HugeGraph configuration

1 Overview

The directory for the configuration files is hugegraph-release/conf, and all the configurations related to the service and the graph itself are located in this directory.

The main configuration files include gremlin-server.yaml, rest-server.properties, and hugegraph.properties.

The HugeGraphServer integrates the GremlinServer and RestServer internally, and gremlin-server.yaml and rest-server.properties are used to configure these two servers.

  • GremlinServer: GremlinServer accepts Gremlin statements from users, parses them, and then invokes the Core code.
  • RestServer: It provides a RESTful API that, based on different HTTP requests, calls the corresponding Core API. If the user’s request body is a Gremlin statement, it will be forwarded to GremlinServer to perform operations on the graph data.

Now let’s introduce these three configuration files one by one.

2. gremlin-server.yaml

The default content of the gremlin-server.yaml file is as follows:

  1. # host and port of gremlin server, need to be consistent with host and port in rest-server.properties
  2. #host: 127.0.0.1
  3. #port: 8182
  5. # timeout in ms of gremlin query
  6. evaluationTimeout: 30000
  8. channelizer: org.apache.tinkerpop.gremlin.server.channel.WsAndHttpChannelizer
  9. # don't set graph at here, this happens after support for dynamically adding graph
  10. graphs: {
  11. }
  12. scriptEngines: {
  13.   gremlin-groovy: {
  14.     staticImports: [
  15.       org.opencypher.gremlin.process.traversal.CustomPredicates.*',
  16.       org.opencypher.gremlin.traversal.CustomFunctions.*
  17.     ],
  18.     plugins: {
  19.       org.apache.hugegraph.plugin.HugeGraphGremlinPlugin: {},
  20.       org.apache.tinkerpop.gremlin.server.jsr223.GremlinServerGremlinPlugin: {},
  21.       org.apache.tinkerpop.gremlin.jsr223.ImportGremlinPlugin: {
  22.         classImports: [
  23.           java.lang.Math,
  24.           org.apache.hugegraph.backend.id.IdGenerator,
  25.           org.apache.hugegraph.type.define.Directions,
  26.           org.apache.hugegraph.type.define.NodeRole,
  27.           org.apache.hugegraph.traversal.algorithm.CollectionPathsTraverser,
  28.           org.apache.hugegraph.traversal.algorithm.CountTraverser,
  29.           org.apache.hugegraph.traversal.algorithm.CustomizedCrosspointsTraverser,
  30.           org.apache.hugegraph.traversal.algorithm.CustomizePathsTraverser,
  31.           org.apache.hugegraph.traversal.algorithm.FusiformSimilarityTraverser,
  32.           org.apache.hugegraph.traversal.algorithm.HugeTraverser,
  33.           org.apache.hugegraph.traversal.algorithm.JaccardSimilarTraverser,
  34.           org.apache.hugegraph.traversal.algorithm.KneighborTraverser,
  35.           org.apache.hugegraph.traversal.algorithm.KoutTraverser,
  36.           org.apache.hugegraph.traversal.algorithm.MultiNodeShortestPathTraverser,
  37.           org.apache.hugegraph.traversal.algorithm.NeighborRankTraverser,
  38.           org.apache.hugegraph.traversal.algorithm.PathsTraverser,
  39.           org.apache.hugegraph.traversal.algorithm.PersonalRankTraverser,
  40.           org.apache.hugegraph.traversal.algorithm.SameNeighborTraverser,
  41.           org.apache.hugegraph.traversal.algorithm.ShortestPathTraverser,
  42.           org.apache.hugegraph.traversal.algorithm.SingleSourceShortestPathTraverser,
  43.           org.apache.hugegraph.traversal.algorithm.SubGraphTraverser,
  44.           org.apache.hugegraph.traversal.algorithm.TemplatePathsTraverser,
  45.           org.apache.hugegraph.traversal.algorithm.steps.EdgeStep,
  46.           org.apache.hugegraph.traversal.algorithm.steps.RepeatEdgeStep,
  47.           org.apache.hugegraph.traversal.algorithm.steps.WeightedEdgeStep,
  48.           org.apache.hugegraph.traversal.optimize.ConditionP,
  49.           org.apache.hugegraph.traversal.optimize.Text,
  50.           org.apache.hugegraph.traversal.optimize.TraversalUtil,
  51.           org.apache.hugegraph.util.DateUtil,
  52.           org.opencypher.gremlin.traversal.CustomFunctions,
  53.           org.opencypher.gremlin.traversal.CustomPredicate
  54.         ],
  55.         methodImports: [
  56.           java.lang.Math#*,
  57.           org.opencypher.gremlin.traversal.CustomPredicate#*,
  58.           org.opencypher.gremlin.traversal.CustomFunctions#*
  59.         ]
  60.       },
  61.       org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin: {
  62.         files: [scripts/empty-sample.groovy]
  63.       }
  64.     }
  65.   }
  66. }
  67. serializers:
  68.   - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphBinaryMessageSerializerV1,
  69.       config: {
  70.         serializeResultToString: false,
  71.         ioRegistries: [org.apache.hugegraph.io.HugeGraphIoRegistry]
  72.       }
  73.   }
  74.   - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0,
  75.       config: {
  76.         serializeResultToString: false,
  77.         ioRegistries: [org.apache.hugegraph.io.HugeGraphIoRegistry]
  78.       }
  79.   }
  80.   - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV2d0,
  81.       config: {
  82.         serializeResultToString: false,
  83.         ioRegistries: [org.apache.hugegraph.io.HugeGraphIoRegistry]
  84.       }
  85.   }
  86.   - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0,
  87.       config: {
  88.         serializeResultToString: false,
  89.         ioRegistries: [org.apache.hugegraph.io.HugeGraphIoRegistry]
  90.       }
  91.   }
  92. metrics: {
  93.   consoleReporter: {enabled: false, interval: 180000},
  94.   csvReporter: {enabled: false, interval: 180000, fileName: ./metrics/gremlin-server-metrics.csv},
  95.   jmxReporter: {enabled: false},
  96.   slf4jReporter: {enabled: false, interval: 180000},
  97.   gangliaReporter: {enabled: false, interval: 180000, addressingMode: MULTICAST},
  98.   graphiteReporter: {enabled: false, interval: 180000}
  99. }
  100. maxInitialLineLength: 4096
  101. maxHeaderSize: 8192
  102. maxChunkSize: 8192
  103. maxContentLength: 65536
  104. maxAccumulationBufferComponents: 1024
  105. resultIterationBatchSize: 64
  106. writeBufferLowWaterMark: 32768
  107. writeBufferHighWaterMark: 65536
  108. ssl: {
  109.   enabled: false
  110. }

