this allows user to choose the compression type (i.e. gzip/zlib/none) using --log-opt=gelf-compression-type=none or the compression level (-1..9) using --log-opt=gelf-compression-level=0 for gelf driver. Signed-off-by: Daniel Dao <dqminh@cloudflare.com> Upstream-commit: bd94baa353498df2457b3d5aa192cc488b9fa0c6 Component: engine