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113 lines
4.1 KiB
Erlang
Executable file
113 lines
4.1 KiB
Erlang
Executable file
#!/usr/bin/env escript
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%% -*- erlang-indent-level: 4;indent-tabs-mode: nil -*-
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%%! -smp enable
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%%% ---------------------------------------------------------------------------
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%%% @doc
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%%% The purpose of this command is to prepare a rebar3 project so that
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%%% rebar3 understands that the dependencies are all already
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%%% installed. If you want a hygienic build on nix then you must run
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%%% this command before running rebar3. I suggest that you add a
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%%% `Makefile` to your project and have the bootstrap command be a
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%%% dependency of the build commands. See the nix documentation for
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%%% more information.
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%%%
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%%% This command designed to have as few dependencies as possible so
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%%% that it can be a dependency of root level packages like rebar3. To
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%%% that end it does many things in a fairly simplistic way. That is
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%%% by design.
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%%%
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%%% ### Assumptions
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%%%
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%%% This command makes the following assumptions:
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%%%
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%%% * It is run in a nix-shell or nix-build environment
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%%% * that all dependencies have been added to the ERL_LIBS
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%%% Environment Variable
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-record(data, {version
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, erl_libs
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, root
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, name
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, registry_snapshot}).
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-define(LOCAL_HEX_REGISTRY, "registry.ets").
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main(Args) ->
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{ok, RequiredData} = gather_required_data_from_the_environment(Args),
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ok = bootstrap_libs(RequiredData).
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%% @doc
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%% This takes an app name in the standard OTP <name>-<version> format
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%% and returns just the app name. Why? because rebar is doesn't
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%% respect OTP conventions in some cases.
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-spec fixup_app_name(file:name()) -> string().
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fixup_app_name(Path) ->
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BaseName = filename:basename(Path),
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case string:tokens(BaseName, "-") of
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[Name, _Version] -> Name;
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Name -> Name
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end.
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-spec gather_required_data_from_the_environment([string()]) -> {ok, #data{}}.
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gather_required_data_from_the_environment(_) ->
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{ok, #data{ version = guard_env("version")
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, erl_libs = os:getenv("ERL_LIBS", [])
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, root = code:root_dir()
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, name = guard_env("name")
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, registry_snapshot = guard_env("HEX_REGISTRY_SNAPSHOT")}}.
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-spec guard_env(string()) -> string().
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guard_env(Name) ->
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case os:getenv(Name) of
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false ->
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stderr("Expected Environment variable ~s! Are you sure you are "
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"running in a Nix environment? Either a nix-build, "
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"nix-shell, etc?~n", [Name]),
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erlang:halt(1);
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Variable ->
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Variable
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end.
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-spec bootstrap_libs(#data{}) -> ok.
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bootstrap_libs(#data{erl_libs = ErlLibs}) ->
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io:format("Bootstrapping dependent libraries~n"),
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Target = "_build/prod/lib/",
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Paths = string:tokens(ErlLibs, ":"),
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CopiableFiles =
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lists:foldl(fun(Path, Acc) ->
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gather_directory_contents(Path) ++ Acc
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end, [], Paths),
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lists:foreach(fun (Path) ->
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ok = link_app(Path, Target)
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end, CopiableFiles).
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-spec gather_directory_contents(string()) -> [{string(), string()}].
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gather_directory_contents(Path) ->
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{ok, Names} = file:list_dir(Path),
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lists:map(fun(AppName) ->
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{filename:join(Path, AppName), fixup_app_name(AppName)}
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end, Names).
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%% @doc
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%% Makes a symlink from the directory pointed at by Path to a
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%% directory of the same name in Target. So if we had a Path of
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%% {`foo/bar/baz/bash`, `baz`} and a Target of `faz/foo/foos`, the symlink
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%% would be `faz/foo/foos/baz`.
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-spec link_app({string(), string()}, string()) -> ok.
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link_app({Path, TargetFile}, TargetDir) ->
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Target = filename:join(TargetDir, TargetFile),
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ok = make_symlink(Path, Target).
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-spec make_symlink(string(), string()) -> ok.
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make_symlink(Path, TargetFile) ->
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file:delete(TargetFile),
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ok = filelib:ensure_dir(TargetFile),
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io:format("Making symlink from ~s to ~s~n", [Path, TargetFile]),
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ok = file:make_symlink(Path, TargetFile).
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%% @doc
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%% Write the result of the format string out to stderr.
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-spec stderr(string(), [term()]) -> ok.
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stderr(FormatStr, Args) ->
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io:put_chars(standard_error, io_lib:format(FormatStr, Args)).
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