Add tag command

by splitting out the code from buildpackage

This is shorter than running

     gbp buildpackage --git-tag-only

Closes: #797086

13 files changed, 483 insertions, 63 deletions

diff --git a/debian/git-buildpackage.install b/debian/git-buildpackage.install
index 0989806c..4ed4cc74 100644
--- a/debian/git-buildpackage.install
+++ b/debian/git-buildpackage.install
@@ -30,6 +30,7 @@ usr/lib/python3.?/dist-packages/gbp/scripts/pristine_tar.py usr/lib/python3/dist
 usr/lib/python3.?/dist-packages/gbp/scripts/pull.py usr/lib/python3/dist-packages/gbp/scripts/
 usr/lib/python3.?/dist-packages/gbp/scripts/push.py usr/lib/python3/dist-packages/gbp/scripts/
 usr/lib/python3.?/dist-packages/gbp/scripts/supercommand.py usr/lib/python3/dist-packages/gbp/scripts/
+usr/lib/python3.?/dist-packages/gbp/scripts/tag.py usr/lib/python3/dist-packages/gbp/scripts/
 usr/lib/python3.?/dist-packages/gbp/tmpfile.py usr/lib/python3/dist-packages/gbp/
 usr/lib/python3.?/dist-packages/gbp/tristate.py usr/lib/python3/dist-packages/gbp/
 usr/lib/python3.?/dist-packages/gbp/version.py usr/lib/python3/dist-packages/gbp/
diff --git a/debian/git-buildpackage.manpages b/debian/git-buildpackage.manpages
index 73ea6b1f..60f37624 100644
--- a/debian/git-buildpackage.manpages
+++ b/debian/git-buildpackage.manpages
@@ -13,4 +13,5 @@ docs/gbp-pq.1
 docs/gbp-pristine-tar.1
 docs/gbp-pull.1
 docs/gbp-push.1
+docs/gbp-tag.1
 docs/git-pbuilder.1
diff --git a/docs/Makefile b/docs/Makefile
index 6ad326a3..4fdbecee 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -15,6 +15,7 @@ MAN1S = \
         gbp-pristine-tar  \
         gbp-pull          \
         gbp-push          \
+        gbp-tag           \
         gbp-buildpackage-rpm \
         gbp-import-srpm   \
         gbp-pq-rpm        \
diff --git a/docs/common.ent b/docs/common.ent
index fd9f68cb..2e3d09b6 100644
--- a/docs/common.ent
+++ b/docs/common.ent
@@ -35,6 +35,7 @@
   <!ENTITY gbp-pull		"<command>gbp&nbsp;pull</command>">
   <!ENTITY gbp-push		"<command>gbp&nbsp;push</command>">
   <!ENTITY gbp-rpm-ch           "<command>gbp rpm-ch</command>">
+  <!ENTITY gbp-tag              "<command>gbp tag</command>">
   <!ENTITY gbp.conf		"<filename>gbp.conf</filename>">
   <!ENTITY git-pbuilder		"<command>git-pbuilder</command>">
   <!ENTITY git-qemubuilder	"<command>git-pbuilder</command>">
diff --git a/docs/man.gbp-tag.sgml b/docs/man.gbp-tag.sgml
new file mode 100644
index 00000000..e4c8dafd
--- /dev/null
+++ b/docs/man.gbp-tag.sgml
@@ -0,0 +1,11 @@
+<!DOCTYPE reference PUBLIC "-//OASIS//DTD DocBook V4.1//EN" [
+  <!ENTITY % COMMON SYSTEM "common.ent">
+  %COMMON;
+  <!ENTITY % MANPAGES SYSTEM "manpages/manpages.ent">
+  %MANPAGES;
+]>
+
+<reference>
+<title>git-buildpackage Manual</title>
+&man.gbp.tag;
+</reference>
diff --git a/docs/manpages/gbp-tag.sgml b/docs/manpages/gbp-tag.sgml
new file mode 100644
index 00000000..48504e2a
--- /dev/null
+++ b/docs/manpages/gbp-tag.sgml
@@ -0,0 +1,197 @@
+<refentry id="man.gbp.tag">
+  <refentryinfo>
+    <address>
+      &dhemail;
+    </address>
+    <author>
+      &dhfirstname;
+      &dhsurname;
+    </author>
+  </refentryinfo>
+  <refmeta><refentrytitle>gbp-tag</refentrytitle>
+    &dhsection;
+  </refmeta>
+  <refnamediv>
+    <refname>gbp-tag</refname>
+    <refpurpose>Tag a &debian; packages in a &git; repository</refpurpose>
+  </refnamediv>
+  <refsynopsisdiv>
+    <cmdsynopsis>
