@camunda8/sdk

Camunda 8 JavaScript SDK

NPM

License

Full API Docs are here.

This is the official Camunda 8 JavaScript SDK. It is written in TypeScript and runs on Node.js. See why this does not run in a web browser.

See the QUICKSTART.md file in the repository for a quick start.

What does "supported" mean?

This is the official supported-by-Camunda Nodejs SDK for Camunda Platform 8.

The Node.js SDK will not always support all features of Camunda Platform 8 immediately upon their release. Complete API coverage for a platform release will lag behind the platform release.

Prioritisation of implementing features is influenced by customer demand.

Semantic versioning

The SDK package tracks Camunda Platform 8 minor versioning. Feature releases to support current Platform minor version features result in a patch release of the SDK.

Using the SDK in your project

Install the SDK as a dependency:

npm i @camunda8/sdk

Usage

In this release, the functionality of Camunda 8 is exposed via dedicated clients for the component APIs.

import { Camunda8 } from '@camunda8/sdk'

const c8 = new Camunda8()
const restClient = c8.getCamundaRestClient() // New REST API
const zeebe = c8.getZeebeGrpcApiClient()
const zeebeRest = c8.getZeebeRestClient() // Deprecated
const operate = c8.getOperateApiClient()
const optimize = c8.getOptimizeApiClient()
const tasklist = c8.getTasklistApiClient()
const modeler = c8.getModelerApiClient()
const admin = c8.getAdminApiClient()

Configuration

The configuration for the SDK can be done by any combination of environment variables and explicit configuration passed to the Camunda8 constructor.

Any configuration passed in to the Camunda8 constructor is merged over any configuration in the environment.

The configuration object fields and the environment variables have exactly the same names. See the file src/lib/Configuration.ts for a complete list of configuration parameters that can be set via environment variables or constructor parameters.

A note on how int64 is handled in the JavaScript SDK

Entity keys in Camunda 8 are stored and represented as int64 numbers. The range of int64 extends to numbers that cannot be represented by the JavaScript number type. To deal with this, int64 keys are serialised by the SDK to the JavaScript string type. See this issue for more details.

Some number values - for example: "total returned results " - may be specified as int64 in the API specifications. Although these numbers will usually not contain unsafe values, they are always serialised to string.

For int64 values whose type is not known ahead of time, such as job variables, you can pass an annotated data transfer object (DTO) to decode them reliably. If no DTO is specified, the default behavior of the SDK is to serialise all numbers to JavaScript number, and to throw an exception if a number value is detected at a runtime that cannot be accurately represented as the JavaScript number type (that is, a value greater than 2^53-1).

Authorization

Calls to APIs can be authorized using basic auth or via OAuth - a token that is obtained via a client id/secret pair exchange.

Disable OAuth

To disable OAuth, set the environment variable CAMUNDA_OAUTH_DISABLED=true. You can use this when running against a minimal Zeebe broker in a development environment, for example. You can also use this when your authentication is being done using an x509 mTLS certificate.

Basic Auth

To use basic auth, set the following values either via the environment or explicitly in code via the constructor:

CAMUNDA_AUTH_STRATEGY=BASIC
CAMUNDA_BASIC_AUTH_USERNAME=....
CAMUNDA_BASIC_AUTH_PASSWORD=...

Bearer Token Auth

To use a Bearer token that you have already obtained, set the following value:

CAMUNDA_AUTH_STRATEGY=BEARER
CAMUNDA_OAUTH_TOKEN=....

OAuth

If your platform is secured with OAuth token exchange (Camunda SaaS or Self-Managed with Identity), provide the following configuration fields at a minimum, either via the Camunda8 constructor or in environment variables:

CAMUNDA_AUTH_STRATEGY=OAUTH
ZEEBE_GRPC_ADDRESS=...
ZEEBE_CLIENT_ID=...
ZEEBE_CLIENT_SECRET=...
CAMUNDA_OAUTH_URL=...

To get a token for the Camunda SaaS Administration API or the Camunda SaaS Modeler API, set the following:

CAMUNDA_AUTH_STRATEGY=OAUTH
CAMUNDA_CONSOLE_CLIENT_ID=...
CAMUNDA_CONSOLE_CLIENT_SECRET=...

