Dynamic Variables

Overview

In Apinizer, dynamic variables can be used in many string fields such as policy settings, connection configurations, and routing addresses. This allows you to define values that change based on environment, request, or runtime instead of using fixed values. There are two types of dynamic variables:

Environment Variable — ${key}

Environment variables are resolved at deploy time. They can have different values for environments such as development, test, and production.

Context Variable — #{key}

Context variables are resolved on each request. They contain system data such as request information, date/time, or custom values assigned via script.

Two Variable Types

Feature	Environment Variable (`${key}`)	Context Variable (`#{key}`)
Format	`${variableName}`	`#{variableName}`
Resolution Time	At deploy time	On each request
Value Source	Defined in Environment Variable management screen	Auto-generated by system or assigned via script
Environment Dependent	Yes — different values for dev, test, prod	No — per-request
Definition Requirement	Requires definition in Environment Variable screen	System variables: not required. Global variables: requires Custom Variable definition
Typical Usage	Host names, base URLs, ports, connection details	User information, request details, date/time, error details
Mutability	Fixed after deployment	Can vary on each request

Environment Variable (`${key}`)

Environment Variables allow you to use different values across environments (development, test, production). They are resolved at deploy time and remain fixed during runtime. Example: ${api.hostname} → localhost:8080 in development, api.example.com in production

For detailed information about Environment Variable definition and management, see the Environment Variable page. For CRUD operations and usage scenarios, see the Environment Variable Management page.

Context Variable (`#{key}`)

Context Variables are resolved on each request and consist of two subcategories: 1. System Context Variables — Auto-generated, no definition required:

#{context.request.httpMethod}, #{context.request.uri}, #{context.request.remoteAddress}
#{context.system.year}, #{context.system.dateTime}
#{context.message.correlationId}
#{context.apiProxy.name}, #{context.apiProxy.id}
#{context.credential.clientId}, #{context.credential.username}
#{error.defaultErrorCode}, #{error.defaultMessage}

2. Global Variables — Created via script, requires Custom Variable definition:

#{userId}, #{tenantId}, #{customValue}
Values are assigned using customVariableMap.put("key", "value") in Script policy

For detailed information about variable definitions, see the Variables page.

Mixed Usage

Both types can be used together:

https://${api.hostname}/v1/users/#{userId}

${api.hostname} is resolved at deploy time (e.g., api.example.com), while #{userId} gets a different value on each request.

Supported Fields

Dynamic variables can be used in nearly all string fields in policy and connection settings.

Policies

Policy	Supported Fields	Variable Types
REST API Call	URL, header, parameter, body	`${key}` and `#{key}`
OIDC	Token endpoint, introspection endpoint, resource endpoint, form parameters	`${key}` and `#{key}`
JOSE Validation / Implementation	Dynamic key HTTP endpoint	`${key}` and `#{key}`
Authentication API	URL, header, parameter	`${key}` and `#{key}`
Message Builder	Template, header, form fields	`${key}` and `#{key}`
Redaction	Key-value list	`${key}` and `#{key}`
Other policies	Text (string) input fields	`${key}` and `#{key}`

Script policy is not included in this table. The #{key} placeholder mechanism is not used in Script policy because variables are already accessed directly via the customVariableMap object and bindings such as request_httpMethod, dateTime_year. See Script Format Difference for details.

Connections

Connection Type	Supported Fields
Database Connection	Host, port, username, password, connection string
LDAP Connection	URL, base DN, username, password
Email Connection	Host, port, username

Other Fields

Field	Supported Types
Routing Address	`${key}` and `#{key}`
JSON Error Response Template	`#{key}` (including error variables)
XML Error Response Template	`#{key}` (including error variables)
Identity Provider (DB, LDAP, API)	`${key}` and `#{key}`
IP Group	`${key}` and `#{key}`
Credential	`${key}` and `#{key}`

In connection settings (Database, LDAP, Email), ${key} (Environment Variable) is typically used because these values are environment-specific and should be resolved at deploy time. #{key} (Context Variable) is resolved at request time and is more commonly used in policy settings and routing addresses.