+      &gbp-tag;
+
+      &man.common.options.synopsis;
+      <arg><option>--ignore-branch</option></arg>
+      <arg><option>--[no-]ignore-new</option></arg>
+      <arg><option>--[no-]sign-tags</option></arg>
+      <arg><option>--keyid=</option><replaceable>GPG-KEYID</replaceable></arg>
+      <arg><option>--debian-branch=</option><replaceable>BRANCH_NAME</replaceable></arg>
+      <arg><option>--debian-tag=</option><replaceable>tag-format</replaceable></arg>
+      <arg><option>--debian-tag-msg=</option><replaceable>tag-msg-format</replaceable></arg>
+      <arg><option>--posttag=</option><replaceable>COMMAND</replaceable></arg>
+      <arg><option>--retag</option></arg>
+    </cmdsynopsis>
+  </refsynopsisdiv>
+  <refsect1>
+    <title>DESCRIPTION</title>
+    <para>
+      &gbp-tag; tags the current head commit appropriately. It will in order:
+    </para>
+    <itemizedlist>
+      <listitem>
+        <para>
+          Verify that it is being executed from the Debian branch.
+        </para>
+      </listitem>
+      <listitem>
+        <para>
+          Verify that the repository doesn't contain any uncommitted source
+          changes.
+        </para>
+      </listitem>
+      <listitem>
+        <para>
+	  Create a git tag using the information from <filename>debian/changelog</filename>.
+        </para>
+      </listitem>
+      <listitem>
+        <para>
+          (Optionally) call a post tag hook.
+        </para>
+      </listitem>
+    </itemizedlist>
+  </refsect1>
+  <refsect1>
+    <title>OPTIONS</title>
+    <variablelist>
+      &man.common.options.description;
+      <varlistentry>
+        <term><option>--posttag=</option><replaceable>COMMAND</replaceable>
+        </term>
+        <listitem>
+          <para>
+            Execute <replaceable>COMMAND</replaceable> after creating the tag.
+          </para>
+          <para>
+            Exported environment variables are: <envar>GBP_TAG</envar> (the name
+            of the generated tag), <envar>GBP_BRANCH</envar> (the branch the
+            package was build from) and <envar>GBP_SHA1</envar> (the sha1 of the
+            commit the tag was created at).
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--[no-]sign-tags</option>
+        </term>
+        <listitem>
+          <para>
+            GPG sign all created tags.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--keyid=</option><replaceable>GPG-KEYID</replaceable>
+        </term>
+        <listitem>
+          <para>
+            Use this keyid for gpg signing tags.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--debian-tag=</option><replaceable>TAG-FORMAT</replaceable>
+        </term>
+        <listitem>
+          <para>
+            Use this tag format when tagging &debian; versions, default is
+            <replaceable>debian/%(version)s</replaceable>.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--debian-tag-msg=</option><replaceable>tag-msg-format</replaceable>
+        </term>
+        <listitem>
+          <para>Use this tag message format when signing &debian; versions,
+            default is <replaceable>%(pkg)s Debian release %(version)s</replaceable></para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--retag</option>
+        </term>
+        <listitem>
+          <para>
+            Don't fail tag operations if a tag with the same version
+            already exists. This is a command line only option that
