JanusGraph Container

Note

even though the examples below and in the Docker Compose config files (*.yml) use the latest image, when running a service in production, be sure to specify a specific numeric version to avoid unexpected behavior changes due to latest pointing to a new release version, see our Docker tagging Policy.

Usage

Start a JanusGraph Server instance

The default configuration uses the Oracle Berkeley DB Java Edition storage backend and the Apache Lucene indexing backend:

docker run --rm --name janusgraph-default docker.io/janusgraph/janusgraph:latest

Connecting with Gremlin Console

Start a JanusGraph container and connect to the janusgraph server remotely using Gremlin Console:

$ docker run --rm --link janusgraph-default:janusgraph -e GREMLIN_REMOTE_HOSTS=janusgraph \
    -it docker.io/janusgraph/janusgraph:latest ./bin/gremlin.sh

         \,,,/
         (o o)
-----oOOo-(3)-oOOo-----
plugin activated: janusgraph.imports
plugin activated: tinkerpop.server
plugin activated: tinkerpop.utilities
plugin activated: tinkerpop.hadoop
plugin activated: tinkerpop.spark
plugin activated: tinkerpop.tinkergraph
gremlin> :remote connect tinkerpop.server conf/remote.yaml
==>Configured janusgraph/172.17.0.2:8182
gremlin> :> g.addV('person').property('name', 'chris')
==>v[4160]
gremlin> :> g.V().values('name')
==>chris

Using Docker Compose

Start a JanusGraph Server instance using docker-compose.yml:

docker-compose -f docker-compose.yml up

Start a JanusGraph container running Gremlin Console in the same network using docker-compose.yml:

docker-compose -f docker-compose.yml run --rm \
    -e GREMLIN_REMOTE_HOSTS=janusgraph janusgraph ./bin/gremlin.sh

Initialization

When the container is started it will execute files with the extension .groovy that are found in /docker-entrypoint-initdb.d with the Gremlin Console. These scripts are only executed after the JanusGraph Server instance was started. So, they can connect to it and execute Gremlin traversals.

For example, to add a vertex to the graph, create a file /docker-entrypoint-initdb.d/add-vertex.groovy with the following content:

g = traversal().withRemote('conf/remote-graph.properties')
g.addV('demigod').property('name', 'hercules').iterate()

Generate Config

JanusGraph-Docker has a single utility method. This method writes the JanusGraph Configuration and show the config afterward.

docker run --rm -it docker.io/janusgraph/janusgraph:latest janusgraph show-config

Default config locations are /etc/opt/janusgraph/janusgraph.properties and /etc/opt/janusgraph/janusgraph-server.yaml.

Configuration

The JanusGraph image provides multiple methods for configuration, including using environment variables to set options and using bind-mounted configuration.

Docker environment variables

The environment variables supported by the JanusGraph image are summarized below.

Variable	Description	Default
`JANUS_PROPS_TEMPLATE`	JanusGraph properties file template (see below).	`berkeleyje-lucene`
`janusgraph.*`	Any JanusGraph configuration option to override in the template properties file, specified with an outer `janusgraph` namespace (e.g., `janusgraph.storage.hostname`). See JanusGraph Configuration for available options.	no default value
`gremlinserver.*`	Any Gremlin Server configuration option to override in the default configuration (YAML) file, specified with an outer `gremlinserver` namespace (e.g., `gremlinserver.threadPoolWorker`). You can set or update nested options using additional dots (e.g., `gremlinserver.graphs.graph`). See Gremlin Server Configuration for available options. See Gremlin Server Environment Variable Syntax section below for help editing gremlin server configuration using environment variables.	no default value`
`JANUS_SERVER_TIMEOUT`	Timeout (seconds) used when waiting for Gremlin Server before executing initialization scripts.	`30`
`JANUS_STORAGE_TIMEOUT`	Timeout (seconds) used when waiting for the storage backend before starting Gremlin Server.	`60`
`GREMLIN_REMOTE_HOSTS`	Optional hostname for external Gremlin Server instance. Enables a container running Gremlin Console to connect to a remote server using `conf/remote.yaml` (or `remote-objects.yaml`).	no default value
`JANUS_INITDB_DIR`	Defines the location of the initialization scripts.	`/docker-entrypoint-initdb.d`

Properties template

The JANUS_PROPS_TEMPLATE environment variable is used to define the base JanusGraph properties file. Values in the template properties file are used unless an alternate value for a given property is provided in the environment. The common usage will be to specify a template for the general environment (e.g., cassandra-es) and then provide additional individual configuration to override/extend the template. The available templates depend on the JanusGraph version (see conf/janusgraph*.properties).

`JANUS_PROPS_TEMPLATE`	Supported Versions
`berkeleyje`	all
`berkeleyje-es`	all
`berkeleyje-lucene` (default)	all
`cassandra-es`	<=0.5.3
`cql-es`	>=0.2.1
`cql`	>=0.5.3
`inmemory`	>=0.5.3

Example: Berkeleyje-Lucene

Start a JanusGraph instance using the default berkeleyje-lucene template with custom storage and server settings:

docker run --name janusgraph-default \
    -e janusgraph.storage.berkeleyje.cache-percentage=80 \
    -e gremlinserver.threadPoolWorker=2 \
    docker.io/janusgraph/janusgraph:latest

Inspect the configuration:

$ docker exec janusgraph-default sh -c 'cat /etc/opt/janusgraph/janusgraph.properties | grep ^[a-z]'
gremlin.graph=org.janusgraph.core.JanusGraphFactory
storage.backend=berkeleyje
storage.directory=/var/lib/janusgraph/data
index.search.backend=lucene
storage.berkeleyje.cache-percentage=80
index.search.directory=/var/lib/janusgraph/index

