feat: add config reloader with diff, validate, and CLI merge
Port of Go server/reload.go option interface and diffing logic. Compares NatsOptions property-by-property to detect changes, tags each with category flags (logging, auth, TLS, non-reloadable), validates that non-reloadable options (Host, Port, ServerName) are not changed at runtime, and provides MergeCliOverrides to ensure CLI flags always take precedence over config file values during hot reload.
This commit is contained in:
Joseph Doherty
341
src/NATS.Server/Configuration/ConfigReloader.cs
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341
src/NATS.Server/Configuration/ConfigReloader.cs
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@@ -0,0 +1,341 @@
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// Port of Go server/reload.go — config diffing, validation, and CLI override merging
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// for hot reload support. Reference: golang/nats-server/server/reload.go.
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namespace NATS.Server.Configuration;
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/// <summary>
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/// Provides static methods for comparing two <see cref="NatsOptions"/> instances,
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/// validating that detected changes are reloadable, and merging CLI overrides
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/// so that command-line flags always take precedence over config file values.
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/// </summary>
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public static class ConfigReloader
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{
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// Non-reloadable options (match Go server — Host, Port, ServerName require restart)
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private static readonly HashSet<string> NonReloadable = ["Host", "Port", "ServerName"];
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// Logging-related options
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private static readonly HashSet<string> LoggingOptions =
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["Debug", "Trace", "TraceVerbose", "Logtime", "LogtimeUTC", "LogFile",
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"LogSizeLimit", "LogMaxFiles", "Syslog", "RemoteSyslog"];
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// Auth-related options
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private static readonly HashSet<string> AuthOptions =
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["Username", "Password", "Authorization", "Users", "NKeys",
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"NoAuthUser", "AuthTimeout"];
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// TLS-related options
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private static readonly HashSet<string> TlsOptions =
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["TlsCert", "TlsKey", "TlsCaCert", "TlsVerify", "TlsMap",
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"TlsTimeout", "TlsHandshakeFirst", "TlsHandshakeFirstFallback",
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"AllowNonTls", "TlsRateLimit", "TlsPinnedCerts"];
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/// <summary>
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/// Compares two <see cref="NatsOptions"/> instances property by property and returns
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/// a list of <see cref="IConfigChange"/> for every property that differs. Each change
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/// is tagged with the appropriate category flags.
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/// </summary>
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public static List<IConfigChange> Diff(NatsOptions oldOpts, NatsOptions newOpts)
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{
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var changes = new List<IConfigChange>();
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// Non-reloadable
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CompareAndAdd(changes, "Host", oldOpts.Host, newOpts.Host);
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CompareAndAdd(changes, "Port", oldOpts.Port, newOpts.Port);
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CompareAndAdd(changes, "ServerName", oldOpts.ServerName, newOpts.ServerName);
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// Logging
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CompareAndAdd(changes, "Debug", oldOpts.Debug, newOpts.Debug);
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CompareAndAdd(changes, "Trace", oldOpts.Trace, newOpts.Trace);
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CompareAndAdd(changes, "TraceVerbose", oldOpts.TraceVerbose, newOpts.TraceVerbose);
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CompareAndAdd(changes, "Logtime", oldOpts.Logtime, newOpts.Logtime);
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CompareAndAdd(changes, "LogtimeUTC", oldOpts.LogtimeUTC, newOpts.LogtimeUTC);
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CompareAndAdd(changes, "LogFile", oldOpts.LogFile, newOpts.LogFile);
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CompareAndAdd(changes, "LogSizeLimit", oldOpts.LogSizeLimit, newOpts.LogSizeLimit);
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CompareAndAdd(changes, "LogMaxFiles", oldOpts.LogMaxFiles, newOpts.LogMaxFiles);
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CompareAndAdd(changes, "Syslog", oldOpts.Syslog, newOpts.Syslog);
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CompareAndAdd(changes, "RemoteSyslog", oldOpts.RemoteSyslog, newOpts.RemoteSyslog);
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// Auth
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CompareAndAdd(changes, "Username", oldOpts.Username, newOpts.Username);
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CompareAndAdd(changes, "Password", oldOpts.Password, newOpts.Password);
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CompareAndAdd(changes, "Authorization", oldOpts.Authorization, newOpts.Authorization);
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CompareCollectionAndAdd(changes, "Users", oldOpts.Users, newOpts.Users);
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CompareCollectionAndAdd(changes, "NKeys", oldOpts.NKeys, newOpts.NKeys);
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CompareAndAdd(changes, "NoAuthUser", oldOpts.NoAuthUser, newOpts.NoAuthUser);
