Store environment variables in a file, and allow init scripts to change environment variables.

Closes GH-23.

image/my_init

@@ -1,5 +1,5 @@
 #!/usr/bin/python2 -u
-import os, sys, stat, signal, errno, argparse, time
+import os, os.path, sys, stat, signal, errno, argparse, time, json, re, posixfile
 
 KILL_PROCESS_TIMEOUT = 5
 KILL_ALL_PROCESSES_TIMEOUT = 5
@@ -54,6 +54,42 @@ def is_exe(path):
 	except OSError:
 		return False
 
+def import_envvars():
+	new_env = {}
+	for envfile in listdir("/etc/container_environment"):
+		name = os.path.basename(envfile)
+		with open("/etc/container_environment/" + envfile, "r") as f:
+			value = f.read()
+		new_env[name] = value
+	os.environ.clear()
+	for name, value in new_env.items():
+		os.environ[name] = value
+
+def export_envvars(to_dir = True):
+	shell_dump = ""
+	for name, value in os.environ.items():
+		if to_dir:
+			with open("/etc/container_environment/" + name, "w") as f:
+				f.write(value)
+		shell_dump += "export " + shquote(name) + "=" + shquote(value) + "\n"
+	with open("/etc/container_environment.sh", "w") as f:
+		f.write(shell_dump)
+	with open("/etc/container_environment.json", "w") as f:
+		f.write(json.dumps(dict(os.environ)))
+
+_find_unsafe = re.compile(r'[^\w@%+=:,./-]').search
+
+def shquote(s):
+	"""Return a shell-escaped version of the string *s*."""
+	if not s:
+		return "''"
+	if _find_unsafe(s) is None:
+		return s
+
+	# use single quotes, and put single quotes into double quotes
+	# the string $'b is then quoted as '$'"'"'b'
+	return "'" + s.replace("'", "'\"'\"'") + "'"
+
 def waitpid_reap_other_children(pid):
 	done = False
 	status = None
@@ -101,6 +137,11 @@ def run_command_killable(*argv):
 		error("%s failed with exit code %d\n" % (filename, status))
 		sys.exit(1)
 
+def run_command_killable_and_import_envvars(*argv):
+	run_command_killable(*argv)
+	import_envvars()
+	export_envvars(False)
+
 def kill_all_processes(time_limit):
 	info("Killing all processes...")
 	try:
@@ -134,12 +175,12 @@ def run_startup_files():
 		filename = "/etc/my_init.d/" + name
 		if is_exe(filename):
 			info("Running %s..." % filename)
-			run_command_killable(filename)
+			run_command_killable_and_import_envvars(filename)
 
 	# Run /etc/rc.local.
 	if is_exe("/etc/rc.local"):
 		info("Running /etc/rc.local...")
-		run_command_killable("/etc/rc.local")
+		run_command_killable_and_import_envvars("/etc/rc.local")
 
 def start_runit():
 	info("Booting runit daemon...")
@@ -172,6 +213,9 @@ def install_insecure_key():
 	run_command_killable("/usr/sbin/enable_insecure_key")
 
 def main(args):
+	import_envvars()
+	export_envvars()
+
 	if args.enable_insecure_key:
 		install_insecure_key()
 
@@ -212,6 +256,9 @@ def main(args):
 parser = argparse.ArgumentParser(description = 'Initialize the system.')
 parser.add_argument('main_command', metavar = 'MAIN_COMMAND', type = str, nargs = '*',
 	help = 'The main command to run. (default: runit)')
+parser.add_argument('--enable-insecure-key', dest = 'enable_insecure_key',
+	action = 'store_const', const = True, default = False,
+	help = 'Install the insecure SSH key')
 parser.add_argument('--skip-startup-files', dest = 'skip_startup_files',
 	action = 'store_const', const = True, default = False,
 	help = 'Skip running /etc/my_init.d/* and /etc/rc.local')
@@ -224,9 +271,6 @@ parser.add_argument('--no-kill-all-on-exit', dest = 'kill_all_on_exit',
 parser.add_argument('--quiet', dest = 'log_level',
 	action = 'store_const', const = LOG_LEVEL_WARN, default = LOG_LEVEL_INFO,
 	help = 'Only print warnings and errors')
-parser.add_argument('--enable-insecure-key', dest = 'enable_insecure_key',
-	action = 'store_const', const = True, default = False,
-	help = 'Install the insecure SSH key')
 args = parser.parse_args()
 log_level = args.log_level