Outcold Solutions LLC

Monitoring Docker, OpenShift and Kubernetes - Version 5 (Application Logs and Annotations)

September 4, 2018

We are happy to announce the 5th version of our applications for Monitoring Docker, OpenShift, and Kubernetes.

First of all, we want to thank our customers! Feedback and close work with our customers help us to build one of the best tools for monitoring container environments.

Now, let us share with you what we worked on this summer.

Application Logs

It is a best practice to forward logs to the standard out and standard error of the container. But that not always achievable, because maybe of the legacy software, or even if you are trying to containerize something very complicated, like a database, and having all the logs in one stream can reduce readability and observability.

Our solutions for monitoring Docker, OpenShift, and Kubernetes offer the simplest way to forward logs, stored inside the container. No need to install any sidecar containers, map host paths, change the configuration for the collector. Just two things: define a volume with local driver (Docker) or emptyDir (Kubernetes/OpenShift), and tell the collector the name of this volume.

An example of forwarding application logs from postgresql container running with Docker.

docker run -d \
    --volume psql_data:/var/lib/postgresql/data \
    --volume psql_logs:/var/log/postgresql/ \
    --label 'collectord.io/volume.1-logs-name=psql_logs' \
    postgres:10.4 \
    docker-entrypoint.sh postgres -c logging_collector=on -c log_min_duration_statement=0 -c log_directory=/var/log/postgresql -c log_min_messages=INFO -c log_rotation_age=1d -c log_rotation_size=10MB

With that you will get logs from the standard output, standard input and stored inside the volume psql_logs.

Container logs

Please read more on the topic:


We used annotations in our solutions for Monitoring OpenShift and Kubernetes for overriding indexes, sources, source types and hosts for data we forward with the collector.

With version 5 we are bringing annotations to Monitoring Docker, and also adding more features, that can be enabled with annotations.

That includes:

  • Extracting fields
  • Extracting timestamps
  • Hiding sensitive information from the logs
  • Redirecting events to /dev/null on some pattern
  • Stripping terminal colors from container logs
  • Defining multi-line event patterns
  • Defining application logs

An example, obfuscating all IP addresses in nginx container logs, running in Kubernetes

apiVersion: v1
kind: Pod
  name: nginx-pod
    collectord.io/logs-replace.1-search: (?P<IPv4p1>\d{1,3})(\.\d{1,3}){3}
    collectord.io/logs-replace.1-val: ${IPv4p1}.X.X.X
  - name: nginx
    image: nginx

Instead of IP Addresses

Nginx Replace Patterns

We have a lot of examples in our documentation.

Splunk Output

There are two significant improvements on configuring HTTP Event Collector with the collector. You can define multiple endpoints, which allows collectors to load balance forwarding between numerous Splunk HTTP Event Collectors if you don't have a Load Balancer in front of them. Or you can use it for fail-overs if your Load Balancer or DNS fails so that collector can switch to the next in the list.

The second improvement is handling invalid Indexes with Splunk HTTP Event Collector. We learned that it is a very common issue to misprint an index name or forget to add the index to the list of the indexes where HTTP Event Collector can write. The collector can recognize error messages from the Splunk HTTP Event Collector and decide how to handle this error. With the version 5 in case of error, it redirects all the data to the default index. You can change this behavior. Specify to Drop messages or Block the pipeline. Waiting on the pipeline is a similar behavior to the previous version with one exception. Previously the whole pipeline could be blocked. Now only data to this index will be blocked, process stats and events. Pod, Container stats, and logs are not affected by the blockage.

You can read more about the configurations for Splunk Output with examples in our documentation.

Installation and Upgrade

As always, this upgrade is available for free for all our customers. And you can try it for free with the embedded trial license.

Release notes:

Installation instructions:

Upgrade instructions:

docker, kubernetes, openshift, splunk

About Outcold Solutions

Outcold Solutions provides solutions for monitoring Kubernetes, OpenShift and Docker clusters in Splunk Enterprise and Splunk Cloud. We offer certified Splunk applications, which gives you insights across all containers environments. We are helping businesses reduce complexity related to logging and monitoring by providing easy-to-use and deploy solutions for Linux and Windows containers. We deliver applications, which helps developers monitor their applications and operators to keep their clusters healthy. With the power of Splunk Enterprise and Splunk Cloud, we offer one solution to help you keep all the metrics and logs in one place, allowing you to quickly address complex questions on container performance.