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CompareAndAdd(changes, "AuthTimeout", oldOpts.AuthTimeout, newOpts.AuthTimeout);
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// TLS
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CompareAndAdd(changes, "TlsCert", oldOpts.TlsCert, newOpts.TlsCert);
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CompareAndAdd(changes, "TlsKey", oldOpts.TlsKey, newOpts.TlsKey);
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CompareAndAdd(changes, "TlsCaCert", oldOpts.TlsCaCert, newOpts.TlsCaCert);
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CompareAndAdd(changes, "TlsVerify", oldOpts.TlsVerify, newOpts.TlsVerify);
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CompareAndAdd(changes, "TlsMap", oldOpts.TlsMap, newOpts.TlsMap);
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CompareAndAdd(changes, "TlsTimeout", oldOpts.TlsTimeout, newOpts.TlsTimeout);
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CompareAndAdd(changes, "TlsHandshakeFirst", oldOpts.TlsHandshakeFirst, newOpts.TlsHandshakeFirst);
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CompareAndAdd(changes, "TlsHandshakeFirstFallback", oldOpts.TlsHandshakeFirstFallback, newOpts.TlsHandshakeFirstFallback);
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CompareAndAdd(changes, "AllowNonTls", oldOpts.AllowNonTls, newOpts.AllowNonTls);
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CompareAndAdd(changes, "TlsRateLimit", oldOpts.TlsRateLimit, newOpts.TlsRateLimit);
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CompareCollectionAndAdd(changes, "TlsPinnedCerts", oldOpts.TlsPinnedCerts, newOpts.TlsPinnedCerts);
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// Limits
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CompareAndAdd(changes, "MaxConnections", oldOpts.MaxConnections, newOpts.MaxConnections);
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CompareAndAdd(changes, "MaxPayload", oldOpts.MaxPayload, newOpts.MaxPayload);
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CompareAndAdd(changes, "MaxPending", oldOpts.MaxPending, newOpts.MaxPending);
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CompareAndAdd(changes, "WriteDeadline", oldOpts.WriteDeadline, newOpts.WriteDeadline);
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CompareAndAdd(changes, "PingInterval", oldOpts.PingInterval, newOpts.PingInterval);
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CompareAndAdd(changes, "MaxPingsOut", oldOpts.MaxPingsOut, newOpts.MaxPingsOut);
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CompareAndAdd(changes, "MaxControlLine", oldOpts.MaxControlLine, newOpts.MaxControlLine);
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CompareAndAdd(changes, "MaxSubs", oldOpts.MaxSubs, newOpts.MaxSubs);
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CompareAndAdd(changes, "MaxSubTokens", oldOpts.MaxSubTokens, newOpts.MaxSubTokens);
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CompareAndAdd(changes, "MaxTracedMsgLen", oldOpts.MaxTracedMsgLen, newOpts.MaxTracedMsgLen);
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CompareAndAdd(changes, "MaxClosedClients", oldOpts.MaxClosedClients, newOpts.MaxClosedClients);
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// Misc
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CompareCollectionAndAdd(changes, "Tags", oldOpts.Tags, newOpts.Tags);
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CompareAndAdd(changes, "LameDuckDuration", oldOpts.LameDuckDuration, newOpts.LameDuckDuration);
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CompareAndAdd(changes, "LameDuckGracePeriod", oldOpts.LameDuckGracePeriod, newOpts.LameDuckGracePeriod);
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CompareAndAdd(changes, "ClientAdvertise", oldOpts.ClientAdvertise, newOpts.ClientAdvertise);
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CompareAndAdd(changes, "DisableSublistCache", oldOpts.DisableSublistCache, newOpts.DisableSublistCache);
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CompareAndAdd(changes, "ConnectErrorReports", oldOpts.ConnectErrorReports, newOpts.ConnectErrorReports);
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CompareAndAdd(changes, "ReconnectErrorReports", oldOpts.ReconnectErrorReports, newOpts.ReconnectErrorReports);
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CompareAndAdd(changes, "NoHeaderSupport", oldOpts.NoHeaderSupport, newOpts.NoHeaderSupport);
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CompareAndAdd(changes, "NoSystemAccount", oldOpts.NoSystemAccount, newOpts.NoSystemAccount);
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CompareAndAdd(changes, "SystemAccount", oldOpts.SystemAccount, newOpts.SystemAccount);
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return changes;
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}
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/// <summary>
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/// Validates a list of config changes and returns error messages for any
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/// non-reloadable changes (properties that require a server restart).
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/// </summary>
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public static List<string> Validate(List<IConfigChange> changes)
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{
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var errors = new List<string>();
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foreach (var change in changes)
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{
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if (change.IsNonReloadable)
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{
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errors.Add($"Config reload: '{change.Name}' cannot be changed at runtime (requires restart)");
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}
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}
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return errors;
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}
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/// <summary>
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/// Merges CLI overrides into a freshly-parsed config so that command-line flags
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/// always take precedence. Only properties whose names appear in <paramref name="cliFlags"/>
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/// are copied from <paramref name="cliValues"/> to <paramref name="fromConfig"/>.
