[flink] 03/03: [FLINK-14907] [filesystems] Add EnvironmentVariableKeyProvider for Azure Blob Storage

[se...@apache.org]

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commit 56cd59f47e31e58e112e260f0f4b43c45c1aa74a
Author: Konstantin Knauf <kn...@gmail.com>
AuthorDate: Fri Nov 29 16:20:29 2019 +0100

    [FLINK-14907] [filesystems] Add EnvironmentVariableKeyProvider for Azure Blob Storage
    
    Also updates the documentation on credential configuration for ABS
    
    This closes #10376
---
 docs/ops/filesystems/azure.md                      | 19 ++++++---
 .../fs/azurefs/EnvironmentVariableKeyProvider.java | 48 ++++++++++++++++++++++
 2 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/docs/ops/filesystems/azure.md b/docs/ops/filesystems/azure.md
index d721be5..d63c9d6 100644
--- a/docs/ops/filesystems/azure.md
+++ b/docs/ops/filesystems/azure.md
@@ -62,17 +62,24 @@ cp ./opt/flink-azure-fs-hadoop-{{ site.version }}.jar ./plugins/azure-fs-hadoop/
 
 `flink-azure-fs-hadoop` registers default FileSystem wrappers for URIs with the *wasb://* and *wasbs://* (SSL encrypted access) scheme.
 
-#### Configurations setup
-After setting up the Azure Blob Storage FileSystem wrapper, you need to configure credentials to make sure that Flink is allowed to access Azure Blob Storage.
+### Credentials Configuration
 
-To allow for easy adoption, you can use the same configuration keys in `flink-conf.yaml` as in Hadoop's `core-site.xml`
+Hadoop's Azure Filesystem supports configuration of credentials via the Hadoop configuration as 
+outlined in the [Hadoop Azure Blob Storage documentation](https://hadoop.apache.org/docs/current/hadoop-azure/index.html#Configuring_Credentials).
+For convenience Flink forwards all Flink configurations with a key prefix of `fs.azure` to the 
+Hadoop configuration of the filesystem. Consequentially, the azure blob storage key can be configured 
+in `flink-conf.yaml` via:
 
-You can see the configuration keys in the [Hadoop Azure Blob Storage documentation](https://hadoop.apache.org/docs/current/hadoop-azure/index.html#Configuring_Credentials).
+{% highlight yaml %}
+fs.azure.account.key.<account_name>.blob.core.windows.net: <azure_storage_key>
+{% endhighlight %}
 
-There are some required configurations that must be added to `flink-conf.yaml`:
+Alternatively, the the filesystem can be configured to read the Azure Blob Storage key from an 
+environment variable `AZURE_STORAGE_KEY` by setting the following configuration keys in 
+`flink-conf.yaml`.  
 
 {% highlight yaml %}
-fs.azure.account.key.youraccount.blob.core.windows.net: Azure Blob Storage access key
+fs.azure.account.keyprovider.<account_name>.blob.core.windows.net: org.apache.flink.fs.azurefs.EnvironmentVariableKeyProvider
 {% endhighlight %}
 
 {% top %}
diff --git a/flink-filesystems/flink-azure-fs-hadoop/src/main/java/org/apache/flink/fs/azurefs/EnvironmentVariableKeyProvider.java b/flink-filesystems/flink-azure-fs-hadoop/src/main/java/org/apache/flink/fs/azurefs/EnvironmentVariableKeyProvider.java
new file mode 100644
index 0000000..a7cd3fa
--- /dev/null
+++ b/flink-filesystems/flink-azure-fs-hadoop/src/main/java/org/apache/flink/fs/azurefs/EnvironmentVariableKeyProvider.java
@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+package org.apache.flink.fs.azurefs;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.azure.KeyProvider;
+import org.apache.hadoop.fs.azure.KeyProviderException;
+
+/**
+ * An implementation of {@link org.apache.hadoop.fs.azure.KeyProvider}, which reads the Azure
+ * storage key from an environment variable named "AZURE_STORAGE_KEY".
+ *
+ */
+public class EnvironmentVariableKeyProvider implements KeyProvider {
+
+	public static final String AZURE_STORAGE_KEY_ENV_VARIABLE = "AZURE_STORAGE_KEY";
+
+	@Override
+	public String getStorageAccountKey(
+			final String s,
+			final Configuration configuration) throws KeyProviderException {
+
+		String azureStorageKey = System.getenv(AZURE_STORAGE_KEY_ENV_VARIABLE);
+
+		if (azureStorageKey != null) {
+			return azureStorageKey;
+		} else {
+			throw new KeyProviderException("Unable to retrieve Azure storage key from environment. \""
+					+ AZURE_STORAGE_KEY_ENV_VARIABLE + "\" not set.");
+		}
+	}
+}