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Fix text output returned despite --output json in detached mode #1588

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Fix text output returned despite --output json in detached mode #1588

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4fe7b17
Initial plan
Copilot Mar 5, 2026
b6ab6d8
Fix text output returned despite --output json in detached mode
Copilot Mar 5, 2026
e760719
Merge branch 'main' into copilot/fix-output-json-bug
waldekmastykarz Mar 5, 2026
183464a
Merge branch 'main' into copilot/fix-output-json-bug
waldekmastykarz Mar 5, 2026
a65e725
Use consistent JSONL envelope format for --output json in detached mode
Copilot Mar 5, 2026
5da4223
Merge branch 'main' into copilot/fix-output-json-bug
waldekmastykarz Mar 6, 2026
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173 changes: 152 additions & 21 deletions DevProxy/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,9 +7,12 @@
using DevProxy.Proxy;
using DevProxy.State;
using System.Diagnostics;
using System.Globalization;
using System.Net;
using System.Runtime.InteropServices;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;

// Handle detached mode - spawn a child process and exit
// Only applies to root command (starting the proxy), not subcommands
Expand Down Expand Up @@ -46,12 +49,22 @@

static async Task<int> StartDetachedProcessAsync(string[] args)
{
var isJsonOutput = IsJsonOutputRequested(args);

// Check if an instance is already running
if (await StateManager.IsInstanceRunningAsync())
{
var existingState = await StateManager.LoadStateAsync();
await Console.Error.WriteLineAsync($"Dev Proxy is already running (PID: {existingState?.Pid}).");
await Console.Error.WriteLineAsync("Use 'devproxy stop' to stop it first.");
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(
FormatJsonLogEntry("error", $"Dev Proxy is already running (PID: {existingState?.Pid}). Use 'devproxy stop' to stop it first."));
}
else
{
await Console.Error.WriteLineAsync($"Dev Proxy is already running (PID: {existingState?.Pid}).");
await Console.Error.WriteLineAsync("Use 'devproxy stop' to stop it first.");
}
return 1;
}

Expand All @@ -68,7 +81,15 @@ static async Task<int> StartDetachedProcessAsync(string[] args)
var executablePath = Environment.ProcessPath;
if (string.IsNullOrEmpty(executablePath))
{
await Console.Error.WriteLineAsync("Could not determine executable path.");
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(
FormatJsonLogEntry("error", "Could not determine executable path."));
}
else
{
await Console.Error.WriteLineAsync("Could not determine executable path.");
}
return 1;
}

Expand All @@ -94,7 +115,15 @@ static async Task<int> StartDetachedProcessAsync(string[] args)
var process = Process.Start(startInfo);
if (process == null)
{
await Console.Error.WriteLineAsync("Failed to start Dev Proxy process.");
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(
FormatJsonLogEntry("error", "Failed to start Dev Proxy process."));
}
else
{
await Console.Error.WriteLineAsync("Failed to start Dev Proxy process.");
}
return 1;
}

Expand All @@ -109,15 +138,27 @@ static async Task<int> StartDetachedProcessAsync(string[] args)
var state = await StateManager.LoadStateAsync();
if (state != null)
{
await Console.Out.WriteLineAsync("Dev Proxy started in background.");
await Console.Out.WriteLineAsync();
await Console.Out.WriteLineAsync($" PID: {state.Pid}");
await Console.Out.WriteLineAsync($" API URL: {state.ApiUrl}");
await Console.Out.WriteLineAsync($" Log file: {state.LogFile}");
await Console.Out.WriteLineAsync();
await Console.Out.WriteLineAsync("Use 'devproxy status' to check status.");
await Console.Out.WriteLineAsync("Use 'devproxy logs' to view logs.");
await Console.Out.WriteLineAsync("Use 'devproxy stop' to stop.");
if (isJsonOutput)
{
await Console.Out.WriteLineAsync(FormatJsonResultEntry(new
{
state.Pid,
state.ApiUrl,
state.LogFile
}));
}
else
{
await Console.Out.WriteLineAsync("Dev Proxy started in background.");
await Console.Out.WriteLineAsync();
await Console.Out.WriteLineAsync($" PID: {state.Pid}");
await Console.Out.WriteLineAsync($" API URL: {state.ApiUrl}");
await Console.Out.WriteLineAsync($" Log file: {state.LogFile}");
await Console.Out.WriteLineAsync();
await Console.Out.WriteLineAsync("Use 'devproxy status' to check status.");
await Console.Out.WriteLineAsync("Use 'devproxy logs' to view logs.");
await Console.Out.WriteLineAsync("Use 'devproxy stop' to stop.");
}
return 0;
}

