add with_sequence lookup plugin

Plugin allows you to do easy counts for items.

docsite/rst/playbooks2.rst

@@ -415,8 +415,8 @@ More Loops
 .. versionadded: 0.8
 
 Various 'lookup plugins' allow additional ways to iterate over data.  Ansible will have more of these
-over time.  In 0.8, the only lookup plugin that comes stock is 'with_fileglob', but you can also write
-your own.
+over time.  In 0.8, the only lookup plugins that comes stock are 'with_fileglob' and 'with_sequence', but
+you can also write your own.
 
 'with_fileglob' matches all files in a single directory, non-recursively, that match a pattern.  It can
 be used like this::
@@ -433,6 +433,52 @@ be used like this::
         - action: copy src=$item dest=/etc/fooapp/ owner=root mode=600
           with_fileglob: /playbooks/files/fooapp/*
 
+.. versionadded: 1.0
+
+'with_sequence' generates a sequence of items in ascending numerical order. You
+can specify a 'start', an 'end' value (inclusive), and a 'stride' value (to skip
+some numbers of values), and a printf-style 'format' string.  It accepts
+arguments both as key-value pairs and in a shortcut of the form
+"[start-]end[/stride][:format]".  All numerical values can be specified in
+hexadecimal (i.e. 0x3f8) or octal (i.e. 0644).  Negative numbers are not
+supported.  Here is an example that leverages most of its features::
+
+    ----
+    - hosts: all
+
+      tasks:
+
+        # create groups
+        - group: name=evens state=present
+
+        - group: name=odds state=present
+
+        # create 32 test users
+        - user: name=$item state=present groups=odds
+          with_sequence: 32/2:testuser%02x
+
+        - user: name=$item state=present groups=evens
+          with_sequence: 2-32/2:testuser%02x
+
+        # create a series of directories for some reason
+        - file: dest=/var/stuff/$item state=directory
+          with_sequence: start=4 end=16
+
+The key-value form also supports a 'count' option, which always generates
+'count' entries regardless of the stride. The count option is mostly useful for
+avoiding off-by-one errors and errors calculating the number of entries in a
+sequence when a stride is specified.  The shortcut form cannot be used to
+specify a count.  As an example::
+
+    ----
+    - hosts: all
+
+      tasks:
+
+        # create 4 groups
+        - group: name=group${item} state=present
+          with_sequence: count=4
+
 Getting values from files
 `````````````````````````
 
@@ -466,7 +512,7 @@ The following example shows how to template out a configuration file that was ve
         - /srv/templates/myapp/${ansible_distribution}.conf
         - /srv/templates/myapp/default.conf
 
-first_available_file is only available to the copy and template modules.  
+first_available_file is only available to the copy and template modules.
 
 Asynchronous Actions and Polling
 ````````````````````````````````

