[META 882] Check classic and OTel agents against serverless

[obltmachine]

See meta issue and spec for the description and details:

• Meta issue: Check classic and OTel agents against serverless apm#882
• Spec issue: [META 882] Spec: Check classic and OTel agents against serverless apm#883

[trentm]

I tested a simple example script instrumented with the OTel distro for Node.js
against a serverless deployment using 3 different flavours of encoding the
OTEL_EXPORTER_OTLP_HEADERS value (see specific values below):

• unencoded
• just encoding the space (via JS encodeURI())
• encoding more chars, i.e. the equals-signs (via JS encodeURIComponent(), https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent)

cd elastic-otel-node
npm ci
cd examples/

export OTEL_EXPORTER_OTLP_ENDPOINT="...REDACTED serverless endpoint URL..."

OTEL_SERVICE_NAME=example-a OTEL_EXPORTER_OTLP_HEADERS="Authorization=ApiKey a1Q0REDACTEDdLdjJGZw==" \
    node -r @elastic/opentelemetry-node just-http-request.js
OTEL_SERVICE_NAME=example-b OTEL_EXPORTER_OTLP_HEADERS="Authorization=ApiKey%20a1Q0REDACTEDdLdjJGZw==" \
    node -r @elastic/opentelemetry-node just-http-request.js
OTEL_SERVICE_NAME=example-c OTEL_EXPORTER_OTLP_HEADERS="Authorization=ApiKey%20a1Q0REDACTEDdLdjJGZw%3D%3D" \
    node -r @elastic/opentelemetry-node just-http-request.js

They were all successful against an Elastic serverless deployment: