Use correct output filename

Also teach sunet-l4lb-namespace to load the nft ruleset if it exists.
While here modify the script so instead of running "once per netns
config file" we merge the interface config from each json file into the
same dict per namespace. Without this we would attempt to load the nft
ruleset twice (once per file that mentioned the namespace) or warn twice
if the file did not exist etc.

global/overlay/etc/puppet/modules/cdn/files/l4lb/sunet-l4lb-namespace

@@ -13,7 +13,9 @@ pylint sunet-l4lb-namespace
 mypy --strict sunet-l4lb-namespace
 """
 
+import ipaddress
 import json
+import os
 import shlex
 import subprocess
 import sys
@@ -21,6 +23,7 @@ import sys
 
 def run_command(cmd: str) -> subprocess.CompletedProcess[str]:
     """Execute subprocess command"""
+    print(f"{cmd}")
     args = shlex.split(cmd)
     try:
         proc = subprocess.run(args, capture_output=True, check=True, encoding="utf-8")
@@ -35,12 +38,15 @@ def run_command(cmd: str) -> subprocess.CompletedProcess[str]:
     return proc
 
 
-def configure_interfaces(
+def configure_interfaces(  # pylint: disable=too-many-locals,too-many-branches
     namespace: str, if_data: dict[str, dict[str, list[str]]]
 ) -> None:
     """Configure interfaces"""
-    proc = run_command("ip netns exec l4lb ip -j addr show")
+    proc = run_command(f"ip netns exec {namespace} ip -j addr show")
     namespace_ifs = json.loads(proc.stdout)
+
+    ipv4_key = "ipv4"
+    ipv6_key = "ipv6"
     for if_name, data in if_data.items():
         if_exists = next(
             (True for interface in namespace_ifs if interface["ifname"] == if_name),
@@ -54,38 +60,73 @@ def configure_interfaces(
             else:
                 run_command(f"ip link set {if_name} netns {namespace}")
 
+            run_command(f"ip netns exec {namespace} ip link set {if_name} up")
+
         proc = run_command(f"ip netns exec {namespace} ip -j addr show dev {if_name}")
         if_conf = json.loads(proc.stdout)
-        for ipv4_cidr in data["ipv4"]:
-            ip4, prefix = ipv4_cidr.split("/")
-            v4_addr_exists = next(
-                (
-                    True
-                    for addr in if_conf[0]["addr_info"]
-                    if addr["local"] == ip4 and addr["prefixlen"] == int(prefix)
-                ),
-                False,
-            )
-            if not v4_addr_exists:
-                run_command(
-                    f"ip netns exec {namespace} ip addr add {ipv4_cidr} dev {if_name}"
+
+        # Add missing addresses from config
+        if ipv4_key in data:
+            for configured_ipv4_cidr in data[ipv4_key]:
+                ip4, prefix = configured_ipv4_cidr.split("/")
+                v4_addr_exists = next(
+                    (
+                        True
+                        for addr in if_conf[0]["addr_info"]
+                        if addr["local"] == ip4 and addr["prefixlen"] == int(prefix)
+                    ),
+                    False,
                 )
-        for ipv6_cidr in data["ipv6"]:
-            ip6, prefix = ipv6_cidr.split("/")
-            v6_addr_exists = next(
-                (
-                    True
-                    for addr in if_conf[0]["addr_info"]
-                    if addr["local"] == ip6 and addr["prefixlen"] == int(prefix)
-                ),
-                False,
-            )
-            if not v6_addr_exists:
-                run_command(
-                    f"ip netns exec {namespace} ip addr add {ipv6_cidr} dev {if_name}"
+                if not v4_addr_exists:
+                    run_command(
+                        f"ip netns exec {namespace} ip addr add {configured_ipv4_cidr} dev {if_name}"  # pylint: disable=line-too-long
+                    )
+        if ipv6_key in data:
+            for ipv6_cidr in data[ipv6_key]:
+                ip6, prefix = ipv6_cidr.split("/")
+                v6_addr_exists = next(
+                    (
+                        True
+                        for addr in if_conf[0]["addr_info"]
+                        if addr["local"] == ip6 and addr["prefixlen"] == int(prefix)
+                    ),
+                    False,
+                )
+                if not v6_addr_exists:
+                    run_command(
+                        f"ip netns exec {namespace} ip addr add {ipv6_cidr} dev {if_name}"
+                    )
+
+        # Remove no longer configured addresseses
+        for addr_info in if_conf[0]["addr_info"]:
+            # Ignore addresses like fe80
+            if addr_info["scope"] != "global":
+                continue
+
+            cidr = "/".join((addr_info["local"], str(addr_info["prefixlen"])))
+
+            # We need strict=False because otherwise ip_network() gets angry if
+            # there are host bits set in the address (which of course there is
+            # because we are parsing actual interface configs, not pure
+            # "networks")
+            cidr_net = ipaddress.ip_network(cidr, strict=False)
+
+            needs_removal = False
+            if cidr_net.version == 4:
+                if ipv4_key not in data or cidr not in data[ipv4_key]:
+                    needs_removal = True
+            elif cidr_net.version == 6:
+                if ipv6_key not in data or cidr not in data[ipv6_key]:
+                    needs_removal = True
+            else:
+                raise ValueError(
+                    f"Expected IPv4 or IPv6, got something else: {cidr_net.version}"
                 )
 