+            cannot be specified via &gbp.conf;.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--debian-branch</option>=<replaceable>BRANCH_NAME</replaceable>
+        </term>
+        <listitem>
+          <para>
+            If you're not on this branch when invoking &gbp-tag; it will
+            fail. Default is <replaceable>master</replaceable>. This is done to
+            make sure you don't accidentally tag on the wrong branch.  Not
+            being on this branch will be ignored when using
+            <option>--ignore-branch</option>.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--ignore-branch</option>
+        </term>
+        <listitem>
+          <para>
+            Don't check if the current branch matches
+            <replaceable>DEBIAN-BRANCH</replaceable>.
+          </para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><option>--[no-]ignore-new</option>
+        </term>
+        <listitem>
+          <para>
+            Don't abort if there are uncommitted changes in the source tree or
+            the current branch doesn't match the
+            <replaceable>DEBIAN-BRANCH</replaceable>.
+          </para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+  <refsect1>
+    <title>EXAMPLES</title>
+    <para>
+      Create a tag with the current defaults
+    </para>
+    <screen>
+      &gbp-tag;
+    </screen>
+    <para>
+      Create using a more upstreamish tag format:
+    </para>
+    <screen>
+      &gbp-tag; --debian-tag='v%(version)s'
+    </screen>
+  </refsect1>
+  <refsect1>
+    &man.gbp.config-files;
+  </refsect1>
+  <refsect1>
+    <title>SEE ALSO</title>
+    <para>
+      <xref linkend="man.gbp.buildpackage"/,
+      <xref linkend="man.gbp.push"/,
+      <xref linkend="man.gbp.conf"/,
+    </para>
+  </refsect1>
+  <refsect1>
+    <title>AUTHOR</title>
+    <para>
+      &dhusername; &dhemail;
+    </para>
+  </refsect1>
+</refentry>
diff --git a/docs/manpages/gbp.sgml b/docs/manpages/gbp.sgml
index eff89f25..1a3c8e93 100644
--- a/docs/manpages/gbp.sgml
+++ b/docs/manpages/gbp.sgml
@@ -155,17 +155,18 @@
     <title>SEE ALSO</title>
     <para>
       <xref linkend="man.gbp.buildpackage"/,
+      <xref linkend="man.gbp.clone"/,
+      <xref linkend="man.gbp.create.remote.repo"/,
+      <xref linkend="man.gbp.dch"/,
+      <xref linkend="man.gbp.export.orig"/,
       <xref linkend="man.gbp.import.dsc"/,
       <xref linkend="man.gbp.import.dscs"/,
       <xref linkend="man.gbp.import.orig"/,
-      <xref linkend="man.gbp.dch"/,
       <xref linkend="man.gbp.pq"/,
       <xref linkend="man.gbp.pristine.tar"/,
-      <xref linkend="man.gbp.export.orig"/,
-      <xref linkend="man.gbp.create.remote.repo"/,
       <xref linkend="man.gbp.pull"/,
       <xref linkend="man.gbp.push"/,
-      <xref linkend="man.gbp.clone"/,
+      <xref linkend="man.gbp.tag"/,
       <citerefentry>
         <refentrytitle>git-pbuilder</refentrytitle>
         <manvolnum>1</manvolnum>
diff --git a/docs/manpages/manpages.ent b/docs/manpages/manpages.ent
index 9415946a..29289684 100644
--- a/docs/manpages/manpages.ent
+++ b/docs/manpages/manpages.ent
@@ -1,23 +1,25 @@
-<!ENTITY man.gbp.importorig SYSTEM "gbp-import-orig.sgml">
-<!ENTITY man.gbp.importdsc SYSTEM "gbp-import-dsc.sgml">
-<!ENTITY man.gbp.importdscs SYSTEM "gbp-import-dscs.sgml">
+<!ENTITY man.gbp SYSTEM "gbp.sgml">
