env vars

docs/docs-beta/docs/guides/external-systems/apis.md

@@ -3,13 +3,15 @@ title: Connecting to APIs
 sidebar_position: 20
 ---
 
-This guide describes how to connect to and interact with APIs in dagster.
+This guide describes how to connect to and interact with APIs in dagster. In this guide you will use dagster Resources to connect to an external API. Using a Resource allows you to standardize how you connect to an external API across your project, use configuration to customize your connections, and use difference implementations of a Resource for different environments.
 
 
 ## What you'll learn
 
 - How to write a dagster Resource to connect to an API
 - How to use that Resource in an asset
+- How to configure a Resource
+- How to source configuration values from environment variables
 
 <details>
   <summary>Prerequisites</summary>
@@ -47,6 +49,13 @@ The configurable Resource written in Step 3 can be provided to an asset exactly
 
 <CodeExample filePath="guides/external-systems/apis/use_configurable_resource_in_asset.py" language="python" title="Use the configurable SunResource in an asset" />
 
+## Step 5: Sourcing configuration values from environment variables
+
+You can configure your Resource using values that are stored in environment variables using the `EnvVar` class. In this example, there is a new `home_sunrise` asset. Rather than hardcoding the location of your home, you can set it in environment variables, and configure the `SunResource` by reading those values:
+
+<CodeExample filePath="guides/external-systems/apis/env_var_configuration.py" language="python" title="Configure the Resource with values from environment variables" />
+
+
 ## Next steps
 
 - [Authenticate to a resource](/guides/external-systems/authentication.md)

examples/docs_beta_snippets/docs_beta_snippets/guides/external-systems/apis/env_var_configuration.py

@@ -0,0 +1,38 @@
+import requests
+
+import dagster as dg
+
+
+class SunResource(dg.ConfigurableResource):
+    latitude: float
+    longitude: float
+    time_zone: str
+
+    @property
+    def query_string(self) -> str:
+        return f"https://api.sunrise-sunset.org/json?lat={self.latitude}&lng={self.longitude}&date=today&tzid={self.time_zone}"
+
+    def sunrise(self) -> str:
+        data = requests.get(self.query_string, timeout=5).json()
+        return data["results"]["sunrise"]
+
+
+# highlight-start
+@dg.asset
+def home_sunrise(context: dg.AssetExecutionContext, sun_resource: SunResource) -> None:
+    sunrise = sun_resource.sunrise()
+    context.log.info(f"Sunrise at home is at {sunrise}.")
+
+
+defs = dg.Definitions(
+    assets=[home_sunrise],
+    resources={
+        "sun_resource": SunResource(
+            latitude=float(dg.EnvVar("HOME_LATITUDE")),
+            longitude=float(dg.EnvVar("HOME_LONGITUDE")),
+            time_zone=dg.EnvVar("HOME_TIMEZONE"),
+        )
+    },
+)
+
+# highlight-end