Renamed python script; changed comment convention; moved printing into

loop instead of accumulating and printing at the end; changed
yaml.load() to safe_load().

Fixed echo via subshell.

live-build/auto/build

@@ -551,7 +551,7 @@ fi
 
 # '--initramfs none' produces different manifest names.
 if [ -e "binary/$INITFS/filesystem.packages" ]; then
-	/build/config/snap_seed_parse "chroot/" >> "binary/${INITFS}/filesystem.packages"
+	/build/config/snap-seed-parse "chroot/" >> "binary/${INITFS}/filesystem.packages"
 	ln "binary/$INITFS/filesystem.packages" "$PREFIX.manifest"
 	chmod 644 "$PREFIX.manifest"
 fi

live-build/auto/config

@@ -33,7 +33,7 @@ fi
 
 mkdir -p config
 cp -af /usr/share/livecd-rootfs/live-build/functions config/functions
-cp -af /usr/share/livecd-rootfs/live-build/snap_seed_parse.py config/snap_seed_parse
+cp -af /usr/share/livecd-rootfs/live-build/snap-seed-parse.py config/snap-seed-parse
 
 mkdir -p config/package-lists
 

live-build/functions

@@ -46,12 +46,12 @@ create_empty_disk_image() {
 create_manifest() {
     local chroot_root=${1}
     local target_file=${2}
-    (echo "create_manifest chroot_root: ${chroot_root}")
+    echo "create_manifest chroot_root: ${chroot_root}"
     dpkg-query --show --admindir="${chroot_root}/var/lib/dpkg" > ${target_file}
-    (echo "create_manifest call to dpkg-query finished.")
+    echo "create_manifest call to dpkg-query finished."
     /build/config/snap_seed_parse "${chroot_root}" >> ${target_file}
-    (echo "create_manifest call to snap_seed_parse finished.")
+    echo "create_manifest call to snap_seed_parse finished."
-    (echo "create_manifest finished")
+    echo "create_manifest finished"
 }
 
 make_ext4_partition() {

live-build/snap-seed-parse.py

@@ -1,8 +1,10 @@
 #!/usr/bin/python3
 
 """
-This file parses the seed.yaml file for the chroot and appends it to the
+Usage: snap-seed-parse ${chroot_dir} > somefile.manifest
-given manifest 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.
 """
 
 import re
@@ -12,49 +14,43 @@ import os.path
 
 
 def log(msg):
-    sys.stderr.write("snap_seed_parse: {}\n".format(msg))
+    sys.stderr.write("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 ''
-'''The chroot rooth path should be passed in by the caller'''
 
+# Trim any trailing slashes for correct appending
 log("CHROOT_ROOT: {}".format(CHROOT_ROOT))
 if len(CHROOT_ROOT) > 0 and CHROOT_ROOT[-1] == '/':
     CHROOT_ROOT = CHROOT_ROOT[:-1]
-'''Trim any trailing slashes for correct appending'''
 
+# This is where we expect to find the seed.yaml file
 YAML_PATH = CHROOT_ROOT + '/var/lib/snapd/seed/seed.yaml'
-'''This is where we expect to find the seed.yaml file'''
 
+# Snaps are prepended with this string in the manifest
 LINE_PREFIX = 'snap:'
-'''Snaps are prepended with this string in the manifest'''
 
 log("yaml path: {}".format(YAML_PATH))
 if not os.path.isfile(YAML_PATH):
-    '''Exit gracefully and issue a warning if seeded snaps not found'''
     log("WARNING: yaml path not found; no seeded snaps found.")
     exit(0)
 else:
     log("yaml path found.")
 
 with open(YAML_PATH, 'r') as fh:
-    '''Open the seed.yaml and ingest its contents'''
+    yaml_lines = yaml.safe_load(fh)['snaps']
-    yaml_lines = yaml.load(fh)['snaps']
 
-to_write = ''
+# Loop over dict items, outputting one manifest line from each triplet
 for item in yaml_lines:
-    '''Loop over dict items, generating one manifest line from each triplet'''
     filestring = item['file']
+    # Pull the revision number off the file name
     revision = filestring[filestring.rindex('_')+1:]
     revision = re.sub(r'[^0-9]', '', revision)
-    to_write += "{}{}\t{}\t{}\n".format(LINE_PREFIX,
+    print("{}{}\t{}\t{}".format(LINE_PREFIX,
                                         item['name'],
                                         item['channel'],
                                         revision,
-                                        )
+                                        ))
-
-print(to_write.strip('\n'))
-'''write accumulated text to stdout for redirection'''