 <!ENTITY man.gbp.buildpackage SYSTEM "gbp-buildpackage.sgml">
+<!ENTITY man.gbp.buildpackage.rpm SYSTEM "gbp-buildpackage-rpm.sgml">
+<!ENTITY man.gbp.clone SYSTEM "gbp-clone.sgml">
+<!ENTITY man.gbp.conf SYSTEM "gbp.conf.sgml">
 <!ENTITY man.gbp.config SYSTEM "gbp-config.sgml">
+<!ENTITY man.gbp.config-files SYSTEM "man.conffiles.sgml">
+<!ENTITY man.gbp.create.remote.repo SYSTEM "gbp-create-remote-repo.sgml">
 <!ENTITY man.gbp.dch SYSTEM "gbp-dch.sgml">
 <!ENTITY man.gbp.exportorig SYSTEM "gbp-export-orig.sgml">
-<!ENTITY man.gbp SYSTEM "gbp.sgml">
+<!ENTITY man.gbp.import.srpm SYSTEM "gbp-import-srpm.sgml">
+<!ENTITY man.gbp.importdsc SYSTEM "gbp-import-dsc.sgml">
+<!ENTITY man.gbp.importdscs SYSTEM "gbp-import-dscs.sgml">
+<!ENTITY man.gbp.importorig SYSTEM "gbp-import-orig.sgml">
+<!ENTITY man.gbp.pq SYSTEM "gbp-pq.sgml">
+<!ENTITY man.gbp.pq.rpm SYSTEM "gbp-pq-rpm.sgml">
 <!ENTITY man.gbp.pristine.tar SYSTEM "gbp-pristine-tar.sgml">
 <!ENTITY man.gbp.pull SYSTEM "gbp-pull.sgml">
 <!ENTITY man.gbp.push SYSTEM "gbp-push.sgml">
-<!ENTITY man.gbp.clone SYSTEM "gbp-clone.sgml">
-<!ENTITY man.gbp.pq SYSTEM "gbp-pq.sgml">
-<!ENTITY man.gbp.create.remote.repo SYSTEM "gbp-create-remote-repo.sgml">
-<!ENTITY man.gbp.conf SYSTEM "gbp.conf.sgml">
-<!ENTITY man.gbp.config-files SYSTEM "man.conffiles.sgml">
-<!ENTITY man.seealso.common SYSTEM "man.seealso.sgml">
-<!ENTITY man.gbp.buildpackage.rpm SYSTEM "gbp-buildpackage-rpm.sgml">
-<!ENTITY man.gbp.import.srpm SYSTEM "gbp-import-srpm.sgml">
-<!ENTITY man.gbp.pq.rpm SYSTEM "gbp-pq-rpm.sgml">
 <!ENTITY man.gbp.rpm.ch SYSTEM "gbp-rpm-ch.sgml">
+<!ENTITY man.gbp.tag SYSTEM "gbp-tag.sgml">
+<!ENTITY man.seealso.common SYSTEM "man.seealso.sgml">
+
 <!ENTITY % COMMON.OPTIONS SYSTEM "man.common-options.ent">
 %COMMON.OPTIONS;
diff --git a/docs/manual.sgml b/docs/manual.sgml
index 35809ada..234e55dc 100644
--- a/docs/manual.sgml
+++ b/docs/manual.sgml
@@ -30,18 +30,19 @@
     <title>Command Reference</title>
     &man.gbp;
     &man.gbp.buildpackage;
+    &man.gbp.clone;
+    &man.gbp.config;
+    &man.gbp.create.remote.repo;
+    &man.gbp.dch;
+    &man.gbp.exportorig;
     &man.gbp.importdsc;
     &man.gbp.importdscs;
     &man.gbp.importorig;
-    &man.gbp.dch;
-    &man.gbp.clone;
-    &man.gbp.config;
+    &man.gbp.pq;
+    &man.gbp.pristine.tar;
     &man.gbp.pull;
     &man.gbp.push;
-    &man.gbp.pristine.tar;
-    &man.gbp.exportorig;
-    &man.gbp.pq;
-    &man.gbp.create.remote.repo;
+    &man.gbp.tag;
     &man.gbp.conf;
   </appendix>
   <appendix id="gbp.copyleft">
diff --git a/gbp/scripts/buildpackage.py b/gbp/scripts/buildpackage.py
index 356fcccf..7ffb5e95 100755
--- a/gbp/scripts/buildpackage.py
+++ b/gbp/scripts/buildpackage.py
@@ -31,11 +31,9 @@ from gbp.config import (GbpOptionParserDebian, GbpOptionGroup)
 from gbp.deb.git import (GitRepositoryError, DebianGitRepository)
 from gbp.deb.source import DebianSource, DebianSourceError, FileVfs
 from gbp.deb.format import DebianSourceFormat
-from gbp.format import format_str
 from gbp.git.vfs import GitVfs
 from gbp.deb.upstreamsource import DebianUpstreamSource
 from gbp.errors import GbpError
-from gbp.scripts.common.pq import is_pq_branch, pq_branch_base
 import gbp.log
 import gbp.notifications
 from gbp.scripts.common.buildpackage import (index_name, wc_name,
@@ -45,6 +43,7 @@ from gbp.scripts.common import ExitCodes
 from gbp.scripts.common.hook import Hook
 
