Fix dashboard dns lookup delay

esphome/address_cache.py

@@ -0,0 +1,131 @@
+"""Address cache for DNS and mDNS lookups."""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+_LOGGER = logging.getLogger(__name__)
+
+
+def normalize_hostname(hostname: str) -> str:
+    """Normalize hostname for cache lookups.
+
+    Removes trailing dots and converts to lowercase.
+    """
+    return hostname.rstrip(".").lower()
+
+
+class AddressCache:
+    """Cache for DNS and mDNS address lookups.
+
+    This cache stores pre-resolved addresses from command-line arguments
+    to avoid slow DNS/mDNS lookups during builds.
+    """
+
+    def __init__(
+        self,
+        mdns_cache: dict[str, list[str]] | None = None,
+        dns_cache: dict[str, list[str]] | None = None,
+    ) -> None:
+        """Initialize the address cache.
+
+        Args:
+            mdns_cache: Pre-populated mDNS addresses (hostname -> IPs)
+            dns_cache: Pre-populated DNS addresses (hostname -> IPs)
+        """
+        self.mdns_cache = mdns_cache or {}
+        self.dns_cache = dns_cache or {}
+
+    def get_mdns_addresses(self, hostname: str) -> list[str] | None:
+        """Get cached mDNS addresses for a hostname.
+
+        Args:
+            hostname: The hostname to look up (should end with .local)
+
+        Returns:
+            List of IP addresses if found in cache, None otherwise
+        """
+        normalized = normalize_hostname(hostname)
+        if addresses := self.mdns_cache.get(normalized):
+            _LOGGER.debug("Using mDNS cache for %s: %s", hostname, addresses)
+            return addresses
+        return None
+
+    def get_dns_addresses(self, hostname: str) -> list[str] | None:
+        """Get cached DNS addresses for a hostname.
+
+        Args:
+            hostname: The hostname to look up
+
+        Returns:
+            List of IP addresses if found in cache, None otherwise
+        """
+        normalized = normalize_hostname(hostname)
+        if addresses := self.dns_cache.get(normalized):
+            _LOGGER.debug("Using DNS cache for %s: %s", hostname, addresses)
+            return addresses
+        return None
+
+    def get_addresses(self, hostname: str) -> list[str] | None:
+        """Get cached addresses for a hostname.
+
+        Checks mDNS cache for .local domains, DNS cache otherwise.
+
+        Args:
+            hostname: The hostname to look up
+
+        Returns:
+            List of IP addresses if found in cache, None otherwise
+        """
+        normalized = normalize_hostname(hostname)
+        if normalized.endswith(".local"):
+            return self.get_mdns_addresses(hostname)
+        return self.get_dns_addresses(hostname)
+
+    def has_cache(self) -> bool:
+        """Check if any cache entries exist."""
+        return bool(self.mdns_cache or self.dns_cache)
+
+    @classmethod
+    def from_cli_args(
+        cls, mdns_args: Iterable[str], dns_args: Iterable[str]
+    ) -> AddressCache:
+        """Create cache from command-line arguments.
+
+        Args:
+            mdns_args: List of mDNS cache entries like ['host=ip1,ip2']
+            dns_args: List of DNS cache entries like ['host=ip1,ip2']
+
+        Returns:
+            Configured AddressCache instance
+        """
+        mdns_cache = cls._parse_cache_args(mdns_args)
+        dns_cache = cls._parse_cache_args(dns_args)
+        return cls(mdns_cache=mdns_cache, dns_cache=dns_cache)
+
+    @staticmethod
+    def _parse_cache_args(cache_args: Iterable[str]) -> dict[str, list[str]]:
+        """Parse cache arguments into a dictionary.
+
+        Args:
+            cache_args: List of cache mappings like ['host1=ip1,ip2', 'host2=ip3']
+
+        Returns:
+            Dictionary mapping normalized hostnames to list of IP addresses
+        """
+        cache: dict[str, list[str]] = {}
+        for arg in cache_args:
+            if "=" not in arg:
+                _LOGGER.warning(
+                    "Invalid cache format: %s (expected 'hostname=ip1,ip2')", arg
+                )
+                continue
+            hostname, ips = arg.split("=", 1)
+            # Normalize hostname for consistent lookups
+            normalized = normalize_hostname(hostname)
+            cache[normalized] = [ip.strip() for ip in ips.split(",")]
+        return cache