feat: add coredns mysql image build and updater

scripts/test-image.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+# SPDX-License-Identifier: MIT
+# Copyright (C) 2026 Bryan Joshua Pedini
+
+set -eu
+image=$1
+version=$2
+output=$(docker run --rm "$image" -plugins)
+printf '%s\n' "$output" | grep -qx 'mysql'
+docker run --rm "$image" -version | grep -F "CoreDNS-${version}"
+network="coredns-ci-$$"
+db="coredns-db-$$"
+dns="coredns-dns-$$"
+config=$(mktemp)
+cleanup() {
+  docker rm -f "$dns" "$db" >/dev/null 2>&1 || true
+  docker network rm "$network" >/dev/null 2>&1 || true
+  rm -f "$config"
+}
+trap cleanup EXIT INT TERM
+docker network create --internal "$network" >/dev/null
+docker run -d --name "$db" --network "$network" --network-alias database -e MARIADB_ROOT_PASSWORD=test -e MARIADB_DATABASE=coredns mariadb:11 >/dev/null
+ready=0
+attempt=0
+while [ "$attempt" -lt 60 ]; do
+  attempt=$((attempt + 1))
+  if docker exec "$db" mariadb -uroot -ptest -e 'SELECT 1' >/dev/null 2>&1; then ready=1; break; fi
+  sleep 1
+done
+[ "$ready" = 1 ] || { docker logs "$db"; exit 1; }
+docker exec -i "$db" mariadb -uroot -ptest coredns <<'SQL'
+CREATE TABLE coredns_records (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, zone VARCHAR(255) NOT NULL, name VARCHAR(255) NOT NULL, ttl INT DEFAULT NULL, content TEXT, record_type VARCHAR(255) NOT NULL);
+INSERT INTO coredns_records (zone, name, ttl, content, record_type) VALUES ('example.test.', 'www', 30, '{"ip":"192.0.2.10"}', 'A');
+SQL
+printf '%s\n' '.:1053 {' '  mysql {' '    dsn root:test@tcp(database:3306)/coredns' '  }' '  errors' '}' > "$config"
+docker create --name "$dns" --network "$network" --network-alias dns "$image" -conf /Corefile >/dev/null
+docker cp "$config" "$dns:/Corefile"
+docker start "$dns" >/dev/null
+docker run --rm --network "$network" python:3.13-slim python -c '
+import socket, struct, time
+query = bytes.fromhex("123401000001000000000000") + b"\x03www\x07example\x04test\0" + struct.pack("!HH", 1, 1)
+for attempt in range(30):
+    try:
+        with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
+            sock.settimeout(1)
+            sock.sendto(query, ("dns", 1053))
+            response, _ = sock.recvfrom(4096)
+        if response[:2] == b"\x12\x34" and response[3] & 15 == 0 and struct.unpack("!H", response[6:8])[0] and b"\xc0\x00\x02\x0a" in response:
+            print("MySQL-backed DNS query passed")
+            break
+    except OSError:
+        pass
+    time.sleep(1)
+else:
+    raise SystemExit("MySQL-backed DNS query failed")
+'

scripts/update.py

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+# SPDX-License-Identifier: MIT
+# Copyright (C) 2026 Bryan Joshua Pedini
+
+import json
+import re
+import urllib.request
+from pathlib import Path
+
+
+def fetch(url):
+    request = urllib.request.Request(url, headers={"Accept": "application/vnd.github+json", "User-Agent": "coredns-mysql-updater"})
+    with urllib.request.urlopen(request, timeout=30) as response:
+        return json.load(response)
+
+
+release = fetch("https://api.github.com/repos/coredns/coredns/releases/latest")
+plugin = fetch("https://api.github.com/repos/cloud66-oss/coredns_mysql/commits/HEAD")
+tag = release["tag_name"]
+revision = plugin["sha"]
+if not re.fullmatch(r"v[0-9]+\.[0-9]+\.[0-9]+", tag):
+    raise SystemExit(f"Unexpected CoreDNS release: {tag}")
+if not re.fullmatch(r"[0-9a-f]{40}", revision):
+    raise SystemExit("Unexpected plugin revision")
+Path("versions.env").write_text(f"COREDNS_VERSION={tag[1:]}\nMYSQL_PLUGIN_REV={revision}\n")