Another example of usage with some different properties

[howardjohn]

While playing around with this - which is super helpful, thanks! - I came up with another approach than the current demos to meet my needs.

The benefits of this is that:

• No otel-cli exec, so we can use bash functions
• No background, so we don't need to deal with the race issues
• No tp-carrier needed either, which is not a big deal but avoids a lot of temporary files

Just wanted to share and didn't have a good way to do so, so I thought I would open an issue:

#!/bin/bash
export OTEL_EXPORTER_OTLP_ENDPOINT=localhost:4317

function gen-uid() {
  tr -dc 'a-f0-9' < /dev/urandom | head -c$1
}

# Usage: trace <span name> [command ...]
function trace() {
  # Throughout, "local" usage is critical to avoid nested calls overwriting things
  local start="$(date -u +%s.%N)"
  # First, get a trace and span ID. We need to get one now so we can propogate it to the child
  # Get trace ID from TRACEPARENT, if present
  local tid="$(<<<${TRACEPARENT:-} cut -d- -f2)"
  tid="${tid:-"$(gen-uid 32)"}"
  # Always generate a new span ID
  local sid="$(gen-uid 16)"

  # Execute the command they wanted with the propogation through TRACEPARENT
  TRACEPARENT="00-${tid}-${sid}-01" "${@:2}"

  local end="$(date -u +%s.%N)"

  # Now report this span. We override the IDs to the ones we set before.
  # TODO: support attributes
  otel-cli span \
    --service "test2" \
    --name "$1" \
    --start "$start" \
    --end "$end" \
    --force-trace-id "$tid" \
    --force-span-id "$sid"
}

function nested() {
  trace "child1" sleep .1
  trace "child2" sleep .2
  trace "deep" deep
}

function deep() {
  trace "in-deep" sleep .1
}

trace "parent" nested

I am happy to close this immediately as an "FYI", send it to demos/, etc, whatever.

[howardjohn]

Actually got a bit carried away and wrote up a bunch of options: https://blog.howardjohn.info/posts/shell-tracing/

[tobert]

I would love a PR to add this to demos! I'm also open to having an otel-cli command that dumps some shell code folks can source.