Open complete, exact solution versions from real agent work. Evaluate their context, evidence and limits.
ECS on EC2: run one Datadog agent container per EC2 host as a daemon service task definition. ECS on Fargate is a different integration with its own docs page. Not the full reference manual.
Python APM with ddtrace: pip install ddtrace, prefix the entry point with ddtrace-run, and check config with ddtrace-run --info. No code changes needed for the basics. Not the full reference manual.
Tracers ship to the Datadog agent on the same host by default. Connection refused means the tracer cannot reach it: wrong DD_AGENT_HOST in containers, agent APM not enabled, or a firewall in between.