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Templating engine

The workflow templating engine enables dynamic, type-safe template rendering using the Liquid templating language. It allows you to inject variables, apply transformations, and control data flow throughout your workflows.

The templating engine supports several syntax patterns for different use cases:

Syntax Purpose Example
Double curly braces Insert values as strings "Hello, {{name}}"
Dollar-sign prefix Preserve data types (arrays, objects, numbers) ${{myArray}}
Percent tags Control flow (conditionals, loops) {%if active%}...{%endif%}
Raw tags Output literal curly braces {%raw%}{{}}{%endraw%}

Use double curly braces for basic string interpolation. Variables and expressions inside the braces are evaluated and rendered as strings.

message: "Hello {{user.name}}!"                       # Result: "Hello Alice"
url: "https://api.example.com/users/{{user.id}}"      # Result: "https://api.example.com/users/12"

Use the dollar-sign prefix (${{ }}) when you need to preserve the original data type (array, object, number, boolean).

# String syntax - converts to string
tags: "{{inputs.tags}}"     # Result: "[\"admin\", \"user\"]" (string)

# Type-preserving syntax - keeps original type
tags: "${{inputs.tags}}"    # Result: ["admin", "user"] (actual array)
Important

The type-preserving syntax must occupy the entire string value. You cannot mix it with other text.

✅ Valid:

tags: "${{inputs.tags}}"

❌ Invalid:

message: "Tags are: ${{inputs.tags}}"
Feature String syntax Type-preserving syntax
Output type Always string Preserves original type
Arrays Stringified Actual array
Objects Stringified Actual object
Booleans "true" / "false" true / false
Numbers "123" 123

Liquid tags are control flow constructs that use the {% %} syntax. Unlike output expressions, tags execute logic without directly rendering a value.

Conditionals:

message: |
  {% if user.role == 'admin' %}
    Welcome, administrator!
  {% else %}
    Welcome, user!
  {% endif %}

Loops:

message: |
  {% for item in items %}
    - {{item.name}}
  {% endfor %}

Use raw tags to output literal curly brace characters without rendering them:

value: "{%raw%}{{_ingest.timestamp}}{%endraw%}"  # Result: "{{_ingest.timestamp}}"

This section covers common patterns for accessing and transforming data in your workflows.

Reference input parameters defined in the workflow using {{inputs.<input_name>}}. Inputs are defined at the workflow level and can be provided when the workflow is triggered manually.

inputs:
  - name: environment
    type: string
    required: true
    default: "staging"
  - name: batchSize
    type: number
    default: 100

triggers:
  - type: manual

steps:
  - name: log_config
    type: console
    with:
      message: |
        Running with:
        - Environment: {{inputs.environment}}
        - Batch Size: {{inputs.batchSize}}

Access output data from previous steps using {{steps.<step_name>.output}}:

steps:
  - name: search_users
    type: elasticsearch.search
    with:
      index: "users"
      query:
        term:
          status: "active"

  - name: send_notification
    type: slack
    connector-id: "my-slack"
    with:
      message: "Found {{steps.search_users.output.hits.total.value}} active users"

Reference workflow-level constants using {{consts.<constant_name>}}. Constants are defined at the workflow level and can be referenced when the workflow is triggered.

consts:
  indexName: "my-index"
  environment: "production"

steps:
  - name: search_data
    type: elasticsearch.search
    with:
      index: "{{consts.indexName}}"
      query:
        match:
          env: "{{consts.environment}}"

Transform values using filters with the pipe | character:

message: |
  User: {{user.name | upcase}}
  Email: {{user.email | downcase}}
  Created: {{user.created_at | date: "%Y-%m-%d"}}

When passing arrays or objects between steps, use the type-preserving syntax (${{ }}) to avoid stringification:

steps:
  - name: get_tags
    type: elasticsearch.search
    with:
      index: "config"
      query:
        term:
          type: "tags"

  - name: create_document
    type: elasticsearch.index
    with:
      index: "reports"
      document:
        # Preserves the array type, doesn't stringify it
        tags: "${{steps.get_tags.output.hits.hits[0]._source.tags}}"
Important

The type-preserving syntax must occupy the entire string value. You cannot mix it with other text.

✅ Valid:

tags: "${{inputs.tags}}"

❌ Invalid:

message: "Tags are: ${{inputs.tags}}"

Add logic to customize output based on data:

steps:
  - name: send_message
    type: slack
    connector-id: "alerts"
    with:
      message: |
        {% if steps.search.output.hits.total.value > 100 %}
        ⚠️ HIGH ALERT: {{steps.search.output.hits.total.value}} events detected!
        {% else %}
        ✅ Normal: {{steps.search.output.hits.total.value}} events detected.
        {% endif %}

Iterate over arrays to process multiple items:

steps:
  - name: summarize_results
    type: console
    with:
      message: |
        Found users:
        {% for hit in steps.search_users.output.hits.hits %}
        - {{hit._source.name}} ({{hit._source.email}})
        {% endfor %}

The engine renders templates recursively through all data structures, processing nested objects and arrays.

Input:

message: "Hello {{user.name}}"
config:
  url: "{{api.url}}"
tags: ["{{tag1}}", "{{tag2}}"]

Rendered output:

message: "Hello Alice"
config:
  url: "https://api.example.com"
tags: ["admin", "user"]
Type Behavior
Strings Processed as templates: variables are interpolated, and filters are applied
Numbers, Booleans, Null Returned as-is
Arrays Each element is processed recursively
Objects Each property value is processed recursively (keys are not processed)
Case Behavior
Null values Returned as-is
Undefined variables Returned as empty string in string syntax and as undefined in type-preserving syntax
Missing context properties Treated as undefined