Sampler - A Tool For Shell Commands Execution (How to install)

Sampler - A Tool For Shell Commands Execution (How To Install)

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

Installation

macOS

brew cask install sampler

oR

curl -Lo /usr/local/bin/sampler https://github.com/sqshq/sampler/releases/download/v1.0.1/sampler-1.0.1-darwin-amd64

chmod +x /usr/local/bin/sampler

Linux

wget https://github.com/sqshq/sampler/releases/download/v1.0.1/sampler-1.0.1-linux-amd64 -O /usr/local/bin/sampler

chmod +x /usr/local/bin/sampler

Note: libasound2-dev system library is required to be installed for Sampler to play a trigger sound tone. Usually the library is in place, but if not - you can do it with your favorite package manager, e.g apt install libasound2-dev

Windows (experimental)

Recommended to use with advanced console emulators, e.g. Cmder

Download .exe

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

Components

The following is a list of configuration examples for each component type, with macOS compatible sampling scripts.

Runchart

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

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

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

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

Textbox

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 \t\t\t"

Asciibox

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

Bells and whistles

Triggers

Triggers allow to perform conditional actions, like visual/sound alerts or an arbitrary shell command. The following examples illustrate the concept.

Clock gauge, which shows minute progress and announces current time at the beginning of each minute

gauges:

- title: MINUTE PROGRESS

position: [[0, 18], [80, 0]]  

cur:

sample: date +%S

max:

sample: echo 60

min:

sample: echo 0

triggers:

- title: CLOCK BELL EVERY MINUTE

condition: '[ $label == "cur" ] && [ $cur -eq 0 ] && echo 1 || echo 0'  # expects "1" as TRUE indicator

actions:

terminal-bell: true  

# standard terminal bell, default = false

sound: true   

# NASA quindar tone, default = false

visual: false 

# notification with current value on top of the component area, default = false

script: say -v samantha `date +%I:%M%p`  # an arbitrary script, which can use $cur, $prev and $label variables

Search engine latency chart, which alerts user when latency exceeds a threshold

runcharts:

- title: SEARCH ENGINE RESPONSE TIME (sec)

rate-ms: 200

items:

- label: GOOGLE

sample: curl -o /dev/null -s -w '%{time_total}'  https://www.google.com

- label: YAHOO

sample: curl -o /dev/null -s -w '%{time_total}'  https://search.yahoo.com     

triggers:

- title: Latency threshold exceeded

condition: echo "$prev < 0.3 && $cur > 0.3" |bc -l  # expects "1" as TRUE indicator

actions:

terminal-bell: true  # standard terminal bell, default = false

sound: true   # NASA quindar tone, default = false

visual: true  # visual notification on top of the component area, default = false

script: 'say alert: ${label} latency exceeded ${cur} second' # an arbitrary script, which can use $cur, $prev and $label variables

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 an interactive shell session.

Basic mode

textboxes:

- title: MongoDB polling

rate-ms: 500

init: mongo --quiet --host=localhost test

# executes only once to start the interactive session

sample: Date.now();                    

# executes with a required rate, in scope of the interactive session

transform: echo result = $sample        

# executes in scope of local session, $sample variable is available for transformation

PTY mode

In some cases interactive shell won't work, because its stdin is not a terminal. We can fool it, using PTY mode:

textboxes:

- title: Neo4j polling

pty: true 

# enables pseudo-terminal mode, default = false

init: cypher-shell -u neo4j -p pwd --format plain

sample: RETURN rand();

transform: echo "$sample" | tail -n 1

- title: Top on a remote server

pty: true  

# enables pseudo-terminal mode, default = false

init: ssh -i ~/user.pem ec2-user@1.2.3.4

sample: top    

Multistep init

It is also possible to execute multiple init commands one after another, before you start sampling.

textboxes:

- title: Java application uptime

multistep-init:

- java -jar jmxterm-1.0.0-uber.jar

- open host:port 



# or local PID

- bean java.lang:type=Runtime

sample: get Uptime

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.

variables:

mongoconnection: mongo --quiet --host=localhost test

barcharts:

- title: MongoDB documents by status



   items:

- label: IN_PROGRESS

init: $mongoconnection

sample: db.getCollection('events').find({status:'IN_PROGRESS'}).count()

- label: SUCCESS

init: $mongoconnection

sample: db.getCollection('events').find({status:'SUCCESS'}).count()

- label: FAIL

init: $mongoconnection

sample: db.getCollection('events').find({status:'FAIL'}).count()

Color theme

theme: light # default = dark

sparklines:

- title: CPU usage

sample: ps -A -o %cpu | awk '{s+=$1} END {print s}'

Real-world recipes

Databases

The following are different database connection examples. Interactive shell (init script) usage is recommended to establish connection only once and then reuse it during sampling.

MySQL

# prerequisite: installed mysql shell



variables:

mysql_connection: mysql -u root -s --database mysql --skip-column-names

sparklines:  

- title: MySQL (random number example)

pty: true

init: $mysql_connection

sample: select rand();

PostgreSQL

# prerequisite: installed psql shell



variables:

PGPASSWORD: pwd

postgres_connection: psql -h localhost -U postgres --no-align --tuples-only

sparklines:

- title: PostgreSQL (random number example)

init: $postgres_connection

sample: select random();

MongoDB

# prerequisite: installed mongo shell



variables:

mongo_connection: mongo --quiet --host=localhost test

sparklines:

- title: MongoDB (random number example)

init: $mongo_connection

sample: Math.random();

Neo4j

# prerequisite: installed cypher shell



variables:

neo4j_connection: cypher-shell -u neo4j -p pwd --format plain

sparklines:

- title: Neo4j (random number example)

pty: true

init: $neo4j_connection

sample: RETURN rand();

transform: echo "$sample" | tail -n 1

Kafka lag per consumer group

variables:

kafka_connection: $KAFKA_HOME/bin/kafka-consumer-groups --bootstrap-server localhost:9092

runcharts:

- title: Kafka lag per consumer group

rate-ms: 5000

scale: 0

items:

- label: A->B

sample: $kafka_connection --group group_a --describe | awk 'NR>1 {sum += $5} END {print sum}'

- label: B->C

sample: $kafka_connection --group group_b --describe | awk 'NR>1 {sum += $5} END {print sum}'

- label: C->D

sample: $kafka_connection --group group_c --describe | awk 'NR>1 {sum += $5} END {print sum}'

Docker containers stats (CPU, MEM, O/I)

textboxes:

- title: Docker containers stats

sample: docker stats --no-stream --format "table \t\t\t\t\t\t"

SSH

TOP command on a remote server

variables:

sshconnection: ssh -i ~/my-key-pair.pem ec2-user@1.2.3.4

textboxes:

- title: SSH

pty: true

init: $sshconnection

sample: top

JMX

Java application uptime example

# prerequisite: download [jmxterm jar file](https://docs.cyclopsgroup.org/jmxterm)



textboxes:

- title: Java application uptime

multistep-init:

- java -jar jmxterm-1.0.0-uber.jar

- open host:port # or local PID

- bean java.lang:type=Runtime

sample: get Uptime

transform: echo $sample | tr -dc '0-9' | awk '{printf "%.1f min", $1/1000/60}'

Download Sampler