Issue #21: implement worker bootstrap and options

src/MxGateway.Worker/Bootstrap/.gitkeep

@@ -1 +0,0 @@
-

src/MxGateway.Worker/Bootstrap/EnvironmentVariableWorkerEnvironment.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public sealed class EnvironmentVariableWorkerEnvironment : IWorkerEnvironment
+{
+    public string? GetEnvironmentVariable(string name)
+    {
+        return Environment.GetEnvironmentVariable(name);
+    }
+}

src/MxGateway.Worker/Bootstrap/IWorkerEnvironment.cs

@@ -0,0 +1,6 @@
+namespace MxGateway.Worker.Bootstrap;
+
+public interface IWorkerEnvironment
+{
+    string? GetEnvironmentVariable(string name);
+}

src/MxGateway.Worker/Bootstrap/IWorkerLogger.cs

@@ -0,0 +1,10 @@
+using System.Collections.Generic;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public interface IWorkerLogger
+{
+    void Information(string eventName, IReadOnlyDictionary<string, object?> fields);
+
+    void Error(string eventName, IReadOnlyDictionary<string, object?> fields);
+}

src/MxGateway.Worker/Bootstrap/WorkerBootstrapResult.cs

@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public sealed class WorkerBootstrapResult
+{
+    private WorkerBootstrapResult(
+        WorkerExitCode exitCode,
+        WorkerOptions? options,
+        IReadOnlyList<string> errors)
+    {
+        ExitCode = exitCode;
+        Options = options;
+        Errors = errors;
+    }
+
+    public WorkerExitCode ExitCode { get; }
+
+    public WorkerOptions? Options { get; }
+
+    public IReadOnlyList<string> Errors { get; }
+
+    public bool Succeeded => ExitCode == WorkerExitCode.Success;
+
+    public static WorkerBootstrapResult Success(WorkerOptions options)
+    {
+        return new WorkerBootstrapResult(WorkerExitCode.Success, options, []);
+    }
+
+    public static WorkerBootstrapResult Failure(WorkerExitCode exitCode, IEnumerable<string> errors)
+    {
+        return new WorkerBootstrapResult(exitCode, null, errors.ToArray());
+    }
+}

src/MxGateway.Worker/Bootstrap/WorkerConsoleLogger.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public sealed class WorkerConsoleLogger : IWorkerLogger
+{
+    private readonly TextWriter _writer;
+
+    public WorkerConsoleLogger(TextWriter writer)
+    {
+        _writer = writer ?? throw new ArgumentNullException(nameof(writer));
+    }
+
+    public void Information(string eventName, IReadOnlyDictionary<string, object?> fields)
+    {
+        Write("Information", eventName, fields);
+    }
+
+    public void Error(string eventName, IReadOnlyDictionary<string, object?> fields)
+    {
+        Write("Error", eventName, fields);
+    }
+
+    private void Write(
+        string level,
+        string eventName,
+        IReadOnlyDictionary<string, object?> fields)
+    {
+        Dictionary<string, object?> redactedFields = WorkerLogRedactor.RedactFields(fields);
+        string fieldText = string.Join(
+            " ",
+            redactedFields.Select(field => $"{field.Key}={FormatValue(field.Value)}"));
+
+        _writer.WriteLine($"level={level} event={eventName} {fieldText}".TrimEnd());
+    }
+
+    private static string FormatValue(object? value)
+    {
+        return value?.ToString() ?? string.Empty;
+    }
+}

src/MxGateway.Worker/Bootstrap/WorkerExitCode.cs

@@ -0,0 +1,10 @@
+namespace MxGateway.Worker.Bootstrap;
+
+public enum WorkerExitCode
+{
+    Success = 0,
+    UnexpectedFailure = 1,
+    InvalidArguments = 2,
+    InvalidProtocolVersion = 3,
+    MissingNonce = 4,
+}

src/MxGateway.Worker/Bootstrap/WorkerLogRedactor.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public static class WorkerLogRedactor
+{
+    public const string RedactedValue = "[redacted]";
+
+    private static readonly string[] SensitiveFieldNameParts =
+    [
+        "nonce",
+        "secret",
+        "password",
+        "token",
+        "credential",
+        "apikey",
+        "api_key",
+    ];
+
+    public static Dictionary<string, object?> RedactFields(IReadOnlyDictionary<string, object?> fields)
+    {
+        Dictionary<string, object?> redactedFields = [];
+
+        foreach (KeyValuePair<string, object?> field in fields)
+        {
+            redactedFields[field.Key] = RedactValue(field.Key, field.Value);
+        }
+
+        return redactedFields;
+    }
+
+    public static object? RedactValue(string fieldName, object? value)
+    {
+        if (value is null)
+        {
+            return null;
+        }
+
+        foreach (string sensitiveFieldNamePart in SensitiveFieldNameParts)
+        {
+            if (fieldName.IndexOf(sensitiveFieldNamePart, StringComparison.OrdinalIgnoreCase) >= 0)
+            {
+                return RedactedValue;
+            }
+        }
+
+        return value;
+    }
+}

src/MxGateway.Worker/Bootstrap/WorkerOptions.cs

@@ -0,0 +1,26 @@
+namespace MxGateway.Worker.Bootstrap;
+
+public sealed class WorkerOptions
+{
+    public const string NonceEnvironmentVariableName = "MXGATEWAY_WORKER_NONCE";
+
+    public WorkerOptions(
+        string sessionId,
+        string pipeName,
+        uint protocolVersion,
+        string nonce)
+    {
+        SessionId = sessionId;
+        PipeName = pipeName;
+        ProtocolVersion = protocolVersion;
+        Nonce = nonce;
+    }
+
+    public string SessionId { get; }
+
+    public string PipeName { get; }
+
+    public uint ProtocolVersion { get; }
+
+    public string Nonce { get; }
+}