lib/ansible/runner/lookup_plugins/sequence.py

+# (c) 2013, Jayson Vantuyl <jayson@aggressive.ly>
+#
+# This file is part of Ansible
+#
+# Ansible 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 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+from ansible.errors import AnsibleError
+from ansible.utils import parse_kv
+from re import compile as re_compile, IGNORECASE
+
+# shortcut format
+NUM = "(0?x?[0-9a-f]+)"
+SHORTCUT = re_compile(
+    "^(" +        # Group 0
+    NUM +         # Group 1: Start
+    "-)?" +
+    NUM +         # Group 2: End
+    "(/" +        # Group 3
+    NUM +         # Group 4: Stride
+    ")?" +
+    "(:(.+))?$",  # Group 5, Group 6: Format String
+    IGNORECASE
+)
+
+
+class LookupModule(object):
+    """
+    sequence lookup module
+
+    Used to generate some sequence of items. Takes arguments in two forms.
+
+    The simple / shortcut form is:
+
+      [start-]end[/stride][:format]
+
+    As indicated by the brackets: start, stride, and format string are all
+    optional.  The format string is in the style of printf.  This can be used
+    to pad with zeros, format in hexadecimal, etc.  All of the numerical values
+    can be specified in octal (i.e. 0664) or hexadecimal (i.e. 0x3f8).
+    Negative numbers are not supported.
+
+    Some examples:
+
+      5 -> ["1","2","3","4","5"]
+      5-8 -> ["5", "6", "7", "8"]
+      2-10/2 -> ["2", "4", "6", "8", "10"]
+      4:host%02d -> ["host01","host02","host03","host04"]
+
+    The standard Ansible key-value form is accepted as well.  For example:
+
+      start=5 end=11 stride=2 format=0x%02x -> ["0x05","0x07","0x09","0x0a"]
+
+    This format takes an alternate form of "end" called "count", which counts
+    some number from the starting value.  For example:
+
+      count=5 -> ["1", "2", "3", "4", "5"]
+      start=0x0f00 count=4 format=%04x -> ["0f00", "0f01", "0f02", "0f03"]
+      start=0 count=5 stride=2 -> ["0", "2", "4", "6", "8"]
+      start=1 count=5 stride=2 -> ["1", "3", "5", "7", "9"]
+
+    The count option is mostly useful for avoiding off-by-one errors and errors
+    calculating the number of entries in a sequence when a stride is specified.
+    """
+
+    def __init__(self, **kwargs):
+        """absorb any keyword args"""
+        pass
+
+    def reset(self):
+        """set sensible defaults"""
+        self.start = 1
+        self.count = None
+        self.end = None
+        self.stride = 1
+        self.format = "%d"
+
+    def parse_kv_args(self, args):
+        """parse key-value style arguments"""
+        for arg in ["start", "end", "count", "stride"]:
+            try:
+                arg_raw = args.pop(arg, None)
+                if arg_raw is None:
+                    continue
+                arg_cooked = int(arg_raw, 0)
+                setattr(self, arg, arg_cooked)
+            except ValueError:
+                raise AnsibleError(
+                    "can't parse arg %s=%r as integer"
+                        % (arg, arg_raw)
+                )
+            if 'format' in args:
+                self.format = args.pop("format")
+        if args:
+            raise AnsibleError(
+                "unrecognized arguments to with_sequence: %r"
+                % args.keys()
+            )
+
+    def parse_simple_args(self, term):
+        """parse the shortcut forms, return True/False"""
+        match = SHORTCUT.match(term)
+        if not match:
+            return False
+
+        _, start, end, _, stride, _, format = match.groups()
+
+        if start is not None:
+            try:
+                start = int(start, 0)
+            except ValueError:
+                raise AnsibleError("can't parse start=%s as integer" % start)
+        if end is not None:
+            try:
+                end = int(end, 0)
+            except ValueError:
+                raise AnsibleError("can't parse end=%s as integer" % end)
+        if stride is not None:
+            try:
+                stride = int(stride, 0)
+            except ValueError:
+                raise AnsibleError("can't parse stride=%s as integer" % stride)
+
+        if start is not None:
+            self.start = start
+        if end is not None:
+            self.end = end
+        if stride is not None:
+            self.stride = stride
+        if format is not None:
+            self.format = format
+
+    def sanity_check(self):
+        if self.count is None and self.end is None:
+            raise AnsibleError(
+                "must specify count or end in with_sequence"
+            )
+        elif self.count is not None and self.end is not None:
+            raise AnsibleError(
+                "can't specify both count and end in with_sequence"
+            )
+        elif self.count is not None:
+            # convert count to end
+            self.end = self.start + self.count * self.stride - 1
+            del self.count
+        if self.end < self.start:
+            raise AnsibleError("can't count backwards")
+        if self.format.count('%') != 1:
+            raise AnsibleError("bad formatting string: %s" % self.format)
+
+    def generate_sequence(self):
+        numbers = xrange(self.start, self.end + 1, self.stride)
+
+        for i in numbers:
+            try:
+                formatted = self.format % i
+                yield formatted
+            except (ValueError, TypeError):
+                raise AnsibleError(
+                    "problem formatting %r with %r" % self.format
+                )
+
+    def run(self, terms, **kwargs):
+        results = []
+
+        if isinstance(terms, basestring):
+            terms = [terms]
+
+        for term in terms:
+            try:
+                self.reset()  # clear out things for this iteration
+
+                try:
+                    if not self.parse_simple_args(term):
+                        self.parse_kv_args(parse_kv(term))
+                except Exception:
+                    raise AnsibleError(
+                        "unknown error parsing with_sequence arguments: %r"
+                        % term
+                    )
+
+                self.sanity_check()
+
+                results.extend(self.generate_sequence())
+            except AnsibleError:
+                raise
+            except Exception:
+                raise AnsibleError(
+                    "unknown error generating sequence"
+                )
+
+        return results

test/TestPlayBook.py

@@ -172,9 +172,9 @@ class TestPlaybook(unittest.TestCase):
        print utils.jsonify(actual, format=True)
        expected =  {
            "localhost": {
-               "changed": 7,
+               "changed": 9,
                "failures": 0,
-               "ok": 9,
+               "ok": 14,
                "skipped": 1,
                "unreachable": 0
            }   
@@ -185,7 +185,7 @@ class TestPlaybook(unittest.TestCase):
        assert utils.jsonify(expected, format=True) == utils.jsonify(actual,format=True)
 
        print "len(EVENTS) = %d" % len(EVENTS)
-       assert len(EVENTS) == 26
+       assert len(EVENTS) == 60
 
    def test_includes(self):
        pb = os.path.join(self.test_dir, 'playbook-includer.yml')

test/lookup_plugins.yml

@@ -26,6 +26,25 @@
   - name: test LOOKUP and PIPE
     action: command test "$LOOKUP(pipe, cat sample.j2)" = "$PIPE(cat sample.j2)"
 
+  - name: test with_sequence, generate
+    command: touch /tmp/seq-${item}
+    with_sequence: 0-16/2:%02x
+
+  - name: test with_sequence, fenceposts 1
+    copy: src=/tmp/seq-00 dest=/tmp/seq-10
+
+  - name: test with_sequence, fenceposts 2
+    file: dest=/tmp/seq-${item} state=absent
+    with_items: [11, 12]
+
+  - name: test with_sequence, missing
+    file: dest=/tmp/seq-${item} state=absent
+    with_sequence: 0x10/02:%02x
+
+  - name: test with_sequence,remove
+    file: dest=/tmp/seq-${item} state=absent
+    with_sequence: 0-0x10/02:%02x
+
   - name: ensure test file doesnt exist
     # command because file will return differently
     action: command rm -f /tmp/ansible-test-with_lines-data