add cli and doc

Author: fabricebrito

bin/get-bearer-token

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+import click
+import requests
+
+def get_access_token(username: str, password: str) -> str:
+    data = {
+        "client_id": "cdse-public",
+        "username": username,
+        "password": password,
+        "grant_type": "password",
+    }
+    try:
+        r = requests.post(
+            "https://identity.dataspace.copernicus.eu/auth/realms/CDSE/protocol/openid-connect/token",
+            data=data,
+        )
+        r.raise_for_status()
+    except Exception as e:
+        raise Exception(
+            f"Access token creation failed. Response from the server was: {r.json()}"
+        )
+    return r.json()["access_token"]
+
+@click.command(
+    short_help="Get bearer token",
+    help="Get a bearer token for the Copernicus Data Space Ecosystem ",
+)
+@click.option(
+    "--username",
+    help="Username for the Copernicus Data Space Ecosystem",
+    required=True,
+)
+@click.option(
+    "--password",
+    help="Password for the Copernicus Data Space Ecosystem",
+    required=True,
+)
+def get_bearer_token(username: str, password: str) -> str:
+    
+    return print(get_access_token(username, password))
+
+if __name__ == "__main__":
+    get_bearer_token()

docs/app/stage-in/app.md

@@ -1 +1,4 @@
-# Stage-in
+# Sentinel-2 Level-1C stage-in
+
+While there are many options to consume Sentinel-2 Level-2A in a Cloud native processing approach, the Level-1C data must instead be staged from the Copernicus Data Space Ecosystem.
+