Templates

OrchStep uses Go templates with Sprig functions for variable interpolation, and supports JavaScript expressions via the Goja VM for complex logic.

Go Template Syntax

Expressions are enclosed in {{ }}:

steps:
  - func: shell
    do: echo "Deploying {{ vars.version }} to {{ vars.environment }}"

Variable Access

Pattern	Description
{{ vars.name }}	Workflow variable
{{ steps.step_name.field }}	Step output
{{ env.VAR_NAME }}	Environment variable
{{ result.output }}	Current step result (in outputs:)
{{ loop.item }}	Current loop item
{{ loop.index }}	Current loop index (zero-based)

Conditionals in Templates

do: |
  echo "Deploying to {{ vars.env }}"
  {{- if eq vars.env "production" }}
  echo "Extra production checks enabled"
  {{- end }}

Iteration in Templates

do: |
  {{ range vars.servers }}
  echo "Server: {{ . }}"
  {{ end }}

Sprig Functions

OrchStep includes Sprig v3 with 100+ utility functions.

String Functions

Function	Example	Result
upper	{{ "hello" | upper }}	HELLO
lower	{{ "HELLO" | lower }}	hello
title	{{ "hello world" | title }}	Hello World
trim	{{ " hello " | trim }}	hello
trimSuffix	{{ "hello.txt" | trimSuffix ".txt" }}	hello
replace	{{ "hello" | replace "l" "r" }}	herro
contains	{{ contains "hello" "ell" }}	true
hasPrefix	{{ hasPrefix "hello" "hel" }}	true
hasSuffix	{{ hasSuffix "hello" "llo" }}	true
repeat	{{ "ab" | repeat 3 }}	ababab
substr	{{ substr 0 5 "hello world" }}	hello
trunc	{{ trunc 5 "hello world" }}	hello
camelcase	{{ "my-service" | camelcase }}	myService
snakecase	{{ "myService" | snakecase }}	my_service
kebabcase	{{ "myService" | kebabcase }}	my-service
split	{{ split "," "a,b,c" }}	list [a, b, c]
join	{{ list "a" "b" "c" | join "," }}	a,b,c

Math Functions

Function	Example	Result
add	{{ add 1 2 }}	3
sub	{{ sub 10 3 }}	7
mul	{{ mul 3 4 }}	12
div	{{ div 10 3 }}	3
mod	{{ mod 10 3 }}	1
max	{{ max 5 10 }}	10
min	{{ min 5 10 }}	5
ceil	{{ ceil 1.5 }}	2
floor	{{ floor 1.5 }}	1

List Functions

Function	Description
first	First element of a list
last	Last element of a list
rest	All elements except first
append	Add element to end of list
concat	Merge two lists
uniq	Remove duplicate elements
has	Check if list contains element
without	Remove elements from list
slice	Sub-list extraction
reverse	Reverse list order

Dictionary Functions

Function	Description
get	Get value by key
set	Set value for key
hasKey	Check if key exists
keys	Get all keys
values	Get all values
pick	Select subset of keys
omit	Exclude subset of keys
merge	Merge dictionaries

Type Conversion

Function	Description
atoi	String to integer
toString	Convert to string
toJson	Serialize to JSON string
toPrettyJson	Serialize to formatted JSON
fromJson	Parse JSON string to object
toYaml	Serialize to YAML string

Date/Time Functions

Function	Example
now	Current time
date	{{ now | date "2006-01-02" }}
dateModify	{{ now | dateModify "+24h" }}
unixEpoch	{{ now | unixEpoch }}

Encoding Functions

Function	Description
b64enc	Base64 encode
b64dec	Base64 decode
sha256sum	SHA-256 hash
urlquery	URL-encode string
uuidv4	Generate UUID v4

Logic Functions

Function	Example
default	{{ vars.port | default 8080 }}
empty	{{ empty vars.name }}
coalesce	{{ coalesce vars.a vars.b "fallback" }}
ternary	{{ ternary "yes" "no" (eq vars.env "prod") }}

Regex Functions

Function	Description	Example
regexMatch	Test if string matches pattern	{{ regexMatch "v[0-9]+" vars.version }}
regexFind	Extract first capture group	{{ result.output | regexFind "ID=(.+)" }}
regexFindAll	Extract all matches	{{ regexFindAll "[0-9]+" result.output -1 }}
regexReplaceAll	Replace all matches	{{ regexReplaceAll "[0-9]+" result.output "X" }}

Semantic Versioning

Function	Example
semver	{{ semver "1.2.3" }} — parse to semver object
semverCompare	{{ semverCompare ">=1.2.0" vars.version }} — compare versions

Output Extraction Patterns

Use regex in outputs: to extract structured data from command output:

steps:
  - name: build
    func: shell
    do: |
      echo "Building..."
      echo "IMAGE=myapp:v1.2.3"
      echo "DIGEST=sha256:abc123"
      echo "SIZE=42MB"
    outputs:
      image: '{{ result.output | regexFind "IMAGE=(.+)" }}'
      digest: '{{ result.output | regexFind "DIGEST=(.+)" }}'
      size: '{{ result.output | regexFind "SIZE=(.+)" }}'

Common Extraction Patterns

# Extract key=value pair
output_field: '{{ result.output | regexFind "KEY=(.+)" }}'

# Extract JSON field from mixed output
json_field: '{{ result.data.field_name }}'

# Trim whitespace from output
clean_output: '{{ result.output | trim }}'

# Default value if empty
safe_value: '{{ result.output | default "unknown" }}'

# Extract version number
version: '{{ result.output | regexFind "([0-9]+\\.[0-9]+\\.[0-9]+)" }}'

JavaScript Expressions

For complex logic that goes beyond Go templates, OrchStep supports JavaScript via the Goja VM. JavaScript is used in:

• assert conditions (when no {{ }} wrapper)
• retry.when conditions
• loop.until conditions
• transform function do: blocks

# Assert with JavaScript
- func: assert
  args:
    condition: 'steps.api.status_code >= 200 && steps.api.status_code < 300'

# Retry with JavaScript condition
retry:
  when: |
    result.exit_code != 0 &&
    !result.output.includes('invalid') &&
    retry.attempt < 3

# Loop until with JavaScript
loop:
  count: 30
  until: 'steps.check.output.includes("READY")'

Best Practices

• Use single quotes around Go template conditions to avoid YAML escaping: '{{ eq vars.x "y" }}'
• Prefer regexFind over complex shell parsing for output extraction
• Use default to provide fallback values: {{ vars.port | default 8080 }}
• Use trim on extracted outputs to remove trailing newlines
• Use JavaScript syntax for complex boolean logic (more readable than nested Go template and/or)