Collecting Prometheus metrics

Most of the components in Kubernetes control plane export metrics in Prometheus format. The collectord can read these metrics forward them to Splunk Enterprise or Splunk Cloud. Our installation has default configurations for collecting metrics from Kubernetes API Server, Scheduler, Controller Manager, Kubelets and etcd cluster. In most Kubernetes providers you don’t need to do additional configuration to see these metrics.

If your applications export metrics in Prometheus format, you can use our collectord to forward these metrics as well to Splunk Enterprise or Splunk Cloud.

Forwarding metrics from Pods

Please read our documentation on annotations, to learn how you can define forwarding metrics from Pods.

Defining prometheus input

We deploy collectord in 3 different workloads. Depending on where you want to collect your metrics, you should plan to include you Prometheus metrics.

002-daemonset.conf is installed on all nodes (masters and non-masters). Use this configuration if you need to collect metrics from all nodes, from local ports. Example of these metrics is Kubelet metrics.
003-daemonset-master.conf is installed only on master nodes. Use this configuration to collect metrics only from master nodes from local ports. Examples of these metrics are control plane processes, etcd running on masters.
004-addon.conf installed as a deployment and used only once in the whole cluster. Place your Prometheus configuration here, if you want to collect metrics from endpoints or service. Examples of these Prometheus configurations are controller manager and scheduler, which can be accessed only from an internal network and can be discovered with endpoints. Another example is etcd cluster running outside of the Kubernetes cluster.

Default configuration

Kubelet

On every node collectord reads and forwards kubelet metrics. We deploy this configuration in 002-daemonset.conf.

[input.prometheus::kubelet]

# disable prometheus kubelet metrics
disabled = false

# override type
type = kubernetes_prometheus

# specify Splunk index
index =

# override host (environment variables are supported, by default Kubernetes node name is used)
host = ${KUBERNETES_NODENAME}

# override source
source = kubelet

# how often to collect prometheus metrics
interval = 60s

# Prometheus endpoint, multiple values can be specified, collectord tries them in order till finding the first
# working endpoint.
# At first trying to get it through proxy
endpoint.1proxy = https://${KUBERNETES_SERVICE_HOST}:${KUBERNETES_SERVICE_PORT}/api/v1/nodes/${KUBERNETES_NODENAME}/proxy/metrics
# In case if cannot get it through proxy, trying localhost
endpoint.2http = http://127.0.0.1:10255/metrics

# token for "Authorization: Bearer $(cat tokenPath)"
tokenPath = /var/run/secrets/kubernetes.io/serviceaccount/token

# server certificate for certificate validation
certPath = /var/run/secrets/kubernetes.io/serviceaccount/ca.crt

# client certificate for authentication
clientCertPath =

# Allow invalid SSL server certificate
insecure = true

# include metrics help with the events
includeHelp = false

Kubernetes API Server

On master nodes collectors reads and forwards metrics from the kubernetes API server. We deploy this configuration using 003-daemonset-master.conf.

[input.prometheus::kubernetes-api]

# disable prometheus kubernetes-api metrics
disabled = false

# override type
type = kubernetes_prometheus

# specify Splunk index
index =

# override host (environment variables are supported, by default Kubernetes node name is used)
host = ${KUBERNETES_NODENAME}

# override source
source = kubernetes-api

# how often to collect prometheus metrics
interval = 60s

# prometheus endpoint
# at first trying to get it from localhost (avoiding load balancer, if multiple api servers)
endpoint.1localhost = https://127.0.0.1:6443/metrics
# as fallback using proxy
endpoint.2kubeapi = https://${KUBERNETES_SERVICE_HOST}:${KUBERNETES_SERVICE_PORT}/metrics

# token for "Authorization: Bearer $(cat tokenPath)"
tokenPath = /var/run/secrets/kubernetes.io/serviceaccount/token

# server certificate for certificate validation
certPath = /var/run/secrets/kubernetes.io/serviceaccount/ca.crt

# client certificate for authentication
clientCertPath =

# Allow invalid SSL server certificate
insecure = true

# include metrics help with the events
includeHelp = false

Scheduler

On master nodes collectors reads and forwards metrics from the scheduler. We deploy this configuration using 003-daemonset-master.conf.

[input.prometheus::scheduler]

# disable prometheus scheduler metrics
disabled = false

# override type
type = kubernetes_prometheus

# specify Splunk index
index =

# override host
host = ${KUBERNETES_NODENAME}

# override source
source = scheduler

# how often to collect prometheus metrics
interval = 60s

# prometheus endpoint
endpoint = http://127.0.0.1:10251/metrics

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

# server certificate for certificate validation
certPath =

# client certificate for authentication
clientCertPath =

# Allow invalid SSL server certificate
insecure = true

# include metrics help with the events
includeHelp = false

Collecting metrics from scheduler using endpoint discovery

The collectord will be able to forward metrics from scheduler only if scheduler binds to the localhost on master nodes. In case if scheduler only binds to the pod network, you need to use a different way of collecting metrics from the scheduler. In 004-addon.conf you can find commented out section [input.prometheus::scheduler], that allows collecting metrics from the scheduler using endpoint discovery.