 from gbp.scripts.export_orig import prepare_upstream_tarballs
+from gbp.scripts.tag import perform_tagging
 
 
 def pristine_tar_commit(repo, source, options, output_dir, orig_file, upstream_tree):
@@ -196,27 +195,6 @@ def check_tag(options, repo, source):
             raise GbpError("Tag '%s' already exists" % tag)
 
 
-def create_debian_tag(repo, source, commit, options):
-    """
-    Create the debian tag
-
-    returns: the created tag
-    """
-    tag = repo.version_to_tag(options.debian_tag, source.version)
-    gbp.log.info("Tagging %s as %s" % (source.version, tag))
-    if options.retag and repo.has_tag(tag):
-        repo.delete_tag(tag)
-    tag_msg = format_str(options.debian_tag_msg,
-                         dict(pkg=source.sourcepkg,
-                              version=source.version))
-    repo.create_tag(name=tag,
-                    msg=tag_msg,
-                    sign=options.sign_tags,
-                    commit=commit,
-                    keyid=options.keyid)
-    return tag
-
-
 def get_pbuilder_dist(options, repo, native=False):
     """
     Determin the dist to build for with pbuilder/cowbuilder
@@ -487,7 +465,6 @@ def main(argv):
     retval = 0
     prefix = "git-"
     source = None
-    branch = None
     hook_env = {}
 
     options, gbp_args, dpkg_args = parse_args(argv, prefix)
@@ -503,8 +480,7 @@ def main(argv):
 
     try:
         clean_working_tree(options, repo)
-        branch = check_branch(repo, options)
-        head = repo.head
+        check_branch(repo, options)
         tree = maybe_write_tree(repo, options)
         source = source_vfs(repo, options, tree)
 
@@ -575,20 +551,8 @@ def main(argv):
                                         'GBP_BUILD_DIR': build_dir})
                      )()
         if options.tag or options.tag_only:
-            if branch and is_pq_branch(branch):
-                commit = repo.get_merge_base(branch, pq_branch_base(branch))
-            else:
-                commit = head
+            perform_tagging(repo, source, options, hook_env)
 
