span & event ideas for otel-cli

otel-cli-ideas.sh

#!/bin/bash
# otel-cli-ideas.sh - some ideas I'm playing with for otel-cli to cover some
# use cases where manual spans or exec don't quite do the trick
#
# another cool outcome is you could run this without the collector in some
# cases without spamming your OTLP endpoint...
#
# I hope to OSS otel-cli under Apache 2 in early April 2021.

# maybe it could background itself and wait for events on a unix socket?
cf=$(mktemp) # carrier file, will be read/written
sfd=$(mktemp -d) # socket file is a unix domain socket in this dir

# start a span in the background, listening on a unix socket
# it will hold the span open until it's ended or timeout
otel-cli span background \
   --service-name $0 \
   --span-name "start a background span" \
   --tp-carrier $cf \
   --bg-socket-dir $sfd \
   --timeout 60 & # run as a background job
# seems like most of the time you *don't* want to nohup this, but I
# don't see why you couldn't, like in one use case I'm working on we
# might start a span in initramfs and end it just before reboot...

# later... add an event to that span
# if a socket is provided, no need for the carrier, we can get that from
# the socket
otel-cli span event \
   --bg-socket-dir $sfd \
   --event-name "this is a span event" \
   --attrs "foo=bar,kernel=2.5.34-hahaharememberthat"

# add a child span to the background span, but do not update carrier
otel-cli span \
   --bg-socket-dir $sfd \
   --span-name "this is a child span on the background span"

# add another child to the bg span, also background it
inner_sfd=$(mktemp -d)
otel-cli span background \
   --bg-socket-dir $inner_sfd \
   --span-name "child to the background" \
   --timeout 30 &

# now we can add another span that's child to the child
otel-cli span \
   --bg-socket-dir $inner_sfd \
   --span-name "3rd level child, inside two open spans"

# now close up the background spans
otel-cli span end --bg-socket-dir $inner_sfd
otel-cli span end --bg-socket-dir $sfd
# and/or
kill $1
kill $(otel-cli span background pid --bg-socket-dir $sfd)