Add support for extra publication metadata.

In particular this change adds support for OSSRH required metadata for
publishing to maven central.  An object is exposed for pantsbuild/pants
use that encapsulates the boilerplate common to all jars it will publish
to maven central and this object is used to prepare all publishable java
targets for maven central publishing.

Testing Done:
Local publishes and verification of most permutations of
OSSRHPublicationMetadata in the existing
JarPublishIntegrationTest#test_scala_publish test via new golden data.

CI went green here:
  https://travis-ci.org/pantsbuild/pants/builds/61845618

Bugs closed: 1411, 1511

Reviewed at https://rbcommons.com/s/twitter/r/2184/

pants-plugins/src/python/internal_backend/repositories/BUILD

@@ -7,6 +7,8 @@ python_library(
   dependencies = [
     'src/python/pants/base:build_file_aliases',
     'src/python/pants/base:build_manual',
+    'src/python/pants/backend/jvm:artifact',
+    'src/python/pants/backend/jvm:ossrh_publication_metadata',
     'src/python/pants/backend/jvm:repository',
   ]
 )

pants-plugins/src/python/internal_backend/repositories/register.py

@@ -7,6 +7,8 @@
 
 import os
 
+from pants.backend.jvm.ossrh_publication_metadata import (Developer, License,
+                                                          OSSRHPublicationMetadata, Scm)
 from pants.backend.jvm.repository import Repository
 from pants.base.build_file_aliases import BuildFileAliases
 from pants.base.build_manual import manual
@@ -21,6 +23,30 @@
                           push_db_basedir=os.path.join('testprojects', 'ivy', 'pushdb'))
 
 
+def org_pantsbuild_publication_metadata(description):
+  return OSSRHPublicationMetadata(
+    description=description,
+    url='http://pantsbuild.github.io/',
+    licenses=[
+      License(
+        name='Apache License, Version 2.0',
+        url='http://www.apache.org/licenses/LICENSE-2.0'
+      )
+    ],
+    developers=[
+      Developer(
+        name='The pants developers',
+        email='[email protected]',
+        url='https://github.com/pantsbuild/pants'
+      )
+    ],
+    scm=Scm.github(
+      user='pantsbuild',
+      repo='pants'
+    )
+  )
+
+
 # Your repositories don't need this manual.builddict magic.
 # It keeps these examples out of http://pantsbuild.github.io/build_dictionary.html
 manual.builddict(suppress=True)(public_repo)
@@ -32,5 +58,6 @@ def build_file_aliases():
     objects={
       'public': public_repo,  # key 'public' must match name='public' above
       'testing': testing_repo,
+      'pants_library': org_pantsbuild_publication_metadata
     },
   )

src/java/org/pantsbuild/args4j/BUILD

@@ -13,5 +13,8 @@ java_library(
     org='org.pantsbuild',
     name='args4j',
     repo=public,
+    publication_metadata=pants_library("""
+      Utilities to make args4j more like com.twitter.common#args
+    """)
   ),
 )

src/java/org/pantsbuild/junit/annotations/BUILD

@@ -7,6 +7,9 @@ java_library(
     org='org.pantsbuild',
     name='junit-runner-annotations',
     repo=public,
+    publication_metadata=pants_library("""
+      Annotations for use with org.pantsbuild#junit-runner that support running tests in parallel.
+    """)
   ),
   sources=globs('*.java')
 )

src/java/org/pantsbuild/tools/jar/BUILD

@@ -14,6 +14,9 @@ java_library(
     org='org.pantsbuild',
     name='jar-tool',
     repo=public,
+    publication_metadata=pants_library("""
+      A command line tool for creating jars given a set of rules.
+    """)
   ),
 )
 

src/java/org/pantsbuild/tools/junit/BUILD

@@ -7,6 +7,10 @@ java_library(
     org='org.pantsbuild',
     name='junit-runner',
     repo=public,
+    publication_metadata=pants_library("""
+      A command line tool for running junit tests that provides functionality above and beyond
+      that provided by org.junit.runner.JUnitCore.
+    """)
   ),
   dependencies=[
     '3rdparty:args4j',

src/java/org/pantsbuild/tools/junit/withretry/BUILD

@@ -7,6 +7,9 @@ java_library(
     org='org.pantsbuild',
     name='junit-runner-withretry',
     repo=public,
+    publication_metadata=pants_library("""
+      Provides an org.junit.runner.Runner that supports retries of failing tests.
+    """)
   ),
   dependencies=[
     '3rdparty:junit',

