I want to run the prometheus as docker instance with mounting file on /var/run/docker.sock, as I want to monitor the hosts from docker.sock file. Currently, I am successfully running the prometheus on host machines using prometheus cli command.

However, when I have mounted the file /var/run/docker.sock from docker cli, I cannot discover the nodes on prometheus web panel that are live in docker.sock file. It implies that docker containers cannot access the docker.sock file. Morover, the read/write access has been granted to docker containers while mounting the file.

Run Prometheus using commands:

./prometheus --config.file /home/**********/prom_conf/prometheus.yml

Prometheus configuration:

# my global config
global:
  scrape_interval: 5s
  scrape_timeout: 3s
  evaluation_interval: 15s

# Alertmanager configuration
alerting:
  alertmanagers:
  - static_configs:
    - targets:
       - 127.0.0.1:5050

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

scrape_configs:

  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'prometheus'
    static_configs:
    - targets: 
        ['localhost:9100']
  - job_name: 'dockerswarm'
    dockerswarm_sd_configs:
      - host: unix:///var/run/docker.sock
        role: tasks
    relabel_configs:
      # Only keep containers that should be running.
      - source_labels: [__meta_dockerswarm_task_desired_state]
        regex: running
        action: keep
      # Only keep containers that have a `prometheus-job` label.
      - source_labels: [__meta_dockerswarm_service_label_prometheus_job]
        regex: .+
        action: keep
      # Use the prometheus-job Swarm label as Prometheus job label.
      - source_labels: [__meta_dockerswarm_service_label_prometheus_job]
        target_label: job

Prometheus with docker-cli:

docker run 
    -p 9090:9090 
    -v /home/**************/prom_conf:/etc/prometheus 
    -v /var/run/docker.sock:/var/run/docker.sock 
    -v /sys/fs/cgroup:/cgroup 
    -v /:/rootfs:ro 
    prom/prometheus

Source: Docker Questions