Go: Difference between revisions

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imported>Mic92
go static linking
imported>Mic92
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== Compile go program with static compile flag ==
== Compile go program with static compile flag ==
If <code>go build -ldflags "-s -w -linkmode external -extldflags -static"</code> fails on NixOS, with the error message <code>cannot find `-lpthread</code> and <code>cannot find -lc</code> - it is because the linker cannot find static glibc to link with. You need to have glibc.static in your environment (and have CFLAGS/LDFLAGS adjusted accordingly).
If <code>go build -ldflags "-s -w -linkmode external -extldflags -static"</code> fails on NixOS, with the error message <code>cannot find `-lpthread</code> and <code>cannot find -lc</code> - it is because the linker cannot find static glibc to link with. You need to have glibc.static in your environment (and have CFLAGS/LDFLAGS adjusted accordingly).
One way to achieve this is to have something like the following as `shell.nix` and run the compilation in a nix-shell:
One way to achieve this is to have something like the following as <code>shell.nix</code> and run the compilation in a nix-shell:


<syntaxHighlight lang=nix>
<syntaxHighlight lang=nix>
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   devEnv = stdenv.mkDerivation {
   devEnv = stdenv.mkDerivation {
     name = "dev";
     name = "dev";
     buildInputs = [ stdenv git go glibc.static ];
     buildInputs = [ stdenv go glibc.static ];
     CFLAGS="-I${pkgs.glibc.dev}/include";
     CFLAGS="-I${pkgs.glibc.dev}/include";
     LDFLAGS="-L${pkgs.glibc}/lib";
     LDFLAGS="-L${pkgs.glibc}/lib";

Revision as of 13:54, 27 September 2018

Go is a statically-typed language with syntax loosely derived from that of C, adding garbage collected memory management, type safety, some dynamic-typing capabilities, additional built-in types such as variable-length arrays and key-value maps, and a large standard library.

Using cgo on NixOS

On NixOS, include files and libraries aren't kept in a system-wide search path. If a Go program uses cgo and attempts to include C header files, or link against libraries, compilation is likely to fail.

In order to expose header files and libraries in environment variable search paths, nix-shell can be used to enter an environment which provides the requested development dependencies.

For example, suppose a Go program includes <sys/capability.h> (provided by libcap), and links against libcap. To obtain an environment in which the program can be compiled, run:

$ nix-shell -p libcap go gcc

You can verify the presence of the necessary environment variables via the following command:

$ export | egrep 'NIX_.*(LDFLAGS|COMPILE|LINK)'

If you intend to compile against glibc statically (such as via go build -ldflags "-s -w -linkmode external -extldflags -static"), add glibc.static to the list of packages passed to nix-shell.

Compile go program with static compile flag

If go build -ldflags "-s -w -linkmode external -extldflags -static" fails on NixOS, with the error message cannot find `-lpthread and cannot find -lc - it is because the linker cannot find static glibc to link with. You need to have glibc.static in your environment (and have CFLAGS/LDFLAGS adjusted accordingly). One way to achieve this is to have something like the following as shell.nix and run the compilation in a nix-shell:

with import <nixpkgs> {}; {
  devEnv = stdenv.mkDerivation {
    name = "dev";
    buildInputs = [ stdenv go glibc.static ];
    CFLAGS="-I${pkgs.glibc.dev}/include";
    LDFLAGS="-L${pkgs.glibc}/lib";
  };
}