我目前正在设置一个高可用性 (HA) 环境，其中两个运行 Ubuntu 的 Azure 虚拟机位于标准 Azure 负载均衡器后面。现在我知道标准负载均衡器只有第 4 层，这意味着它不能进行 SSL 卸载。
这两个 VM 都在运行 .NET Core Web API。他们显然都需要 SSL 证书来处理来自负载均衡器的 SSL 连接。
我知道我可以购买 SSL 证书并设置 Kestrel 以在 Web API 本身上使用该证书，但我想要免费证书。我知道另一种选择是使用 nginx 服务器生成证书，然后将证书复制到 Web API，但这意味着我需要每 3 个月重复一次该过程，这非常痛苦，因为这意味着我将有停机时间我使 HA 集群脱机以更新证书。
有谁知道在负载均衡器后面的两个虚拟机上使用 Lets Encrypt 的方法？
好的，所以我就按照上面的方法来了。它要求我编写一个实用程序，使用DNS验证自动更新我的 Lets Encrypt 证书。它使用 Azure DNS 或其他具有 API 的 DNS 提供程序非常重要，因为您需要能够直接使用 API 或与您的提供程序的某些其他接口修改您的 DNS 记录。
我正在使用 Azure DNS，它为我管理整个域，因此下面的代码适用于 Azure DNS，但您可以修改 API 以与您选择的任何具有某种 API 的提供商一起使用。
第二部分是在我的高可用性 (HA) 集群中没有任何停机时间。所以我所做的是，将证书写入数据库，然后在我的虚拟机启动时动态读取它。所以基本上每次 Kestrel 启动它都会从数据库中读取证书然后使用它。
您需要将以下模型添加到您的数据库中，以便您可以将实际的证书详细信息存储在某处。
public class Certificate
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public long Id { get; set; }
public string FullChainPem { get; set; }
public string CertificatePfx { get; set; }
public string CertificatePassword { get; set; }
public DateTime CertificateExpiry { get; set; }
public DateTime? CreatedAt { get; set; }
public DateTime? UpdatedAt { get; set; }
}
创建模型后，您需要将其放置在您的上下文中，如下所示：
public DbSet<Certificate> Certificates { get; set; }
在您的应用程序服务器上，您希望Kestrel用作 Web 服务器，然后从数据库中动态加载证书。因此，将以下内容添加到您的CreateWebHostBuilder方法中。重要的是，这是在.UseStartup<Startup>()
.UseKestrel(opt = >{
//Get the application services
var applicationServices = opt.ApplicationServices;
//Create and use scope
using(var scope = applicationServices.CreateScope()) {
//Get the database context to work with
var context = scope.ServiceProvider.GetService < DBContext > ();
//Get the certificate
var certificate = context.Certificates.Last();
var pfxBytes = Convert.FromBase64String(certificate.CertificatePfx);
var pfxPassword = certificate.CertificatePassword;
//Create the certificate
var cert = new X509Certificate2(pfxBytes, pfxPassword);
//Listen on the specified IP and port
opt.Listen(IPAddress.Any, 443, listenOpts = >{
//Use HTTPS
listenOpts.UseHttps(cert);
});
}
});
所以这是解决方案的核心。它处理证书请求、质询、DNS 验证以及证书的存储。它还将自动重新启动 Azure 中使用证书的每个 VM 实例，以便它们提取新证书。
逻辑如下，Main它会检查证书是否需要更新。
static void Main(string[] args) {
while (true) {
//Get the latest certificate in the DB for the servers
var lastCertificate = _db.Certificates.LastOrDefault();
//Check if the expiry date of last certificate is more than a month away
if (lastCertificate != null && (lastCertificate.CertificateExpiry - DateTime.Now).TotalDays > 31) {
//Log out some info
Console.WriteLine($ "[{DateTime.Now}] - Certificate still valid, sleeping for a day.");
//Sleep the thread
Thread.Sleep(TimeSpan.FromDays(1));
}
else {
//Renew the certificates
RenewCertificates();
}
}
}
好的，这要经历很多，但如果你把它分解，它实际上很简单
实际RenewCertificates方法如下：
/// <summary>
/// Method that will renew the domain certificates and update the database with them
/// </summary>
public static void RenewCertificates() {
Console.WriteLine($ "[{DateTime.Now}] - Starting certificate renewal.");
//Instantiate variables
AcmeContext acme;
IAccountContext account;
//Try and get the setting value for ACME Key
var acmeKey = _db.Settings.FirstOrDefault(s = >s.Key == "ACME");
//Check if acme key is null
if (acmeKey == null) {
//Set the ACME servers to use
#if DEBUG
acme = new AcmeContext(WellKnownServers.LetsEncryptStagingV2);
#else
acme = new AcmeContext(WellKnownServers.LetsEncryptV2);
#endif
//Create the new account
account = acme.NewAccount("yourname@yourdomain.tld", true).Result;
//Save the key to the DB to be used
_db.Settings.Add(new Setting {
Key = "ACME",
Value = acme.AccountKey.ToPem()
});
//Save DB changes
_db.SaveChanges();
}
else {
//Get the account key from PEM
