# Sampler. Visualization for any shell command. 
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Sampler is a tool for shell commands execution, visualization and alerting. Configured with a simple YAML file.

![sampler](https://user-images.githubusercontent.com/6069066/56404396-70b14d00-6234-11e9-93cd-54461bf40c96.gif)

## Installation

### macOS
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### Linux
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### Windows
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## Usage
You specify shell commands, Sampler executes them with a required rate. The output is used for visualization.

One can sample any dynamic process right from the terminal - observe changes in the database, monitor MQ in-flight messages, trigger deployment process and get notification when it's done. 

Using Sampler is basically a 3-step process:
- Define your configuration in a YAML file
- Run `sampler -c config.yml`
- Adjust components size and location on UI

## Configuration

- [Components](#components)
  - [Runchart](#runchart)
  - [Sparkline](#sparkline)
  - [Barchart](#barchart)
  - [Gauge](#gauge)
  - [Textbox](#textbox)
  - [Asciibox](#asciibox)
- [Bells and whistles](#bells-and-whistles)
  - [Triggers (conditional actions)](#triggers)
  - [Interactive shell (for database interaction, remote server access, etc)](#interactive-shell-support)
  - [Variables](#variables)
  - [Color theme](#color-theme)
- [Real-world examples (contributions welcome)](#real-world-examples)  

### Components
#### Runchart
![runchart](https://user-images.githubusercontent.com/6069066/59168666-aff96d00-8b04-11e9-99b6-34d8bae37bd2.png)
```yml
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
```
#### Sparkline
![sparkline](https://user-images.githubusercontent.com/6069066/59167746-de754900-8b00-11e9-9305-c9a4176634d2.png)
```yml
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}'
```
#### Barchart
![barchart](https://user-images.githubusercontent.com/6069066/59167751-de754900-8b00-11e9-8d01-efd04ae1eec6.png)
```yml
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}'
```
#### Gauge
![gauge](https://user-images.githubusercontent.com/6069066/59168667-b0920380-8b04-11e9-852b-5e7810fab640.png)
```yml
gauges:
  - title: Minute progress
    rate-ms: 500        # sampling rate, default = 1000
    scale: 2            # number of digits after sample decimal point, default = 1
    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
```
#### Textbox
![textbox](https://user-images.githubusercontent.com/6069066/59167747-de754900-8b00-11e9-887b-a9fce57d9a72.png)
```yml
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}}"
```
#### Asciibox
![asciibox](https://user-images.githubusercontent.com/6069066/59167749-de754900-8b00-11e9-9157-cc9809fbc622.png)
```yml
asciiboxes:
  - title: UTC time
    rate-ms: 500        # sampling rate, default = 1000
    font: 3d            # font type, default = 2d
    color: 178          # 8-bit color number, default is white
    sample: env TZ=UTC date +%r
```

### Bells and whistles

#### Triggers
Triggers allow to perform conditional actions, like visual/sound alerts or an arbitrary shell command.

#### Interactive shell support
In addition to the `sample` command, one can specify `init` command (executed only once before sampling) and `transform` command (to post-process `sample` command output). That covers interactive shell use case, e.g. to establish connection to a database only once, and then perform polling within interactive shell session. MongoDB example: ...

#### Variables
If the configuration file contains repeated patterns, they can be extracted into the `variables` section.
Also variables can be specified using `-v`/`--variable` flag on startup, and any system environment variables will also be available in the scripts.

#### Color theme
...

### Real-world examples
...