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Developer's Guide

Contents

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  • Will be replaced with the ToC, excluding the "Contents" header {:toc}

Technology Overview

With GeoServer being a traditional, Spring Framework based, monolithic servlet application, a logical choice has been made to base the GeoServer derived microservices in the Spring Boot framework.

Additionally, Spring Cloud technologies enable crucial capabilities such as dynamic service discovery, externalized configuration, distributed events, API gateway, and more.

Only a curated list of the vast amount of GeoServer extensions will be supported, as they are verified and possibly adapted to work with this project's architecture.

System Architecture

The following diagram depicts the System's general architecture:

Cloud Native GeoServer Architecture Diagram

  • Hexagons represent microservices;
  • coloured rectangles, logical groupings of components;
  • lines connecting a group to another component: connector applies to all services of the outgoing end, to all components of the incoming end;
  • white rectangles, components that are platform/deployment choices. For example:
    • "Event bus" could be a cloud provider's native service (event queue), or a microservice implementing a distributed event broker;
    • "Catalog/Config backend" is the software component used to access the catalog and configuration. Might be a microservice itself, catalog/config provider for "data directory", database, or other kind of external service store, catalog/config backend implementations;
    • "Catalog/Config storage" is the storage mechanism that backs the catalog/config software component. Might be a shared "data directory" or database, a "per instance" data directory or database, and so on, depending on the available catalog/config backend implementations, and how they're configured and provisioned;
    • "Geospatial data sources" is whatever method is used to access the actual data served up by the microservices.

Does that mean GeoServer's .war is deployed several times, with each instance exposing a given "business capability"? ABSOLUTELY NOT. Each microservice is its own self-contained application, including only the GeoServer dependencies it needs. Moreover, care has been taken so that when a dependency has both required and non-required components, only the required ones are loaded.

Note the above diagram represents the overall system's architecture. This is not a deployment diagram. Deployment involves choice of platforms, configurations, and more; without affecting the general architecture. Some microservices/components, though planned and represented in the architecture diagram, have not yet been developed/integrated. For instance: the logging, tracing, and monitoring components, as well as the GWC and WPS microservices.

Components Overview

  • Front services:
    • Gateway
    • Monitoring
  • Infrastructure:
    • Discovery
    • Config
    • Event bus
    • Logging
    • Tracing
    • Cache
  • GeoServer:
    • Catalog
    • OWS services
    • REST API service
    • Web-UI service
    • GWC service

