

# elasticsearch.conf
<label @elastic-search>
  # the remainder of this file is the same as above

# s3.conf
<label @s3>
  # the remainder of this file is the same as the stock s3.conf file
  # that comes with Krill Manager.

Installing Additional Fluentd Plugins

Krill Manager comes with the following Fluentd plugins pre-installed:

  • fluent-plugin-elasticsearch
  • fluent-plugin-prometheus
  • fluent-plugin-rewrite-tag-filter
  • fluent-plugin-s3
  • fluent-plugin-systemd


The Elasticsearch plugin is included with Krill Manager from v0.2.2.

$ CONTAINER_ID=$(sudo docker ps -q --filter "name=krill_log_uploader")
$ sudo docker exec -it ${CONTAINER_ID} /bin/bash
# gem install fluent-plugin-XXX
# exit
$ sudo docker commit ${CONTAINER_ID} krillmanager/log-streamer:custom
$ sudo docker service update krill_log_uploader --image krillmanager/log-streamer:custom


An upgrade of Krill Manager may cause the service to revert to a stock Krill Manager image. Repeat the steps above to re-install the missing plugin. You can also request inclusion of the plugin in the next Krill Manager release by submitting an issue to the Krill Manager GitHub issue tracker.