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Advanced configuration

Environment variables

User can set environment variables to change DJL Serving behavior, following is a list of variables that user can set for DJL Serving:


Note: environment variable has higher priority that command line or It will override other property values.

Command line parameters

User can use the following parameters to start djl-serving, those parameters will override default behavior:

djl-serving -h

usage: djl-serving [OPTIONS]
 -f,--config-file <CONFIG-FILE>    Path to the configuration properties file.
 -h,--help                         Print this help.
 -m,--models <MODELS>              Models to be loaded at startup.
 -s,--model-store <MODELS-STORE>   Model store location where models can be loaded.
 -w,--workflows <WORKFLOWS>   Workflows to be loaded at startup.

Details about the models, model-store, and workflows can be found in the equivalent configuration properties. file

DJL Serving use a file to store configurations.

Configure listening port

DJL Serving only allows localhost access by default.

  • inference_address: inference API binding address, default:
  • management_address: management API binding address, default:

Here are a couple of examples:

# bind inference API to all network interfaces with SSL enabled

# bind inference API to private network interfaces

Configure initial models and workflows

Model Store

The model_store config property can be used to define a directory where each file/folder in it is a model to be loaded. It will then attempt to load all of them by default. Here is an example:


Load Models

The load_models config property can be used to define a list of models to be loaded. The list should be defined as a comma separated list of urls to load models from.

Each model can be defined either as a URL directly or optionally with prepended endpoint data like [EndpointData]=modelUrl. The endpoint is a list of data items separated by commas. The possible variations are:

  • [modelName]
  • [modelName:version]
  • [modelName:version:engine]
  • [modelName:version:engine:deviceNames]

The version can be an arbitrary string. The engines uses the standard DJL Engine names.

Possible deviceNames strings include * for all devices and a ; separated list of device names following the format defined in DJL Device.fromName. If no device is specified, it will use the DJL default device (usually GPU if available else CPU).



Use the load_workflows config property to define initial workflows that should be loaded on startup. It should be a comma separated list of workflow URLs.

You can also specify the device that the model should be loaded on by using modelUrl:deviceNames. The deviceNames matches the format used in the load_models property described above. An example is shown below:


View the workflow documentation to see more information about workflows and their configuration format.

Enable SSL

For users who want to enable HTTPs, you can change inference_address or management_addrss protocol from http to https, for example: inference_addrss= This will make DJL Serving listen on localhost 443 port to accepting https request.

User also must provide certificate and private keys to enable SSL. DJL Serving support two ways to configure SSL: 1. Use keystore * keystore: Keystore file location, if multiple private key entry in the keystore, first one will be picked. * keystore_pass: keystore password, key password (if applicable) MUST be the same as keystore password. * keystore_type: type of keystore, default: PKCS12

  1. Use private-key/certificate files
    • private_key_file: private key file location, support both PKCS8 and OpenSSL private key.
    • certificate_file: X509 certificate chain file location.

Self-signed certificate example

This is a quick example to enable SSL with self-signed certificate

  1. User java keytool to create keystore
keytool -genkey -keyalg RSA -alias djl -keystore keystore.p12 -storepass changeit -storetype PKCS12 -validity 3600 -keysize 2048 -dname ", OU=Cloud Service, O=model server, L=Palo Alto, ST=California, C=US"

Config following property in

  1. User OpenSSL to create private key and certificate
# generate a private key with the correct length
openssl genrsa -out private-key.pem 2048

# generate corresponding public key
openssl rsa -in private-key.pem -pubout -out public-key.pem

# create a self-signed certificate
openssl req -new -x509 -key private-key.pem -out cert.pem -days 360

# convert pem to pfx/p12 keystore
openssl pkcs12 -export -inkey private-key.pem -in cert.pem -out keystore.p12

Config following property in