There are many configuration options mentioned above, but for now, let’s focus on the following options: channelizer and graphs.

  • graphs: This option specifies the graphs that need to be opened when the GremlinServer starts. It is a map structure where the key is the name of the graph and the value is the configuration file path for that graph.
  • channelizer: The GremlinServer supports two communication modes with clients: WebSocket and HTTP (default). If WebSocket is chosen, users can quickly experience the features of HugeGraph using Gremlin-Console, but it does not support importing large-scale data. It is recommended to use HTTP for communication, as all peripheral components of HugeGraph are implemented based on HTTP.

By default, the GremlinServer serves at localhost:8182. If you need to modify it, configure the host and port settings.

  • host: The hostname or IP address of the machine where the GremlinServer is deployed. Currently, HugeGraphServer does not support distributed deployment, and GremlinServer is not directly exposed to users.
  • port: The port number of the machine where the GremlinServer is deployed.

Additionally, you need to add the corresponding configuration gremlinserver.url=http://host:port in rest-server.properties.

3. rest-server.properties

The default content of the rest-server.properties file is as follows:

  1. # bind url
  2. restserver.url=http://127.0.0.1:8080
  3. # gremlin server url, need to be consistent with host and port in gremlin-server.yaml
  4. #gremlinserver.url=http://127.0.0.1:8182
  6. # graphs list with pair NAME:CONF_PATH
  7. graphs=[hugegraph:conf/hugegraph.properties]
  9. # authentication
  10. #auth.authenticator=
  11. #auth.admin_token=
  12. #auth.user_tokens=[]
  14. server.id=server-1
  15. server.role=master
  • restserver.url: The URL at which the RestServer provides its services. Modify it according to the actual environment.
  • graphs: The RestServer also needs to open graphs when it starts. This option is a map structure where the key is the name of the graph and the value is the configuration file path for that graph.

Note: Both gremlin-server.yaml and rest-server.properties contain the graphs configuration option, and the init-store command initializes based on the graphs specified in the graphs section of gremlin-server.yaml.

The gremlinserver.url configuration option is the URL at which the GremlinServer provides services to the RestServer. By default, it is set to http://localhost:8182. If you need to modify it, it should match the host and port settings in gremlin-server.yaml.

