---
title: Architecture & Terminology
metaTitle: "LGTM Stack vs OpenObserve - Architecture & Terminology"
description: "How Loki, Grafana, Tempo, and Mimir map to OpenObserve: architecture comparison, terminology reference, and protocol compatibility for LGTM migrations."
---

# Architecture & Terminology

## Architecture: LGTM vs OpenObserve

### Before — LGTM Stack

![LGTM Stack telemetry flow](../../images/migration/lgtm/grafana-stack.png)

**Components to operate: 6+** — Collector + Loki + Mimir + Tempo + Grafana + object storage (often with MinIO or separate S3 buckets per component). Each has its own Helm chart, config format, scaling knobs, and upgrade path.

### After — OpenObserve

![OpenObserve Stack telemetry flow](../../images/migration/lgtm/openobserve-stack.png)

**Components to operate: 2** — Collector + OpenObserve. One Helm chart, one config, one storage backend, one upgrade path.


### What Changes and What Doesn't

The important thing to understand: **your data collection layer stays the same**. The applications, exporters, and agents that generate telemetry don't know or care whether the data ends up in Loki or OpenObserve. Only the destination endpoints change.

| Layer | Changes? | Details |
|---|---|---|
| Applications (your code) | No | OTel SDKs, Prometheus client libraries — unchanged |
| Exporters (node_exporter, cAdvisor, etc.) | No | They expose metrics, they don't care who scrapes |
| Collector (OTel Collector, Alloy, Telegraf) | Config only | Swap exporter endpoints, same receivers and processors |
| Backend (Loki/Mimir/Tempo) | Replaced | By OpenObserve |
| Visualization (Grafana) | Replaced | By OpenObserve's built-in UI |

---

## Terminology Mapping

If you're coming from the LGTM stack, most concepts have direct equivalents in OpenObserve. The mapping isn't always 1:1 — some things are simpler in OpenObserve because there's less to name when everything lives in one system.

### Concepts

| LGTM Stack Concept | OpenObserve Equivalent | Notes |
|---|---|---|
| Data Source | Data Source | Same concept — where telemetry originates (apps, infra, cloud) |
| Loki (log backend) | Logs (built-in) | Logs are a stream type in OpenObserve, not a separate system |
| Mimir (metrics backend) | Metrics (built-in) | Metrics are a stream type in OpenObserve |
| Tempo (trace backend) | Traces (built-in) | Traces are a stream type in OpenObserve |
| Grafana (visualization) | OpenObserve UI (built-in) | Dashboards, exploration, alerting — all in one UI |
| Stream (Loki log stream) | Stream | Same concept — a named flow of data. OpenObserve uses streams for logs, metrics, and traces |
| Label (Loki/Prometheus) | Field / Column | In Loki, labels are indexed keys. In OpenObserve, every field is queryable via SQL |
| LogQL | SQL | OpenObserve uses SQL for log queries (with functions like `match_all()`, `re_match()`) |
| PromQL | PromQL | Same — OpenObserve supports PromQL for metrics queries |
| TraceQL | SQL | OpenObserve uses SQL for trace queries |
| Alertmanager | OpenObserve Alerts | Built-in alerting with Slack, email, PagerDuty, webhook support |
| Tenant / Org (Mimir multi-tenancy) | Organization | OpenObserve uses orgs for multi-tenancy (default org is `default`) |
| Grafana Agent / Alloy | OpenObserve Collector (optional) | OTel-based collector optimized for OpenObserve. Or keep using any OTel-compatible collector |
| Promtail | No equivalent needed | Replace with OTel Collector or Fluent Bit — Promtail is Loki-specific |
| Chunk Store (Loki) | Apache Parquet files | OpenObserve stores data as columnar Parquet files in object storage |
| TSDB blocks (Mimir) | Apache Parquet files | Same — unified columnar storage for all signal types |
| Grafana Dashboard | OpenObserve Dashboard | Built-in drag-and-drop dashboard builder with 18+ chart types |

### Protocol Compatibility

The key insight for migration: **OpenObserve speaks the same ingestion protocols your data sources already use**. You're not changing how data is collected — just where it's sent.

| Protocol | LGTM Endpoint | OpenObserve Endpoint |
|---|---|---|
| Prometheus Remote Write | `http://mimir:9009/api/v1/push` | `http://openobserve:5080/api/default/prometheus/api/v1/write` |
| OTLP HTTP | `http://tempo:4318` | `http://openobserve:5080/api/default/` |
| OTLP gRPC | `tempo:4317` | `openobserve:5081` |
| Loki Push API | `http://loki:3100/loki/api/v1/push` | `http://openobserve:5080/api/{org}/loki/api/v1/push` |
| JSON over HTTP | N/A | `http://openobserve:5080/api/default/<stream>/_json` |

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## Next Steps

- [Migrating Metrics](metrics.md) — start with metrics, the simplest endpoint swap
- [Migrating Traces](traces.md) — usually the easiest signal since most setups already use OTLP
- [Migrating Logs](logs.md) — migrate log sources from Loki

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[Back to Overview](index.md) | Next: [Migrating Metrics](metrics.md)