Send gtm-sdk telemetry to Dash0 with the otel-collector

This guide walks through setting up Dash0 as a telemetry provider for the otel-collector Modal app. The collector fans out every batch to all configured providers; the architecture itself is covered in Telemetry overview. This page covers only the Dash0-specific wiring: the collector registers an otlphttp/dash0 exporter and sends the Dash0-Dataset header when DASH0_DATASET is set.

Endpoints

Dash0 provides regional endpoints:

US: https://otel-ingest.us.dash0.com
EU: https://otel-ingest.eu.dash0.com

Choose the one nearest your data location.

Setup

Add secrets to Infisical

Add three secrets to your Infisical project (prod environment):

Name	Value	Required
`DASH0_AUTH_TOKEN`	Your Dash0 API token	Yes
`DASH0_OTLP_ENDPOINT`	Your regional endpoint: `https://otel-ingest.us.dash0.com` (US) or `https://otel-ingest.eu.dash0.com` (EU)	Yes
`DASH0_DATASET`	`default`, or your dataset name	No

You can set them from the CLI. Run this from the repo root:

# Source your Infisical credentials
set -a && source .env.local && set +a

# Set each secret
infisical secrets set \
  DASH0_AUTH_TOKEN "<YOUR_DASH0_AUTH_TOKEN>" \
  --env=prod \
  --projectId "$INFISICAL_PROJECT_ID" \
  --token "$INFISICAL_TOKEN"

infisical secrets set \
  DASH0_OTLP_ENDPOINT "https://otel-ingest.us.dash0.com" \
  --env=prod \
  --projectId "$INFISICAL_PROJECT_ID" \
  --token "$INFISICAL_TOKEN"

infisical secrets set \
  DASH0_DATASET "default" \
  --env=prod \
  --projectId "$INFISICAL_PROJECT_ID" \
  --token "$INFISICAL_TOKEN"

Deploy the collector

Once the secrets are set, deploy the otel-collector app:

set -a && source .env.local && set +a

infisical run --projectId "$INFISICAL_PROJECT_ID" --token "$INFISICAL_TOKEN" \
  --env=prod -- uv run modal deploy src/otel_collector.py

The collector image build fetches the secrets and embeds them, so when the container starts, Dash0 is already configured.

Verify the configuration

Check that Dash0 was included in the collector config:

uv run python -c "
from src.otel_collector import build_collector_config
config = build_collector_config()
exporters = config.get('exporters', {})
print('Exporters:', list(exporters.keys()))
if 'otlphttp/dash0' in exporters:
    print('Dash0 is configured')
else:
    print('Dash0 is NOT configured')
"

Output

Exporters: ['otlphttp/dash0']
Dash0 is configured

Test the telemetry flow

Use the verification script to test end-to-end telemetry:

# Set environment (usually injected via Infisical, but can override)
export DASH0_AUTH_TOKEN="<YOUR_DASH0_AUTH_TOKEN>"
export DASH0_OTLP_ENDPOINT="https://otel-ingest.us.dash0.com"
# Collector fan-out is the default (app name hard-coded in libs/telemetry.py);
# only set this to override the app name, or to "" to force the direct fallback.
export TELEMETRY_COLLECTOR_APP="otel-collector"

# Run tests
uv run pytest tests/src/test_dash0_telemetry_integration.py -v

# Or emit test telemetry (requires collector running on Modal)
uv run scripts/dash0-telemetry-verify.py

How Dash0 fits into the collector

Apps never talk to Dash0 directly. The app-side exporter in libs/telemetry.py serializes each batch to OTLP protobuf and spawns the collector Modal function fire-and-forget; a localhost otelcol sidecar in that container handles retry, queueing, and fan-out to every configured provider, Dash0 included. See Telemetry overview for the full architecture, and src/otel_collector.py for the config builder.

Troubleshooting

Secrets not found

Verify the secrets exist in Infisical:

set -a && source .env.local && set +a
infisical secrets get DASH0_AUTH_TOKEN --env=prod \
  --projectId "$INFISICAL_PROJECT_ID" \
  --token "$INFISICAL_TOKEN"

Collector not starting

Check the Modal logs for the otel-collector app:

set -a && source .env.local && set +a
infisical run --projectId "$INFISICAL_PROJECT_ID" --token "$INFISICAL_TOKEN" \
  --env=prod -- uv run modal app logs otel-collector

Look for errors like “exporters config: *conf.ExportersConfig.Validate()…”, which indicate a config build error.

No telemetry in Dash0

Verify the collector is running: uv run modal serve src/otel_collector.py
Check Modal logs for export errors
Verify the OTLP endpoint is reachable from the collector container
Check that the Bearer token is valid

Mixing Dash0 with other providers

You can enable multiple providers simultaneously — the collector fans out to all configured exporters:

# These don't conflict; all three will export
DASH0_AUTH_TOKEN=...
HYPERDX_API_KEY=...
LOGFIRE_WRITE_TOKEN=...

Reference

Dash0 docs
OpenTelemetry Collector OTLPHTTP exporter
src/otel_collector.py — collector app and config builder
libs/telemetry.py — app-side telemetry initialization

Get started

Concepts

Telemetry

Contributing

Changelog

Send gtm-sdk telemetry to Dash0 with the otel-collector

Endpoints

Setup

How Dash0 fits into the collector

Troubleshooting

Reference

​Endpoints

​Setup

​How Dash0 fits into the collector

​Troubleshooting

​Reference

Endpoints

Setup

How Dash0 fits into the collector

Troubleshooting

Reference