Re-order the default credential providers

The EC2 provider uniquely has to make network requests even when not configured to determine failure,
whereas all the other providers can quickly fail due to missing config. This generates delay and
log noise when using one of the providers listed after EC2. Reordering them should continue to be
fast for all providers including EC2, and improve the performance for eks and web_identity.

Author: ry4n1m3

README.md

@@ -10,9 +10,9 @@ sources in the following default order:
 2. OS environment variables
 3. An AWS [credentials file][1]
 4. ECS task credentials
-5. EC2 metadata
-6. EKS Pod Identity
-7. Web Identity
+5. EKS Pod Identity
+6. Web Identity
+7. EC2 metadata
 
 Usage
 -----

src/aws_credentials_provider.erl

@@ -35,9 +35,9 @@
 -type provider() :: aws_credentials_env
                   | aws_credentials_file
                   | aws_credentials_ecs
-                  | aws_credentials_ec2
                   | aws_credentials_eks
                   | aws_credentials_web_identity
+                  | aws_credentials_ec2
                   | module().
 -type error_log() :: [{provider(), term()}].
 -export_type([ options/0, expiration/0, provider/0, error_log/0 ]).
@@ -50,9 +50,9 @@
 -define(DEFAULT_PROVIDERS, [aws_credentials_env,
                             aws_credentials_file,
                             aws_credentials_ecs,
-                            aws_credentials_ec2,
                             aws_credentials_eks,
-                            aws_credentials_web_identity]).
+                            aws_credentials_web_identity,
+                            aws_credentials_ec2]).
 
 -spec fetch() ->
         {ok, aws_credentials:credentials(), expiration()} |