[dns] Implement config and show commands for static DNS.

Implement unit tests for all added commands.
Coverage for config/dns.py : 94%
Coverage for show/dns.py : 86%

Author: oleksandrivantsiv

config/dns.py

@@ -0,0 +1,96 @@
+
+import click
+from swsscommon.swsscommon import ConfigDBConnector
+from .validated_config_db_connector import ValidatedConfigDBConnector
+import ipaddress
+
+
+ADHOC_VALIDATION = True
+NAMESERVERS_MAX_NUM = 3
+
+
+def to_ip_address(address):
+    """Check if the given IP address is valid"""
+    try:
+        ip = ipaddress.ip_address(address)
+
+        if ADHOC_VALIDATION:
+            if ip.is_reserved or ip.is_multicast or ip.is_loopback:
+                return
+
+            invalid_ips = [
+                ipaddress.IPv4Address('0.0.0.0'),
+                ipaddress.IPv4Address('255.255.255.255'),
+                ipaddress.IPv6Address("0::0"),
+                ipaddress.IPv6Address("0::1")
+                ]
+            if ip in invalid_ips:
+                return
+
+        return ip
+    except Exception:
+        return
+
+
+def get_nameservers(db):
+    nameservers = db.get_table('DNS_NAMESERVER')
+    return [ipaddress.ip_address(ip) for ip in nameservers]
+
+
+# 'dns' group ('config dns ...')
+@click.group()
+@click.pass_context
+def dns(ctx):
+    """Static DNS configuration"""
+    config_db = ValidatedConfigDBConnector(ConfigDBConnector())
+    config_db.connect()
+    ctx.obj = {'db': config_db}
+
+
+# dns nameserver config
+@dns.group('nameserver')
+@click.pass_context
+def nameserver(ctx):
+    """Static DNS nameservers configuration"""
+    pass
+
+
+# dns nameserver add
+@nameserver.command('add')
+@click.argument('ip_address_str', metavar='<ip_address>', required=True)
+@click.pass_context
+def add_dns_nameserver(ctx, ip_address_str):
+    """Add static DNS nameserver entry"""
+    ip_address = to_ip_address(ip_address_str)
+    if not ip_address:
+        ctx.fail(f"{ip_address_str} invalid nameserver ip address")
+
+    db = ctx.obj['db']
+
+    nameservers = get_nameservers(db)
+    if ip_address in nameservers:
+        ctx.fail(f"{ip_address} nameserver is already configured")
+
+    if len(nameservers) >= NAMESERVERS_MAX_NUM:
+        ctx.fail(f"The maximum number ({NAMESERVERS_MAX_NUM}) of nameservers exceeded.")
+
+    db.set_entry('DNS_NAMESERVER', ip_address, {})
+
+# dns nameserver delete
+@nameserver.command('del')
+@click.argument('ip_address_str', metavar='<ip_address>', required=True)
+@click.pass_context
+def del_dns_nameserver(ctx, ip_address_str):
+    """Delete static DNS nameserver entry"""
+
+    ip_address = to_ip_address(ip_address_str)
+    if not ip_address:
+        ctx.fail(f"{ip_address_str} invalid nameserver ip address")
+
+    db = ctx.obj['db']
+
+    nameservers = get_nameservers(db)
+    if ip_address not in nameservers:
+        ctx.fail(f"DNS nameserver {ip_address} is not configured")
+
+    db.set_entry('DNS_NAMESERVER', ip_address, None)

config/main.py

@@ -54,6 +54,7 @@
 from .config_mgmt import ConfigMgmtDPB, ConfigMgmt
 from . import mclag
 from . import syslog
+from . import dns
 
 # mock masic APIs for unit test
 try:
@@ -1200,6 +1201,9 @@ def config(ctx):
 # syslog module
 config.add_command(syslog.syslog)
 
+# DNS module
+config.add_command(dns.dns)
+
 @config.command()
 @click.option('-y', '--yes', is_flag=True, callback=_abort_if_false,
                 expose_value=False, prompt='Existing files will be overwritten, continue?')

show/dns.py

@@ -0,0 +1,30 @@
+import click
+import utilities_common.cli as clicommon
+from natsort import natsorted
+from tabulate import tabulate
+
+from swsscommon.swsscommon import ConfigDBConnector
+from utilities_common.cli import pass_db
+
+
+# 'dns' group ("show dns ...")
+@click.group(cls=clicommon.AliasedGroup)
+@click.pass_context
+def dns(ctx):
+    """Show details of the static DNS configuration """
+    config_db = ConfigDBConnector()
+    config_db.connect()
+    ctx.obj = {'db': config_db}
+
+
+# 'nameserver' subcommand ("show dns nameserver")
+@dns.command()
+@click.pass_context
+def nameserver(ctx):
+    """ Show static DNS configuration """
+    header = ["Nameserver"]
+    db = ctx.obj['db']
+
+    nameservers = db.get_table('DNS_NAMESERVER')
+
+    click.echo(tabulate([(ns,) for ns in nameservers.keys()], header, tablefmt='simple', stralign='right'))

show/main.py

@@ -63,6 +63,7 @@
 from . import warm_restart
 from . import plugins
 from . import syslog
+from . import dns
 
 # Global Variables
 PLATFORM_JSON = 'platform.json'
@@ -289,6 +290,7 @@ def cli(ctx):
 cli.add_command(vxlan.vxlan)
 cli.add_command(system_health.system_health)
 cli.add_command(warm_restart.warm_restart)
+cli.add_command(dns.dns)
 
