For the past year or so I’ve been working with Observability and quite a bit of Open Telemetry. One of the requirements of triggering a great front-to-back trace is providing a W3C compliant header in the Open Telemetry format. That format detailed in W3C Trance Context.
Very simply in bash, we were able to use the following, which when we lit up for example Application Insights in Azure, a fully holistic view with all sub-spans appears providing a great analytics experience.
#!/usr/bin/env bash
# set -eox
# see spec: https://www.w3.org/TR/trace-context
# version-format = trace-id "-" parent-id "-" trace-flags
# trace-id = 32HEXDIGLC ; 16 bytes array identifier. All zeroes forbidden
# parent-id = 16HEXDIGLC ; 8 bytes array identifier. All zeroes forbidden
# trace-flags = 2HEXDIGLC ; 8 bit flags. Currently, only one bit is used. See below for detail
VERSION="00" # fixed in spec at 00
TRACE_ID="$(cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 32 | head -n 1)"
PARENT_ID="00$(cat /dev/urandom | tr -dc 'a-f0-9' | fold -w 14 | head -n 1)"
TRACE_FLAG="01" # sampled
TRACE_PARENT="$VERSION-$TRACE_ID-$PARENT_ID-$TRACE_FLAG"
TRACE_STATE="mystate"
MESSAGE="Lorem ipsum $(cat /dev/urandom | tr -dc 'a-zA-Z' | fold -w 20 | head -n 1)"
URL="http://localhost:8080/messages"
echo "sending to host $URL"
echo "sending a trace-parent of: $TRACE_PARENT"
curl --location --request POST "${URL}" \
--header "traceparent: $TRACE_PARENT" \
--header "Content-Type: application/json" \
--data-raw "{\"message\":\"$MESSAGE\",\"traceparent\":\"$TRACE_PARENT\" }"
