EnvironmentVariablesConfigurationGatherer.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.Extensions.Logging;

namespace Aspire.Hosting.ApplicationModel;

/// <summary>
/// Gathers environment variables for resources.
/// </summary>
internal class EnvironmentVariablesExecutionConfigurationGatherer : IExecutionConfigurationGatherer
{
    /// <inheritdoc/>
    public async ValueTask GatherAsync(IExecutionConfigurationGathererContext context, IResource resource, ILogger resourceLogger, DistributedApplicationExecutionContext executionContext, CancellationToken cancellationToken = default)
    {
        if (resource.TryGetEnvironmentVariables(out var envVarAnnotations))
        {
            var envVars = new Dictionary<string, object>(context.EnvironmentVariables);
            var callbackContext = new EnvironmentCallbackContext(executionContext, resource, envVars, cancellationToken: cancellationToken)
            {
                Logger = resourceLogger,
            };

            foreach (var ann in envVarAnnotations)
            {
                // Each annotation operates on a shared context.
                envVars = await ann.AsCallbackAnnotation().EvaluateOnceAsync(callbackContext).ConfigureAwait(false);
            }

            // Take the final result and apply to the gatherer context.
            foreach (var kvp in envVars)
            {
                context.EnvironmentVariables[kvp.Key] = kvp.Value;
            }
        }
    }
}