add write-files module for "injecting" files (LP: #1012854)

This implements file writing via cloud-config.  It also 
 * adjusts other code to have user/group parsing in util instead
   of in stages.py, 
 * renames decomp_str to decomp_gzip since it is more meaningful when named
   that (as thats all it can decompress).

LP: #1012854

1 files changed, 102 insertions, 0 deletions

diff --git a/cloudinit/config/cc_write_files.py b/cloudinit/config/cc_write_files.py
new file mode 100644
index 00000000..1bfa4c25
--- /dev/null
+++ b/cloudinit/config/cc_write_files.py
@@ -0,0 +1,102 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    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, see <http://www.gnu.org/licenses/>.
+
+import base64
+import os
+
+from cloudinit import util
+from cloudinit.settings import PER_INSTANCE
+
+frequency = PER_INSTANCE
+
+DEFAULT_OWNER = "root:root"
+DEFAULT_PERMS = 0644
+UNKNOWN_ENC = 'text/plain'
+
+
+def handle(name, cfg, _cloud, log, _args):
+    files = cfg.get('write_files')
+    if not files:
+        log.debug(("Skipping module named %s,"
+                   " no/empty 'write_files' key in configuration"), name)
+        return
+    write_files(name, files, log)
+
+
+def canonicalize_extraction(encoding_type, log):
+    if not encoding_type:
+        encoding_type = ''
+    encoding_type = encoding_type.lower().strip()
+    if encoding_type in ['gz', 'gzip']:
+        return ['application/x-gzip']
+    if encoding_type in ['gz+base64', 'gzip+base64', 'gz+b64', 'gzip+b64']:
+        return ['application/base64', 'application/x-gzip']
+    # Yaml already encodes binary data as base64 if it is given to the 
+    # yaml file as binary, so those will be automatically decoded for you.
+    # But the above b64 is just for people that are more 'comfortable'
+    # specifing it manually (which might be a possiblity)
+    if encoding_type in ['b64', 'base64']:
+        return ['application/base64']
+    if encoding_type:
+        log.warn("Unknown encoding type %s, assuming %s",
+                 encoding_type, UNKNOWN_ENC)
+    return [UNKNOWN_ENC]
+
+
+def write_files(name, files, log):
+    if not files:
+        return
+
+    for (i, f_info) in enumerate(files):
+        path = f_info.get('path')
+        if not path:
+            log.warn("No path provided to write for entry %s in module %s",
+                     i + 1, name)
+            continue
+        path = os.path.abspath(path)
+        extractions = canonicalize_extraction(f_info.get('encoding'), log)
+        contents = extract_contents(f_info.get('content', ''), extractions)
+        (u, g) = util.extract_usergroup(f_info.get('owner', DEFAULT_OWNER))
+        perms = decode_perms(f_info.get('permissions'), DEFAULT_PERMS, log)
+        util.write_file(path, contents, mode=perms)
+        util.chownbyname(path, u, g)
+
+
+def decode_perms(perm, default, log):
+    try:
+        if isinstance(perm, (int, long, float)):
+            # Just 'downcast' it (if a float)
+            return int(perm)
+        else:
+            # Force to string and try octal conversion
+            return int(str(perm), 8)
+    except (TypeError, ValueError):
+        log.warn("Undecodable permissions %s, assuming %s", perm, default)
+        return default
+
+
+def extract_contents(contents, extraction_types):
+    result = str(contents)
+    for t in extraction_types:
+        if t == 'application/x-gzip':
+            result = util.decomp_gzip(result, quiet=False)
+        elif t == 'application/base64':
+            result = base64.b64decode(result)
+        elif t == UNKNOWN_ENC:
+            pass
+    return result