var accountKey = KeyFactory.FromPem(acmeKey.Value);
//Set the ACME servers to use
#if DEBUG
acme = new AcmeContext(WellKnownServers.LetsEncryptStagingV2, accountKey);
#else
acme = new AcmeContext(WellKnownServers.LetsEncryptV2, accountKey);
#endif
//Get the actual account
account = acme.Account().Result;
}
//Create an order for wildcard domain and normal domain
var order = acme.NewOrder(new[] {
"*.yourdomain.tld",
"yourdomain.tld"
}).Result;
//Generate the challenges for the domains
var authorizations = order.Authorizations().Result;
//Error flag
var hasFailed = false;
foreach(var authorization in authorizations) {
//Get the DNS challenge for the authorization
var dnsChallenge = authorization.Dns().Result;
//Get the DNS TXT
var dnsTxt = acme.AccountKey.DnsTxt(dnsChallenge.Token);
Console.WriteLine($ "[{DateTime.Now}] - Received DNS challenge data.");
//Set the DNS record
Azure.SetAcmeTxtRecord(dnsTxt);
Console.WriteLine($ "[{DateTime.Now}] - Updated DNS challenge data.");
Console.WriteLine($ "[{DateTime.Now}] - Waiting 1 minute before checking status.");
dnsChallenge.Validate();
//Wait 1 minute
Thread.Sleep(TimeSpan.FromMinutes(1));
//Check the DNS challenge
var valid = dnsChallenge.Validate().Result;
//If the verification fails set failed flag
if (valid.Status != ChallengeStatus.Valid) hasFailed = true;
}
//Check whether challenges failed
if (hasFailed) {
Console.WriteLine($ "[{DateTime.Now}] - DNS challenge(s) failed, retrying.");
//Recurse
RenewCertificates();
return;
}
else {
Console.WriteLine($ "[{DateTime.Now}] - DNS challenge(s) successful.");
//Generate a private key
var privateKey = KeyFactory.NewKey(KeyAlgorithm.ES256);
//Generate certificate
var cert = order.Generate(new CsrInfo {
CountryName = "ZA",
State = "Gauteng",
Locality = "Pretoria",
Organization = "Your Organization",
OrganizationUnit = "Production",
},
privateKey).Result;
Console.WriteLine($ "[{DateTime.Now}] - Certificate generated successfully.");
//Get the full chain
var fullChain = cert.ToPem();
//Generate password
var pass = Guid.NewGuid().ToString();
//Export the pfx
var pfxBuilder = cert.ToPfx(privateKey);
var pfx = pfxBuilder.Build("yourdomain.tld", pass);
//Create database entry
_db.Certificates.Add(new Certificate {
FullChainPem = fullChain,
CertificatePfx = Convert.ToBase64String(pfx),
CertificatePassword = pass,
CertificateExpiry = DateTime.Now.AddMonths(2)
});
//Save changes
_db.SaveChanges();
Console.WriteLine($ "[{DateTime.Now}] - Database updated with new certificate.");
Console.WriteLine($ "[{DateTime.Now}] - Restarting VMs.");
//Restart the VMS
Azure.RestartAllVms();
}
}
无论我在哪里打电话Azure，您都需要编写 API 包装器来设置 DNS TXT 记录，然后才能从托管服务提供商处重新启动虚拟机。我的都是 Azure 的，所以做起来很简单。这是 Azure 代码：
/// <summary>
/// Method that will set the TXT record value of the ACME challenge
/// </summary>
/// <param name="txtValue">Value for the TXT record</param>
/// <returns>Whether call was successful or not</returns>
public static bool SetAcmeTxtRecord(string txtValue) {
//Set the zone endpoint
const string url = "https://management.azure.com/subscriptions/{subId}/resourceGroups/{resourceGroup}/providers/Microsoft.Network/dnsZones/{dnsZone}/txt/_acme-challenge?api-version=2018-03-01-preview";
//Authenticate API
AuthenticateApi();
//Build up the body to put
var body = $ "{{\"properties\": {{\"metadata\": {{}},\"TTL\": 225,\"TXTRecords\": [{{\"value\": [\"{txtValue}\"]}}]}}}}";
//Build up the string content
var content = new StringContent(body, Encoding.UTF8, "application/json");
//Create the response
var response = client.PutAsync(url, content).Result;
//Return the response
return response.IsSuccessStatusCode;
}
我希望这能够帮助与我处于同样困境的其他人。