-        run_command(f"ip netns exec {namespace} ip link set {if_name} up")
+            if needs_removal:
+                run_command(
+                    f"ip netns exec {namespace} ip addr del {cidr} dev {if_name}"
+                )
 
 
 def setup_namespaces(netns_data: dict[str, dict[str, dict[str, list[str]]]]) -> None:
@@ -99,8 +140,17 @@ def setup_namespaces(netns_data: dict[str, dict[str, dict[str, list[str]]]]) ->
         if not netns_exists:
             run_command(f"ip netns add {namespace}")
 
-        # Make localhost available
-        run_command(f"ip netns exec {namespace} ip link set lo up")
+            # Make localhost available
+            run_command(f"ip netns exec {namespace} ip link set lo up")
+
+        # (Re)load the nft ruleset for the given namespace
+        nft_ruleset = f"/opt/sunet-cdn/l4lb/conf/nft-{namespace}.conf"
+        if os.path.isfile(nft_ruleset):
+            run_command(f"ip netns exec {namespace} nft -f {nft_ruleset}")
+        else:
+            print(
+                f"WARNING: no nft ruleset found for namespace '{namespace}' ({nft_ruleset}), the namespace will not be firewalled"  # pylint: disable=line-too-long
+            )
 
         configure_interfaces(namespace, if_data)
 
@@ -129,10 +179,30 @@ def main() -> None:
     #    }
     #  }
     # }
-    with open("/opt/sunet-cdn/l4lb/conf/netns.json", encoding="utf-8") as f:
-        netns_data = json.load(f)
 
-    setup_namespaces(netns_data)
+    input_files = [
+        "/opt/sunet-cdn/l4lb/conf/netns-base.json",
+        "/opt/sunet-cdn/l4lb/conf/netns-sunet-cdn-agent.json",
+    ]
+
+    merged_netns_data: dict[str, dict[str, dict[str, list[str]]]] = {}
+    for input_file in input_files:
+        try:
+            with open(input_file, encoding="utf-8") as f:
+                netns_data = json.load(f)
+
+            # Combine interface config from multiple files belonging to the same namespace
+            for ns, ns_data in netns_data.items():
+                if ns in merged_netns_data:
+                    merged_netns_data[ns].update(ns_data)
+                else:
+                    merged_netns_data[ns] = ns_data
+
+        except FileNotFoundError:
+            print(f"skipping nonexistant file '{input_file}'")
+            continue
+
+    setup_namespaces(merged_netns_data)
 
 
 if __name__ == "__main__":

global/overlay/etc/puppet/modules/cdn/manifests/l4lb.pp

@@ -17,6 +17,8 @@ class cdn::l4lb(
 
   include sunet::systemd_reload
 
+  package {'conntrack': ensure => installed }
+
   package {'bird2': ensure => installed }
 
   file { '/opt/sunet-cdn':
@@ -54,12 +56,20 @@ class cdn::l4lb(
     mode   => '0640',
   }
 
-  file { '/opt/sunet-cdn/l4lb/conf/netns.json':
+  file { '/opt/sunet-cdn/l4lb/conf/netns-base.json':
     ensure  => file,
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('cdn/l4lb/netns.json.erb'),
+    content => template('cdn/l4lb/netns-base.json.erb'),
+  }
+
+  file { '/opt/sunet-cdn/l4lb/conf/nft-l4lb.conf':
+    ensure  => file,
+    owner   => 'root',
+    group   => 'root',
+    mode    => '0644',
+    content => template('cdn/l4lb/nft-l4lb.conf.erb'),
   }
 
   file { '/usr/local/bin/sunet-l4lb-namespace':

global/overlay/etc/puppet/modules/cdn/templates/l4lb/netns-base.json.erb

@@ -15,14 +15,6 @@
       "ipv6": [
         "2001:6b0:2006:75::1/127"
       ]
-    },
-    "dummy0": {
-      "ipv4": [
-        "188.240.152.1/32"
-      ],
-      "ipv6": [
-        "2001:6b0:2100::1/128"
-      ]
     }
   }
 }

global/overlay/etc/puppet/modules/cdn/templates/l4lb/nft-l4lb.conf.erb

@@ -0,0 +1,40 @@
+#!/usr/sbin/nft -f
+
+flush ruleset
+
+table inet filter {
+        chain input {
+                type filter hook input priority 0; policy drop;
+
+                # accept any localhost traffic
+                iif lo counter accept
+
+                # accept icmp
+                ip protocol icmp counter accept
+                ip6 nexthdr icmpv6 icmpv6 type { destination-unreachable, packet-too-big, time-exceeded,
+                                                 parameter-problem, echo-request, mld-listener-query,
+                                                 nd-router-solicit, nd-router-advert, nd-neighbor-solicit,
+                                                 nd-neighbor-advert } counter accept
+
+                # accept traffic originated from us
+                ct state established counter accept
+                # silently drop invalid packets
+                ct state invalid counter drop
+        }
+        chain forward {
+                type filter hook forward priority 0; policy drop;
+        }
+        chain output {
+                type filter hook output priority 0;
+        }
+}
+
+# HTTP and HTTPS
+add rule inet filter input tcp dport 80 counter accept comment "l4lb HTTP"
+add rule inet filter input tcp dport 443 counter accept comment "l4lb HTTPS"
+
+# BGP
+add rule inet filter input ip saddr { 130.242.64.232 } tcp dport 179 counter accept comment "tug-r11-v4"
+add rule inet filter input ip saddr { 130.242.64.234 } tcp dport 179 counter accept comment "tug-r12-v4"
+add rule inet filter input ip6 saddr { 2001:6b0:2006:74:: } tcp dport 179 counter accept comment "tug-r11-v6"
+add rule inet filter input ip6 saddr { 2001:6b0:2006:75:: } tcp dport 179 counter accept comment "tug-r12-v6"