For some time I had big problem with Mix that it didn’t supported fetching project version from Git, like Rebar3 does with {version, git}
in .app.src
. So finally I have crafted the snippet that works and does exactly that:
defp version do
case :file.consult('hex_metadata.config') do
{:ok, data} ->
{"version", version} = List.keyfind(data, "version", 0)
version
_ ->
version =
case System.cmd("git", ~w[describe --dirty=+dirty]) do
{version, 0} ->
String.trim(version)
{_, code} ->
Mix.shell().error("Git exited with code #{code}, falling back to 0.0.0")
"0.0.0"
end
case Version.parse(version) do
{:ok, %Version{pre: ["pre" <> _ | _]} = version} ->
to_string(version)
{:ok, %Version{pre: []} = version} ->
to_string(version)
{:ok, %Version{patch: patch, pre: pre} = version} ->
to_string(%{version | patch: patch + 1, pre: ["dev" | pre]})
:error ->
Mix.shell().error("Failed to parse #{version}, falling back to 0.0.0")
"0.0.0"
end
end
end
And now use [version: version()]
and it will automatically use version from Hex when available, Git version when project is fetched via Git, if everything fails then it will fall back to 0.0.0
.
Unfortunately as Mix do not have a way to have per-project extensions preloaded it need to be distributed as such snippet and I cannot make it into library that would make it clearer.
I have used above in Watermelon and I have tested that it works as expected.