AWS Maven Wagon

This project is a Maven Wagon for Amazon S3. In order to to publish artifacts to an S3 bucket, the user (as identified by their access key) must be listed as an owner on the bucket.

Why this fork?

This fork's enhancement is the ability to customize the AWS credentials provider chain that is used to resolve credentials for the S3 bucket that hosts the Maven artifacts you deploy. The upstream version uses a default provider chain that includes an InstanceProfileCredentialsProvider that, in my opinion, just takes too darn long to realize it's not going to be able to resolve any credentials and should give up.

Usage

To publish Maven artifacts to S3 a build extension must be defined in a project's pom.xml. The latest version of the wagon can be found in the mvn-repo branch of this repository.

<project>
  ...
  <repositories>
    ...
    <repository>
      <id>mike10004-snapshots</id>
      <url>https://oss.sonatype.org/content/repositories/snapshots</url>
    </repository>
    ...
  </repositories>
  ...
  <build>
    ...
    <extensions>
      ...
      <extension>
        <groupId>com.github.mike10004</groupId>
        <artifactId>aws-maven</artifactId>
        <version>5.1.1</version>
      </extension>
      ...
    </extensions>
    ...
  </build>
  ...
</project>

Once the build extension is configured distribution management repositories can be defined in the pom.xml with an s3:// scheme.

<project>
  ...
  <distributionManagement>
    <repository>
      <id>aws-release</id>
      <name>AWS Release Repository</name>
      <url>s3://<BUCKET>/release</url>
    </repository>
    <snapshotRepository>
      <id>aws-snapshot</id>
      <name>AWS Snapshot Repository</name>
      <url>s3://<BUCKET>/snapshot</url>
    </snapshotRepository>
  </distributionManagement>
  ...
</project>

Finally the ~/.m2/settings.xml must be updated to include access and secret keys for the account. The access key should be used to populate the username element, and the secret access key should be used to populate the password element.

<settings>
  ...
  <servers>
    ...
    <server>
      <id>aws-release</id>
      <username>0123456789ABCDEFGHIJ</username>
      <password>0123456789abcdefghijklmnopqrstuvwxyzABCD</password>
    </server>
    <server>
      <id>aws-snapshot</id>
      <username>0123456789ABCDEFGHIJ</username>
      <password>0123456789abcdefghijklmnopqrstuvwxyzABCD</password>
    </server>
    ...
  </servers>
  ...
</settings>

Customizing the credentials provider chain

To authenticate in AWS so that you can deploy artifacts to your S3 bucket, the AWS SDK traverses a (credentials provider chain)[http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/AWSCredentialsProviderChain.html], which is a sequence of objects that may or may not be able to pass credentials along. By default, the chain checks environment variables, system properties, the EC2 Instance Metadata Service, and then the username and password you have specified for your repository in the <server> entry in ~/.m2/settings.xml.

To customize the credentials provider chain, edit that server entry in ~/.m2/settings.xml to include a <configuration><credentialsProviders> setting whose value is one or more of the following credentials provider specification tokens:

• EnvironmentVariable - use an (EnvironmentVariableCredentialsProvider)[http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/EnvironmentVariableCredentialsProvider.html] that checks AWS_ACCESS_KEY_ID and AWS_SECRET_KEY environment variables
• SystemProperties - use a (SystemPropertiesCredentialsProvider)[http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/SystemPropertiesCredentialsProvider.html] that checks the aws.accessKeyId and aws.secretKey Java system properties
• InstanceProfile - use an (InstanceProfileCredentialsProvider)[http://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/auth/InstanceProfileCredentialsProvider.html] that tries to load credentials from the Amazon EC2 Instance Metadata Service
• AuthenticationInfo - use an org.springframework.build.aws.maven.AuthenticationInfoAWSCredentialsProvider that gets credentials from the <server> username and password settings from ~/.m2/settings.xml

Delimit multiple tokens with commas. For example, if you only want to try providing credentials first through environment variables and next through authentication info, then the server entry would look like

<settings>
  ...
  <servers>
    ...
    <server>
      <id>aws-snapshot</id>
      <username>0123456789ABCDEFGHIJ</username>
      <password>0123456789abcdefghijklmnopqrstuvwxyzABCD</password>
      <configuration>
        <credentialsProviders>EnvironmentVariable,AuthenticationInfo</credentialsProviders>
      </configuration>
    </server>
    ...
  </servers>
  ...
</settings>

If you do not specify the credentials providers configuration element, then the default chain mentioned above will be used.

Making Artifacts Public

This wagon doesn't set an explict ACL for each artfact that is uploaded. Instead you should create an AWS Bucket Policy to set permissions on objects. A bucket policy can be set in the AWS Console and can be generated using the AWS Policy Generator.

In order to make the contents of a bucket public you need to add statements with the following details to your policy:

Effect	Principal	Action	Amazon Resource Name (ARN)
Allow	*	ListBucket	arn:aws:s3:::<BUCKET>
Allow	*	GetObject	arn:aws:s3:::<BUCKET>/*

If your policy is setup properly it should look something like:

{
  "Id": "Policy1397027253868",
  "Statement": [
    {
      "Sid": "Stmt1397027243665",
      "Action": [
        "s3:ListBucket"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:s3:::<BUCKET>",
      "Principal": {
        "AWS": [
          "*"
        ]
      }
    },
    {
      "Sid": "Stmt1397027177153",
      "Action": [
        "s3:GetObject"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:s3:::<BUCKET>/*",
      "Principal": {
        "AWS": [
          "*"
        ]
      }
    }
  ]
}

If you prefer to use the command line, you can use the following script to make the contents of a bucket public:

BUCKET=<BUCKET>
TIMESTAMP=$(date +%Y%m%d%H%M)
POLICY=$(cat<<EOF
{
  "Id": "public-read-policy-$TIMESTAMP",
  "Statement": [
    {
      "Sid": "list-bucket-$TIMESTAMP",
      "Action": [
        "s3:ListBucket"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:s3:::$BUCKET",
      "Principal": {
        "AWS": [
          "*"
        ]
      }
    },
    {
      "Sid": "get-object-$TIMESTAMP",
      "Action": [
        "s3:GetObject"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:s3:::$BUCKET/*",
      "Principal": {
        "AWS": [
          "*"
        ]
      }
    }
  ]
}
EOF
)

aws s3api put-bucket-policy --bucket $BUCKET --policy "$POLICY"