Project source code structure

        src/ ......................................... Project source code root directory
        |_ apps ...................................... Root directory for microservice applications
        |    |_ infrastructure/ ...................... Infrastructure services
        |    |     |_ config/ ........................ Spring-cloud config service
        |    |     |_ gateway/ ....................... Spring-cloud gateway service
        |    |     |_ discovery/...................... Spring-cloud discovery service
        |    |     |_ admin/ ......................... Spring-cloud admin service
        |    |
        |    |_ geoserver/ ........................... Root directory for geoserver based microservices
        |          |_ wms/ ........................... Web Map Service
        |          |_ wfs/ ........................... Web Feature Service
        |          |_ wcs/ ........................... Web Coverage Service
        |          |_ wps/ ........................... Web Processing Service
        |          |_ gwc/ ........................... GeoWebcache Service
        |          |_ restconfig/ .................... GeoServer REST config API Service
        |          |_ webui/ ......................... GeoServer administration Web User Interface
        |
        |_ catalog/ .................................. Root directory for GeoServer Catalog and Config libraries
        |    |_ plugin/ .............................. Core Catalog and Config implementation and extensions
        |    |
        |    |_ backends/ ............................ Spring Boot AutoConfigurations for specific catalog back-ends
        |    |     |_ common/ ........................ Basic catalog and config bean wiring common to all back-ends
        |    |     |_ datadir/ ....................... Shared "data directory" catalog back-end
        |    |     |_ jdbcconfig/ .................... "jdbcconfig" catalog back-end
        |    |
        |    |_ jackson-bindings/ .................... Libraries to encode and decode configuration objects as JSON
        |    |     |_ geotools/ ...................... Jackson bindings for JTS Geometries and org.opengis.filter.Filter
        |    |     |_ geoserver/ ..................... Jackson bindings for GeoServer Catalog and Config object model
        |    |     |_ starter/ ....................... Spring Boot starter module to automate GeoTools and GeoServer Jackson bindings
        |    |
        |    |_ cache/ ............................... Spring Boot JCache support and auto-configurations for the Catalog
        |    |_ events/ .............................. No-framework object model and runtime for catalog and config application events
        |    |_ event-bus/ ........................... Integration layer for events with Spring Cloud Bus
        |
        |_ gwc ....................................... GeoWebCache modules
        |    |_ core/ ................................ Basic integration for GeoWebCache with GeoServer Cloud
        |    |_ backends/ ............................ Integration of GWC storage backends (File, S3, Azure, etc.)
        |    |_ services/ ............................ Support for GWC services integration (TMS, WMTS, etc.)
        |    |_ tiling/ .............................. Support for GWC distributed tile cache seeding, agnostic of distributed events technologies
        |    |_ integration-bus/ ..................... Integration layer for GWC application events with Spring Cloud Bus
        |    |_ autoconfigure/ ....................... Auto configurations for all GWC functionalities
        |    |_ starter/ ............................. Spring Boot starter for integrating GWC aspects with services (webui, gwc-service, wms)
        |
        |_ starters .................................. Spring Boot starters for GeoServer microservices
        |    |_ spring-boot/ ......................... Basic Spring Boot integration and application startup logging
        |    |_ catalog-backend/ ..................... Groups all supported catalog back-ends
        |    |_ security/ ............................ Additional GeoServer security plugins (e.g. Authkey)
        |    |_ webmvc/ .............................. Spring Cloud and basic GeoServer integrations for spring-webmvc based applications
        |    |_ reactive/ ............................ Spring Cloud and basic GeoServer integrations for reactive (WebFlux-based) applications
        |    |_ event-bus/ ........................... Binds Spring Cloud Bus integration layer with a concrete event-bridge (RabbitMQ)
        |    |_ raster-formats/ ...................... Dependencies for all supported GeoSever raster formats (GeoTiff, ImageMosaic, etc.)
        |    |_ vector-formats/ ...................... Dependencies for all supported GeoSever vector formats (PostGIS, Shapefile, etc.)
        |    |_ wms-extensions/ ...................... WMS extensions autoconfigurations needed not only by wms-service (CSS, VectorTiles, etc.)
        |
        |_ integration-tests ......................... Integration tests

Building

Check out the build instructions document.

Running for development and testing

The ./compose folder contains docker-compose files intended only for development.

For instructions on running GeoServer Cloud in your environment, follow the Quick Start guide on the user guide.

Run as non-root

First thing first, edit the .env file to set the GS_USER variable to the user and group ids the applications should run as.

Usually the GID and UID of your user, such as:

echo `id -g`:`id -u`
1000:1000

Choose your Catalog and Configuration back-end

You need to run compose.yml and pick one compose override file for a given GeoServer Catalog and Configuration back-end.

DataDirectory Catalog back-end

The datadir spring boot profile enables the traditional "data directory" catalog back-end, with all GeoServer containers sharing the same directory. On a k8s deployment you would need a ReadWriteMany persistent volume.

GeoServer-Cloud can start from an empty data directory.

The catalog-datadir.yml docker compose override enables the datadir profile and initializes a volume with the default GeoServer release data directory.

Run with:

$ docker compose -f compose.yml -f catalog-datadir.yml

or the more convenient shell script:

$ ./datadir up -d

PostgreSQL Catalog back-end

The pgconfig spring boot profile enables the PostgreSQL catalog back-end.

This is the preferred Catalog back-end for production deployments, and requires a PostgreSQL 15.0+ database

The catalog-pgconfig.yml docker compose override enables the pgconfig profile and sets up a PostgreSQL container named pgconfigdb.

On a production deployment, it is expected that the database is a provided service and not part of the GeoServer Cloud deployment.

Run with:

$ docker compose -f compose.yml -f catalog-pgconfig.yml

Or the more convenient shell script:

$ ./pgconfig up -d

PGBouncer:

Given the pgconfig catalog back-end will set up a database connection pool on each container, when scaling out you might run out of available connections in the Postgres server. A good way to avoid that and make better use of resources is to use a connection pooling service, such as pgbouncer.