$ docker exec janusgraph-default grep threadPoolWorker /etc/opt/janusgraph/janusgraph-server.yaml
threadPoolWorker: 2

Example: Cassandra-ES with Docker Compose

Start a JanusGraph instance with Cassandra and Elasticsearch using the cql-es template through docker-compose-cql-es.yml:

docker-compose -f docker-compose-cql-es.yml up

Inspect the configuration using docker-compose-cql-es.yml:

$ docker-compose -f docker-compose-cql-es.yml exec \
      janusgraph sh -c 'cat /etc/opt/janusgraph/janusgraph.properties | grep ^[a-z]'
gremlin.graph=org.janusgraph.core.JanusGraphFactory
storage.backend=cql
storage.hostname=jce-cassandra
cache.db-cache = true
cache.db-cache-clean-wait = 20
cache.db-cache-time = 180000
cache.db-cache-size = 0.25
index.search.backend=elasticsearch
index.search.hostname=jce-elastic
index.search.elasticsearch.client-only=true
storage.directory=/var/lib/janusgraph/data
index.search.directory=/var/lib/janusgraph/index

Gremlin Server Environment Variable Syntax

Environment Variables that start with the prefix gremlinserver. or gremlinserver%d. are used to edit the base janusgraph-server.yaml file. The text after the prefix in the environment variable name should follow a specific syntax. This syntax is implemented using the yq write and delete commands and the yq documentation can be used as a reference for this syntax. Secondly, the value of the environment variable will be used to set the value of the key specified in the environment variable name.

Let's take a look at a few examples:

Nested Properties

For example, say we want to add a configuration property graphs.ConfigurationMangementGraph with the value conf/JanusGraph-configurationmanagement.properties:

$ docker run --rm -it -e gremlinserver.graphs.ConfigurationManagementGraph=\
conf/JanusGraph-configurationmanagement.properties docker.io/janusgraph/janusgraph:latest janusgraph show-config
...
graphs:
  graph: conf/janusgraph-cql-es-server.properties
  ConfigurationManagementGraph: conf/JanusGraph-configurationmanagement.properties
scriptEngines:
...

Delete a component

To delete a component append %d to the 'gremlinserver.' prefix before the closing dot and then select the component following the prefix. Don't forget the trailing '='. For example to delete the graphs.graph configuration property we can do the following:

$ docker run --rm -it -e gremlinserver%d.graphs.graph= docker.io/janusgraph/janusgraph:latest janusgraph show-config
...
channelizer: org.apache.tinkerpop.gremlin.server.channel.WebSocketChannelizer
graphs: {}
scriptEngines:
...

Append item and alternate indexing syntax

This example shows how to append an item to a list. This can be done by adding "[+]" at the end of the environment variable name. This example also shows how to use square bracket syntax as an alternative to the dot syntax. This alternate syntax is useful if one of the keys in the property path contains special characters as we see in the example below.

$ docker run --rm -it -e gremlinserver.scriptEngines.gremlin-groovy\
.plugins["org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin"]\
.files[+]=/scripts/another-script.groovy docker.io/janusgraph/janusgraph:latest janusgraph show-config
...
scriptEngines:
  gremlin-groovy:
    plugins:
      org.janusgraph.graphdb.tinkerpop.plugin.JanusGraphGremlinPlugin: {}
      org.apache.tinkerpop.gremlin.server.jsr223.GremlinServerGremlinPlugin: {}
      org.apache.tinkerpop.gremlin.tinkergraph.jsr223.TinkerGraphGremlinPlugin: {}
      org.apache.tinkerpop.gremlin.jsr223.ImportGremlinPlugin:
        classImports:
        - java.lang.Math
        methodImports:
        - java.lang.Math#*
      org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin:
        files:
        - scripts/empty-sample.groovy
        - /scripts/another-script.groovy
...

Mounted Configuration

By default, the container stores both the janusgraph.properties and janusgraph-server.yaml files in the JANUS_CONFIG_DIR directory which maps to /etc/opt/janusgraph. When the container starts, it updates those files using the environment variable values. If you have a specific configuration and do not wish to use environment variables to configure JanusGraph, you can mount a directory containing your own version of those configuration files into the container through a bind mount, e.g., -v /local/path/on/host:/etc/opt/janusgraph:ro. You'll need to bind the files as read-only, however, if you do not wish to have the environment variables override the values in that file.

Example with mounted configuration

Start a JanusGraph instance with mounted configuration using docker-compose-mount.yml:

$ docker-compose -f docker-compose-mount.yml up
janusgraph-mount | chown: changing ownership of '/etc/opt/janusgraph/janusgraph.properties': Read-only file system
...

Default user JanusGraph

Note: The default user of the image changed for all version beginning with the newest image version of 0.5.3.

The user is created with uid 999 and gid 999 and user's a home dir is /var/lib/janusgraph.

Following folder are created with these user rights: * /var/lib/janusgraph * /etc/opt/janusgraph * /opt/janusgraph * /docker-entrypoint-initdb.d

Image Tagging Policy

Here's the policy we follow for tagging our container images:

Tag	Config	Support level	Docker base image
latest	latest JanusGraph release	no breaking changes guarantees	eclipse-temurin:11-jre
x.x	newest patch-level version of JanusGraph	expect breaking changes	eclipse-temurin:11-jre
x.x.x, x.x.x-revision	defined JanusGraph version	static tag	eclipse-temurin:11-jre
x.x.x-SNAPSHOT	latest snapshot build	expect breaking changes	eclipse-temurin:11-jre
x.x.x-SNAPSHOT-revision	latest snapshot build	static tag	eclipse-temurin:11-jre