chore(python open): Refactor open and gzip.open to use context manager (#2203)

Co-authored-by: Hugh Secker-Walker <hsw+miac@hodain.net>

management/backup.py

@@ -531,7 +531,8 @@ def get_backup_config(env, for_save=False, for_ui=False):
 
 	# Merge in anything written to custom.yaml.
 	try:
-		custom_config = rtyaml.load(open(os.path.join(backup_root, 'custom.yaml')))
+		with open(os.path.join(backup_root, 'custom.yaml'), 'r') as f:
+			custom_config = rtyaml.load(f)
 		if not isinstance(custom_config, dict): raise ValueError() # caught below
 		config.update(custom_config)
 	except:
@@ -556,7 +557,8 @@ def get_backup_config(env, for_save=False, for_ui=False):
 		config["target"] = "file://" + config["file_target_directory"]
 	ssh_pub_key = os.path.join('/root', '.ssh', 'id_rsa_miab.pub')
 	if os.path.exists(ssh_pub_key):
-		config["ssh_pub_key"] = open(ssh_pub_key, 'r').read()
+		with open(ssh_pub_key, 'r') as f:
+			config["ssh_pub_key"] = f.read()
 
 	return config
 

management/cli.py

@@ -47,7 +47,8 @@ def read_password():
     return first
 
 def setup_key_auth(mgmt_uri):
-	key = open('/var/lib/mailinabox/api.key').read().strip()
+	with open('/var/lib/mailinabox/api.key', 'r') as f:
+		key = f.read().strip()
 
 	auth_handler = urllib.request.HTTPBasicAuthHandler()
 	auth_handler.add_password(

management/dns_update.py

@@ -815,7 +815,8 @@ def write_opendkim_tables(domains, env):
 
 def get_custom_dns_config(env, only_real_records=False):
 	try:
-		custom_dns = rtyaml.load(open(os.path.join(env['STORAGE_ROOT'], 'dns/custom.yaml')))
+		with open(os.path.join(env['STORAGE_ROOT'], 'dns/custom.yaml'), 'r') as f:
+			custom_dns = rtyaml.load(f)
 		if not isinstance(custom_dns, dict): raise ValueError() # caught below
 	except:
 		return [ ]

management/mail_log.py

@@ -73,7 +73,8 @@ def scan_files(collector):
             continue
         elif fn[-3:] == '.gz':
             tmp_file = tempfile.NamedTemporaryFile()
-            shutil.copyfileobj(gzip.open(fn), tmp_file)
+            with gzip.open(fn, 'rb') as f:
+                shutil.copyfileobj(f, tmp_file)
 
         if VERBOSE:
             print("Processing file", fn, "...")

management/ssl_certificates.py

@@ -535,7 +535,8 @@ def check_certificate(domain, ssl_certificate, ssl_private_key, warn_if_expiring
 	# Second, check that the certificate matches the private key.
 	if ssl_private_key is not None:
 		try:
-			priv_key = load_pem(open(ssl_private_key, 'rb').read())
+			with open(ssl_private_key, 'rb') as f:
+				priv_key = load_pem(f.read())
 		except ValueError as e:
 			return ("The private key file %s is not a private key file: %s" % (ssl_private_key, str(e)), None)
 

management/status_checks.py

@@ -207,7 +207,8 @@ def check_ssh_password(env, output):
 	# the configuration file.
 	if not os.path.exists("/etc/ssh/sshd_config"):
 		return
-	sshd = open("/etc/ssh/sshd_config").read()
+	with open("/etc/ssh/sshd_config", "r") as f:
+		sshd = f.read()
 	if re.search("\nPasswordAuthentication\s+yes", sshd) \
 		or not re.search("\nPasswordAuthentication\s+no", sshd):
 		output.print_error("""The SSH server on this machine permits password-based login. A more secure
@@ -594,7 +595,8 @@ def check_dnssec(domain, env, output, dns_zonefiles, is_checking_primary=False):
 			# record that we suggest using is for the KSK (and that's how the DS records were generated).
 			# We'll also give the nice name for the key algorithm.
 			dnssec_keys = load_env_vars_from_file(os.path.join(env['STORAGE_ROOT'], 'dns/dnssec/%s.conf' % alg_name_map[ds_alg]))
-			dnsssec_pubkey = open(os.path.join(env['STORAGE_ROOT'], 'dns/dnssec/' + dnssec_keys['KSK'] + '.key')).read().split("\t")[3].split(" ")[3]
+			with open(os.path.join(env['STORAGE_ROOT'], 'dns/dnssec/' + dnssec_keys['KSK'] + '.key'), 'r') as f:
+				dnsssec_pubkey = f.read().split("\t")[3].split(" ")[3]
 
 			expected_ds_records[ (ds_keytag, ds_alg, ds_digalg, ds_digest) ] = {
 				"record": rr_ds,
@@ -956,7 +958,8 @@ def run_and_output_changes(env, pool):
 	# Load previously saved status checks.
 	cache_fn = "/var/cache/mailinabox/status_checks.json"
 	if os.path.exists(cache_fn):
-		prev = json.load(open(cache_fn))
+		with open(cache_fn, 'r') as f:
+			prev = json.load(f)
 
