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

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?')

doc/Command-Reference.md

@@ -194,12 +194,15 @@
  * [MACsec config command](#macsec-config-command)
  * [MACsec show command](#macsec-show-command)
  * [MACsec clear command](#macsec-clear-command)
-
+* [Static DNS Commands](#static-dns-commands)
+ * [Static DNS config command](#static-dns-config-command)
+ * [Static DNS show command](#static-dns-show-command)
 
 ## Document History
 
 | Version | Modification Date | Details |
 | --- | --- | --- |
+| v7 | Jun-22-2023 | Add static DNS show and config commands |
 | v6 | May-06-2021 | Add SNMP show and config commands |
 | v5 | Nov-05-2020 | Add document for console commands |
 | v4 | Oct-17-2019 | Unify usage statements and other formatting; Replace tabs with spaces; Modify heading sizes; Fix spelling, grammar and other errors; Fix organization of new commands |
@@ -12103,3 +12106,55 @@ Clear MACsec counters which is to reset all MACsec counters to ZERO.
  ```
 
 Go Back To [Beginning of the document](#) or [Beginning of this section](#macsec-commands)
+
+# Static DNS Commands
+
+This sub-section explains the list of the configuration options available for static DNS feature.
+
+## Static DNS config command
+
+- Add static DNS nameserver entry
+
+```
+admin@sonic:~$ config dns nameserver add -h
+Usage: config dns nameserver add [OPTIONS] <ip_address>
+
+ Add static DNS nameserver entry
+
+Options:
+ -?, -h, --help Show this message and exit.
+```
+
+- Delete static DNS nameserver entry
+
+```
+admin@sonic:~$ config dns nameserver del -h
+Usage: config dns nameserver del [OPTIONS] <ip_address>
+
+ Delete static DNS nameserver entry
+
+Options:
+ -h, -?, --help Show this message and exit.
+```
+
+## Static DNS show command
+
+- Show static DNS configuration
+
+```
+admin@sonic:~$ show dns nameserver -h
+Usage: show dns nameserver [OPTIONS]
+
+ Show static DNS configuration
+
+Options:
+ -h, -?, --help Show this message and exit.
+```
+```
+admin@sonic:~$ show dns nameserver
+ Nameserver
+------------
+ 1.1.1.1
+ 8.8.8.8
+
+```

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)