Token caching

OAuth tokens are cached in-memory and on-disk. The disk cache is useful to prevent token endpoint saturation when restarting or rolling over workers, for example. They can all hit the cache instead of requesting new tokens.

You can turn off the disk caching by setting CAMUNDA_TOKEN_DISK_CACHE_DISABLE to true. This will cache tokens in-memory only.

By default, the token cache directory is $HOME/.camunda. You can specify a different directory by providing a full file path value for CAMUNDA_TOKEN_CACHE_DIR.

Here is an example of specifying a different cache directory via the constructor:

import { Camunda8 } from '@camunda8/sdk'

const c8 = new Camunda8({
    CAMUNDA_TOKEN_CACHE_DIR: '/tmp/cache',
})

If the cache directory does not exist, the SDK will attempt to create it (recursively). If the SDK is unable to create it, or the directory exists but is not writeable by your application, the SDK will throw an exception.

Connection configuration examples

Self-Managed

This is the complete environment configuration needed to run against the Dockerised Self-Managed stack in the docker subdirectory:

# Self-Managed
export ZEEBE_GRPC_ADDRESS='localhost:26500'
export ZEEBE_REST_ADDRESS='http://localhost:8080'
export ZEEBE_CLIENT_ID='zeebe'
export ZEEBE_CLIENT_SECRET='zecret'
export CAMUNDA_OAUTH_STRATEGY='OAUTH'
export CAMUNDA_OAUTH_URL='http://localhost:18080/auth/realms/camunda-platform/protocol/openid-connect/token'
export CAMUNDA_TASKLIST_BASE_URL='http://localhost:8082'
export CAMUNDA_OPERATE_BASE_URL='http://localhost:8081'
export CAMUNDA_OPTIMIZE_BASE_URL='http://localhost:8083'
export CAMUNDA_MODELER_BASE_URL='http://localhost:8070/api'

# Turn off the tenant ID, which may have been set by multi-tenant tests
# You can set this in a constructor config, or in the environment if running multi-tenant
export CAMUNDA_TENANT_ID=''

# TLS for gRPC is on by default. If the Zeebe broker is not secured by TLS, turn it off
export CAMUNDA_SECURE_CONNECTION=false

If you are using an OIDC that requires a scope parameter to be passed with the token request, set the following variable:

CAMUNDA_TOKEN_SCOPE

Here is an example of doing this via the constructor, rather than via the environment:

import { Camunda8 } from '@camunda8/sdk'

const c8 = new Camunda8({
    ZEEBE_GRPC_ADDRESS: 'localhost:26500',
    ZEEBE_REST_ADDRESS: 'http://localhost:8080',
    ZEEBE_CLIENT_ID: 'zeebe',
    ZEEBE_CLIENT_SECRET: 'zecret',
    CAMUNDA_OAUTH_STRATEGY: 'OAUTH',
    CAMUNDA_OAUTH_URL:
        'http://localhost:18080/auth/realms/camunda-platform/protocol/openid-connect/token',
    CAMUNDA_TASKLIST_BASE_URL: 'http://localhost:8082',
    CAMUNDA_OPERATE_BASE_URL: 'http://localhost:8081',
    CAMUNDA_OPTIMIZE_BASE_URL: 'http://localhost:8083',
    CAMUNDA_MODELER_BASE_URL: 'http://localhost:8070/api',
    CAMUNDA_TENANT_ID: '', // We can override values in the env by passing an empty string value
    CAMUNDA_SECURE_CONNECTION: false,
})

