Mapserver docker

TL;DR

docker build -t pdok/mapserver .
docker run -e MS_MAPFILE=/srv/data/example.map --rm -d -p 80:80 --name mapserver-example -v `pwd`/example:/srv/data pdok/mapserver

docker stop mapserver-example

Introduction

This project aims to fulfill two needs:

1. create OGC services that are deployable on a scalable infrastructure.
2. create a useable Docker base image.

Fulfilling the first need the main purpose is to create an Docker base image that can be run on a platform like Kubernetes.

Regarding the second need, finding a usable Mapserver Docker image is a challenge. Most images expose the &map=... QUERY_STRING in the GetCapabilities, don't run in FastCGI and are based on Apache.

What will it do

It will create an Mapserver application run with Lighttpd in which the map=... QUERY_STRING 'issue' is 'fixed'. This means that the MAP query parameter is removed from the QUERY_STRING.

The included EPSG file containing the projection parameters only contains a small set of available EPSG code, namely the once used by our organization. If one wants to use additional EPSG projections one can overwrite this file.

Docker image

The Docker image contains 2 stages:

1. builder
2. service

builder

The builder stage compiles Mapserver. The Dockerfile contains all the available Mapserver build option explicitly, so it is clear which options are enabled and disabled.

service

The service stage copies the Mapserver application, build in the first stage to the service stage, and configures Lighttpd

Usage

Build

docker build -t pdok/mapserver .

Run

This image can be run straight from the CLI. A volume needs to be mounted on the container directory /srv/data. The mounted volume needs to contain a mapserver *.map file that matches the MS_MAPFILE env.

docker run -e MS_MAPFILE=/srv/data/example.map -d -p 80:80 --name mapserver-example -v `pwd`/example:/srv/data pdok/mapserver

Running the example above will create a service on the url http://localhost/?request=getcapabilities&service=wms

The ENV variables that can be set are the following

DEBUG
MIN_PROCS
MAX_PROCS
MAX_LOAD_PER_PROC
IDLE_TIMEOUT
MS_MAPFILE

PROJ_LIB

The ENV variables, with the exception of MS_MAPFILE have a default value set in the Dockerfile.

The GDAL PROJ_LIB env is default set with the value /usr/share/proj. For performance reasons one would like to set a custom PROJ_LIB containing a minimum of available EPSG codes. This can be done with the mentioned PROJ_LIB env.

docker run -e DEBUG=0 -e MIN_PROCS=1 -e MAX_PROCS=3 -e MAX_LOAD_PER_PROC=4 -e IDLE_TIMEOUT=20 -e MS_MAPFILE=/srv/data/example.map --rm -d -p 80:80 --name mapserver-run-example -v `pwd`/example:/srv/data pdok/mapserver

Example

When starting the container it will create a WMS & WFS service on the end-point

http://localhost?

Example request

http://localhost/?request=getfeature&service=wfs&VERSION=2.0.0&typename=example:example&count=1

http://localhost/?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&BBOX=50,2,54,9&CRS=EPSG:4326&WIDTH=905&HEIGHT=517&LAYERS=example&STYLES=&FORMAT=image/png&DPI=96&MAP_RESOLUTION=96&FORMAT_OPTIONS=dpi:96&TRANSPARENT=TRUE

http://localhost/?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetFeatureInfo&BBOX=48.9306039592783506,0.48758765231731171,55.46504193821721884,12.33319204541738756&CRS=EPSG:4326&WIDTH=1530&HEIGHT=844&LAYERS=example&STYLES=&FORMAT=image/png&QUERY_LAYERS=example&INFO_FORMAT=text/html&I=389&J=537&FEATURE_COUNT=10

Misc

Why Lighttpd

In our previous configurations we would run NGINX, while this is a good web service and has a lot of configuration options, it runs with multiple processes. There for we needed supervisord for managing this, whereas Lighttpd runs as a single process. Also all the routing configuration options aren't needed, because that is handled by the infrastructure/platform, like Kubernetes. If one would like to configure some simple routing is still can be done in the lighttpd.conf.

Used examples

• https://github.com/srounet/docker-mapserver
• https://github.com/Amsterdam/mapserver