-            tag = create_debian_tag(repo, source, commit, options)
-            if options.posttag:
-                sha = repo.rev_parse("%s^{}" % tag)
-                Hook('Posttag', options.posttag,
-                     extra_env=Hook.md(hook_env,
-                                       {'GBP_TAG': tag,
-                                        'GBP_BRANCH': branch or '(no branch)',
-                                        'GBP_SHA1': sha})
-                     )()
     except KeyboardInterrupt:
         retval = 1
         gbp.log.err("Interrupted. Aborting.")
diff --git a/gbp/scripts/tag.py b/gbp/scripts/tag.py
new file mode 100755
index 00000000..7cc93dab
--- /dev/null
+++ b/gbp/scripts/tag.py
@@ -0,0 +1,161 @@
+#!/usr/bin/python3
+# vim: set fileencoding=utf-8 :
+#
+# (C) 2017 Guido Günther <agx@sigxcpu.org>
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 2 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program; if not, please see
+#    <http://www.gnu.org/licenses/>
+"""Create a Debian tag"""
+
+import os
+import sys
+
+import gbp.log
+from gbp.format import format_str
+from gbp.config import GbpOptionParserDebian
+from gbp.deb.git import DebianGitRepository, GitRepositoryError
+from gbp.deb.source import DebianSourceError
+from gbp.deb.source import DebianSource
+from gbp.errors import GbpError
+
+from gbp.scripts.common import ExitCodes
+from gbp.scripts.common.hook import Hook
+
+from gbp.scripts.common.pq import is_pq_branch, pq_branch_base
+
+
+def create_debian_tag(repo, source, commit, options):
+    """
+    Create the debian tag
+
+    returns: the created tag
+    """
+    tag = repo.version_to_tag(options.debian_tag, source.version)
+    gbp.log.info("Tagging %s as %s" % (source.version, tag))
+    if options.retag and repo.has_tag(tag):
+        repo.delete_tag(tag)
+    tag_msg = format_str(options.debian_tag_msg,
+                         dict(pkg=source.sourcepkg,
+                              version=source.version))
+    repo.create_tag(name=tag,
+                    msg=tag_msg,
+                    sign=options.sign_tags,
+                    commit=commit,
+                    keyid=options.keyid)
+    return tag
+
+
+def perform_tagging(repo, source, options, hook_env=None):
+    """
+    Perform the tagging
+
+    Select brach to tag, create tag and run hooks
+    """
+    branch = repo.branch
+    if branch and is_pq_branch(branch):
+        commit = repo.get_merge_base(branch, pq_branch_base(branch))
+    else:
+        commit = repo.head
+
+    tag = create_debian_tag(repo, source, commit, options)
+    if options.posttag:
+        sha = repo.rev_parse("%s^{}" % tag)
+        Hook('Posttag', options.posttag,
+             extra_env=Hook.md(hook_env or {},
+                               {'GBP_TAG': tag,
+                                'GBP_BRANCH': branch or '(no branch)',
+                                'GBP_SHA1': sha})
+             )()
+
+
+def build_parser(name):
+    try:
+        parser = GbpOptionParserDebian(command=os.path.basename(name),
+                                       usage='%prog [options]')
+    except GbpError as err:
+        gbp.log.err(err)
+        return None
+
+    parser.add_option("--retag", action="store_true", dest="retag", default=False,
+                      help="don't fail if the tag already exists")
+    parser.add_config_file_option(option_name="debian-branch",
+                                  dest="debian_branch")
+    parser.add_config_file_option(option_name="debian-tag",
+                                  dest="debian_tag")
+    parser.add_config_file_option(option_name="debian-tag-msg", dest="debian_tag_msg")
+    parser.add_boolean_config_file_option(option_name="sign-tags", dest="sign_tags")
+    parser.add_config_file_option(option_name="keyid", dest="keyid")
+    parser.add_config_file_option(option_name="posttag", dest="posttag",
+                                  help="hook run after a successful tag operation, "
+                                  "default is '%(posttag)s'")
+    parser.add_boolean_config_file_option(option_name="ignore-branch", dest="ignore_branch")
+    parser.add_boolean_config_file_option(option_name="ignore-new", dest="ignore_new")
+    parser.add_config_file_option(option_name="color", dest="color", type='tristate')
+    parser.add_config_file_option(option_name="color-scheme",
+                                  dest="color_scheme")
+    parser.add_option("--verbose", action="store_true", dest="verbose",
+                      default=False, help="verbose command execution")
+    return parser
+
+
+def parse_args(argv):
+    parser = build_parser(argv[0])
+    if not parser:
+        return None, None
+    return parser.parse_args(argv)
+
+
+def main(argv):
+    retval = 1
+
+    (options, args) = parse_args(argv)
+    if not options:
+        return ExitCodes.parse_error
+
+    gbp.log.setup(options.color, options.verbose, options.color_scheme)
+    try:
+        repo = DebianGitRepository(os.path.curdir, toplevel=False)
+    except GitRepositoryError:
+        gbp.log.err("%s is not inside a git repository" % (os.path.abspath('.')))
+        return 1
+
+    try:
+        source = DebianSource(repo.path)
+        if not (options.ignore_branch or options.ignore_new):
+            if repo.branch != options.debian_branch:
+                gbp.log.err("You are not on branch '%s' but on '%s'"
+                            % (options.debian_branch,
+                               repo.branch or 'no branch'))
+                raise GbpError("Use --ignore-branch to ignore or "
+                               "--debian-branch to set the branch name.")
+
+        if not options.ignore_new:
+            (ret, out) = repo.is_clean()
+            if not ret:
+                gbp.log.err("You have uncommitted changes in your source tree:")
+                gbp.log.err(out)
+                raise GbpError("Use --ignore-new to ignore.")
+
+        perform_tagging(repo, source, options)
+        retval = 0
+    except (GbpError, GitRepositoryError, DebianSourceError) as err:
+        if str(err):
+            gbp.log.err(err)
+
+    return retval
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
+
+# vim:et:ts=4:sw=4:et:sts=4:ai:set list listchars=tab\:»·,trail\:·:
diff --git a/packaging/git-buildpackage.spec b/packaging/git-buildpackage.spec
index 045688c5..f9f36824 100644
--- a/packaging/git-buildpackage.spec
+++ b/packaging/git-buildpackage.spec
@@ -227,6 +227,7 @@ done
 %{python_sitelib}/gbp/scripts/pull.py*
 %{python_sitelib}/gbp/scripts/push.py*
 %{python_sitelib}/gbp/scripts/supercommand.py*
+%{python_sitelib}/gbp/scripts/tag.py*
 %{python_sitelib}/gbp/scripts/common/*.py*
 %{python_sitelib}/gbp/git/*.py*
 %{python_sitelib}/gbp/pkg/*.py*
@@ -238,6 +239,7 @@ done
 %{_mandir}/man1/gbp-pristine-tar.1*
 %{_mandir}/man1/gbp-pull.1*
 %{_mandir}/man1/gbp-push.1*
+%{_mandir}/man1/gbp-tag.1*
 %{_mandir}/man5/*.5*
 %endif
 
