Setup GeoServer
A docker hub image is provided by oscarfonts is extended with OGC API plugin. The binaries of the plugin, as well as the data folder are mounted into the container. The Oscar Fonts image runs as a tomcat user, which by itself is a good practice from security prespective, but files are created on the data folder by a user unknown to the docker host, which causes problems at redeployment. We have overridden this behaviour and run as root user.
The data folder is created by deploying geoserver locally, setting up the required services and commit the changes to github. You can either embed a data file inside the data folder, alternatively you can upload data to the PostGreSQL database and configure a layer on data from the database.
The OGC API is available from the geoserver homepage at /ogc/features, or on the workspace endpoint /{workspace}/agc/features.
OGC API Community module
The GeoServer community has been involved in the OGC sprints while the standards were shaped to its current form. The implementation of OGC API currently has the form of a community plugin, which can be installed on recent versions of GeoServer.
Scripted configuration vs dynamic configuration
GeoServer has an extended web user interface as well as a rest api to configure the publication of datasets. These configurations are persisted as xml files in the config folder. Alternatively you can use a scripted approach to configure the server, the xml files in the conig folder are deployed as part of the deployment. Both approaches can however not easily be combined. It means you have to decide for a server if you set it up scripted or dynamically. The scripted approach is mostly used in advanced setups such as App Schema INSPIRE.
Most challenging is a sequential update number which is updated with every dynamic update of the configuration via the api.
The configuration with xml files is also a challenge when scaling out and load balancing GeoServer. When these files are updated by one instance, the other instances need to be synchronised. Some community plugins are available, such as jdbc-config, which enables the storage of configuration in a central database.
GeoServer behind a gateway (traefik)
Running GeoServer behind a gateway, which exposes geoserver at an alternative domain, requires a proxy url to be configured on GeoServer. You need to manage this in an xml file, because the admin interface (which offers an option to configure this also) doesn't work correctly if the proxy url is not correctly set up.
Recent versions of GeoServer have added a CSRF protection against script attacks. This CSRF leads to unexpected results when running GeoServer via a gateway. The gateway domain needs to be whitelisted or CSRF vealidation deactivated. Read more at https://docs.geoserver.org/stable/en/user/security/webadmin/csrf.html
GeoServer and docker
The installation of GeoServer requires to add the OGC API plugin (check a matching version number). It is quite common that GeoServer is extended with plugins. We used the docker image provided by oscarfonts, which has a nice mechanism to place plugins (and data folder) on a mounted volume.
In order to configure a new resource on GeoServer we added the required configuration files to the geonovum github repository. GeoServer also has a web interface and rest api to configure resources, but note that any resource added manually may be overwritten from github with the new deployment of the software.
An alternative for manual setup us the GeoCat bridge tool, which is a typical tool to configure new resources on GeoServer from within the QGIS or ArcMAP Desktop application.
Issues
Some issues found during deployment (and solutions where found)
- Issue #22 - Permission Issue for mounted dirs: the GeoServer Container permanently changes the ownership of mounted dirs
- Issue #21 - OGC API Plugin: running on subpath with https does not render linked resources correctly
Open research questions
- how are metadata links configured on layers, exposed in ogc api features
- are there an options to fetch gml, app-schema gml and/or geopackage via ogc-api features