prometheus config example:

~]$ cat prometheus.yml 
# my global config
global:
  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).

# Alertmanager configuration
alerting:
  alertmanagers:
  - static_configs:
    - targets:
      # - alertmanager:9093

# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
rule_files:
  # - "first_rules.yml"
  # - "second_rules.yml"

# A scrape configuration containing exactly one endpoint to scrape:
# Here it's Prometheus itself.
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'prometheus'

    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.

    static_configs:
      - targets: ['10.10.200.50:9090']
        labels:
          env: dev


  - job_name: 'node_exporter'
    static_configs:
      ##### k8s-dev
      - targets: ['10.10.240.101:9100', '10.10.240.102:9100', '10.10.240.103:9100']
        labels:
          env: dev
          role: k8s-master
          app: all
      - targets: ['10.10.240.201:9100', '10.10.240.202:9100']
        labels:
          env: dev
          role: k8s-worker
          app: all

      ##### swarm-qa
      - targets: ['10.10.241.81:9100']
        labels:
          env: qa
          role: swarm-master
          app: car2share
      - targets: ['10.10.241.91:9100']
        labels:
          env: qa
          role: swarm-worker
          app: car2share

      ##### swarm-prod
      - targets: ['10.101.2.190:9100', '10.101.2.191:9100', '10.101.2.192:9100']
        labels:
          env: prod
          role: swarm-master
          app: car2share

      - targets: ['10.101.2.201:9100', '10.101.2.202:9100']
        labels:
          env: prod
          role: swarm-worker
          app: car2share