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/// </summary>
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public static void MergeCliOverrides(NatsOptions fromConfig, NatsOptions cliValues, HashSet<string> cliFlags)
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{
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foreach (var flag in cliFlags)
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{
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switch (flag)
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{
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// Non-reloadable
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case "Host":
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fromConfig.Host = cliValues.Host;
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break;
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case "Port":
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fromConfig.Port = cliValues.Port;
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break;
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case "ServerName":
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fromConfig.ServerName = cliValues.ServerName;
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break;
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// Logging
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case "Debug":
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fromConfig.Debug = cliValues.Debug;
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break;
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case "Trace":
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fromConfig.Trace = cliValues.Trace;
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break;
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case "TraceVerbose":
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fromConfig.TraceVerbose = cliValues.TraceVerbose;
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break;
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case "Logtime":
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fromConfig.Logtime = cliValues.Logtime;
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break;
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case "LogtimeUTC":
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fromConfig.LogtimeUTC = cliValues.LogtimeUTC;
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break;
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case "LogFile":
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fromConfig.LogFile = cliValues.LogFile;
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break;
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case "LogSizeLimit":
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fromConfig.LogSizeLimit = cliValues.LogSizeLimit;
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break;
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case "LogMaxFiles":
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fromConfig.LogMaxFiles = cliValues.LogMaxFiles;
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break;
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case "Syslog":
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fromConfig.Syslog = cliValues.Syslog;
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break;
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case "RemoteSyslog":
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fromConfig.RemoteSyslog = cliValues.RemoteSyslog;
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break;
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// Auth
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case "Username":
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fromConfig.Username = cliValues.Username;
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break;
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case "Password":
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fromConfig.Password = cliValues.Password;
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break;
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case "Authorization":
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fromConfig.Authorization = cliValues.Authorization;
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break;
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case "Users":
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fromConfig.Users = cliValues.Users;
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break;
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case "NKeys":
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fromConfig.NKeys = cliValues.NKeys;
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break;
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case "NoAuthUser":
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fromConfig.NoAuthUser = cliValues.NoAuthUser;
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break;
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case "AuthTimeout":
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fromConfig.AuthTimeout = cliValues.AuthTimeout;
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break;
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// TLS
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case "TlsCert":
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fromConfig.TlsCert = cliValues.TlsCert;
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break;
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case "TlsKey":
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fromConfig.TlsKey = cliValues.TlsKey;
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break;
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case "TlsCaCert":
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fromConfig.TlsCaCert = cliValues.TlsCaCert;
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break;
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case "TlsVerify":
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fromConfig.TlsVerify = cliValues.TlsVerify;
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break;
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case "TlsMap":
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fromConfig.TlsMap = cliValues.TlsMap;
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break;
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case "TlsTimeout":
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fromConfig.TlsTimeout = cliValues.TlsTimeout;
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break;
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case "TlsHandshakeFirst":
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fromConfig.TlsHandshakeFirst = cliValues.TlsHandshakeFirst;
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break;
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case "TlsHandshakeFirstFallback":
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fromConfig.TlsHandshakeFirstFallback = cliValues.TlsHandshakeFirstFallback;
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break;
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case "AllowNonTls":
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fromConfig.AllowNonTls = cliValues.AllowNonTls;
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break;
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case "TlsRateLimit":
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fromConfig.TlsRateLimit = cliValues.TlsRateLimit;
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break;
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case "TlsPinnedCerts":
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fromConfig.TlsPinnedCerts = cliValues.TlsPinnedCerts;
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break;
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// Limits
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case "MaxConnections":
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fromConfig.MaxConnections = cliValues.MaxConnections;
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break;
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case "MaxPayload":
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fromConfig.MaxPayload = cliValues.MaxPayload;
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break;
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case "MaxPending":
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fromConfig.MaxPending = cliValues.MaxPending;
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break;
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case "WriteDeadline":
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fromConfig.WriteDeadline = cliValues.WriteDeadline;
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break;
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case "PingInterval":
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fromConfig.PingInterval = cliValues.PingInterval;
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break;
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case "MaxPingsOut":
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fromConfig.MaxPingsOut = cliValues.MaxPingsOut;
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break;
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case "MaxControlLine":
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fromConfig.MaxControlLine = cliValues.MaxControlLine;
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break;
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case "MaxSubs":
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fromConfig.MaxSubs = cliValues.MaxSubs;
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break;
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case "MaxSubTokens":
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fromConfig.MaxSubTokens = cliValues.MaxSubTokens;
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break;
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case "MaxTracedMsgLen":
