Workflow Variables

Some fields in a workflow specification allow for variable references which are automatically substituted by Argo.

How to use variables

Variables are enclosed in curly braces:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: hello-world-parameters-
spec:
  entrypoint: whalesay
  arguments:
    parameters:
      - name: message
        value: hello world
  templates:
    - name: whalesay
      inputs:
        parameters:
          - name: message
      container:
        image: docker/whalesay
        command: [ cowsay ]
        args: [ "{{inputs.parameters.message}}" ]

The following variables are made available to reference various meta-data of a workflow:

Template Tag Kinds

There are two kinds of template tag:

• simple The default, e.g. {{workflow.name}}
• expression Where{{ is immediately followed by =, e.g. {{=workflow.name}}.

Simple

The tag is substituted with the variable that has a name the same as the tag.

Simple tags may have white-space between the brackets and variable as seen below. However, there is a known issue where variables may fail to interpolate with white-space, so it is recommended to avoid using white-space until this issue is resolved. Please report unexpected behavior with reproducible examples.

args: [ "{{ inputs.parameters.message }}" ]  

Expression

Since v3.1

The tag is substituted with the result of evaluating the tag as an expression.

Note that any hyphenated parameter names or step names will cause a parsing error. You can reference them by indexing into the parameter or step map, e.g. inputs.parameters['my-param'] or steps['my-step'].outputs.result.

Learn about the expression syntax.

Examples

Plain list:

[1, 2]

Filter a list:

filter([1, 2], { # > 1})

Map a list:

map([1, 2], { # * 2 })

We provide some core functions:

Cast to int:

asInt(inputs.parameters['my-int-param'])

Cast to float:

asFloat(inputs.parameters['my-float-param'])

Cast to string:

string(1)

Convert to a JSON string (needed for withParam):

toJson([1, 2])

Extract data from JSON:

jsonpath(inputs.parameters.json, '$.some.path')

You can also use Sprig functions:

Trim a string:

sprig.trim(inputs.parameters['my-string-param'])

!!! Warning In Sprig functions, errors are often not raised. E.g. if int is used on an invalid value, it returns 0. Please review the Sprig documentation to understand which functions do and which do not.

Reference

All Templates

Variable	Description
inputs.parameters.<NAME>	Input parameter to a template
inputs.parameters	All input parameters to a template as a JSON string
inputs.artifacts.<NAME>	Input artifact to a template

Steps Templates

Variable	Description
steps.name	Name of the step
steps.<STEPNAME>.id	unique id of container step
steps.<STEPNAME>.ip	IP address of a previous daemon container step
steps.<STEPNAME>.status	Phase status of any previous step
steps.<STEPNAME>.exitCode	Exit code of any previous script or container step
steps.<STEPNAME>.startedAt	Time-stamp when the step started
steps.<STEPNAME>.finishedAt	Time-stamp when the step finished
steps.<STEPNAME>.outputs.result	Output result of any previous container or script step
steps.<STEPNAME>.outputs.parameters	When the previous step uses withItems or withParams, this contains a JSON array of the output parameter maps of each invocation
steps.<STEPNAME>.outputs.parameters.<NAME>	Output parameter of any previous step. When the previous step uses withItems or withParams, this contains a JSON array of the output parameter values of each invocation
steps.<STEPNAME>.outputs.artifacts.<NAME>	Output artifact of any previous step

DAG Templates

Variable	Description
tasks.name	Name of the task
tasks.<TASKNAME>.id	unique id of container task
tasks.<TASKNAME>.ip	IP address of a previous daemon container task
tasks.<TASKNAME>.status	Phase status of any previous task
tasks.<TASKNAME>.exitCode	Exit code of any previous script or container task
tasks.<TASKNAME>.startedAt	Time-stamp when the task started
tasks.<TASKNAME>.finishedAt	Time-stamp when the task finished
tasks.<TASKNAME>.outputs.result	Output result of any previous container or script task
tasks.<TASKNAME>.outputs.parameters	When the previous task uses withItems or withParams, this contains a JSON array of the output parameter maps of each invocation
tasks.<TASKNAME>.outputs.parameters.<NAME>	Output parameter of any previous task. When the previous task uses withItems or withParams, this contains a JSON array of the output parameter values of each invocation
tasks.<TASKNAME>.outputs.artifacts.<NAME>	Output artifact of any previous task

HTTP Templates

Since v3.3

Only available for successCondition

Variable	Description
request.method	Request method (string)
request.url	Request URL (string)
request.body	Request body (string)
request.headers	Request headers (map[string][]string)
response.statusCode	Response status code (int)
response.body	Response body (string)
response.headers	Response headers (map[string][]string)

RetryStrategy

When using the expression field within retryStrategy, special variables are available.

