Aspire do prepare-compose + aspire do push generate different tags

^{Originally posted by **thomasreuvers** February 17, 2026}
I'm using `aspire do prepare-compose` to generate my `docker-compose.yaml` with the correct credentials and image tags, then `aspire do push` to push images to a self-hosted GitLab container registry. The push works fine, but `prepare-compose` ignores my custom tag and instead generates datetime-based tags like `20262058`. This means when I run `docker compose up`, it tries to pull images that don't exist in the registry.

Here's my setup:
```csharp
var builder = DistributedApplication.CreateBuilder(args);
var imageTag = Environment.GetEnvironmentVariable("IMAGE_TAG") ?? "dev"; // commit SHA in CI

var compose = builder.AddDockerComposeEnvironment("compose")
.WithDashboard(dashboard => dashboard.WithHostPort(8080));

var registry = builder.AddContainerRegistry(
"gitlab",
"gitlab..nl:5050",
"namespace/project")
.WithImagePushOptions(options => options.Options.RemoteImageTag = imageTag);
```

My understanding is that `WithImagePushOptions` controls what tag gets pushed, but `prepare-compose` seems to have its own tag generation logic that doesn't respect it. So the compose file and the registry end up out of sync.

Is there a way to make `prepare-compose` use the same tag? Am I missing something in the API, or is this a bug/limitation?

---

As a workaround I'm currently doing a sed replace on the generated file, but that's obviously not ideal:
```bash
IMAGE_TAG=$(git rev-parse --short HEAD)
aspire do prepare-compose
sed -i "s|:20[0-9]\{6\}|:$IMAGE_TAG|g" docker-compose.yaml
aspire do push
```