provider: Support multiple remote URLS

Signed-off-by: Fabian Mettler <fabian@mettler.cc>

Author: maveonair

docs/index.md

@@ -39,14 +39,14 @@ provider "incus" {
   default_remote               = "local"
 
   remote {
-    name    = "local"
-    address = "unix://"
+    name      = "local"
+    addresses = ["unix://"]
   }
 
   remote {
-    name    = "incus-server-2"
-    address = "https://10.1.2.8"
-    token   = "token"
+    name      = "incus-server-2"
+    addresses = ["https://10.1.2.8"]
+    token     = "token"
   }
 }
 ```
@@ -77,10 +77,10 @@ The following arguments are supported:
 
 The `remote` block supports:
 
-* `address` - *Optional* - The address of the Incus remote.
-
 * `name` - *Required* - The name of the Incus remote.
 
+* `addresses` - *Optional* - The addresses of the Incus remote. Multiple addresses can be provided for clustered remotes. If omitted, the provider uses the remote definition from the local Incus config.
+
 * `protocol` - *Optional* - The server protocol to use. Valid values are `incus`, `oci`, or `simplestreams`. Defaults to `incus`.
 
 * `credentials_helper` - *Optional* - Credential helper executable used for OCI registry authentication. Only valid when `protocol` is set to `oci`.
@@ -103,7 +103,7 @@ It is possible to define a single `remote` through environment variables.
 The required variables are:
 
 * `INCUS_REMOTE` - The name of the remote.
-* `INCUS_ADDR` - The address of the Incus remote.
+* `INCUS_ADDR` - The address of the Incus remote. Multiple addresses can be provided as a comma-separated string.
 * `INCUS_PROTOCOL` - The server protocol to use.
 * `INCUS_AUTHENTICATION_TYPE` - Server authentication type.
 * `INCUS_TOKEN` - The trust token of the Incus remote.