Variable	Description
lastRetry.exitCode	Exit code of the last retry
lastRetry.Status	Status of the last retry
lastRetry.Duration	Duration in seconds of the last retry

Note: These variables evaluate to a string type. If using advanced expressions, either cast them to int values (expression: "{{=asInt(lastRetry.exitCode) >= 2}}") or compare them to string values (expression: "{{=lastRetry.exitCode != '2'}}").

Container/Script Templates

Variable	Description
pod.name	Pod name of the container/script
retries	The retry number of the container/script if retryStrategy is specified
inputs.artifacts.<NAME>.path	Local path of the input artifact
outputs.artifacts.<NAME>.path	Local path of the output artifact
outputs.parameters.<NAME>.path	Local path of the output parameter

Loops (withItems / withParam)

Variable	Description
item	Value of the item in a list
item.<FIELDNAME>	Field value of the item in a list of maps

Metrics

When emitting custom metrics in a template, special variables are available that allow self-reference to the current step.

Variable	Description
status	Phase status of the metric-emitting template
duration	Duration of the metric-emitting template in seconds (only applicable in Template-level metrics, for Workflow-level use workflow.duration)
exitCode	Exit code of the metric-emitting template
inputs.parameters.<NAME>	Input parameter of the metric-emitting template
outputs.parameters.<NAME>	Output parameter of the metric-emitting template
outputs.result	Output result of the metric-emitting template
resourcesDuration.{cpu,memory}	Resources duration in seconds. Must be one of resourcesDuration.cpu or resourcesDuration.memory, if available. For more info, see the Resource Duration doc.

Real-Time Metrics

Some variables can be emitted in real-time (as opposed to just when the step/task completes). To emit these variables in real time, set realtime: true under gauge (note: only Gauge metrics allow for real time variable emission). Metrics currently available for real time emission:

For Workflow-level metrics:

• workflow.duration

For Template-level metrics:

• duration

Global

Variable	Description
workflow.name	Workflow name
workflow.namespace	Workflow namespace
workflow.serviceAccountName	Workflow service account name
workflow.uid	Workflow UID. Useful for setting ownership reference to a resource, or a unique artifact location
workflow.parameters.<NAME>	Input parameter to the workflow
workflow.parameters	All input parameters to the workflow as a JSON string (this is deprecated in favor of workflow.parameters.json as this doesn't work with expression tags and that does)
workflow.parameters.json	All input parameters to the workflow as a JSON string
workflow.outputs.parameters.<NAME>	Global parameter in the workflow
workflow.outputs.artifacts.<NAME>	Global artifact in the workflow
workflow.annotations.<NAME>	Workflow annotations
workflow.annotations.json	all Workflow annotations as a JSON string
workflow.labels.<NAME>	Workflow labels
workflow.labels.json	all Workflow labels as a JSON string
workflow.creationTimestamp	Workflow creation time-stamp formatted in RFC 3339 (e.g. 2018-08-23T05:42:49Z)
workflow.creationTimestamp.<STRFTIMECHAR>	Creation time-stamp formatted with a strftime format character.
workflow.creationTimestamp.RFC3339	Creation time-stamp formatted with in RFC 3339.
workflow.priority	Workflow priority
workflow.duration	Workflow duration estimate, may differ from actual duration by a couple of seconds
workflow.scheduledTime	Scheduled runtime formatted in RFC 3339 (only available for CronWorkflow)

Exit Handler

Variable	Description
workflow.status	Workflow status. One of: Succeeded, Failed, Error
workflow.failures	A list of JSON objects containing information about nodes that failed or errored during execution. Available fields: displayName, message, templateName, phase, podName, and finishedAt.

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