4. hugegraph.properties

hugegraph.properties is a type of file. If the system has multiple graphs, there will be multiple similar files. This file is used to configure parameters related to graph storage and querying. The default content of the file is as follows:

  1. # gremlin entrence to create graph
  2. gremlin.graph=org.apache.hugegraph.HugeFactory
  4. # cache config
  5. #schema.cache_capacity=100000
  6. # vertex-cache default is 1000w, 10min expired
  7. #vertex.cache_capacity=10000000
  8. #vertex.cache_expire=600
  9. # edge-cache default is 100w, 10min expired
  10. #edge.cache_capacity=1000000
  11. #edge.cache_expire=600
  13. # schema illegal name template
  14. #schema.illegal_name_regex=\s+|~.*
  16. #vertex.default_label=vertex
  18. backend=rocksdb
  19. serializer=binary
  21. store=hugegraph
  23. raft.mode=false
  24. raft.safe_read=false
  25. raft.use_snapshot=false
  26. raft.endpoint=127.0.0.1:8281
  27. raft.group_peers=127.0.0.1:8281,127.0.0.1:8282,127.0.0.1:8283
  28. raft.path=./raft-log
  29. raft.use_replicator_pipeline=true
  30. raft.election_timeout=10000
  31. raft.snapshot_interval=3600
  32. raft.backend_threads=48
  33. raft.read_index_threads=8
  34. raft.queue_size=16384
  35. raft.queue_publish_timeout=60
  36. raft.apply_batch=1
  37. raft.rpc_threads=80
  38. raft.rpc_connect_timeout=5000
  39. raft.rpc_timeout=60000
  41. # if use 'ikanalyzer', need download jar from 'https://github.com/apache/hugegraph-doc/raw/ik_binary/dist/server/ikanalyzer-2012_u6.jar' to lib directory
  42. search.text_analyzer=jieba
  43. search.text_analyzer_mode=INDEX
  45. # rocksdb backend config
  46. #rocksdb.data_path=/path/to/disk
  47. #rocksdb.wal_path=/path/to/disk
  49. # cassandra backend config
  50. cassandra.host=localhost
  51. cassandra.port=9042
  52. cassandra.username=
  53. cassandra.password=
  54. #cassandra.connect_timeout=5
  55. #cassandra.read_timeout=20
  56. #cassandra.keyspace.strategy=SimpleStrategy
  57. #cassandra.keyspace.replication=3
  59. # hbase backend config
  60. #hbase.hosts=localhost
  61. #hbase.port=2181
  62. #hbase.znode_parent=/hbase
  63. #hbase.threads_max=64
  65. # mysql backend config
  66. #jdbc.driver=com.mysql.jdbc.Driver
  67. #jdbc.url=jdbc:mysql://127.0.0.1:3306
  68. #jdbc.username=root
  69. #jdbc.password=
  70. #jdbc.reconnect_max_times=3
  71. #jdbc.reconnect_interval=3
  72. #jdbc.ssl_mode=false
  74. # postgresql & cockroachdb backend config
  75. #jdbc.driver=org.postgresql.Driver
  76. #jdbc.url=jdbc:postgresql://localhost:5432/
  77. #jdbc.username=postgres
  78. #jdbc.password=
  80. # palo backend config
  81. #palo.host=127.0.0.1
  82. #palo.poll_interval=10
  83. #palo.temp_dir=./palo-data
  84. #palo.file_limit_size=32

Pay attention to the following uncommented items:

  • gremlin.graph: The entry point for GremlinServer startup. Users should not modify this item.
  • backend: The backend storage used, with options including memory, cassandra, scylladb, mysql, hbase, postgresql, and rocksdb.
  • serializer: Mainly for internal use, used to serialize schema, vertices, and edges to the backend. The corresponding options are text, cassandra, scylladb, and binary (Note: The rocksdb backend should have a value of binary, while for other backends, the values of backend and serializer should remain consistent. For example, for the hbase backend, the value should be hbase).
  • store: The name of the database used for storing the graph in the backend. In Cassandra and ScyllaDB, it corresponds to the keyspace name. The value of this item is unrelated to the graph name in GremlinServer and RestServer, but for clarity, it is recommended to use the same name.
  • cassandra.host: This item is only meaningful when the backend is set to cassandra or scylladb. It specifies the seeds of the Cassandra/ScyllaDB cluster.
  • cassandra.port: This item is only meaningful when the backend is set to cassandra or scylladb. It specifies the native port of the Cassandra/ScyllaDB cluster.
  • rocksdb.data_path: This item is only meaningful when the backend is set to rocksdb. It specifies the data directory for RocksDB.
  • rocksdb.wal_path: This item is only meaningful when the backend is set to rocksdb. It specifies the log directory for RocksDB.
  • admin.token: A token used to retrieve server configuration information. For example: http://localhost:8080/graphs/hugegraph/conf?token=162f7848-0b6d-4faf-b557-3a0797869c55

