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Fix endpoint resolution for Host/Port in WithEnvironment

In Aspire 9.5, endpoint property resolution inside WithEnvironment delegates is corrected so that Host and Port each resolve accurately when accessed independently. Previously, accessing only Host returned localhost and only Port returned the host (published) port unless both properties were accessed together.

Version introduced

Aspire 9.5

Previous behavior

Inside a WithEnvironment delegate, accessing Host alone produced localhost instead of the container (resource) name. Accessing Port alone produced the published (host) port. To coerce correct values, some code accessed multiple endpoint properties in a single expression or used combined properties as a workaround.

var redis = builder.AddRedis("redis");

var app = builder.AddContainer("myapp", "mycontainer")
  .WithEnvironment(context =>
  {
    var endpoint = redis.GetEndpoint("tcp");

    // Workaround: force evaluation of multiple properties
    _ = endpoint.Property(EndpointProperty.HostAndPort);

    // Still: Host would resolve to "localhost" unless both Host and Port
    // were referenced in certain combinations.
    var host = endpoint.Property(EndpointProperty.Host);   // "localhost" (incorrect)
    var port = endpoint.Property(EndpointProperty.Port);   // Published host port, not container port

    context.EnvironmentVariables["REDIS_HOST"] = host;
    context.EnvironmentVariables["REDIS_PORT"] = port;
  })
  .WithReference(redis);

New behavior

Each endpoint property now resolves independently and correctly:

  • Host resolves to the container (resource) name (for example, redis).
  • Port resolves to the container's internal (target) port.
  • No combined or chained property access is required.
var redis = builder.AddRedis("redis");

var app = builder.AddContainer("myapp", "mycontainer")
  .WithEnvironment(context =>
  {
      var endpoint = redis.GetEndpoint("tcp");
    
      var host = endpoint.Property(EndpointProperty.Host); // "redis"
      var port = endpoint.Property(EndpointProperty.Port); // Container port (e.g., 6379)
    
      context.EnvironmentVariables["REDIS_HOST"] = host;
      context.EnvironmentVariables["REDIS_PORT"] = port;
  })
  .WithReference(redis);

Type of breaking change

This is a behavioral change.

Reason for change

The previous resolution logic forced workarounds that accessed multiple properties to obtain correct values, making configuration unintuitive, and error prone. The fix aligns per-property resolution with developer expectations and eliminates reliance on indirect or combined property accesses.

Remove any workarounds that:

  1. Access EndpointProperty.HostAndPort solely to force evaluation.
  2. Access both Host and Port together to coerce correct Host behavior.
  3. Depend on the published host port being returned from EndpointProperty.Port.

Use the individual properties directly:

var endpoint = redis.GetEndpoint("tcp");
var host = endpoint.Property(EndpointProperty.Host); // Container name
var port = endpoint.Property(EndpointProperty.Port); // Container port

If you previously stored the published port for external binding, explicitly retrieve that value via the appropriate API (for example, a published ports collection) instead of relying on EndpointProperty.Port's former behavior.

Affected APIs

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