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Posted on Aug 19, 2019

Sampler. Dashboards, monitoring and alerting — right from your terminal

#devops #bash #productivity #go

As a backend developer, I always need to monitor something. State machine in the database, records count, message queue lag, custom application metrics, system performance, progress of my deployment scripts. Tons of stuff!

For a long time I was trying to find a tool which can save me time — will be able to keep everything in one place, and notify me when needed. Heavy production monitoring systems can't help with the development tasks, I needed a swiss army knife - something that can be configured in a minute and give me the results right away.

There were no such thing, so I wrote my own. Meet Sampler - command-line UI for any shell commands, written in pure Go.

To install, follow the instructions for macOS, Linux or Windows

How does it work?

The idea is very simple - almost all metrics you might want to monitor and visualize are available via CLI:

The basics: CPU, memory, disk space, network
Telemetry from a remote machine via SSH
Any database metrics and results of your custom queries
Kafka, RabbitMQ, ActiveMQ
K8s RAM/CPU/events
Everything available via http, e.g. Spring Boot Actuator metrics
Docker
JMX
Logs

That means we can create our dashboards without complex integrations, drivers and dependencies. We can do it right from the terminal.

Using Sampler is basically a 3-step process:

Define your configuration in a YAML file
Run sampler -c your-config-file.yml
Adjust components size and location on UI

Examples

Visualizations and their YAML configuration

Runcharts

runcharts:
  - title: Search engine response time
    rate-ms: 500        # sampling rate, default = 1000
    scale: 2            # number of digits after sample decimal point, default = 1
    legend:
      enabled: true     # enables item labels, default = true
      details: false    # enables item statistics: cur/min/max/dlt values, default = true
    items:
      - label: GOOGLE
        sample: curl -o /dev/null -s -w '%{time_total}'  https://www.google.com
        color: 178      # 8-bit color number, default one is chosen from a pre-defined palette
      - label: YAHOO
        sample: curl -o /dev/null -s -w '%{time_total}'  https://search.yahoo.com
      - label: BING
        sample: curl -o /dev/null -s -w '%{time_total}'  https://www.bing.com

Sparklines

sparklines:
  - title: CPU usage
    rate-ms: 200
    scale: 0
    sample: ps -A -o %cpu | awk '{s+=$1} END {print s}'
  - title: Free memory pages
    rate-ms: 200
    scale: 0
    sample: memory_pressure | grep 'Pages free' | awk '{print $3}'

Barcharts

barcharts:
  - title: Local network activity
    rate-ms: 500        # sampling rate, default = 1000
    scale: 0            # number of digits after sample decimal point, default = 1
    items:
      - label: UDP bytes in
        sample: nettop -J bytes_in -l 1 -m udp | awk '{sum += $4} END {print sum}'
      - label: UDP bytes out
        sample: nettop -J bytes_out -l 1 -m udp | awk '{sum += $4} END {print sum}'
      - label: TCP bytes in
        sample: nettop -J bytes_in -l 1 -m tcp | awk '{sum += $4} END {print sum}'
      - label: TCP bytes out
        sample: nettop -J bytes_out -l 1 -m tcp | awk '{sum += $4} END {print sum}'

Gauges

gauges:
  - title: Minute progress
    rate-ms: 500        # sampling rate, default = 1000
    scale: 2            # number of digits after sample decimal point, default = 1
    percent-only: false # toggle display of the current value, default = false
    color: 178          # 8-bit color number, default one is chosen from a pre-defined palette
    cur:
      sample: date +%S  # sample script for current value
    max:
      sample: echo 60   # sample script for max value
    min:
      sample: echo 0    # sample script for min value
  - title: Year progress
    cur:
      sample: date +%j
    max:
      sample: echo 365
    min:
      sample: echo 0

Textboxes

textboxes:
  - title: Local weather
    rate-ms: 10000      # sampling rate, default = 1000
    sample: curl wttr.in?0ATQF
    border: false       # border around the item, default = true
    color: 178          # 8-bit color number, default is white
  - title: Docker containers stats
    rate-ms: 500
    sample: docker stats --no-stream --format "table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.PIDs}}"

Asciiboxes

asciiboxes:
  - title: UTC time
    rate-ms: 500        # sampling rate, default = 1000
    font: 3d            # font type, default = 2d
    border: false       # border around the item, default = true    
    color: 43           # 8-bit color number, default is white
    sample: env TZ=UTC date +%r

There is more!

Interactive shell support, PTY mode, triggers, alerts and variables. Real-world recipes to work with MySQL, PostgreSQL, MongoDB, Neo4J, Kafka, SSH and JMX. You can read about advanced capabilities in the documentation.

Don't hesitate to ask questions, contribute and ⭐ star ⭐ the project on Github!

Top comments (7)

José Coelho • Aug 22 '19

Great article! Such an awesome tool! I like that you don’t need to know how to program to use it😁

If you ever want to get away from the terminal check out this article I wrote about a similar tool 😝 dev.to/jcoelho/powershell-universa...

Tom Wright • Aug 21 '19

Love love love this. Going to build one and stick it on a 40" display! 😆

Georgi Tenev • Aug 21 '19

Good job, mate !

Daniel Starner • Aug 21 '19

Pretty cool project, thanks for sharing! Does this work with Prometheus? Because that would be bomb 💣 I could look at my server metrics while on the server