Installation instructions for Fission Workflows (#453)
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Erwin van Eyk
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Ta-Ching Chen
Ta-Ching Chen
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# Fission Documentation Website
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## Development
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* [Hugo Installation Guide](https://gohugo.io/getting-started/installing/)
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* Local Preview
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```
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$ hugo server --buildDrafts --disableFastRender
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```
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---
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title: "Workflows Installation Guide"
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date: 2018-01-22T16:03:27.761Z
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draft: false
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---
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### Prerequisites
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Fission Workflows requires the following components to be installed on your local machine:
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- [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/)
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- [helm](https://github.com/kubernetes/helm)
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Fission Workflows is deployed on top of a Kubernetes cluster.
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If you don't have a Kubernetes cluster, [here's a quick guide to set one up](../kubernetessetup).
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It also requires a [Fission](https://github.com/fission/fission) deployment to be present on your Kubernetes cluster.
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If you do not have a Fission deployment, follow [Fission's installation guide](../install).
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**(Note that Fission Workflows 0.2.0 requires Fission 0.4.1 or higher, with the NATS component installed!)**
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### Installing Fission Workflows
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Fission Workflows is an add-on to Fission. You can install both
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Fission and Fission Workflows using helm charts.
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Assuming you have your Kubernetes cluster set up with a functioning deployment of Fission 0.4.1 or higher, run the following commands:
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```bash
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# If you haven't already, add the Fission charts repo
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$ helm repo add fission-charts https://fission.github.io/fission-charts/
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$ helm repo update
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# Install Fission Workflows
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$ helm install --wait -n fission-workflows fission-charts/fission-workflows --version 0.2.0
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```
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### Creating your first workflow
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After installing Fission and Workflows, you're all set to run a simple
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test workflow.
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With the following code snippet you will be able to deploy and run a small workflow example:
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```bash
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# Fetch the required files, alternatively you could clone the fission-workflow repo
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$ curl https://raw.githubusercontent.com/fission/fission-workflows/0.2.0/examples/whales/fortune.sh > fortune.sh
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$ curl https://raw.githubusercontent.com/fission/fission-workflows/0.2.0/examples/whales/whalesay.sh > whalesay.sh
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$ curl https://raw.githubusercontent.com/fission/fission-workflows/0.2.0/examples/whales/fortunewhale.wf.yaml > fortunewhale.wf.yaml
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#
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# Add binary environment and create two test functions on your Fission setup:
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#
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$ fission env create --name binary --image fission/binary-env
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$ fission function create --name whalesay --env binary --deploy ./whalesay.sh
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$ fission function create --name fortune --env binary --deploy ./fortune.sh
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#
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# Create a workflow that uses those two functions. A workflow is just
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# a function that uses the "workflow" environment.
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#
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$ fission function create --name fortunewhale --env workflow --src ./fortunewhale.wf.yaml
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#
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# Map an HTTP GET to your new workflow function:
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#
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$ fission route create --method GET --url /fortunewhale --function fortunewhale
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#
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# Invoke the workflow with an HTTP request:
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#
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$ curl ${FISSION_ROUTER}/fortunewhale
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```
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This last command, the invocation of the workflow, should return a whale saying something wise
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```
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______________________________________
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/ Anthony's Law of Force: \
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\ Don't force it; get a larger hammer. /
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--------------------------------------
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\
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\
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\
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## .
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## ## ## ==
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## ## ## ## ## ===
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/"""""""""""""""""\___/ ===
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{ / ===-
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\______ O __/
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\ \ __/
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\____\_______/
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```
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So what happened here?
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Let's see what the workflow consists of (for example by running `cat fortunewhale.wf.yaml`):
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```yaml
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# This whale shows off a basic workflow that combines both Fission Functions (fortune, whalesay) and internal functions (noop)
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apiVersion: 1
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output: WhaleWithFortune
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tasks:
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InternalFuncShowoff:
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run: noop
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GenerateFortune:
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run: fortune
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requires:
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- InternalFuncShowoff
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WhaleWithFortune:
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run: whalesay
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inputs: "{$.Tasks.GenerateFortune.Output}"
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requires:
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- GenerateFortune
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```
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What you see is the [YAML](http://yaml.org/)-based workflow definition of the `fortunewhale` workflow.
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A workflow consists of multiple tasks, which are steps that it needs to complete.
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Each task has a unique identifier, such as `GenerateFortune`, a reference to a Fission function in the `run` field.
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Optionally, it can contain `inputs` which allows you to specify inputs to the task,
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as well as contain `requires` which allows you to specify which tasks need to complete before this task can start.
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Finally, at the top you will find the `output` field, which specifies the task whose output is used as the workflow's output.
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In this case, the `fortunewhale` workflow consists of a sequence of 3 tasks:
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```
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InternalFuncShowoff -> GenerateFortune -> WhaleWithFortune
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```
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First, it starts with `InternalFuncShowoff` by running `noop`, which is an *internal function* in the workflow engine.
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Internal functions are run inside of the workflow engine, which makes them run much faster at the cost of expressiveness and scalability.
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So typically, light-weight functions, such as logic or control flow operations, are good candidates to be used as internal functions.
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Besides, a minimal set of predefined internal functions, you can define internal function - there is nothing special about them.
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After `InternalFuncShowff` completes, the `GenerateFortune` task can start as its `requires` has been fulfilled.
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It runs the `fortune` Fission function, which outputs a random piece of wisdom.
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After `GenerateFortune` completes, the `WhaleWithFortune` task can start.
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This task uses a javascript expression in its `inputs` to reference the output of the `GenerateFortune` task.
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In the inputs of a task you can reference anything in the workflow, such as outputs, inputs, and task definitions, or just provide a constant value.
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The workflow engine invokes the `whalesay` fission function with as input the piece of wisdom, which outputs the ASCI whale that wraps the phrase.
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Finally, with all tasks completed, the workflow engine uses the top-level `output` field to fetch the output of the `WhaleWithFortune` and return it to the user.
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As the workflow engine adheres to the Fission function specification, a Fission workflow is just another Fission Function.
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This means that you could use this workflow as a function in the `run` in other workflows.
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### What's next?
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To learn more about the Fission Workflows system and its advanced concepts, see the [documentation on Github](https://github.com/fission/fission-workflows/tree/master/Docs).
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Or, check out the [examples](https://github.com/fission/fission-workflows/tree/0.2.0/examples) for more example workflows.
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If something went wrong, we'd love to help -- please [drop by the slack channel](http://slack.fission.io) and ask for help.
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