Camunda SaaS

Here is a complete configuration example for connection to Camunda SaaS:

export ZEEBE_GRPC_ADDRESS='5c34c0a7-7f29-4424-8414-125615f7a9b9.syd-1.zeebe.camunda.io:443'
export ZEEBE_REST_ADDRESS='https://syd-1.zeebe.camunda.io/5c34c0a7-7f29-4424-8414-125615f7a9b9'
export ZEEBE_CLIENT_ID='yvvURO9TmBnP3zx4Xd8Ho6apgeiZTjn6'
export ZEEBE_CLIENT_SECRET='iJJu-SHgUtuJTTAMnMLdcb8WGF8s2mHfXhXutEwe8eSbLXn98vUpoxtuLk5uG0en'
# export CAMUNDA_CREDENTIALS_SCOPES='Zeebe,Tasklist,Operate,Optimize' # What APIs these client creds are authorised for
export CAMUNDA_TASKLIST_BASE_URL='https://syd-1.tasklist.camunda.io/5c34c0a7-7f29-4424-8414-125615f7a9b9'
export CAMUNDA_OPTIMIZE_BASE_URL='https://syd-1.optimize.camunda.io/5c34c0a7-7f29-4424-8414-125615f7a9b9'
export CAMUNDA_OPERATE_BASE_URL='https://syd-1.operate.camunda.io/5c34c0a7-7f29-4424-8414-125615f7a9b9'
export CAMUNDA_OAUTH_URL='https://login.cloud.camunda.io/oauth/token'
export CAMUNDA_AUTH_STRATEGY='OAUTH'

# This is on by default, but we include it in case it got turned off for local tests
export CAMUNDA_SECURE_CONNECTION=true

# Admin Console and Modeler API Client
export CAMUNDA_CONSOLE_CLIENT_ID='e-JdgKfJy9hHSXzi'
export CAMUNDA_CONSOLE_CLIENT_SECRET='DT8Pe-ANC6e3Je_ptLyzZvBNS0aFwaIV'
export CAMUNDA_CONSOLE_BASE_URL='https://api.cloud.camunda.io'
export CAMUNDA_CONSOLE_OAUTH_AUDIENCE='api.cloud.camunda.io'

Logging

The SDK uses a Winston / Pino compatible logging setup. By default it uses Winston.

When using the default logging library, you can set the logging level of the SDK via the environment variable (or constructor configuration property) CAMUNDA_LOG_LEVEL. This defaults to 'info'. Values (in order of priority): error, warn, info, http, verbose, debug, silly.

Custom logger

You can supply a custom logger via the constructor. For example, to use the Pino logging library:

import pino from 'pino'

import { Camunda8 } from '../../c8/index'

const level = process.env.CAMUNDA_LOG_LEVEL ?? 'trace'
const logger = pino({ level }) // Logging level controlled via the logging library

logger.info('Pino logger created')
const c8 = new Camunda8({
    logger,
})
c8.log.info('Using pino logger')

Debugging

The SDK uses the debug library to help you debug specific issues. This produces verbose, low-level output from specific components to the console.

To enable debugging output, set a value for the DEBUG environment variable. The value is a comma-separated list of debugging namespaces. The SDK has the following namespaces:

Value Component
camunda:adminconsole Administration API
camunda:modeler Modeler API
camunda:operate Operate API
camunda:optimize Optimize API
camunda:tasklist Tasklist API
camunda:oauth OAuth Token Exchange
camunda:grpc Zeebe gRPC channel
camunda:worker Zeebe Worker
camunda:worker:verbose Zeebe Worker (additional detail)
camunda:zeebeclient Zeebe Client

Here is an example of turning on debugging for the OAuth and Operate components:

DEBUG=camunda:oauth,camunda:operate node app.js

Process Variable Typing

Process variables - the variables of Zeebe messages, jobs, and process instance creation requests and responses - are stored in the broker as key:value pairs. They are transported as a JSON string. The SDK parses the JSON string into a JavaScript object.

Various Zeebe methods accept DTO classes for variable input and output. These DTO classes are used to provide design-time type information on the variables object. They are also used to safely decode 64-bit integer values that cannot be accurately represented by the JavaScript number type.

To create a DTO to represent the expected shape and type of the variables object, extend the LosslessDto class:

class myVariableDTO extends LosslessDto {
    firstName!: string
    lastName!: string
    age!: number
    optionalValue?: number
    @Int64String
    veryBigInteger?: string
    constructor(data: Partial<myVariableDTO>) {
        super(data)
    }
}

Typing of Zeebe worker variables

The variable payload in a Zeebe worker task handler is available as an object job.variables. By default, this is of type any for the gRPC API, and unknown for the REST API.

