extremely normal shell script

Dockerfile

FROM ubuntu

RUN apt-get update
RUN apt-get -y install gdal-bin

RUN apt-get -y install jq

RUN >x.csv printf 'id,WKT\n1,%s\n' "$(echo '[[0.2,0.2],[0.75,0.75],[0.25,0.75],[0.2,0.2]]' \
  | jq '(2*(-1|acos)*6378137)as$c|[.[]|[(.[0]-0.5)*$c,(0.5-.[1])*$c]|join(" ")]|join(",")|"LINESTRING("+.+")"')"; \
  echo EPSG:3857 >x.prj

RUN ogrinfo --version
RUN ogr2ogr -t_srs WGS84 -f GeoJSONSeq y.geojsons x.csv -dialect sqlite -sql 'select ST_Length(geometry) from x'

RUN <y.geojsons jq '(2*(-1|acos)*6378137)as$c|.properties."ST_Length(geometry)"/$c'