support for credential providers. (#518)

Minio.Examples/Cases/ChainedCredentialProvider.cs

@@ -0,0 +1,56 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+using System;
+using System.Threading.Tasks;
+
+using Minio.Credentials;
+using Minio.DataModel;
+using Minio.Exceptions;
+
+namespace Minio.Examples.Cases
+{
+    public class ChainedCredentialProvider
+    {
+        // Establish Credentials with AWS Session token
+        public async static Task Run()
+        {
+            ChainedProvider provider = new ChainedProvider()
+                                                .AddProviders(new ClientProvider[]{new AWSEnvironmentProvider(), new MinioEnvironmentProvider()});
+            //Chained provider definition here.
+            MinioClient minioClient = new MinioClient()
+                                                .WithEndpoint("s3.amazonaws.com")
+                                                .WithSSL()
+                                                .WithCredentialsProvider(provider)
+                                                .Build();
+            try
+            {
+                StatObjectArgs statObjectArgs = new StatObjectArgs()
+                                                            .WithBucket("my-bucket-name")
+                                                            .WithObject("my-object-name");
+                ObjectStat result = await minioClient.StatObjectAsync(statObjectArgs);
+            }
+            catch (MinioException me)
+            {
+                Console.WriteLine($"[Bucket] ChainedCredentialProvider example case encountered Exception: {me}");
+            }
+            catch (Exception e)
+            {
+                Console.WriteLine($"[Bucket] ChainedCredentialProvider example case encountered Exception: {e}");
+            }
+        }
+    }
+}

Minio/Credentials/AWSEnvironmentProvider.cs

@@ -0,0 +1,58 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+using System.Threading.Tasks;
+using Minio.DataModel;
+
+namespace Minio.Credentials
+{
+    public class AWSEnvironmentProvider : EnvironmentProvider
+    {
+        public override AccessCredentials GetCredentials()
+        {
+            AccessCredentials credentials = new AccessCredentials(GetAccessKey(), GetSecretKey(), GetEnvironmentVariable("AWS_SESSION_TOKEN"), default(DateTime));
+            return credentials;
+        }
+
+        public override Task<AccessCredentials> GetCredentialsAsync()
+        {
+            throw new InvalidOperationException("Please use the non-async function GetCredentials()");
+        }
+
+        protected string GetAccessKey()
+        {
+            string accessKey = Environment.GetEnvironmentVariable("AWS_ACCESS_KEY_ID");
+            if (string.IsNullOrEmpty(accessKey) || string.IsNullOrWhiteSpace(accessKey))
+            {
+                accessKey = Environment.GetEnvironmentVariable("AWS_ACCESS_KEY");
+            }
+            return accessKey;
+        }
+
+        protected string GetSecretKey()
+        {
+            string secretKey = Environment.GetEnvironmentVariable("AWS_SECRET_ACCESS_KEY");
+            if (string.IsNullOrEmpty(secretKey) || string.IsNullOrWhiteSpace(secretKey))
+            {
+                secretKey = Environment.GetEnvironmentVariable("AWS_SECRET_KEY");
+            }
+            return secretKey;
+        }
+
+    }
+}

Minio/Credentials/ChainedProvider.cs

@@ -0,0 +1,80 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Minio.DataModel;
+
+namespace Minio.Credentials
+{
+    public class ChainedProvider : ClientProvider
+    {
+        internal List<ClientProvider> Providers { get; set; }
+        internal ClientProvider CurrentProvider { get; set; }
+        internal AccessCredentials Credentials { get; set; }
+
+        public ChainedProvider()
+        {
+            this.Providers = new List<ClientProvider>();
+        }
+
+        public ChainedProvider AddProvider(ClientProvider provider)
+        {
+            this.Providers.Add(provider);
+            return this;
+        }
+
+        public ChainedProvider AddProviders(ClientProvider[] providers)
+        {
+            this.Providers.AddRange(providers.ToList());
+            return this;
+        }
+
+        public override AccessCredentials GetCredentials()
+        {
+            if (this.Credentials != null && !this.Credentials.AreExpired())
+            {
+                return this.Credentials;
+            }
+            if (this.CurrentProvider != null && !this.Credentials.AreExpired())
+            {
+                this.Credentials = this.CurrentProvider.GetCredentials();
+                return this.CurrentProvider.GetCredentials();
+            }
+            foreach (var provider in this.Providers)
+            {
+                var credentials = provider.GetCredentials();
+                if (credentials != null && !credentials.AreExpired())
+                {
+                    this.CurrentProvider = provider;
+                    this.Credentials = credentials;
+                    return credentials;
+                }
+            }
+            throw new InvalidOperationException("None of the assigned providers were able to provide valid credentials.");
+        }
+
+        public override async Task<AccessCredentials> GetCredentialsAsync()
+        {
+            AccessCredentials credentials = this.GetCredentials();
+            await Task.Yield();
+            return credentials;
+        }
+    }
+}