Variable Selection in UI

In policy and connection edit screens, a “Variable” button is available in the breadcrumb area. Clicking this button opens a menu providing access to two dialogs:

Environment Variable Dialog

When “Environment Variable” is selected from the menu, the dialog lists all defined environment variables:

Global Variables — Variables valid across all environments
Environment-Specific Variables — Variables defined for specific environments

Clicking a variable copies it to the clipboard in ${variableName} format, ready to be pasted into the relevant field.

Context Variable Dialog

When “Context Variable” is selected from the menu, the dialog lists all available context variables organized by category:

Error Variables — Error information
Request Variables — Request information
Message Variables — Message information
API Variables — API Proxy information
Credential Variables — Authenticated credential information
DateTime Variables — Date/time information

Clicking a variable copies it to the clipboard in #{variableName} format.

Both dialogs are independent. You can use both ${key} and #{key} in the same field.

Context Variable Reference

Request

Format	Description	Example Value
`#{context.request.httpMethod}`	HTTP method	`GET`, `POST`
`#{context.request.uri}`	Request URI	`/api/users/123`
`#{context.request.contentType}`	Content type	`application/json`
`#{context.request.remoteAddress}`	Client IP address	`192.168.1.100`
`#{context.request.queryString}`	Query parameters	`?id=123`
`#{context.request.pathInfo}`	Path information	`/api/users`
`#{context.request.contextPath}`	Context path	`/apinizer`

DateTime

All context.system.* date/time variables return UTC values. To get time in a specific timezone, use dtf.format('+03:00') inside a JEXL expression in the Message Builder policy.

Format	Description	Example Value
`#{context.system.year}`	Year	`2026`
`#{context.system.month}`	Month (1-12)	`2`
`#{context.system.dayOfMonth}`	Day (1-31)	`4`
`#{context.system.dayOfWeek}`	Day of week (1=Monday, 7=Sunday)	`3`
`#{context.system.hour}`	Hour (0-23)	`14`
`#{context.system.minute}`	Minute (0-59)	`30`
`#{context.system.second}`	Second (0-59)	`45`
`#{context.system.epochMillis}`	Unix timestamp (milliseconds)	`1707058245000`
`#{context.system.dateTime}`	Formatted date/time (UTC)	`2026-02-04T14:30:45.000Z`
`#{context.system.date}`	Formatted date	`2026-02-04`
`#{context.system.time}`	Formatted time	`14:30:45`

Message

Format	Description	Example Value
`#{context.message.correlationId}`	Unique request ID	`abc123-def456-ghi789`

Custom message variables defined on API Proxy or Proxy Group are also displayed in this category.

API

Format	Description	Example Value
`#{context.apiProxy.id}`	API Proxy ID	`api-proxy-123`
`#{context.apiProxy.name}`	API Proxy name	`User Management API`

Credential

Format	Description	Example Value
`#{context.credential.clientId}`	Authenticated credential key/username	`my-app-key`
`#{context.credential.username}`	Credential username	`admin`
`#{context.credential.email}`	Credential email	`admin@example.com`
`#{context.credential.fullName}`	Credential full name	`John Doe`

Error

Format	Description	Example Value
`#{error.customizedErrorCode}`	Customized error code	`CUSTOM_001`
`#{error.customizedHttpCode}`	Customized HTTP code	`400`
`#{error.customizedMessage}`	Customized message	`Please try again`
`#{error.defaultErrorCode}`	Default error code	`DEFAULT_001`
`#{error.defaultMessage}`	Default message	`An error occurred`
`#{error.defaultHttpCode}`	Default HTTP code	`500`

Script Format Difference

Context variables use a different format inside Script policy. The dot (.) separator used at runtime is replaced with underscore (_) in scripts:

Runtime Format	Script Format
`#{context.request.httpMethod}`	`request_httpMethod`
`#{context.system.year}`	`dateTime_year`
`#{context.message.correlationId}`	`message_correlationId`
`#{context.apiProxy.name}`	`apiProxy_name`
`#{error.defaultErrorCode}`	`error_defaultErrorCode`

// Using context variables inside script
String method = request_httpMethod
String year = dateTime_year
String correlationId = message_correlationId

Global Variable Usage

Global variables are created through Custom Variable definitions and assigned values via script. They are used for data transfer between policies.

