dish (golang1.21)

• tiny monitoring one-shot service
• remote configuration of independent 'dish network' (-source=$REMOTE_JSON_API_URL)
• fast (quick load and exec time, 10 sec timeout per socket by default), instant messenger connectors

$ go install go.savla.dev/dish@1.3.0

$ dish -h
Usage of ./dish:
  -hname string
     a string, custom additional header name
  -hvalue string
     a string, custom additional header value
  -name string
     a string, dish instance name (default "generic-dish")
  -pushgw
     a bool, enable reporter module to post dish results to pushgateway
  -source string
     a string, path to/URL JSON socket list (default "demo_sockets.json")
  -target string
     a string, result update path/URL, plaintext/byte output
  -telegram
     a bool, Telegram provider usage toggle
  -telegramBotToken string
     a string, Telegram bot private token
  -telegramChatID string
     a string/signet int, Telegram chat/channel ID
  -timeout int
     an int, timeout in seconds for http and tcp calls (default 10)
  -verbose
     a bool, console stdout logging toggle (default true)

use-cases

savla-dish history article

the idea of a tiny one-shot service comes with the need of a quick monitoring service implementation over HTTP/S and generic TCP endpoints (more like 'sockets' = hosts and their ports)

it is not meant to be a competition with blackbox exporter, this is just another implementation approach

socket list

the list of sockets can be provided via a local JSON-formated file, or via remote REST/RESTful JSON-returning API (JSON structure has to be of the same structure anyway; see demo_sockets.json)

./dish -source=http://restapi.example.com/dish/sockets/:instance

alerting

as the alerting system (in case of socket test timeout threshold hit, or an unexpected HTTP response code) we provide a simple embedded messenger with Telegram IM implementation example (see messenger/messenger.go); since the Telegram bot token and the potential Telegram chat ID are considered as the secrets, we do recommend including these to the custom, local, binary executable instead of passing them into the CLI shell (security breach as secrets can then leak in process list --- to be reviewed)

pushgateway

to keep dish simple and light, we decided not to import http server (even though net/http package is used) and use just its Client interface to push/post results to Pushgateway by Prometheus (TODO: insert pushgateway into docker-compose.yml config)

job name and instance name are hardcoded constants in the reporter module source

short article on motivation and history behind dish

examples

# get the actual git version
go install go.savla.dev/dish@latest

# load sockets from demo_sockets.json file (by default) and use telegram provider for alerting (hardcoded token and chatID -- messenger/messenger.go)
dish -source=demo_sockets.json -telegram

# use remote RESTful API service's socket list, use _explicit_ telegram bot and chat
dish -source='https://api.example.com/dish/source' -telegram -telegramChatID=-123456789 -telegramBotToken='idk:00779988ddd'

docker it

we use .env and gnumake (Makefile) to simplify/semiautomate our development procedures, feel free to give it a try

# copy, and/or edit dot-env file
cp .env.example .env
vim .env

# build an image
make build

# run! (not the same as `make run`, but it should've been so)
docker run --rm -i savla-dish:golang-1.19 -verbose -pushgw -source=http://[...] -target=http://pushgateway.example.com

cronjob example

# non-root user!
crontab -e

# m h  dom mon dow   command
MAILTO=monitoring@example.com

TELEGRAM_TOKEN="000001:AFFDS45454d5ccfsadf34" 
TELEGRAM_CHATID="-12345678900"
DISH_EXECUTABLE_PATH=/home/dish/golang/bin/dish
DISH_SOURCE=http://restapi.example.com/dish/sockets/${HOSTNAME}

*/1 * * * * ${DISH_EXECUTABLE_PATH} -source=${DISH_SOURCE} -telegram -telegramBotToken=${TELEGRAM_TOKEN} -telegramChatID=${TELEGRAM_CHATID}

Please note, that dish executable returns "dish run: all tests ok" and exit code 0, as soon as the execution ends (and no problems are present to report).