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Configuring OpenTripPlanner

Note: if you are familiar with OTP1 configuration and are migrating to OTP2, please read the OTP2 Migration Guide to learn what has changed.

Base Directory

On the OTP2 command line you must always specify a single directory after all the switches. This tells OTP2 where to look for any configuration files. By default OTP will also scan this directory for input files to build a graph (GTFS, OSM, elevation, and base street graphs) or the graph.obj file to load when starting a server.

A typical OTP2 directory for a New York City graph might include the following:

otp-config.json
build-config.json
router-config.json
new-york-city-no-buildings.osm.pbf
nyc-elevation.tiff
long-island-rail-road.gtfs.zip
mta-new-york-city-transit.gtfs.zip
port-authority-of-new-york-new-jersey.gtfs.zip
graph.obj

You could have more than one of these directories if you are building separate graphs for separate regions. Each one should contain one or more GTFS feeds, a PBF OpenStreetMap file, some JSON configuration files, and any output files such as graph.obj. For convenience, especially if you work with only one graph at a time, you may want to place your OTP2 JAR file in this same directory. Note that file types are detected through a case-insensitive combination of file extension and words within the file name. GTFS file names must end in .zip and contain the letters gtfs, and OSM files must end in .pbf.

It is also possible to provide a list of input files in the configuration, which will override the default behavior of scanning the base directory for input files. Scanning is overridden independently for each file type, and can point to remote cloud storage with arbitrary URIs. See the storage section for further details.

Three Scopes of Configuration

OTP is configured via three configuration JSON files which are read from the directory specified on its command line. We try to provide sensible defaults for every option, so all three of these files are optional, as are all the options within each file. Each configuration file corresponds to options that are relevant at a particular phase of OTP usage.

Options and parameters that are taken into account during the graph building process will be "baked into" the graph, and cannot be changed later in a running server. These are specified in build-config.json. Other details of OTP operation can be modified without rebuilding the graph. These run-time configuration options are found in router-config.json. Finally, otp-config.json contains simple switches that enable or disable system-wide features.

Configuration types

The OTP configuration files use the JSON file format. OTP allows comments and unquoted field names in the JSON configuration files to be more human-friendly. OTP supports all the basic JSON types: nested objects {...}, arrays [], numbers 789.0 and boolean true or false. In addition to these basic types some configuration parameters are parsed with some restrictions. In the documentation below we will refer to the following types:

Type Description Examples
boolean This is the Boolean JSON type true, false
string This is the String JSON type. "This is a string!"
double A decimal floating point number. 64 bit. 3.15
integer A decimal integer number. 32 bit. 1, -7, 2100
long A decimal integer number. 64 bit. -1234567890
enum A fixed set of string literals. "RAIL", "BUS"
enum-map List of key/value pairs, where the key is a enum and the value can be any given type. { "RAIL: 1.2, "BUS": 2.3 }
enum-set List of enum string values [ "RAIL", "TRAM" ]
locale Language[\_country[\_variant]]. A Locale object represents a specific geographical, political, or cultural region. For more information see the Java Locale. "en_US", "nn_NO"
date Local date. The format is YYYY-MM-DD (ISO-8601). "2020-09-21"
date-or-period A local date, or a period relative to today. The local date has the format YYYY-MM-DD and the period has the format PnYnMnD or -PnYnMnD where n is a integer number. "P1Y", "-P3M2D", "P1D"
duration A duration is a amount of time. The format is PnDTnHnMnS or nDnHnMnS where n is a integer number. The D(days), H(hours), M(minutes) and S(seconds) are not case sensitive. "3h", "2m", "1d5h2m3s", "-P2dT-1s"
regexp A regular expression pattern used to match a sting. "$^", "gtfs", "\w{3})-.*\.xml"
uri An URI path to a resource like a file or a URL. Relative URIs are resolved relative to the OTP base path. "http://foo.bar/", "file:///Users/jon/local/file", "graph.obj"
time-zone Time-Zone ID "UTC", "Europe/Paris", "-05:00"
feed-scoped-id FeedScopedId "NO:1001", "1:101"
linear-function A linear function with one input parameter(x) used to calculate a value. Usually used to calculate a limit or cost.
map List of key/value pairs, where the key is a string and the value can be any given type. { "one": 1.2, "two": 2.3 }
object Config object containing nested elements "walk": { "speed": 1.3, "reluctance": 5 }
array Config object containing an array/list of elements "array": [ 1, 2, 3 ]

System environment and project information substitution

OTP support injecting system environment variables and project information parameters into the configuration. A pattern like ${VAR_NAME} in a configuration file is substituted with an environment variable with name VAR_NAME. The substitution is done BEFORE the JSON is parsed, so both json keys and values is subject to substitution. This is useful if you want OTPs version number to be part of the graph-file-name, or you want to inject credentials in a cloud based deployment.

