This Dockerfile is used to build a Docker image in two stages, each serving a specific purpose. The resulting image is intended to be lightweight and efficient. Below is a brief explanation of each stage and its purpose
In this stage, the Docker image starts with the base image of Ubuntu 20.04. This stage aims to set up a clean environment for building the desired software.
. apt-get update -y: Updates the package manager repository with the latest information.
. apt-get install -y --no-install-recommends: Installs the specified packages (curl and osmium-tool) without installing any recommended additional packages.
. && rm -rf /var/lib/apt/lists/*: Clean up the package manager's cache to reduce the image size.
. mkdir /osmfiles /merged: Creates two directories, /osmfiles and /merged, to store OpenStreetMap (OSM) data files.
. && curl -o /osmfiles/monaco.osm.pbf http://download.geofabrik.de/europe/monaco-latest.osm.pbf: Downloads an OSM data file for Monaco and places it in the /osmfiles directory.
. && curl -o /osmfiles/andorra.osm.pbf http://download.geofabrik.de/europe/andorra-latest.osm.pbf: Downloads an OSM data file for Andorra and places it in the /osmfiles directory.
. && osmium merge /osmfiles/monaco.osm.pbf /osmfiles/andorra.osm.pbf -o /merged/merged.osm.pbf: Merges the OSM data files for Monaco and Andorra into a single file named merged.osm.pbf in the /merged directory.
In this final stage, the Docker image is further optimized for production use:
. FROM alpine AS final switches to a minimal Alpine Linux base image to create a lightweight final image.
. mkdir /merged: Creates a directory named /merged in the final image.
. COPY --from=build /merged /merged : Copies the merged OSM data files from the build stage into the /merged directory of the final image.
The resulting Docker image contains the merged OSM data files and is ready for use in a production environment. This two-stage build process helps keep the final image small and efficient by eliminating unnecessary build artifacts and dependencies.