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Fluid: A Tutorial

This tutorial shows you how to write a Fluid program, convert it into a Tekton workflow, and run it on a Kubernetes cluster on your computer.

Setup Minikube and Tekton

  1. Install Minikube on macOS.

    brew install minikube
minikube start

    If you are not using macOS, please follow this tutorial. After a successful installation, you can check the nodes (VM) running Minikube using the command kubectl get nodes.

  2. Install Tekton.

    kubectl apply --filename https://storage.googleapis.com/tekton-releases/pipeline/latest/release.yaml

    For more details, you can check this tutorial. You can type the command kubectl get pods --namespace tekton-pipelines to check related Pods are running.

  3. Install the Tekton Dashboard (optional).

    kubectl apply --filename https://github.com/tektoncd/dashboard/releases/download/v0.3.0/dashboard-latest-release.yaml

Install Fluid

To check Fluid from Github, type the following command.

git clone https://github.com/wangkuiyi/fluid

To tell Python where Fluid is, you can set the PYTHONPATH environment variable.

export PYTHONPATH=$PWD/fluid:$PYTHONPATH

Program, Compile and Run

The following example.py file defines a Task with two steps and two input parameters and runs the Task.

import fluid

@fluid.task
def echo_hello_world(hello, world="El mundo"):
    fluid.step(image="ubuntu", cmd=["echo"], args=[hello])
    fluid.step(image="ubuntu", cmd=["echo"], args=[world])

echo_hello_world("Aloha")

To compile it into a Tekton YAML file, run the Python program.

python example.py > example.yaml

The Python function definition of echo_hello_world becomes the Task object in example.yaml. The call to echo_hello_world becomes a TaskRun object.

To run the example.yaml file, type the following command.

kubectl apply -f example.yaml

To check the status, type the kubectl get tekton-pipelines command. You will see some output like the following.

$ kubectl get tekton-pipelines
NAME                               AGE
task.tekton.dev/echo-hello-world   4m18s

NAME                                      SUCCEEDED   REASON      STARTTIME   COMPLETIONTIME
taskrun.tekton.dev/echo-hello-world-run   True        Succeeded   4m18s       117s

The command tkn taskrun describe echo-hello-world-run checks details of the TaskRun object. Type tkn taskrun logs echo-hello-world-run to check logs.

$ tkn taskrun logs echo-hello-world-run
[example-py-12] Aloha
[example-py-13] El mundo

To view the dashboard in a Web browser, you need to map the Tekton Dashboard to a local port using the following command.

kubectl --namespace tekton-pipelines port-forward svc/tekton-dashboard 9097:9097

Then, direct your Web browser to localhost:9097. You will be able to check all kinds of Kubernetes objects supported by Tekton.