Minio/Credentials/EnvironmentProvider.cs

@@ -0,0 +1,29 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+
+namespace Minio.Credentials
+{
+    public abstract class EnvironmentProvider : ClientProvider
+    {
+        internal string GetEnvironmentVariable(string env)
+        {
+            return Environment.GetEnvironmentVariable(env);
+        }
+    }
+}

Minio/Credentials/IClientProvider.cs

@@ -0,0 +1,28 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.Threading.Tasks;
+using Minio.DataModel;
+
+namespace Minio.Credentials
+{
+    public abstract class ClientProvider
+    {
+        public abstract AccessCredentials GetCredentials();
+        public abstract Task<AccessCredentials> GetCredentialsAsync();
+    }   
+}

Minio/Credentials/MinioEnvironmentProvider.cs

@@ -0,0 +1,40 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+using System.Threading.Tasks;
+
+using Minio.DataModel;
+
+namespace Minio.Credentials
+{
+    public class MinioEnvironmentProvider : EnvironmentProvider
+    {
+        public override AccessCredentials GetCredentials()
+        {
+            AccessCredentials credentials = new AccessCredentials(GetEnvironmentVariable("MINIO_ACCESS_KEY"), GetEnvironmentVariable("MINIO_SECRET_KEY"), null, default(DateTime));
+            return credentials;
+        }
+
+        public override async Task<AccessCredentials> GetCredentialsAsync()
+        {
+            AccessCredentials credentials = this.GetCredentials();
+            await Task.Yield();
+            return credentials;
+        }
+    }
+}

Minio/DataModel/AccessCredentials.cs

@@ -0,0 +1,60 @@
+/*
+ * MinIO .NET Library for Amazon S3 Compatible Cloud Storage,
+ * (C) 2021 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System;
+using System.Xml.Serialization;
+
+namespace Minio.DataModel
+{
+    [Serializable]
+    [XmlRoot(ElementName = "Credentials")]
+    public class AccessCredentials
+    {
+        [XmlElement(ElementName = "AccessKeyId", IsNullable = true)]
+        public string AccessKey { get; set; }
+        [XmlElement(ElementName = "SecretAccessKey", IsNullable = true)]
+        public string SecretKey { get; set; }
+        [XmlElement(ElementName = "SessionToken", IsNullable = true)]
+        public string SessionToken { get; set; }
+        // Needs to be stored in ISO8601 format from Datetime
+        [XmlElement(ElementName = "Expiration", IsNullable = true)]
+        public string Expiration { get; set; }
+        public AccessCredentials(string accessKey, string secretKey,
+                            string sessionToken, DateTime expiration)
+        {
+            if (string.IsNullOrEmpty(accessKey) || string.IsNullOrEmpty(secretKey) ||
+                string.IsNullOrWhiteSpace(accessKey) || string.IsNullOrWhiteSpace(secretKey))
+            {
+                throw new ArgumentNullException(nameof(this.AccessKey) + " and " + nameof(this.SecretKey) + " cannot be null or empty.");
+            }
+            this.AccessKey = accessKey;
+            this.SecretKey = secretKey;
+            this.SessionToken = sessionToken;
+            this.Expiration = (expiration.Equals(default(DateTime)))?null:utils.To8601String(expiration);
+        }
+
+        public bool AreExpired()
+        {
+            if (string.IsNullOrEmpty(this.Expiration))
+            {
+                return false;
+            }
+            DateTime expiry = utils.From8601String(this.Expiration);
+            return DateTime.Now.CompareTo(expiry) > 0;
+        }
+    }
+}

Minio/DataModel/MinioClientBuilder.cs

@@ -17,6 +17,7 @@
 
 using System;
 using System.Net;
+using Minio.Credentials;
 using Minio.Exceptions;
 
 namespace Minio
@@ -144,7 +145,11 @@ public MinioClient Build()
             {
                 throw new MinioException("Endpoint not initialized.");
             }
-            if (string.IsNullOrEmpty(this.AccessKey) || string.IsNullOrEmpty(this.SecretKey) )
+            if (this.Provider != null && this.Provider.GetType() != (typeof(ChainedProvider)) && this.SessionToken == null)
+            {
+                throw new MinioException("User Access Credentials Provider not initialized correctly.");
+            }
+            if (this.Provider == null && (string.IsNullOrEmpty(this.AccessKey) || string.IsNullOrEmpty(this.SecretKey)))
             {
                 throw new MinioException("User Access Credentials not initialized.");
             }

Minio/Helper/utils.cs

@@ -880,5 +880,11 @@ public static string To8601String(DateTime dt)
         {
             return dt.ToString("yyyy-MM-dd'T'HH:mm:ssZ", CultureInfo.InvariantCulture);
         }
+
+        public static DateTime From8601String(string dt)
+        {
+            return DateTime.Parse(dt, null, System.Globalization.DateTimeStyles.RoundtripKind);
+        }
+
     }
 }