Fission — Fast Serverless Functions on Kubernetes

What it is

Fission is an open-source serverless framework that runs on Kubernetes. It lets developers deploy functions in Python, Go, Node.js, Java, and other languages without building container images. Fission maintains pre-warmed containers (environments) that load function code at invocation time, achieving sub-second cold starts.

Fission targets teams running Kubernetes who want serverless capabilities without vendor lock-in. It brings the function-as-a-service model to any Kubernetes cluster, on-premises or cloud.

How it saves time or tokens

Fission eliminates the Docker build step from the deploy cycle. Write a function, upload it, and it runs immediately on your existing Kubernetes cluster. Pre-warmed environments mean cold starts are sub-second instead of the multi-second delays common with container-based serverless. HTTP triggers, message queue triggers (Kafka, NATS), and timer triggers are configured declaratively.

How to use

1. Install the Fission CLI and deploy Fission to your Kubernetes cluster.
2. Create an environment for your language: fission env create --name python --image fission/python-env.
3. Deploy a function: fission function create --name hello --env python --code hello.py.

Example

# Install Fission CLI
curl -Lo fission https://github.com/fission/fission/releases/latest/download/fission-cli-linux
chmod +x fission && sudo mv fission /usr/local/bin/

# Install on K8s cluster
kubectl create -k 'github.com/fission/fission/crds/v1?ref=v1.20.5'
kubectl create namespace fission
helm install fission fission-charts/fission-all --namespace fission

# Create a Python environment
fission env create --name python --image fission/python-env

# Deploy a function
echo 'def main():
    return "Hello from Fission"' > hello.py
fission function create --name hello --env python --code hello.py

# Create HTTP trigger
fission route create --method GET --url /hello --function hello

# Test
curl http://$FISSION_ROUTER/hello

Related on TokRepo

• DevOps Tools — Kubernetes and serverless tools
• Coding AI Tools — Developer deployment tools

Common pitfalls

• Fission requires a running Kubernetes cluster. It is not a standalone serverless platform. If you do not already run Kubernetes, the operational overhead may outweigh the benefits.
• Pre-warmed environments consume cluster resources even when idle. Size your environment pool based on expected concurrency.
• Function dependencies must be baked into the environment image or uploaded as packages. Large dependency sets require custom environment images.