src/MxGateway.Worker/Bootstrap/WorkerOptionsParser.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Generic;
+using MxGateway.Contracts;
+
+namespace MxGateway.Worker.Bootstrap;
+
+public sealed class WorkerOptionsParser
+{
+    private const string SessionIdOptionName = "--session-id";
+    private const string PipeNameOptionName = "--pipe-name";
+    private const string ProtocolVersionOptionName = "--protocol-version";
+
+    private readonly IWorkerEnvironment _environment;
+
+    public WorkerOptionsParser(IWorkerEnvironment environment)
+    {
+        _environment = environment ?? throw new ArgumentNullException(nameof(environment));
+    }
+
+    public WorkerBootstrapResult Parse(string[] args)
+    {
+        if (args is null)
+        {
+            throw new ArgumentNullException(nameof(args));
+        }
+
+        Dictionary<string, string> values = new(StringComparer.OrdinalIgnoreCase);
+        List<string> errors = [];
+
+        for (int index = 0; index < args.Length; index++)
+        {
+            string arg = args[index];
+            if (!IsKnownOption(arg))
+            {
+                errors.Add($"Unknown option '{arg}'.");
+                continue;
+            }
+
+            if (index + 1 >= args.Length || args[index + 1].StartsWith("--", StringComparison.Ordinal))
+            {
+                errors.Add($"Option '{arg}' requires a value.");
+                continue;
+            }
+
+            values[arg] = args[index + 1];
+            index++;
+        }
+
+        string? sessionId = ReadRequired(values, SessionIdOptionName, errors);
+        string? pipeName = ReadRequired(values, PipeNameOptionName, errors);
+        string? protocolVersionText = ReadRequired(values, ProtocolVersionOptionName, errors);
+
+        if (errors.Count > 0)
+        {
+            return WorkerBootstrapResult.Failure(WorkerExitCode.InvalidArguments, errors);
+        }
+
+        if (!uint.TryParse(protocolVersionText, out uint protocolVersion)
+            || protocolVersion != GatewayContractInfo.WorkerProtocolVersion)
+        {
+            return WorkerBootstrapResult.Failure(
+                WorkerExitCode.InvalidProtocolVersion,
+                [$"Unsupported protocol version '{protocolVersionText}'."]);
+        }
+
+        string? nonce = _environment.GetEnvironmentVariable(WorkerOptions.NonceEnvironmentVariableName);
+
+        if (string.IsNullOrWhiteSpace(nonce))
+        {
+            return WorkerBootstrapResult.Failure(
+                WorkerExitCode.MissingNonce,
+                ["Required worker nonce environment variable is missing."]);
+        }
+
+        return WorkerBootstrapResult.Success(new WorkerOptions(
+            sessionId!,
+            pipeName!,
+            protocolVersion,
+            nonce!));
+    }
+
+    private static string? ReadRequired(
+        IReadOnlyDictionary<string, string> values,
+        string optionName,
+        List<string> errors)
+    {
+        if (!values.TryGetValue(optionName, out string value)
+            || string.IsNullOrWhiteSpace(value))
+        {
+            errors.Add($"Required option '{optionName}' is missing.");
+            return null;
+        }
+
+        return value;
+    }
+
+    private static bool IsKnownOption(string optionName)
+    {
+        return optionName is SessionIdOptionName or PipeNameOptionName or ProtocolVersionOptionName;
+    }
+}

src/MxGateway.Worker/WorkerApplication.cs

@@ -1,16 +1,77 @@
 using System;
+using System.Collections.Generic;
+using MxGateway.Worker.Bootstrap;
 
 namespace MxGateway.Worker;
 
 public static class WorkerApplication
 {
     public static int Run(string[] args)
+    {
+        return Run(
+            args,
+            new EnvironmentVariableWorkerEnvironment(),
+            new WorkerConsoleLogger(Console.Error));
+    }
+
+    public static int Run(
+        string[] args,
+        IWorkerEnvironment environment,
+        IWorkerLogger logger)
     {
         if (args is null)
         {
             throw new ArgumentNullException(nameof(args));
         }
 
-        return 0;
+        if (environment is null)
+        {
+            throw new ArgumentNullException(nameof(environment));
+        }
+
+        if (logger is null)
+        {
+            throw new ArgumentNullException(nameof(logger));
+        }
+
+        try
+        {
+            WorkerOptionsParser parser = new(environment);
+            WorkerBootstrapResult result = parser.Parse(args);
+
+            if (!result.Succeeded)
+            {
+                logger.Error("WorkerBootstrapFailed", new Dictionary<string, object?>
+                {
+                    ["exit_code"] = result.ExitCode,
+                    ["errors"] = string.Join(";", result.Errors),
+                });
+
+                return (int)result.ExitCode;
+            }
+
+            WorkerOptions options = result.Options
+                ?? throw new InvalidOperationException("Successful bootstrap result did not include worker options.");
+
+            logger.Information("WorkerBootstrapSucceeded", new Dictionary<string, object?>
+            {
+                ["session_id"] = options.SessionId,
+                ["pipe_name"] = options.PipeName,
+                ["protocol_version"] = options.ProtocolVersion,
+                ["nonce"] = options.Nonce,
+            });
+
+            return (int)WorkerExitCode.Success;
+        }
+        catch (Exception exception)
+        {
+            logger.Error("WorkerBootstrapUnexpectedFailure", new Dictionary<string, object?>
+            {
+                ["exit_code"] = WorkerExitCode.UnexpectedFailure,
+                ["exception_type"] = exception.GetType().FullName,
+            });
+
+            return (int)WorkerExitCode.UnexpectedFailure;
+        }
     }
 }