{
    "gsCredentials": "${GCS_SERVICE_CREDENTIALS}",
    "graph": "file:///var/otp/graph-${otp.serialization.version.id}.obj"
}

In the example above the environment variable GCS_SERVICE_CREDENTIALS on the local machine where OTP is deployed is injected into the config. Also, the OTP serialization version id is injected.

The project information variables available are:

  • maven.version
  • maven.version.short
  • maven.version.major
  • maven.version.minor
  • maven.version.patch
  • maven.version.qualifier
  • git.branch
  • git.commit
  • git.commit.timestamp
  • graph.file.header
  • otp.serialization.version.id

Config version

All three configuration files have an optional configVersion property. The property can be used to version the configuration in a deployment pipeline. The configVersion is not used by OTP in any way, but is logged at startup and is available as part of the server-info data in the REST API. The intended usage is to be able to check which version of the configuration the graph was build with and which version the router uses. In an deployment with many OTP instances it can be useful to ask an instance about the version, instead of tracking the deployment pipeline backwards to find the version used. How you inject a version into the configuration file is up to you, but you can do it in your build-pipeline, at deployment time or use system environment variable substitution.

OTP Serialization version id and Graph.obj file header

OTP has a OTP Serialization Version Id maintained in the pom.xml_ file. OTP store the id in the serialized Graph.obj file header, allowing OTP the check for compatibility issues when loading the graph. The header info is available to configuration substitution:

  • ${graph.file.header} Will expand to: OpenTripPlannerGraph;0000007;
  • ${otp.serialization.version.id} Will expand to: 7

The intended usage is to be able to have a graph build pipeline which "knows" which graph that matches OTP planner instances. For example, you may build new graphs for every OTP serialization version id in use by the planning OTP instances you have deployed and plan to deploy. This way you can roll forward and backward new OTP instances without worrying about building new graphs.

There are various ways to access this information. To get the Graph.obj serialization version id you can run the following bash command:

  • head -c 29 Graph.obj ==> OpenTripPlannerGraph;0000007; (file header)
  • head -c 28 Graph.obj | tail -c 7 ==> 0000007 (version id)

The Maven pom.xml, the META-INF/MANIFEST.MF, the OTP command line(--serVerId), log start-up messages and all OTP APIs can be used to get the OTP Serialization Version Id.

Include file directive

It is possible to inject the contents of another file into a configuration file. This makes it possible to keep parts of the configuration in separate files. To include the contents of a file, use ${includeFile:FILE_NAME}. The FILE_NAME must be the name of a file in the configuration directory. Relative paths are not supported.

To allow both files (the configuration file and the injected file) to be valid JSON files, a special case is supported. If the include file directive is quoted, then the quotes are removed, if the text inserted is valid JSON (starts with { and ends with }).

Variable substitution is performed on configuration file after the include file directive; Hence variable substitution is also performed on the text in the injected file.

Here is an example including variable substitution, assuming version 2.2.0 of OTP:

// build-config.json
{
  "transitFeeds" : "${includeFile:transit.json}"
} 
// transit.json
[
  {
  "source": "netex-v${maven.version.short}.obj"
}
]

The result will look like this:

{
      "transitFeeds": [
        {
          "source": "netex-v2.2.0.obj"
        }
      ]
} 

System-wide Configuration

Using the file otp-config.json you can enable or disable different APIs and experimental Sandbox Extensions. By default, all supported APIs are enabled and all sandbox features are disabled. So for most OTP2 use cases it is not necessary to create this file. Features that can be toggled in this file are generally only affect the routing phase of OTP2 usage, but for consistency all such "feature flags", even those that would affect graph building, are managed in this one file.

OTP Features

Here is a list of all features which can be toggled on/off and their default values.