diff --git a/tests/component/deb/test_tag.py b/tests/component/deb/test_tag.py
new file mode 100644
index 00000000..f56dabb3
--- /dev/null
+++ b/tests/component/deb/test_tag.py
@@ -0,0 +1,77 @@
+# vim: set fileencoding=utf-8 :
+#
+# (C) 2015-2017 Guido Günther <agx@sigxcpu.org>
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 2 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program; if not, please see
+#    <http://www.gnu.org/licenses/>
+
+import os
+
+from tests.component import ComponentTestBase
+from tests.component.deb import DEB_TEST_DATA_DIR
+from tests.component.deb.fixtures import RepoFixtures
+
+from nose.tools import ok_, eq_
+
+from gbp.scripts.tag import main as tag
+from gbp.scripts.pq import main as pq
+
+
+class TestTag(ComponentTestBase):
+    """Test tagging a debian package"""
+
+    @staticmethod
+    def _dsc_name(pkg, version, dir):
+        return os.path.join(DEB_TEST_DATA_DIR,
+                            dir,
+                            '%s_%s.dsc' % (pkg, version))
+
+    @RepoFixtures.native()
+    def test_tag(self, repo):
+        """Test that tagging a native debian package works"""
+        repo.delete_tag('debian/0.4.14')  # make sure we can tag again
+        eq_(repo.has_tag('debian/0.4.14'), False)
+        ret = tag(['arg0',
+                   '--posttag=printenv > posttag.out'])
+        ok_(ret == 0, "Tagging the package failed")
+        eq_(os.path.exists('posttag.out'), True)
+        self.check_hook_vars('posttag', [("GBP_TAG", "debian/0.4.14"),
+                                         ("GBP_BRANCH", "master"),
+                                         "GBP_SHA1"])
+        eq_(repo.head, repo.rev_parse('debian/0.4.14^{}'))
+
+    @RepoFixtures.quilt30()
+    def test_tag_pq_branch(self, repo):
+        ret = pq(['argv0', 'import'])
+        eq_(repo.rev_parse('master'), repo.rev_parse('debian/2.8-1^{}'))
+        eq_(ret, 0)
+        eq_(repo.branch, 'patch-queue/master')
+        self.add_file(repo, 'foo.txt')
+        ret = tag(['argv0', '--retag', '--ignore-branch'])
+        eq_(ret, 0)
+        eq_(repo.branch, 'patch-queue/master')
+        eq_(repo.rev_parse('patch-queue/master^{}^'), repo.rev_parse('debian/2.8-1^{}'))
+
+    @RepoFixtures.quilt30()
+    def test_tag_detached_head(self, repo):
+        """
+        Test that tagging works with an detached head (#863167)
+        """
+        eq_(repo.rev_parse('master^{}'), repo.rev_parse('debian/2.8-1^{}'))
+        self.add_file(repo, 'debian/foo.txt')
+        repo.checkout("HEAD~")
+        ret = tag(['argv0', '--retag', '--ignore-branch'])
+        eq_(ret, 0)
+        repo.checkout("master")
+        eq_(repo.rev_parse('master~^{}'), repo.rev_parse('debian/2.8-1^{}'))