5. Multi-Graph Configuration

Our system can have multiple graphs, and the backend of each graph can be different, such as hugegraph_rocksdb and hugegraph_mysql, where hugegraph_rocksdb uses RocksDB as the backend, and hugegraph_mysql uses MySQL as a backend.

The configuration method is simple:

[Optional]: Modify rest-server.properties

You can modify the graph profile directory in the graphs option of rest-server.properties. The default configuration is graphs=./conf/graphs, if you want to change it to another directory then adjust the graphs option, e.g. adjust it to graphs=/etc/hugegraph/graphs, example is as follows:

  1. graphs=./conf/graphs

Modify hugegraph_mysql_backend.properties and hugegraph_rocksdb_backend.properties based on hugegraph.properties under conf/graphs path

The modified part of hugegraph_mysql_backend.properties is as follows:

  1. backend=mysql
  2. serializer=mysql
  4. store=hugegraph_mysql
  6. # mysql backend config
  7. jdbc.driver=com.mysql.cj.jdbc.Driver
  8. jdbc.url=jdbc:mysql://127.0.0.1:3306
  9. jdbc.username=root
  10. jdbc.password=123456
  11. jdbc.reconnect_max_times=3
  12. jdbc.reconnect_interval=3
  13. jdbc.ssl_mode=false

The modified part of hugegraph_rocksdb_backend.properties is as follows:

  1. backend=rocksdb
  2. serializer=binary
  4. store=hugegraph_rocksdb

Stop the server, execute init-store.sh (to create a new database for the new graph), and restart the server.

  1. $ ./bin/stop-hugegraph.sh
  1. $ ./bin/init-store.sh
  3. Initializing HugeGraph Store...
  4. 2023-06-11 14:16:14 [main] [INFO] o.a.h.u.ConfigUtil - Scanning option 'graphs' directory './conf/graphs'
  5. 2023-06-11 14:16:14 [main] [INFO] o.a.h.c.InitStore - Init graph with config file: ./conf/graphs/hugegraph_rocksdb_backend.properties
  6. ...
  7. 2023-06-11 14:16:15 [main] [INFO] o.a.h.StandardHugeGraph - Graph 'hugegraph_rocksdb' has been initialized
  8. 2023-06-11 14:16:15 [main] [INFO] o.a.h.c.InitStore - Init graph with config file: ./conf/graphs/hugegraph_mysql_backend.properties
  9. ...
  10. 2023-06-11 14:16:16 [main] [INFO] o.a.h.StandardHugeGraph - Graph 'hugegraph_mysql' has been initialized
  11. 2023-06-11 14:16:16 [main] [INFO] o.a.h.StandardHugeGraph - Close graph standardhugegraph[hugegraph_rocksdb]
  12. ...
  13. 2023-06-11 14:16:16 [main] [INFO] o.a.h.HugeFactory - HugeFactory shutdown
  14. 2023-06-11 14:16:16 [hugegraph-shutdown] [INFO] o.a.h.HugeFactory - HugeGraph is shutting down
  15. Initialization finished.
  1. $ ./bin/start-hugegraph.sh
  3. Starting HugeGraphServer...
  4. Connecting to HugeGraphServer (http://127.0.0.1:8080/graphs)...OK
  5. Started [pid 21614]

Check out created graphs:

  1. curl http://127.0.0.1:8080/graphs/
  3. {"graphs":["hugegraph_rocksdb","hugegraph_mysql"]}

Get details of the graph

  1. curl http://127.0.0.1:8080/graphs/hugegraph_mysql_backend
  3. {"name":"hugegraph_mysql","backend":"mysql"}
  1. curl http://127.0.0.1:8080/graphs/hugegraph_rocksdb_backend
  3. {"name":"hugegraph_rocksdb","backend":"rocksdb"}

Last modified November 1, 2023: doc: optimize description about preload, init-store and others (#293) (62101543)