The ZBClient.createWorker() method accepts an inputVariableDto to control the parsing of number values and provide design-time type information. Passing an inputVariableDto class to a Zeebe worker is optional. If a DTO class is passed to the Zeebe worker, it is used for two purposes:

  • To provide design-time type information on the job.variables object.
  • To specify the parsing of JSON number fields. These can potentially represent int64 values that cannot be represented accurately by the JavaScript number type. With a DTO, you can specify that a specific JSON number fields be parsed losslessly to a string or BigInt.

With no DTO specified, there is no design-time type safety. At run-time, all JSON numbers are converted to the JavaScript number type. If a variable field has a number value that cannot be safely represented using the JavaScript number type (a value greater than 2^53 -1), an exception is thrown.

To provide a DTO, extend the LosslessDto class like so:

class MyVariableDto extends LosslessDto {
    name!: string
    maybeAge?: number
    @Int64String
    veryBigNumber!: string
    @BigIntValue
    veryBigInteger!: bigint
}

In this case, veryBigNumber is an int64 value. It is transferred as a JSON number on the wire, but the parser will parse it into a string so that no loss of precision occurs. Similarly, veryBigInteger is a very large integer value. In this case, we direct the parser to parse this variable field as a bigint.

You can nest DTOs like this:

class MyLargerDto extends LosslessDto {
    id!: string
    @ChildDto(MyVariableDto)
    entry!: MyVariableDto
}

Typing of custom headers

The Zeebe worker receives custom headers as job.customHeaders. The ZBClient.createWorker() method accepts a customHeadersDto to control the behavior of custom header parsing of number values and provide design-time type information.

This follows the same strategy as the job variables, as previously described.

Zeebe User Tasks

From 8.5, you can use Zeebe user tasks. See the documentation on how to migrate to Zeebe user tasks.

The SDK supports the Zeebe REST API. Be sure to set the ZEEBE_REST_ADDRESS either via environment variable or configuration field.

Job Streaming

The Zeebe gRPC API supports streaming available jobs, rather than polling for them.

The ZeebeGrpcClient method StreamJobs allows you to use this API.

Please note that only jobs that become available after the stream is opened are pushed to the client. For jobs that were already activatable before the method is called, you need to use a polling worker.

In this release, this is not handled for you. You must both poll and stream jobs to make sure that you get jobs that were available before your application started as well as jobs that become available after your application starts.

In a subsequent release, the ZeebeWorker will transparently handle this for you.

Multi-tenant workers

Workers, both polling and streaming, can be multi-tenanted, requesting jobs from more than one tenant.

Example:

client.createWorker({
    taskHandler: (job) => {
        console.log(job.tenantId) // '<default>' | 'green'
        return job.complete()
    },
    taskType: 'multi-tenant-work',
    tenantIds: ['<default>', 'green'],
})

client.streamJobs({
    taskHandler: async (job) => {
        console.log(job.tenantId) // '<default>' | 'green'
        return job.complete()
    },
    type: 'multi-tenant-stream-work',
    tenantIds: ['<default>', 'green'],
    worker: 'stream-worker',
    timeout: 2000,
})

Polling worker backoff in error conditions

When a polling worker encounters an error, including not being authenticated, the worker will back off subsequent polls by +2 seconds with each subsequent failure, up to a maximum of CAMUNDA_JOB_WORKER_MAX_BACKOFF_MS, which is 15000 by default (15 seconds). If the failure is due to invalid credentials and occurs during the token request, then the worker backoff will be compounded with a token endpoint backoff, which is +1000ms for each subsequent failure up to a maximum of 15s.

This means that if you start a worker with invalid credentials, then the polling backoff will look like this, by default (times in seconds): 3, 6, 9, 12, 15, 18, 21, 23, 24, 25, 26, 27, 28, 29, 30, 30, 30...

If the worker is backing off for a reason other than invalid credentials - for example a backpressure signal from the gateway - it will be: 2, 4, 6, 8, 10, 12, 14, 15, 15, 15.....

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