Expand All @@ -127,30 +168,120 @@ static async Task<int> StartDetachedProcessAsync(string[] args)
var errorOutput = await process.StandardError.ReadToEndAsync();
var standardOutput = await process.StandardOutput.ReadToEndAsync();

await Console.Error.WriteLineAsync("Dev Proxy failed to start.");
if (!string.IsNullOrEmpty(errorOutput))
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(errorOutput);
var message = "Dev Proxy failed to start.";
if (!string.IsNullOrEmpty(errorOutput))
{
message += $" {errorOutput.Trim()}";
}
if (!string.IsNullOrEmpty(standardOutput))
{
message += $" {standardOutput.Trim()}";
}
await Console.Error.WriteLineAsync(FormatJsonLogEntry("error", message));
}
if (!string.IsNullOrEmpty(standardOutput))
else
{
await Console.Error.WriteLineAsync(standardOutput);
await Console.Error.WriteLineAsync("Dev Proxy failed to start.");
if (!string.IsNullOrEmpty(errorOutput))
{
await Console.Error.WriteLineAsync(errorOutput);
}
if (!string.IsNullOrEmpty(standardOutput))
{
await Console.Error.WriteLineAsync(standardOutput);
}
}
return process.ExitCode;
}
}

await Console.Error.WriteLineAsync("Timeout waiting for Dev Proxy to start.");
await Console.Error.WriteLineAsync($"Check the log folder: {StateManager.GetLogsFolder()}");
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(
FormatJsonLogEntry("error", $"Timeout waiting for Dev Proxy to start. Check the log folder: {StateManager.GetLogsFolder()}"));
}
else
{
await Console.Error.WriteLineAsync("Timeout waiting for Dev Proxy to start.");
await Console.Error.WriteLineAsync($"Check the log folder: {StateManager.GetLogsFolder()}");
}
return 1;
}
catch (Exception ex)
{
await Console.Error.WriteLineAsync($"Failed to start Dev Proxy: {ex.Message}");
if (isJsonOutput)
{
await Console.Error.WriteLineAsync(
FormatJsonLogEntry("error", $"Failed to start Dev Proxy: {ex.Message}"));
}
else
{
await Console.Error.WriteLineAsync($"Failed to start Dev Proxy: {ex.Message}");
}
return 1;
}
}

/// <summary>
/// Formats a result entry matching the JSONL envelope produced by JsonConsoleFormatter:
/// {"type":"result","data":{...},"timestamp":"..."}
/// </summary>
static string FormatJsonResultEntry(object data)
{
#pragma warning disable CA1869 // Called at most once per process lifetime
var jsonlOptions = new JsonSerializerOptions
{
PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
};
#pragma warning restore CA1869
var entry = new
{
type = "result",
data = JsonSerializer.SerializeToElement(data, jsonlOptions),
timestamp = DateTime.UtcNow.ToString("O", CultureInfo.InvariantCulture)
};
return JsonSerializer.Serialize(entry, jsonlOptions);
}

/// <summary>
/// Formats a log entry matching the JSONL envelope produced by JsonConsoleFormatter:
/// {"type":"log","level":"...","message":"...","timestamp":"..."}
/// </summary>
static string FormatJsonLogEntry(string level, string message)
{
#pragma warning disable CA1869 // Called at most once per process lifetime
var jsonlOptions = new JsonSerializerOptions
{
PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
};
#pragma warning restore CA1869
var entry = new
{
type = "log",
level,
message,
timestamp = DateTime.UtcNow.ToString("O", CultureInfo.InvariantCulture)
};
return JsonSerializer.Serialize(entry, jsonlOptions);
}

static bool IsJsonOutputRequested(string[] args)
{
for (var i = 0; i < args.Length; i++)
{
if (string.Equals(args[i], DevProxyCommand.OutputOptionName, StringComparison.OrdinalIgnoreCase) &&
i + 1 < args.Length)
{
return string.Equals(args[i + 1], "json", StringComparison.OrdinalIgnoreCase);
}
}
return false;
}

static string EscapeArgument(string arg)
{
// Simple escaping for command line arguments
Expand Down
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