Fix snap-seed-parse to take filename argument instead of printing to

stdout

debian/changelog

@@ -1,8 +1,13 @@
 livecd-rootfs (2.545) UNRELEASED; urgency=medium
 
+  [ Dimitri John Ledkov ]
   * Do not mount result, on top of lowerdir, appears to fail in
     disco. Should unblock building server-live images in disco.
 
+  [ Cody Shepherd ]
+  * Fix snap-seed-parse to take filename argument instead of printing to
+    stdout
+
  -- Dimitri John Ledkov <xnox@ubuntu.com>  Fri, 09 Nov 2018 22:13:49 +0000
 
 livecd-rootfs (2.544) disco; urgency=medium

live-build/auto/build

@@ -552,7 +552,7 @@ fi
 # '--initramfs none' produces different manifest names.
 # NB! we want stdout appended to the manifest, yet stderr to be printed on stdout
 if [ -e "binary/$INITFS/filesystem.packages" ]; then
-	./config/snap-seed-parse "chroot/" 2>&1 >> "binary/${INITFS}/filesystem.packages"
+	./config/snap-seed-parse "chroot/" "binary/${INITFS}/filesystem.packages"
 	ln "binary/$INITFS/filesystem.packages" "$PREFIX.manifest"
 	chmod 644 "$PREFIX.manifest"
 fi

live-build/functions

@@ -50,7 +50,7 @@ create_manifest() {
     echo "create_manifest chroot_root: ${chroot_root}"
     dpkg-query --show --admindir="${chroot_root}/var/lib/dpkg" > ${target_file}
     echo "create_manifest call to dpkg-query finished."
-    ./config/snap-seed-parse "${chroot_root}" 2>&1 >> ${target_file}
+    ./config/snap-seed-parse "${chroot_root}" "${target_file}"
     echo "create_manifest call to snap_seed_parse finished."
     echo "create_manifest finished"
 }

live-build/snap-seed-parse.py

@@ -1,26 +1,35 @@
 #!/usr/bin/python3
 
 """
-Usage: snap-seed-parse ${chroot_dir} > somefile.manifest
+Usage: snap-seed-parse [${chroot_dir}] <output file>
 
 This script looks for a seed.yaml path in the given root directory, parsing
-it and printing generated manifest lines to stdout for easy redirection.
+it and appending the parsed lines to the given output file.
+
+The $chroot_dir argument is optional and will default to the empty string.
 """
 
+import argparse
+import os.path
 import re
-import sys
 import yaml
-import os.path
 
 
 def log(msg):
-    sys.stderr.write("snap-seed-parse: {}\n".format(msg))
+    print("snap-seed-parse: {}\n".format(msg))
 
 
 log("Parsing seed.yaml")
 
-CHROOT_ROOT = sys.argv[1] if len(sys.argv) > 1 and len(sys.argv[1]) > 0 \
-                          else ''
+parser = argparse.ArgumentParser()
+parser.add_argument('chroot', nargs='?', default='',
+                    help='root dir for the chroot from which to generate the '
+                         'manifest')
+parser.add_argument('file', help='Output manifest to this file')
+
+ARGS = parser.parse_args()
+CHROOT_ROOT = ARGS.chroot
+FNAME = ARGS.file
 
 # Trim any trailing slashes for correct appending
 log("CHROOT_ROOT: {}".format(CHROOT_ROOT))
@@ -43,14 +52,17 @@ else:
 with open(YAML_PATH, 'r') as fh:
     yaml_lines = yaml.safe_load(fh)['snaps']
 
-# Loop over dict items, outputting one manifest line from each triplet
-for item in yaml_lines:
-    filestring = item['file']
-    # Pull the revision number off the file name
-    revision = filestring[filestring.rindex('_')+1:]
-    revision = re.sub(r'[^0-9]', '', revision)
-    print("{}{}\t{}\t{}".format(LINE_PREFIX,
-                                        item['name'],
-                                        item['channel'],
-                                        revision,
-                                        ))
+log('Writing manifest to {}'.format(FNAME))
+
+with open(FNAME, 'a+') as fh:
+    for item in yaml_lines:
+        filestring = item['file']
+        # Pull the revision number off the file name
+        revision = filestring[filestring.rindex('_')+1:]
+        revision = re.sub(r'[^0-9]', '', revision)
+        fh.write("{}{}\t{}\t{}\n".format(LINE_PREFIX,
+                                         item['name'],
+                                         item['channel'],
+                                         revision,
+                                         ))
+log('Manifest output finished.')