Sampler - A Tool For Shell Commands Execution, Visualization And Alerting (Configured With A Simple YAML File)


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 {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.PIDs}}"

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 [email protected]
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 {{.Name}}\t{{.CPUPerc}}\t{{.MemPerc}}\t{{.MemUsage}}\t{{.NetIO}}\t{{.BlockIO}}\t{{.PIDs}}"

SSH

TOP command on a remote server
variables:
sshconnection: ssh -i ~/my-key-pair.pem [email protected]
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}'


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