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fromConfig.MaxTracedMsgLen = cliValues.MaxTracedMsgLen;
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break;
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case "MaxClosedClients":
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fromConfig.MaxClosedClients = cliValues.MaxClosedClients;
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break;
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// Misc
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case "Tags":
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fromConfig.Tags = cliValues.Tags;
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break;
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case "LameDuckDuration":
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fromConfig.LameDuckDuration = cliValues.LameDuckDuration;
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break;
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case "LameDuckGracePeriod":
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fromConfig.LameDuckGracePeriod = cliValues.LameDuckGracePeriod;
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break;
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case "ClientAdvertise":
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fromConfig.ClientAdvertise = cliValues.ClientAdvertise;
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break;
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case "DisableSublistCache":
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fromConfig.DisableSublistCache = cliValues.DisableSublistCache;
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break;
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case "ConnectErrorReports":
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fromConfig.ConnectErrorReports = cliValues.ConnectErrorReports;
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break;
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case "ReconnectErrorReports":
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fromConfig.ReconnectErrorReports = cliValues.ReconnectErrorReports;
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break;
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case "NoHeaderSupport":
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fromConfig.NoHeaderSupport = cliValues.NoHeaderSupport;
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break;
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case "NoSystemAccount":
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fromConfig.NoSystemAccount = cliValues.NoSystemAccount;
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break;
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case "SystemAccount":
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fromConfig.SystemAccount = cliValues.SystemAccount;
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break;
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}
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}
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}
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// ─── Comparison helpers ─────────────────────────────────────────
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private static void CompareAndAdd<T>(List<IConfigChange> changes, string name, T oldVal, T newVal)
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{
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if (!Equals(oldVal, newVal))
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{
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changes.Add(new ConfigChange(
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name,
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isLoggingChange: LoggingOptions.Contains(name),
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isAuthChange: AuthOptions.Contains(name),
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isTlsChange: TlsOptions.Contains(name),
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isNonReloadable: NonReloadable.Contains(name)));
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}
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}
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private static void CompareCollectionAndAdd<T>(List<IConfigChange> changes, string name, T? oldVal, T? newVal)
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where T : class
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{
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// For collections we compare by reference and null state.
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// A change from null to non-null (or vice versa), or a different reference, counts as changed.
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if (ReferenceEquals(oldVal, newVal))
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return;
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if (oldVal is null || newVal is null || !ReferenceEquals(oldVal, newVal))
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{
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changes.Add(new ConfigChange(
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name,
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isLoggingChange: LoggingOptions.Contains(name),
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isAuthChange: AuthOptions.Contains(name),
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isTlsChange: TlsOptions.Contains(name),
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isNonReloadable: NonReloadable.Contains(name)));
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}
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}
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}
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54
src/NATS.Server/Configuration/IConfigChange.cs
Normal file
54
src/NATS.Server/Configuration/IConfigChange.cs
Normal file
@@ -0,0 +1,54 @@
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// Port of Go server/reload.go option interface — represents a single detected
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// configuration change with category flags for reload handling.
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// Reference: golang/nats-server/server/reload.go lines 42-74.
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namespace NATS.Server.Configuration;
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/// <summary>
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/// Represents a single detected configuration change during a hot reload.
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/// Category flags indicate what kind of reload action is needed.
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/// </summary>
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public interface IConfigChange
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{
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/// <summary>
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/// The property name that changed (matches NatsOptions property name).
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/// </summary>
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string Name { get; }
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/// <summary>
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/// Whether this change requires reloading the logger.
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/// </summary>
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bool IsLoggingChange { get; }
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/// <summary>
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/// Whether this change requires reloading authorization.
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/// </summary>
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bool IsAuthChange { get; }
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/// <summary>
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/// Whether this change requires reloading TLS configuration.
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/// </summary>
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bool IsTlsChange { get; }
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/// <summary>
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/// Whether this option cannot be changed at runtime (requires restart).
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/// </summary>
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bool IsNonReloadable { get; }
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}
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/// <summary>
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/// Default implementation of <see cref="IConfigChange"/> using a primary constructor.
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/// </summary>
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public sealed class ConfigChange(
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string name,
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bool isLoggingChange = false,
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bool isAuthChange = false,
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bool isTlsChange = false,
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bool isNonReloadable = false) : IConfigChange
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{
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public string Name => name;
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public bool IsLoggingChange => isLoggingChange;
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public bool IsAuthChange => isAuthChange;
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public bool IsTlsChange => isTlsChange;
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public bool IsNonReloadable => isNonReloadable;
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}
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Reference in New Issue
Block a user