Flow YAML Syntax

jina.Flow can be loaded from a YAML config file. It follows the following syntax as the example below:

!Flow
version: '1.0'
with:
    restful: true
pods:
  - name: pod0  # notice the change here, name is now an attribute
    method: add  # by default method is always add, available: add, needs, inspect
    uses: _pass
    needs: gateway
  - name: pod1  # notice the change here, name is now an attribute
    method: add  # by default method is always add, available: add, needs, inspect
    uses: _pass
    needs: gateway
  - method: inspect  # add an inspect node on pod1
  - method: needs  # let's try something new in Flow YAML v1: needs
    needs: [pod1, pod0]

A valid Flow specification starts with !Flow as the first line.

version

The version number string of Flow YAML schema.

Warning

Don’t forget to quote your version number, it must be a string.

with

A list of arguments in the jina.Flow.__init__() function. Check jina flow --help for details. Extra kwargs will be passed to all pods as the common kwargs.

pods

The list of jina.peapods.Pod contained in the flow. The key is the name of this pod and the value is a map of arguments accepted by jina pod --help. Besides those kwargs, there are some optional fields one can set:

pods[*].name

The user defined name of the Pod. Optional. When not given, it will named as pod0, pod1, etc.

pods[*].method

The method for appending this Pod into the Flow. Optional, by default it’s add:

  • add: same as Flow.add(...)

  • needs: same as Flow.needs(...)

  • inspect: same as Flow.inspect(...)

pods[*].needs

Identifies any Pods that must complete successfully before this Pod will run. It can be a string or array of strings. By default, needs always contains the previous Pod, unless written in other way. needs can be used to create intra-Pod parallelization. For example, the Flow below runs pod2 and pod3 in parallel:

!Flow
version: '1.0'
pods:
    - name: pod1
    - name: pod2
    - name: pod3
      needs: pod1
    - name: pod4
      needs: [pod2, pod3]