Use the catalog-pgconfig.yml in combination with the pgbouncer.yml docker compose override. pgbouncer.yml will override the three database containers with separate pgbouncer instances for each:

  • pgconfigdb becomes a pgbouncer container pointing to the pgconfigdb_pg container.
  • acldb becomes a pgbouncer container pointing to the acldb_pg container, and holds the GeoServer ACL database
  • postgis becomes a pgbouncer container pointing to the postgis_pg container.

The postgis is container used to host sample data, it is not required but useful during development.

Access GeoServer

Verify the services are running with dcd ps or dcp ps as appropriate.

$ curl "http://localhost:9090/geoserver/cloud/ows?request=getcapabilities&service={WMS,WFS,WCS,WPS}"
$ curl -u admin:geoserver "http://localhost:9090/geoserver/cloud/rest/workspaces.json"

Browse to http://localhost:9090/geoserver/cloud/

Note the /geoserver/cloud context path is set up in the gateway-service's externalized configuration, and enforced through the GEOSERVER_BASE_PATH in compose.yml. You can change it to whatever you want. The default gateway-service.yml configuration file does not set up a context path at all, and hence GeoServer will be available at the root URL.

Running for development

docker-compose

Now run the docker composition as follows, the first time it might need to download some additional images for the rabbitmq event broker and the postgresql config database:

$ docker compose up -d

Run docker compose logs -f to watch startup progress of all services.

Watch the output of docker compose ps until all services are healthy:

$ docker compose ps
       Name                      Command                  State                   Ports                                                      
-----------------------------------------------------------------------------------------------------------------
gscloud_config_1      dockerize -wait http://dis ...   Up (healthy)                                                                                                                   
gscloud_database_1    docker-entrypoint.sh postgres    Up (healthy)   0.0.0.0:5432->5432/tcp                                                                                          
gscloud_discovery_1   /bin/sh -c exec java $JAVA ...   Up (healthy)   0.0.0.0:8761->8761/tcp                                                                                          
gscloud_gateway_1     dockerize -wait http://con ...   Up (healthy)   0.0.0.0:9090->8080/tcp                                                                                          
gscloud_rabbitmq_1    docker-entrypoint.sh rabbi ...   Up             15671/tcp, 0.0.0.0:15672->15672/tcp, ...
gscloud_rest_1        dockerize -wait http://con ...   Up (healthy)                                                                                                                   
gscloud_wcs_1         dockerize -wait http://con ...   Up (healthy)                                                                                                                   
gscloud_webui_1       dockerize -wait http://con ...   Up (healthy)                                                                                                                   
gscloud_wfs_1         dockerize --timeout 60s -w ...   Up (healthy)                                                                                                                   
gscloud_wms_1         dockerize -wait http://con ...   Up (healthy)

Now you can access all front-services (wms, wfs, wcs, rest, and webui) through the gateway service at http://localhost:9090

Running a service in development/debug mode

Running a single service in "local" mode (that is, outside the docker composition) can be done either through the command line or through the IDE.

First, make sure at least the essential infrastructure services are running:

$ docker compose up -d discovery rabbitmq config database gateway

The gateway service is not essential, but useful to check it's correctly proxy'ing requests to your locally running services as well as the ones in the docker composition.

To run a specific service through the command line, for example, wfs-service, run:

$ ./mvnw -f services/wfs spring-boot:run -Dspring-boot.run.profiles=local

To run a service through the IDE, execute the specific application class (for example, org.geoserver.cloud.wfs.app.WfsApplication), which is a regular Java class with a main() method, passing the JVM argument -Dspring-boot.run.profiles=local.

The "local" spring profile in each config/<service>.yml file sets a different hard-coded port for each service, which aids in debugging a locally running service:

At startup time, as configured in its src/main/resources/bootstrap.yml file, the service will contact the discovery-service at the default http://localhost:8761/eureka location, given there's no eureka.server.url configuration property set (which is otherwise provided by compose.yml). Since compose.yml exposes the discovery-service at the local port 8761, that's all the service being run locally needs to engage in the cluster. The discovery service will provide it with the location of any other service it needs to contact, starting with the config-service, where it will ultimatelly get the rest of the application configuration from.