Feature Description Enabled by default Sandbox
APIBikeRental Enable the bike rental endpoint. ✓️
APIServerInfo Enable the server info endpoint. ✓️
APIGraphInspectorTile Enable the inspector endpoint for graph information for inspection/debugging purpose. ✓️
APIUpdaterStatus Enable endpoint for graph updaters status. ✓️
ConsiderPatternsForDirectTransfers Enable limiting transfers so that there is only a single transfer to each pattern. ✓️
DebugClient Enable the debug web client located at the root of the web server. ✓️
FloatingBike Enable floating bike routing. ✓️
MinimumTransferTimeIsDefinitive If the minimum transfer time is a lower bound (default) or the definitive time for the transfer. Set this to true if you want to set a transfer time lower than what OTP derives from OSM data.
OptimizeTransfers OTP will inspect all itineraries found and optimize where (which stops) the transfer will happen. Waiting time, priority and guaranteed transfers are taken into account. ✓️
ParallelRouting Enable performing parts of the trip planning in parallel.
TransferConstraints Enforce transfers to happen according to the transfers.txt(GTFS) and Interchanges(NeTEx). Turing this off will increase the routing performance a little. ✓️
ActuatorAPI Endpoint for actuators (service health status). ✓️
DataOverlay Enable usage of data overlay when calculating costs for the street network. ✓️
FaresV2 Enable import of GTFS-Fares v2 data. ✓️
FlexRouting Enable FLEX routing. ✓️
GoogleCloudStorage Enable Google Cloud Storage integration. ✓️
RealtimeResolver When routing with ignoreRealtimeUpdates=true, add an extra step which populates results with realtime data ✓️
ReportApi Enable the report API. ✓️
SandboxAPIGeocoder Enable the Geocoder API. ✓️
SandboxAPILegacyGraphQLApi Enable (GTFS) GraphQL API. ✓️
SandboxAPIMapboxVectorTilesApi Enable Mapbox vector tiles API. ✓️
SandboxAPIParkAndRideApi Enable park-and-ride endpoint. ✓️
SandboxAPITransmodelApi Enable Entur Transmodel(NeTEx) GraphQL API. ✓️
SandboxAPITravelTime Enable the isochrone/travel time surface API. ✓️
TransferAnalyzer Analyze transfers during graph build. ✓️
VehicleToStopHeuristics Enable improved heuristic for park-and-ride queries. ✓️

Example

// otp-config.json
{
    "otpFeatures" : {
        "APIBikeRental" : false,
        "ActuatorAPI" : true
    }
}

JVM configuration

This section contains general recommendations for tuning the JVM in a production environment.
It focuses mainly on garbage collection configuration and memory settings.
See Garbage Collector Tuning for general information on garbage collection.
See Large Pages in Java and Transparent Huge Pages for general information on large memory pages.

OTP server

The OTP server processes concurrent routing requests in real time.
The main optimization goal for the OTP server is minimizing response time.

Garbage collector

  • The G1 garbage collector (default since Java 9) offers a good compromise between low latency (i.e. low GC pause time) and GC overhead.
  • If latency spikes are an issue, the ZGC garbage collector is an alternative. It produces in general more overhead than G1.

Memory settings

  • Using Large Memory Pages can reduce pressure on the TLB cache and increase performance.
  • It is in general not recommended to use large memory page in Transparent Huge Page mode (-XX:+UseTransparentHugePages) for latency-sensitive applications, since memory is allocated on-demand and this can induce latency spikes if the memory is fragmented.
    Thus TLBFS mode (-XX:+UseHugeTLBFS) should be the first choice.
  • If TLBFS mode is not an option, Transparent Huge Page mode (-XX:+UseTransparentHugePages) can be used instead, with additional provisions to mitigate the risk of latency spikes:
    The physical memory can be committed upfront, at JVM startup time. This can be done by forcing a fixed heap size and pre-touching the memory.
    Example: -Xms18g -Xmx18g -XX:+UseTransparentHugePages -XX:+AlwaysPreTouch

Graph Builder

The Graph Builder is the non-interactive mode used to build street graphs and transit graphs.
The main optimization goal for the Graph Builder is minimizing total build time.

Garbage collector

  • In theory, the Parallel garbage collector offers the best throughput.
    In practice, it can be challenging to optimize the Parallel GC to build both a street graph and a transit graph, the memory usage patterns being different.
  • The G1 garbage collector provides in general a good compromise.

Memory settings

  • Using Large Memory Pages can reduce pressure on the TLB cache and increase performance.
  • Since latency is not an issue, Large Memory Pages can be used indifferently in TLBFS mode (-XX:+UseHugeTLBFS) or Transparent Huge Page mode (-XX:+UseTransparentHugePages)