UPX¶

Having small binary sizes are important, and Go is known for generating rather big binaries.

GoReleaser has had -s -w as default ldflags since the beginning, which help shaving off some bytes, but if you want to shave it even more, upx is the de facto tool for the job.

GoReleaser has been able to integrate with it via custom build hooks, and now UPX has its own configuration section:

# .goreleaser.yaml
upx:
  - # Whether to enable it or not.
    #
    # Templates: allowed.
    enabled: true

    # Filter by build ID.
    ids: [build1, build2]

    # Filter by GOOS.
    goos: [linux, darwin]

    # Filter by GOARCH.
    goarch: [arm, amd64]

    # Filter by GOARM.
    goarm: [8]

    # Filter by GOAMD64.
    goamd64: [v1]

    # Compress argument.
    # Valid options are from '1' (faster) to '9' (better), and 'best'.
    compress: best

    # Whether to try LZMA (slower).
    lzma: true

    # Whether to try all methods and filters (slow).
    brute: true

Notice you can define multiple upx definitions, filtering by various fields. You can use that to have different compression options depending on the target OS, for instance - or even to run it only on a few selected platforms.