depths 0.1.1

S3-native observability layer

Depths

Unified, OTel-compatible, S3-native telemetry layer. Built by Depths AI.

Depths collects traces, logs, and metrics over OTLP HTTP, writes them into Delta Lake tables by UTC day, and can ship sealed days to S3. You get a simple CLI to boot the service, a tiny query API, and a clean Python surface for programmatic ingest and reads.

Docs live at https://docs.depthsai.com.

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Why Depths

• OTel first – accept standard OTLP JSON today, add protobuf by installing an extra
• Delta Lake tables by default – predictable schema across six OTel tables
• S3 native – seal a past UTC day, upload, verify rowcounts, then clean local state
• Polars inside – fast typed DataFrames and LazyFrames for compact reads
• Simple to start – depths init then depths start

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Install

# core (JSON ingest)
pip install depths

# optional protobuf ingest (OTLP x-protobuf)
pip install "depths[proto]"

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Quick start

1) Initialize an instance

depths init

This lays out ./depths_data/default with configs, index, and day staging dirs.

2) Start the OTLP HTTP server

# foreground
depths start -F

# or background
depths start

This triggers a FastAPI+uvicorn server. By default the host address is 0.0.0.0 and port 4318. Moreover, it picks up the default instance created during init.

You can also customize that by doing:

depths start -F -I default -H 0.0.0.0 -P 4318 

The server exposes:

• OTLP ingest: POST /v1/traces, POST /v1/logs, POST /v1/metrics
• Health: GET /healthz
• Simple reads: GET /api/spans, GET /api/logs, GET /api/metrics_points, GET /api/metrics_hist

3) Point your SDK or Collector

Most OTLP HTTP exporters default to port 4318. Example cURL for JSON:

curl -X POST http://localhost:4318/v1/logs \
  -H 'content-type: application/json' \
  -d '{"resourceLogs":[{"resource":{"attributes":[{"key":"service.name","value":{"stringValue":"demo"}}]},"scopeLogs":[{"scope":{},"logRecords":[{"timeUnixNano":"1710000000000000000","body":{"stringValue":"hello depths"}}]}]}]}'

If you installed the protobuf extra, you can send application/x-protobuf too.

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Reading your data

Depths builds one Delta table per OTel family under a day root:

<instance_root>/staging/days/<YYYY-MM-DD>/otel/
  spans/
  span_events/
  span_links/
  logs/
  metrics_points/
  metrics_hist/

Quick reads over HTTP

Each endpoint accepts useful filters and returns JSON rows.

# last 100 logs with severity >= 9 that contain "error"
curl 'http://localhost:4318/api/logs?severity_ge=9&body_like=error&max_rows=100'

# spans for a trace
curl 'http://localhost:4318/api/spans?trace_id=<traceidhex>&max_rows=100'

Programmatic reads in Python

from depths.core.logger import DepthsLogger

logger = DepthsLogger(instance_id="default", instance_dir="./depths_data")
results = logger.read_logs(body_like="timeout", max_rows=50)     
print(rows[:3])

You can also read spans, metric points, and metric histograms with the matching helpers.

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S3 shipping

Turn on shipping and the background worker will seal completed days and upload them to S3, then verify remote rowcounts and clean the local day on a match.

S3 is configured from environment variables. See the docs for the full list and examples. A typical flow is:

1. Run with S3 configured in the environment
2. Depths rolls over at UTC midnight and enqueues yesterday for shipping
3. Shipper seals each Delta table, uploads, verifies, and cleans the local day

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Architecture at a glance

• DepthsLogger – one place that ties everything together. Owns the instance layout, one Producer and one Aggregator per table, rollover at UTC midnight, a small background shipper, and reader helpers.
• OTLP Mapper – shapes decoded OTLP JSON into six row types. Handles timestamp selection, resource and scope attributes, and consistent ID normalization.
• Producer – validates, normalizes, and buffers rows against the table schema. Backpressure policy is configurable.
• Aggregator – drains the producer queue and appends typed DataFrames to Delta tables based on quiet time, age, and near full triggers.
• Delta helpers – predictable create, insert, upsert, delete, optimize, checkpoint, vacuum, and read with Polars and delta-rs.
• Shipper – seal a finished day, upload to S3 in a Delta-safe order, verify rowcounts, and clean up.

Everything is typed with Polars schemas that match OpenTelemetry naming, with stable UTC semantics.

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Configuration

• Instance identity and data dir come from DEPTHS_INSTANCE_ID and DEPTHS_INSTANCE_DIR when launched by the CLI.
• S3 configuration is read from environment variables.
• Runtime knobs such as queue sizes, flush triggers, and shipper timeouts live in the options objects.

See https://docs.depthsai.com for the complete reference and examples.

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Development notes

• Package import is depths and can be installed with the protobuf extra using depths[proto].
• The service lives at depths.cli.app:app for uvicorn.
• CLI commands are available as depths init, depths start, and depths stop.

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Status

Version v0.1.0. Early but already useful for getting OTel data into Delta and S3 with a minimal footprint.

If you try it, tell us what worked and what did not. The best place to start is the docs: https://docs.depthsai.com.