 		# Group the serial output into categories by the headings.
 		def group_by_heading(lines):

management/utils.py

@@ -14,7 +14,9 @@ def load_env_vars_from_file(fn):
     # Load settings from a KEY=VALUE file.
     import collections
     env = collections.OrderedDict()
-    for line in open(fn): env.setdefault(*line.strip().split("=", 1))
+    with open(fn, 'r')  as f:
+        for line in f:
+            env.setdefault(*line.strip().split("=", 1))
     return env
 
 def save_environment(env):
@@ -34,7 +36,8 @@ def load_settings(env):
     import rtyaml
     fn = os.path.join(env['STORAGE_ROOT'], 'settings.yaml')
     try:
-        config = rtyaml.load(open(fn, "r"))
+        with open(fn, "r") as f:
+            config = rtyaml.load(f)
         if not isinstance(config, dict): raise ValueError() # caught below
         return config
     except:

management/web_update.py

@@ -63,7 +63,8 @@ def get_web_domains_with_root_overrides(env):
 	root_overrides = { }
 	nginx_conf_custom_fn = os.path.join(env["STORAGE_ROOT"], "www/custom.yaml")
 	if os.path.exists(nginx_conf_custom_fn):
-		custom_settings = rtyaml.load(open(nginx_conf_custom_fn))
+		with open(nginx_conf_custom_fn, 'r') as f:
+			custom_settings = rtyaml.load(f)
 		for domain, settings in custom_settings.items():
 			for type, value in [('redirect', settings.get('redirects', {}).get('/')),
 				('proxy', settings.get('proxies', {}).get('/'))]:
@@ -75,13 +76,18 @@ def do_web_update(env):
 	# Pre-load what SSL certificates we will use for each domain.
 	ssl_certificates = get_ssl_certificates(env)
 
+	# Helper for reading config files and templates
+	def read_conf(conf_fn):
+		with open(os.path.join(os.path.dirname(__file__), "../conf", conf_fn), "r") as f:
+			return f.read()
+
 	# Build an nginx configuration file.
-	nginx_conf = open(os.path.join(os.path.dirname(__file__), "../conf/nginx-top.conf")).read()
+	nginx_conf = read_conf("nginx-top.conf")
 
 	# Load the templates.
-	template0 = open(os.path.join(os.path.dirname(__file__), "../conf/nginx.conf")).read()
+	template0 = read_conf("nginx.conf")
-	template1 = open(os.path.join(os.path.dirname(__file__), "../conf/nginx-alldomains.conf")).read()
+	template1 = read_conf("nginx-alldomains.conf")
-	template2 = open(os.path.join(os.path.dirname(__file__), "../conf/nginx-primaryonly.conf")).read()
+	template2 = read_conf("nginx-primaryonly.conf")
 	template3 = "\trewrite ^(.*) https://$REDIRECT_DOMAIN$1 permanent;\n"
 
 	# Add the PRIMARY_HOST configuration first so it becomes nginx's default server.
@@ -141,11 +147,8 @@ def make_domain_config(domain, templates, ssl_certificates, env):
 	def hashfile(filepath):
 		import hashlib
 		sha1 = hashlib.sha1()
-		f = open(filepath, 'rb')
+		with open(filepath, 'rb') as f:
-		try:
 			sha1.update(f.read())
-		finally:
-			f.close()
 		return sha1.hexdigest()
 	nginx_conf_extra += "\t# ssl files sha1: %s / %s\n" % (hashfile(tls_cert["private-key"]), hashfile(tls_cert["certificate"]))
 
@@ -153,7 +156,8 @@ def make_domain_config(domain, templates, ssl_certificates, env):
 	hsts = "yes"
 	nginx_conf_custom_fn = os.path.join(env["STORAGE_ROOT"], "www/custom.yaml")
 	if os.path.exists(nginx_conf_custom_fn):
-		yaml = rtyaml.load(open(nginx_conf_custom_fn))
+		with open(nginx_conf_custom_fn, 'r') as f:
+			yaml = rtyaml.load(f)
 		if domain in yaml:
 			yaml = yaml[domain]
 

tools/editconf.py

@@ -76,7 +76,8 @@ for setting in settings:
 
 found = set()
 buf = ""
-input_lines = list(open(filename))
+with open(filename, "r") as f:
+        input_lines = list(f)
 
 while len(input_lines) > 0:
 	line = input_lines.pop(0)

tools/parse-nginx-log-bootstrap-accesses.py

@@ -17,13 +17,8 @@ accesses = set()
 # Scan the current and rotated access logs.
 for fn in glob.glob("/var/log/nginx/access.log*"):
 	# Gunzip if necessary.
-	if fn.endswith(".gz"):
-		f = gzip.open(fn)
-	else:
-		f = open(fn, "rb")
-
 	# Loop through the lines in the access log.
-	with f:
+	with (gzip.open if fn.endswith(".gz") else open)(fn, "rb") as f:
 		for line in f:
 			# Find lines that are GETs on the bootstrap script by either curl or wget.
 			# (Note that we purposely skip ...?ping=1 requests which is the admin panel querying us for updates.)
@@ -43,7 +38,8 @@ for date, ip in accesses:
 # Since logs are rotated, store the statistics permanently in a JSON file.
 # Load in the stats from an existing file.
 if os.path.exists(outfn):
-	existing_data = json.load(open(outfn))
+	with open(outfn, "r") as f:
+		existing_data = json.load(f)
 	for date, count in existing_data:
 		if date not in by_date:
 			by_date[date] = count

tools/readable_bash.py

@@ -124,7 +124,8 @@ def generate_documentation():
  """)
 
 	parser = Source.parser()
-	for line in open("setup/start.sh"):
+	with open("setup/start.sh", "r") as start_file: 
+                for line in start_file:
                         try:
                                 fn = parser.parse_string(line).filename()
                         except:
@@ -401,7 +402,8 @@ class BashScript(Grammar):
 	@staticmethod
 	def parse(fn):
 		if fn in ("setup/functions.sh", "/etc/mailinabox.conf"): return ""
-		string = open(fn).read()
+		with open(fn, "r") as f:
+			string = f.read()
 
 		# tokenize
 		string = re.sub(".* #NODOC\n", "", string)