Monitoring and Data Visualization

The JuiceFS client exposes real-time metrics in Prometheus format through the monitoring API. Users configure Prometheus to scrape metrics data, and then use tools such as Grafana to realize data visualization.

Add scrape config in Prometheus

After JuiceFS is mounted on a host, you can access its metrics using http://localhost:9567/metrics, other types of JuiceFS Client (CSI Driver, S3 Gateway, Hadoop SDK) is slightly different in this regard, see Collecting metrics data.

Here, taking collect metrics of the mount point as an example, edit prometheus.yml to add a new scrape config (scrape_configs):

global:
  scrape_interval: 15s
  evaluation_interval: 15s

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

rule_files:
  # - "first_rules.yml"
  # - "second_rules.yml"

scrape_configs:
  - job_name: "prometheus"
    static_configs:
      - targets: ["localhost:9090"]

  - job_name: "juicefs"
    static_configs:
      - targets: ["localhost:9567"]

Start the Prometheus service:

./prometheus --config.file=prometheus.yml

Visit http://localhost:9090 to see the Prometheus interface.

Visualizing metrics using Grafana

Create a new Prometheus-type data source in Grafana:

• Name: For identification purposes, you can fill it in with the name of the file system.
• URL: Data interface for Prometheus, which defaults to http://localhost:9090.

JuiceFS provides some dashboard templates for Grafana, which can be imported to show the collected metrics in Prometheus:

Name	Description
grafana_template.json	For show metrics collected from mount point, S3 gateway (non-Kubernetes deployment) and Hadoop Java SDK
grafana_template_k8s.json	For show metrics collected from Kubernetes CSI Driver and S3 gateway (Kubernetes deployment)

Our Grafana dashboard looks like this:

Collecting metrics data

For different types of JuiceFS Client, metrics data is handled slightly differently.

Mount point

When the JuiceFS file system is mounted via the juicefs mount command, you can collect monitoring metrics via the address http://localhost:9567/metrics, or you can customize it via the --metrics option. For example:

juicefs mount --metrics localhost:9567 ...

You can view these monitoring metrics using the command line tool:

curl http://localhost:9567/metrics

In addition, the root directory of each JuiceFS file system has a hidden file called .stats, through which you can also view monitoring metrics. For example (assuming here that the path to the mount point is /jfs):

cat /jfs/.stats

tip

If you want to view the metrics in real-time, you can use the juicefs stats command.

Kubernetes

See CSI Driver documentation.

S3 Gateway

note

This feature needs to run JuiceFS client version 0.17.1 and above.

The JuiceFS S3 Gateway will provide monitoring metrics at the address http://localhost:9567/metrics by default, or you can customize it with the -metrics option. For example:

juicefs gateway --metrics localhost:9567 ...

If you are deploying JuiceFS S3 Gateway in Kubernetes, you can refer to the Prometheus configuration in the Kubernetes section to collect monitoring metrics (the difference is mainly in the regular expression for the label __meta_kubernetes_pod_label_app_kubernetes_io_name), e.g.:

scrape_configs:
  - job_name: 'juicefs-s3-gateway'
    kubernetes_sd_configs:
      - role: pod
    relabel_configs:
      - source_labels: [__meta_kubernetes_pod_label_app_kubernetes_io_name]
        action: keep
        regex: juicefs-s3-gateway
      - source_labels: [__address__]
        action: replace
        regex: ([^:]+)(:\d+)?
        replacement: $1:9567
        target_label: __address__
      - source_labels: [__meta_kubernetes_pod_node_name]
        target_label: node
        action: replace

Collected via Prometheus Operator

Prometheus Operator enables users to quickly deploy and manage Prometheus in Kubernetes. With the ServiceMonitor CRD provided by Prometheus Operator, scrape configuration can be automatically generated. For example (assuming that the Service of the JuiceFS S3 Gateway is deployed in the kube-system namespace):

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: juicefs-s3-gateway
spec:
  namespaceSelector:
    matchNames:
      - kube-system
  selector:
    matchLabels:
      app.kubernetes.io/name: juicefs-s3-gateway
  endpoints:
    - port: metrics

For more information on Prometheus Operator, please refer to the official documentation.

Hadoop Java SDK

JuiceFS Hadoop Java SDK supports reporting monitoring metrics to Pushgateway and Graphite.

Pushgateway

Report metrics to Pushgateway:

<property>
  <name>juicefs.push-gateway</name>
  <value>host:port</value>
</property>

At the same time, the frequency of reporting metrics can be modified through the juicefs.push-interval configuration. The default is to report once every 10 seconds.

info

According to the suggestion of Pushgateway official document, it is required to set honor_labels: true in the Prometheus's scrape configuration.

It is important to note that the timestamp of the metrics scraped by Prometheus from Pushgateway is not the time when the JuiceFS Hadoop Java SDK reported it, but the time when it scraped. For details, please refer to Pushgateway official document.

By default, Pushgateway will only save metrics in memory. If you need to persist metrics to disk, you can specify the file path for saving by the --persistence.file option and the frequency of saving to the file with the --persistence.interval option (by default, the metrics will be saved every 5 minutes).

note

Each process using JuiceFS Hadoop Java SDK will have a unique metric, and Pushgateway will always remember all the collected metrics. This may cause the continuous accumulation of metrics and taking up too much memory, and it will also make Prometheus scraping metrics slow. Therefore, it is recommended to clean up metrics on Pushgateway regularly.

For this, the following command can help. Clearing the metrics will not affect the running JuiceFS Hadoop Java SDK to continuously report data. Note that the --web.enable-admin-api option must be specified when Pushgateway is started, and the following command will clear all monitoring metrics in Pushgateway.

curl -X PUT http://host:9091/api/v1/admin/wipe

For more information about Pushgateway, please check official document.

Graphite

Report metrics to Graphite:

<property>
  <name>juicefs.push-graphite</name>
  <value>host:port</value>
</property>

At the same time, the frequency of reporting metrics can be modified through the juicefs.push-interval configuration. The default is to report every 10 seconds.

For all configurations supported by JuiceFS Hadoop Java SDK, please refer to documentation.

Use Consul as registration center

note

This feature needs to run JuiceFS client version 1.0.0 and above.

JuiceFS support to use Consul as registration center for metrics API. The default Consul address is 127.0.0.1:8500. You could customize the address through --consul option, e.g.:

juicefs mount --consul 1.2.3.4:8500 ...

When the Consul address is configured, the configuration of the --metrics option is not needed, and JuiceFS will automatically configure metrics URL according to its own network and port conditions. If --metrics is set at the same time, it will first try to listen on the configured metrics URL.

For each service registered to Consul, the service name is always juicefs, and the format of service ID is <IP>:<mount-point>, for example: 127.0.0.1:/tmp/jfs.

The meta of each service contains two keys hostname and mountpoint, the corresponding values ​​represent the host name and path of the mount point respectively. In particular, the mountpoint value for the S3 Gateway is always s3gateway.

After successfully registering with Consul, you need to add a new consul_sd_config configuration to prometheus.yml and fill in the services with juicefs.

Monitoring metrics reference

Refer to JuiceFS Metrics.