PYD-1399: Add environments documentation (#591)

Co-authored-by: ChristopherGS <chris@pydantic.dev>
Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>
Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>

docs/guides/advanced/index.md

@@ -4,3 +4,4 @@
 * **[Backfill](backfill.md):** Recover lost data and bulk load historical data into Logfire with the `logfire backfill` command, ensuring data continuity.
 * **[Creating Write Tokens](creating-write-tokens.md):** Generate and manage multiple write tokens for different services.
 * **[Using Read Tokens](query-api.md):** Generate and manage read tokens for programmatic querying of your Logfire data.
+* **[Using Environments](using-environments.md):** Group data between environments (e.g. dev, staging, prod) within a project.

docs/guides/advanced/using-environments.md

@@ -0,0 +1,54 @@
+As a developer, we find ourselves working on different environments for a project: local, production, sometimes staging, and depending on your company deployment strategy... You can have even more! 😅
+
+With **Logfire** you can distinguish which environment you are sending data to.
+You just need to set the `environment` parameter in [`logfire.configure()`][logfire.configure]
+
+    ```py title="main.py"
+    import logfire
+
+    logfire.configure(environment='local')  # (1)!
+    ```
+(1) Usually you would retrieve the environment information from an environment variable.
+
+Under the hood, this sets the OTel [`deployment.environment.name`](https://opentelemetry.io/docs/specs/semconv/resource/deployment-environment/).
+Note that you can also set this via the `LOGFIRE_ENVIRONMENT` environment variable.
+
+#### Setting environments in other languages
+
+If you are using languages other than Python, you can set the environment like this:
+`OTEL_RESOURCE_ATTRIBUTES="deployment.environment.name=prod"`
+
+---
+
+Once set, you will see your environment in the Logfire UI `all envs` dropdown, which appears
+on the [Live View](../web-ui/live.md), [Dashboards](../web-ui/dashboards.md) and [Explore](../web-ui/explore.md) pages:
+
+![Environments](../../images/guide/environments.png)
+
+Note that by default there are system generated environments:
+
+- `all envs`: Searches will include everything, including spans that had no environment set.
+- `not specified`: Searches will *only* include spans that had no environment set
+
+So `not specified` is a subset of `all envs`.
+
+Any environments you create via the SDK will appear below the system generated environments.
+When you select an environment, all subsequent queries (e.g. on live view, dashboards or explore)
+will filter by that environment.
+
+## Can I create an environment in the UI?
+
+No, you cannot create or delete set environments via the UI, instead use the SDK.
+
+## How do I delete an environment?
+
+Once an environment has been configured and received by logfire, technically it’s available for
+the length of the data retention period while that environment exists in the data.
+You can however add new ones, and change the configuration of which data is assigned to which
+environment name.
+
+## Should I use environments or projects?
+
+Environments are more lightweight than projects. Projects give you the ability to assign specific
+user groups and permissions levels (see this [organization structure diagram](../../reference/organization-structure.md)
+for details). So if you need to allow different team members to view dev vs. prod traces, then projects would be a better fit.

mkdocs.yml

@@ -93,6 +93,7 @@ nav:
           - SQL Explorer: guides/web-ui/explore.md
       - Advanced User Guide:
           - Advanced User Guide: guides/advanced/index.md
+          - Using Environments: guides/advanced/using-environments.md
           - Alternative Clients: guides/advanced/alternative-clients.md
           - Alternative Backends: guides/advanced/alternative-backends.md
           - Sampling: guides/advanced/sampling.md