You can comment out section [input.prometheus::scheduler] in 003-daemonset-master.conf and uncomment in 004-addon.conf.

# Example on how to get scheduler metrics with endpoint discovery
[input.prometheus::scheduler]
# disable prometheus scheduler
disabled = false
# override type
type = kubernetes_prometheus
# specify Splunk index
index =
# override host (using discovery from endpoint)
host =
# override source
source = scheduler
# how often to collect prometheus metrics
interval = 60s
# prometheus endpoint
endpoint = endpoint-http://kube-scheduler-collectorforkubernetes-discovery:10251/metrics
# token for "Authorization: Bearer $(cat tokenPath)"
tokenPath =
# server certificate for certificate validation
certPath =
# client certificate for authentication
clientCertPath =
# Allow invalid SSL server certificate
insecure = false
# include metrics help with the events
includeHelp = true

In this configuration, the collectord is using endpoint endpoint-http://kube-scheduler-collectorforkubernetes-discovery:10251/metrics, that syntax defines endpoint auto-discovery, it is listing all endpoints with port 10251 defined under name kube-scheduler-collectorforkubernetes-discovery and using all endpoints to collect the metrics.

Endpoint kube-scheduler-collectorforkubernetes-discovery is created with service, defined in our configuration.

apiVersion: v1
kind: Service
metadata:
  namespace: kube-system
  name: kube-scheduler-collectorforkubernetes-discovery
  labels:
    k8s-app: kube-scheduler
spec:
  selector:
    k8s-app: kube-scheduler
  type: ClusterIP
  clusterIP: None
  ports:
  - name: http-metrics
    port: 10251
    targetPort: 10251
    protocol: TCP

Controller Manager

On master nodes collectors reads and forwards metrics from controller manager. We deploy this configuration using 003-daemonset-master.conf.

# This configuration works if controller-manager is bind to the localhost:10252
[input.prometheus::controller-manager]

# disable prometheus controller-manager metrics
disabled = false

# override type
type = kubernetes_prometheus

# specify Splunk index
index =

# override host
host = ${KUBERNETES_NODENAME}

# override source
source = controller-manager

# how often to collect prometheus metrics
interval = 60s

# prometheus endpoint
endpoint = http://127.0.0.1:10252/metrics

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

# server certificate for certificate validation
certPath =

# client certificate for authentication
clientCertPath =

# Allow invalid SSL server certificate
insecure = false

# include metrics help with the events
includeHelp = false

Collecting metrics from controller manager using endpoint discovery

The collectord will be able to forward metrics from controller manager only if controller manager binds to the localhost on master nodes. In case if controller manager only binds to the pod network, you need to use a different way of collecting metrics from the controller manager. In 004-addon.conf you can find commented out section [input.prometheus::controller-manager], that allows to collect metrics from the controller manager using endpoint discovery.

You can comment out section [input.prometheus::controller-manager] in 003-daemonset-master.conf and uncomment in 004-addon.conf.

# Example on how to get controller-manager metrics with endpoint discovery
[input.prometheus::controller-manager]
# disable prometheus controller-manager
disabled = false
# override type
type = kubernetes_prometheus
# specify Splunk index
index =
# override host (using discovery from endpoint)
host =
# override source
source = controller-manager
# how often to collect prometheus metrics
interval = 60s
# prometheus endpoint
endpoint = endpoint-http://kube-controller-manager-collectorforkubernetes-discovery:10252/metrics
# token for "Authorization: Bearer $(cat tokenPath)"
tokenPath =
# server certificate for certificate validation
certPath =
# client certificate for authentication
clientCertPath =
# Allow invalid SSL server certificate
insecure = false
# include metrics help with the events
includeHelp = true

In this configuration, the collectord is using endpoint endpoint-http://kube-controller-manager-collectorforkubernetes-discovery:10252/metrics, that syntax defines endpoint auto-discovery, it is listing all endpoints with port 10252 defined under name kube-controller-manager-collectorforkubernetes-discovery and using all endpoints to collect the metrics.

Endpoint kube-controller-manager-collectorforkubernetes-discovery is created with service, defined in our configuration.

apiVersion: v1
kind: Service
metadata:
  namespace: kube-system
  name: kube-controller-manager-collectorforkubernetes-discovery
  labels:
    k8s-app: kube-controller-manager
spec:
  selector:
    k8s-app: kube-controller-manager
  type: ClusterIP
  clusterIP: None
  ports:
  - name: http-metrics
    port: 10252
    targetPort: 10252
    protocol: TCP

etcd

On master nodes, collectors read and forward metrics from etcd processes. We deploy this configuration using 003-daemonset-master.conf.

