BellaBaxter.SourceGenerator 0.1.1-preview.21

BellaBaxter.SourceGenerator

A Roslyn source generator + MSBuild task that gives your .NET project typed, compile-time access to your Bella secrets — with zero values stored in the binary.

How it works

BeforeBuild (MSBuild)
  └── BellaSecretsManifestTask
        → GET /api/v1/projects/{slug}/environments/{slug}/secrets?keys-only=true
        → writes  bella-secrets.manifest.json   ← commit this for offline builds

Compile (Roslyn)
  └── BellaSecretsSourceGenerator
        → reads bella-secrets.manifest.json (AdditionalFiles)
        → emits  AppSecrets.g.cs              ← auto-generated, never edited

Secret values are never stored anywhere. At runtime each property reads from Environment.GetEnvironmentVariable(). The generator only needs the key names and their types at build time.

Installation

<PackageReference Include="BellaBaxter.SourceGenerator" Version="0.1.0">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>

Configuration

Add to your .csproj:

<PropertyGroup>
  
  <BellaProject>my-project</BellaProject>
  <BellaEnvironment>dev</BellaEnvironment>
  <BellaApiUrl>https://bella.example.com</BellaApiUrl>
  <BellaApiKey>$(BELLA_API_KEY)</BellaApiKey>   

  
  <BellaSecretsClassName>AppSecrets</BellaSecretsClassName>
  <BellaSecretsNamespace>$(RootNamespace)</BellaSecretsNamespace>
  <BellaManifestPath>$(ProjectDir)bella-secrets.manifest.json</BellaManifestPath>
  <BellaSkipFetch>false</BellaSkipFetch>   
</PropertyGroup>

Generated code

Given a project with secrets:

The generator emits:

// <auto-generated>
// This file was generated by BellaBaxter.SourceGenerator.
// Project: my-project  Environment: dev
// Do not edit this file manually.
// </auto-generated>
#nullable enable

namespace MyApp.Config
{
    public sealed partial class AppSecrets
    {
        private static string _env(string key) =>
            System.Environment.GetEnvironmentVariable(key)
            ?? throw new System.InvalidOperationException(
                $"Required secret '{key}' is not set in the environment.");

        public string DatabaseUrl => _env("DATABASE_URL");
        public int MaxRetries => int.Parse(_env("MAX_RETRIES"));
        public bool FeatureEnabled => string.Equals(_env("FEATURE_ENABLED"), "true", System.StringComparison.OrdinalIgnoreCase);
        public System.Uri ServiceUrl => new System.Uri(_env("SERVICE_URL"));
    }
}

Using the generated class

var secrets = new AppSecrets();

string connStr = secrets.DatabaseUrl;      // string
int retries    = secrets.MaxRetries;       // int  — already parsed
bool flag      = secrets.FeatureEnabled;   // bool — already parsed
Uri svcUrl     = secrets.ServiceUrl;       // Uri  — already parsed

If a required environment variable is missing at runtime, InvalidOperationException is thrown with a clear message.

Offline / CI builds

Commit bella-secrets.manifest.json to your repository:

# Generate or update the manifest locally
BELLA_API_KEY=... dotnet build /p:BellaSkipFetch=false

git add bella-secrets.manifest.json
git commit -m "chore: update bella secrets manifest"

CI can then build without Bella credentials:

# No BELLA_API_KEY needed — uses committed manifest
- run: dotnet build /p:BellaSkipFetch=true

If BellaApiKey is absent the manifest fetch is skipped automatically.
If the API is unreachable but a cached manifest exists, a build warning is emitted and the cached copy is used.
If neither a key nor a manifest is available, the build fails with a diagnostic error.

Manifest format

{
  "version": "1",
  "project": "my-project",
  "environment": "dev",
  "fetchedAt": "2026-03-01T12:00:00Z",
  "secrets": [
    { "key": "DATABASE_URL",   "type": "ConnectionString", "description": "Postgres connection" },
    { "key": "MAX_RETRIES",    "type": "Integer" },
    { "key": "FEATURE_ENABLED","type": "Boolean" }
  ]
}

Type mappings

Diagnostic codes

Project layout

apps/sdk/dotnet/
├── BellaBaxter.SourceGenerator/           # netstandard2.0 — Roslyn IIncrementalGenerator
│   ├── BellaSecretsSourceGenerator.cs
│   ├── ManifestParser.cs
│   ├── SecretsManifest.cs
│   ├── TypeMapper.cs
│   ├── CodeEmitter.cs
│   └── DiagnosticDescriptors.cs
├── BellaBaxter.SourceGenerator.MSBuild/   # net8.0 — MSBuild Task + .targets file
│   ├── BellaSecretsManifestTask.cs
│   └── BellaBaxter.SourceGenerator.targets
└── BellaBaxter.SourceGenerator.Tests/    # xUnit tests
    ├── ManifestParserTests.cs
    ├── TypeMapperTests.cs
    └── CodeEmitterTests.cs