Create Variable Definition

Go to Project > Variables and create a new definition with Custom Variable type.

Assign Value via Script

In Script policy, assign a value using customVariableMap.put("variableName", "value").

Use the Variable

Use #{variableName} format in other policies and settings.

Script Example:

// Extract user information from request body
if (bodyTextFC != null && !bodyTextFC.isEmpty()) {
    def jsonBody = new groovy.json.JsonSlurper().parseText(bodyTextFC)
    if (jsonBody.userId) {
        customVariableMap.put("userId", jsonBody.userId.toString())
    }
}

// Get value from header
String token = headerMapFC.get("X-Custom-Token")
if (token != null) {
    customVariableMap.put("customToken", token)
}

Global variables are available only after the script policy executes. The policy that uses the variable must run after the script policy that assigns the value (policy order matters).

Usage Examples

Error Response Template

{
  "error": {
    "code": "#{error.defaultErrorCode}",
    "message": "#{error.defaultMessage}",
    "requestId": "#{context.message.correlationId}",
    "timestamp": "#{context.system.epochMillis}"
  }
}

Dynamic Routing

https://${api.hostname}/v1/#{tenantId}/users/#{context.request.pathInfo}

${api.hostname} is resolved at deploy time, while #{tenantId} and #{context.request.pathInfo} are resolved on each request.

Response Header Addition

X-Request-ID: #{context.message.correlationId}
X-API-Name: #{context.apiProxy.name}
X-Processed-At: #{context.system.dateTime}

Behavior Rules

Missing #{key} values are replaced with empty string (""); no exception is thrown, a warning-level log is written
Missing ${key} values cannot be resolved and remain as-is
In Script policy, the custom variable map is accessed directly, so the #{...} placeholder mechanism is not used there
Variable names are case-insensitive

Next Steps

Environment Variable

Learn about environment variables in detail

Variables

Learn about variable definitions

Script Policy

Variable usage in Script policy

Environment Variable Management

Environment Variable CRUD operations

Getting Started

Understanding Apinizer

Overview

Environment Variable — ${key}

Context Variable — #{key}

Two Variable Types

Environment Variable (`${key}`)

Context Variable (`#{key}`)

Mixed Usage

Supported Fields

Policies

Connections

Other Fields

Variable Selection in UI

Environment Variable Dialog

Context Variable Dialog

Context Variable Reference

Request

DateTime

Message

API

Credential

Error

Script Format Difference

Global Variable Usage

Usage Examples

Error Response Template

Dynamic Routing

Response Header Addition

Behavior Rules

Next Steps

Environment Variable

Variables

Script Policy

Environment Variable Management

Getting Started

Understanding Apinizer

​Overview

Environment Variable — ${key}

Context Variable — #{key}

​Two Variable Types

​Environment Variable (${key})

​Context Variable (#{key})

​Mixed Usage

​Supported Fields

​Policies

​Connections

​Other Fields

​Variable Selection in UI

​Environment Variable Dialog

​Context Variable Dialog

​Context Variable Reference

​Request

​DateTime

​Message

​API

​Credential

​Error

​Script Format Difference

​Global Variable Usage

​Usage Examples

​Error Response Template

​Dynamic Routing

​Response Header Addition

​Behavior Rules

​Next Steps

Environment Variable

Variables

Script Policy

Environment Variable Management

Overview

Two Variable Types

Environment Variable (`${key}`)

Context Variable (`#{key}`)

Mixed Usage

Supported Fields

Policies

Connections

Other Fields

Variable Selection in UI

Environment Variable Dialog

Context Variable Dialog

Context Variable Reference

Request

DateTime

Message

API

Credential

Error

Script Format Difference

Global Variable Usage

Usage Examples

Error Response Template

Dynamic Routing

Response Header Addition

Behavior Rules

Next Steps