 # syslog module
 cli.add_command(syslog.syslog)

tests/dns_test.py

@@ -0,0 +1,193 @@
+import os
+import pytest
+
+from click.testing import CliRunner
+
+import config.main as config
+import show.main as show
+from utilities_common.db import Db
+
+test_path = os.path.dirname(os.path.abspath(__file__))
+
+dns_show_nameservers_header = """\
+  Nameserver
+------------
+"""
+
+dns_show_nameservers = """\
+          Nameserver
+--------------------
+             1.1.1.1
+2001:4860:4860::8888
+"""
+
+class TestDns(object):
+
+    valid_nameservers = (
+        ("1.1.1.1",),
+        ("1.1.1.1", "8.8.8.8", "10.10.10.10",),
+        ("1.1.1.1", "2001:4860:4860::8888"),
+        ("2001:4860:4860::8888", "2001:4860:4860::8844", "2001:4860:4860::8800")
+    )
+
+    invalid_nameservers = (
+        "0.0.0.0",
+        "255.255.255.255",
+        "224.0.0.0",
+        "0::0",
+        "0::1",
+        "1.1.1.x",
+        "2001:4860:4860.8888",
+        "ff02::1"
+    )
+
+    config_dns_ns_add = config.config.commands["dns"].commands["nameserver"].commands["add"]
+    config_dns_ns_del = config.config.commands["dns"].commands["nameserver"].commands["del"]
+    show_dns_ns = show.cli.commands["dns"].commands["nameserver"]
+
+    @classmethod
+    def setup_class(cls):
+        print("SETUP")
+        os.environ["UTILITIES_UNIT_TESTING"] = "1"
+
+    @classmethod
+    def teardown_class(cls):
+        os.environ['UTILITIES_UNIT_TESTING'] = "0"
+        print("TEARDOWN")
+
+    @pytest.mark.parametrize('nameservers', valid_nameservers)
+    def test_dns_config_nameserver_add_del_with_valid_ip_addresses(self, nameservers):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        for ip in nameservers:
+            # config dns nameserver add <ip>
+            result = runner.invoke(self.config_dns_ns_add, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert ip in db.cfgdb.get_table('DNS_NAMESERVER')
+
+        for ip in nameservers:
+            # config dns nameserver del <ip>
+            result = runner.invoke(self.config_dns_ns_del, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert ip not in db.cfgdb.get_table('DNS_NAMESERVER')
+
+    @pytest.mark.parametrize('nameserver', invalid_nameservers)
+    def test_dns_config_nameserver_add_del_with_invalid_ip_addresses(self, nameserver):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        # config dns nameserver add <nameserver>
+        result = runner.invoke(self.config_dns_ns_add, [nameserver], obj=obj)
+        print(result.exit_code, result.output)
+        assert result.exit_code != 0
+        assert "invalid nameserver ip address" in result.output
+
+        # config dns nameserver del <nameserver>
+        result = runner.invoke(self.config_dns_ns_del, [nameserver], obj=obj)
+        print(result.exit_code, result.output)
+        assert result.exit_code != 0
+        assert "invalid nameserver ip address" in result.output
+
+    @pytest.mark.parametrize('nameservers', valid_nameservers)
+    def test_dns_config_nameserver_add_existing_ip(self, nameservers):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        for ip in nameservers:
+            # config dns nameserver add <ip>
+            result = runner.invoke(self.config_dns_ns_add, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert ip in db.cfgdb.get_table('DNS_NAMESERVER')
+
+            # Execute command once more
+            result = runner.invoke(self.config_dns_ns_add, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code != 0
+            assert "nameserver is already configured" in result.output
+
+            # config dns nameserver del <ip>
+            result = runner.invoke(self.config_dns_ns_del, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+
+    @pytest.mark.parametrize('nameservers', valid_nameservers)
+    def test_dns_config_nameserver_del_unexisting_ip(self, nameservers):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        for ip in nameservers:
+            # config dns nameserver del <ip>
+            result = runner.invoke(self.config_dns_ns_del, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code != 0
+            assert "is not configured" in result.output
+
+    def test_dns_config_nameserver_add_max_number(self):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        nameservers = ("1.1.1.1", "2.2.2.2", "3.3.3.3")
+        for ip in nameservers:
+            # config dns nameserver add <ip>
+            result = runner.invoke(self.config_dns_ns_add, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+
+        # config dns nameserver add <ip>
+        result = runner.invoke(self.config_dns_ns_add, ["4.4.4.4"], obj=obj)
+        print(result.exit_code, result.output)
+        assert result.exit_code != 0
+        assert "nameservers exceeded" in result.output
+
+        for ip in nameservers:
+            # config dns nameserver del <ip>
+            result = runner.invoke(self.config_dns_ns_del, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+
+    def test_dns_show_nameserver_empty_table(self):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        # show dns nameserver
+        result = runner.invoke(self.show_dns_ns, [], obj=obj)
+        print(result.exit_code, result.output)
+        assert result.exit_code == 0
+        assert result.output == dns_show_nameservers_header
+
+    def test_dns_show_nameserver(self):
+        db = Db()
+        runner = CliRunner()
+        obj = {'db': db.cfgdb}
+
+        nameservers = ("1.1.1.1", "2001:4860:4860::8888")
+
+        for ip in nameservers:
+            # config dns nameserver add <ip>
+            result = runner.invoke(self.config_dns_ns_add, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert ip in db.cfgdb.get_table('DNS_NAMESERVER')
+
+        # show dns nameserver
+        result = runner.invoke(self.show_dns_ns, [], obj=obj)
+        print(result.exit_code, result.output)
+        assert result.exit_code == 0
+        assert result.output == dns_show_nameservers
+
+        for ip in nameservers:
+            # config dns nameserver del <ip>
+            result = runner.invoke(self.config_dns_ns_del, [ip], obj=obj)
+            print(result.exit_code, result.output)
+            assert result.exit_code == 0
+            assert ip not in db.cfgdb.get_table('DNS_NAMESERVER')