[input.prometheus::etcd]

# disable prometheus etcd metrics
disabled = false

# override type
type = kubernetes_prometheus

# specify Splunk index
index =

# override host
host = ${KUBERNETES_NODENAME}

# override source
source = etcd

# how often to collect prometheus metricd
interval = 30s

# prometheus endpoint
endpoint.http = http://:2379/metrics
endpoint.https = https://:2379/metrics

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

# server certificate for certificate validation
certPath = /rootfs/etc/kubernetes/pki/etcd/ca.pem

# client certificate for authentication
clientCertPath = /rootfs/etc/kubernetes/pki/etcd/client.pem
clientKeyPath = /rootfs/etc/kubernetes/pki/etcd/client-key.pem

# Allow invalid SSL server certificate
insecure = true

# include metrics help with the events
includeHelp = false

This configuration works when you run etcd cluster with master nodes. With this configuration, collectord tries to collect metrics using http scheme at first, and https after that. For https collector uses certPath, clientCertPath and clientKeyPath, which are mounted from the host.

...
  volumeMounts:
  ...
  - name: k8s-certs
    mountPath: /rootfs/etc/kubernetes/pki/
    readOnly: true
...
volumes:
- name: k8s-certs
  hostPath:
  path: /etc/kubernetes/pki/

Verify that these certificates are available, if not, make appropriate changes. Check certificates used by the Kubernetes API Server, they are defined with 3 command line arguments

--etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
--etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
--etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key

You can find these arguments by executing ps aux | grep apiserver on one of the master node, or try to find the API Server definition under /etc/kubernetes/manifests/kube-apiserver.yaml.

If your etcd cluster is a dedicated set of nodes, you can define prometheus collection in 004-addon.conf.

CoreDNS

If you are using CoreDNS in Kubernetes, you can collect metrics exported in Prometheus format, and we have provided for you a Dashboard and Alerts for monitoring CoreDNS.

To start collecting metrics from CoreDNS, you need to annotate CoreDNS deployment to let Collectord to know that you want to collect these metrics

kubectl annotate deployment/coredns --namespace kube-system 'collectord.io/prometheus.1-path=/metrics' 'collectord.io/prometheus.1-port=9153' 'collectord.io/prometheus.1-source=coredns' --overwrite

Metrics format (Splunk Index Type = Events)

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
- s - period for which this difference is calculated (in seconds)
- p - (deprecated) 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.

sourcetype="prometheus"
|  stats latest(_raw) by source, metric_type, metric_name, metric_help

Metrics format (Splunk Index Type = Metrics)

Using Collectord version 5.24+ you can configure Prometheus metrics to be forwarded in the Splunk Metrics Index, by configuring indexType = metrics in the ConfigMap under the [input.prometheus::X] stanza. Or by using annotations like collectord.io/prometheus.1-indexType=metrics.

The values of prometheus metrics are being sent as metrics values, and additional labels being attached as metric_label_XXX fields.

You can leverage Splunk Analytics dashboard to explore the metrics.

When you decide to configure Prometheus metrics to be sent to the Splunk Metrics Index, we suggest defining an additional Splunk Ouput, that will forward to the Token that is set by default to be forwarded to Metrics Indexes (by default and additional indexes).

Links

Installation
- Start monitoring your Kubernetes environments in under 10 minutes.
- Automatically forward host, container and application logs.
- Test our solution with the embedded 30 days evaluation license.
Collectord Configuration
- Collectord configuration reference.
Annotations
- Changing index, source, sourcetype for namespaces, workloads and pods.
- Forwarding application logs.
- Multi-line container logs.
- Fields extraction for application and container logs (including timestamp extractions).
- Hiding sensitive data, stripping terminal escape codes and colors.
- Forwarding Prometheus metrics from Pods.
Audit Logs
- Configure audit logs.
- Forwarding audit logs.
Prometheus metrics
- Collect metrics from control plane (etcd cluster, API server, kubelet, scheduler, controller).
- Configure the collectord to forward metrics from the services in Prometheus format.
Configuring Splunk Indexes
- Using not default HTTP Event Collector index.
- Configure the Splunk application to use not searchable by default indexes.
Splunk fields extraction for container logs
- Configure search-time field extractions for container logs.
- Container logs source pattern.
Configurations for Splunk HTTP Event Collector
- Configure multiple HTTP Event Collector endpoints for Load Balancing and Fail-overs.
- Secure HTTP Event Collector endpoint.
- Configure the Proxy for HTTP Event Collector endpoint.
Monitoring multiple clusters
- Learn how to monitor multiple clusters.
- Learn how to set up ACL in Splunk.
Streaming Kubernetes Objects from the API Server
- Learn how to stream all changes from the Kubernetes API Server.
- Stream changes and objects from Kubernetes API Server, including Pods, Deployments or ConfigMaps.
License Server
- Learn how to configure a remote License URL for Collectord.
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