Outcold Solutions LLC

Monitoring Docker - Version 5

Prometheus Metrics

By default collector for docker does not collect any metrics in Prometheus format. But it has capabilities to do so.


The generic Prometheus configuration section is


# disable input
disabled = false

# specify the type for current input
type = docker_prometheus

# specify Splunk index for current input
index =

# specify the host for current input
host =

# specify the source
source =

# how often to collect prometheus metrics
interval = 60s

# Prometheus endpoint, multiple values can be specified, collector tries them in order till finding the first
# working endpoint.
# At first trying to get it through proxy
endpoint.1 = 
# endpoint.2 =

# token for "Authorization: Bearer $(cat tokenPath)"
tokenPath =

# server certificate for certificate validation
certPath =

# client certificate and key for authentication
clientCertPath =
clientKeyPath =

# Allow invalid SSL server certificate
insecure = false

# include metrics help with the events
includeHelp = false

You can find variety of the services, exporting metrics in Prometheus format.

Example. Collecting metrics from nginx service.

For this example we will use sophos/nginx-prometheus-metrics image.

The image sophos/nginx-prometheus-metrics is not an official nginx image. We use it only for demo purposes.

We use a command from the image example to run it

docker run -d --rm -it -p 80:80 -p 1314:1314 -p 9527:9527 sophos/nginx-prometheus-metrics

For this input we define configuration with 002.conf. The most important part of configuration is to specify how collector can get to the endpoint with metrics. We use simple approach by publishing port in outside world, and accessing it with the hostname of the host.

acceptEULA = true

url = https://hec.example.com:8088/services/collector/event/1.0
token = B5A79AAD-D822-46CC-80D1-819F80D7BFB0
insecure = true

disabled = false
type = docker_prometheus
index =
host =
source = docker_nginx_example
interval = 60s
endpoint.1 = http://host.docker.internal:9527/metrics
tokenPath =
certPath =
clientCertPath =
clientKeyPath =
insecure = false
includeHelp = true

Build the image with the embedded configuration.

FROM outcoldsolutions/collectorfordocker:5.4.201

COPY 002.conf /config/002.conf

Run it with provided installation guidance.

Explore Prometheus Metrics

Metrics format

Prometheus defines several types of metrics.

Each metric value in Splunk has fields:

  • metric_type - one of the types from the Prometheus metric types.
  • metric_name - the name of the metric.
  • metric_help - only if includeHelp is set to true<, you will see definition of this metric.
  • metric_label_XXX - if the metric has labels, you will be able to see them attached to the metric values.
  • seed - unique value from the host for specific metric collection.

Based on the metric type you can find various values for the metrics.

  • counter
    • v - current counter value
    • d - the difference with a previous value
    • p - period for which this difference is calculated (in nanoseconds)
  • summary and histogram
    • v - value
    • c - counter specified for this summary or histogram metric
  • All others
    • v - value

If you have specified to include help with the metrics, you can explore all available metrics with the search.

|  stats latest(_raw) by source, metric_type, metric_name, metric_help

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 give 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 help 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.