Quick Start

This walkthrough brings up the full Fleans stack from a published release, deploys a sample workflow through the admin UI, and starts an instance via the REST API.

Prerequisites

• Docker Engine 24+ with the Compose v2 plugin (docker compose version).
• ~2 GB free disk for images and the Postgres data volume.

No .NET SDK, no source checkout — the bundle pulls signed container images from ghcr.io/nightbaker/fleans-*.

1. Download and run the release bundle

The release pipeline attaches docker-compose-v<VER>.zip to every GitHub Release. Grab the latest:

gh CLI

gh release download v0.3.0 --repo nightBaker/fleans -p 'docker-compose-*.zip'
unzip docker-compose-v0.3.0.zip -d fleans
cd fleans
docker compose up -d

curl

curl -LO https://github.com/nightBaker/fleans/releases/download/v0.3.0/docker-compose-v0.3.0.zip
unzip docker-compose-v0.3.0.zip -d fleans
cd fleans
docker compose up -d

Pick the latest tag

Substitute the current release tag (see Releases) for v0.3.0. For production installs and full configuration reference, see Self-host with Docker Compose.

docker compose ps should show every service as running. The admin UI lands at http://localhost:8080 and the REST API at http://localhost:8081.

2. Deploy a workflow

Fleans deploys workflows through the admin UI, not via a REST endpoint.

1. Open http://localhost:8080.
2. Navigate to the Editor page.
3. Download the sample workflow: my-process.bpmn — a minimal workflow with a single script task that sets a greeting variable.
4. Import the file, then click Deploy.

<!-- Excerpt from my-process.bpmn -->
<scriptTask id="greet" name="Set Greeting" scriptFormat="csharp">
  <script>_context.greeting = "Hello from Fleans!";</script>
</scriptTask>

After clicking Deploy, the Editor shows a green success message bar reading Deployed 'my-process' v1 (N activities, M flows), the breadcrumb displays the process key, and an accent-colored v1 badge appears next to it. Deploying again produces v2, and so on.

Note

Script tasks execute automatically — no external complete-activity call is needed. The engine runs the C# script inline and advances the workflow to the next element.

3. Start an instance

curl -X POST http://localhost:8081/Workflow/start \
  -H "Content-Type: application/json" \
  -d '{"WorkflowId":"my-process"}'

Expected output

HTTP 200 with a JSON body like:

{"workflowInstanceId":"<guid>"}

The <guid> is new for every run.

Because my-process contains only a script task, the instance runs to completion immediately. Verify the result in the admin UI: from the Workflows page, click the my-process row to open the process-instances list. The instance appears as Completed, and opening it shows the variables panel containing greeting = "Hello from Fleans!".

Where to next

• Self-host with Docker Compose — .env reference, secrets, upgrades, troubleshooting.
• Self-host with Helm — Kubernetes install.
• REST API reference — wire shapes for every endpoint.
• Service Tasks — start of the Building Workflows guides.