src/python/pants/backend/jvm/BUILD

@@ -3,20 +3,21 @@
 
 
 python_library(
-  name = 'artifact',
-  sources = ['artifact.py'],
-  dependencies = [
+  name='artifact',
+  sources=['artifact.py'],
+  dependencies=[
     '3rdparty/python:six',
     ':repository',
     'src/python/pants/base:payload_field',
   ],
 )
 
 python_library(
-  name = 'plugin',
-  sources = ['__init__.py', 'register.py'],
-  dependencies = [
+  name='plugin',
+  sources=['__init__.py', 'register.py'],
+  dependencies=[
     ':artifact',
+    ':ossrh_publication_metadata',
     ':repository',
     'src/python/pants/backend/core/tasks:group_task',
     'src/python/pants/backend/jvm/targets:all',
@@ -28,10 +29,10 @@ python_library(
 )
 
 python_library(
-  name = 'ivy_utils',
-  sources = ['ivy_utils.py'],
-  resources = globs('tasks/templates/ivy_resolve/*.mustache'),
-  dependencies = [
+  name='ivy_utils',
+  sources=['ivy_utils.py'],
+  resources=globs('tasks/templates/ivy_resolve/*.mustache'),
+  dependencies=[
     '3rdparty/python/twitter/commons:twitter.common.collections',
     'src/python/pants/backend/jvm/targets:jvm',
     'src/python/pants/base:build_environment',
@@ -45,6 +46,16 @@ python_library(
 )
 
 python_library(
-  name = 'repository',
-  sources = ['repository.py'],
+  name='repository',
+  sources=['repository.py'],
 )
+
+python_library(
+  name='ossrh_publication_metadata',
+  sources=['ossrh_publication_metadata.py'],
+  dependencies=[
+    '3rdparty/python:six',
+    ':artifact',
+    'src/python/pants/base:validation',
+  ],
+)

src/python/pants/backend/jvm/artifact.py

@@ -5,26 +5,28 @@
 from __future__ import (absolute_import, division, generators, nested_scopes, print_function,
                         unicode_literals, with_statement)
 
-from hashlib import sha1
-
 from six import string_types
 
 from pants.backend.jvm.repository import Repository
 from pants.base.payload_field import PayloadField, stable_json_sha1
 
 
+class PublicationMetadata(PayloadField):
+  """Extra metadata required to publish an artifact beyond its coordinates."""
+
+
 class Artifact(PayloadField):
-  """Represents a jvm artifact ala maven or ivy.
+  """Represents a publishable jvm artifact ala maven or ivy.
 
   Used in the ``provides`` parameter to *jvm*\_library targets.
   """
 
-  def __init__(self, org, name, repo, description=None):
+  def __init__(self, org, name, repo, publication_metadata=None):
     """
     :param string org: Organization of this artifact, or groupId in maven parlance.
     :param string name: Name of the artifact, or artifactId in maven parlance.
     :param repo: The ``repo`` this artifact is published to.
-    :param string description: Description of this artifact.
+    :param publication_metadata: Optional extra publication metadata required by the ``repo``.
     """
     if not isinstance(org, string_types):
       raise ValueError("org must be {} but was {}".format(string_types, org))
@@ -33,15 +35,15 @@ def __init__(self, org, name, repo, description=None):
     if not isinstance(repo, Repository):
       raise ValueError("repo must be an instance of Repository")
 
-    if description is not None and not isinstance(description, string_types):
-      raise ValueError("description must be None or {} but was {}"
-                       .format(string_types, description))
+    if (publication_metadata is not None
+        and not isinstance(publication_metadata, PublicationMetadata)):
+      raise ValueError("publication_metadata must be a {} but was a {}"
+                       .format(PublicationMetadata, type(publication_metadata)))
 
     self.org = org
     self.name = name
-    self.rev = None
     self.repo = repo
-    self.description = description
+    self.publication_metadata = publication_metadata
 
   def __eq__(self, other):
     return (type(other) == Artifact and
@@ -52,7 +54,18 @@ def __hash__(self):
     return hash((self.org, self.name))
 
   def _compute_fingerprint(self):
-    return stable_json_sha1((self.org, self.name, self.rev))
+    data = (self.org, self.name)
+
+    # NB: The None occupies the legacy rev 3rd slot.  The rev was never populated and always None,
+    # so maintaining the slot and its value just serve to preserve the fingerprint and thus
+    # containing targets in caches out in the world.
+    data += (None,)
+
+    if self.publication_metadata:
+      fingerprint = self.publication_metadata.fingerprint()
+      if fingerprint:
+        data += (fingerprint,)
+    return stable_json_sha1(data)
 
   def __ne__(self, other):
     return not self.__eq__(other)