geoserver_migrations

Manage your geoserver configuration similar to ActiveRecord migrations

Maybe not your typical use-case, but I develop I geographic information systems using Ruby on Rails, and when I add a new geographic feature, I add an ActiveRecord migration which is automatically deployed on my development/test/quality assurance/production servers.

However, keeping my geoserver configuration in sync is a different beast: I create and test the geoserver styles and layers on my development machine and then I have to deploy those.

My first attempt to automate this was to check in relevant parts of the data-directory into a separate repository, which I could then easily deploy and then use a script to copy those and replace the identifiers with local versions (e.g. workspace/datastore identifiers).

While this worked it proved so cumbersome I skipped it altogether and just manually copied and defined styles/images/layers. However, you can imagine, this was making my deployment procedure very manually intensive and brittle (forgot to deploy a layer?). Editing and creating layers in geoserver is not really the most user-friendly thing to do (at least not in the versions I am using right now).

So I imagined: wouldn't it be nice if I could have a similar system to my database migrations but for geoserver? Where if I finally deployed to my production server (after having three intermediary deploys to my test/acceptance servers) it would remember which layers still had to be created.

This is a work in progress, not sure if it will be available/usable for the public straightaway.

Add gem to your project

gem 'geoserver_migrations'

when it will be deployed, for now you should link to github to use

gem 'geoserver_migrations', git: 'nathanvda/geoserver_migrations'

Then run the generator to create the config-file and folder containing the migrations

rails g geoserver_migrations:install

Inside the config-file you can edit the settings to connect to the geoserver API

  geoserver_base: "http://localhost:8080/geoserver"
  api:
    user: admin
    password: *******
  workspace: your-workspace
  datastore: your-datastore

and if needed you can add a different path for storing the migrations:

  migrations_path: 'geoserver/migrate'

Then you can add a new migration by doing

  rails g geoserver_migrations:add a_meaningfull_migration_name

To run the migrations

  rails g geoserver_migrations:migrate

In a migration we intend to create a new layer, linked to a database feature. We assume that the workspaces and datastores are already setup in your geoserver.

add_resource "some_icon.png"

create_layer :welds do
  style_name :welds
  feature_name :welds
end

create_layer :settlement_gauges do
  settlement_gauges_sld = <<-SLD
    this is a test
  SLD
  sld settlement_gauges_sld
  feature_name :settlement_gauges
end

The add_resource will look for the given file in $RAILS/geoserver/migrate/assets and upload to geoserver, so you can reference it in later defined styles (SLD).

For the moment I am most interested in automated my personal use-case, which is

• defining layers/styles based on a single (postgis) datastore

So for now :

• generate layers/styles/feature-types using API
• store migration-numbers in table (e.g. similar to schema-migrations table)
• define simple DSL
• use hand-made migration files at first?
• add rake/rails tasks to generate geoserver migrations

Later we could add something like

• define workspace/datastore (to really allow deployment from scratch?)
• define print-styles? is this possible through API?
• maybe make it rails-independant? I can imagine people would want to manage geoserver migrations outside of rails?

Practical:

• I intend to use HTTPClient and my own (small) API library for now/for starting (because I use HTTPClient by preference)
• there is a gem to consume geoserver API called rgeoserver but it uses RestClient instead but it seems wise to use that instead? Maybe adapt it to use Faraday so people can use any underlying http-library they like?