easy-dhall-nix/fetch.py

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#!/usr/bin/env nix-shell
#!nix-shell -I nixpkgs=./nixpkgs.nix -i python3 -p python3 curl nix
import json
import re
import subprocess as sub
import sys
# fetch the release info from releases/latest
def curl_latest_release():
url = "https://api.github.com/repos/dhall-lang/dhall-haskell/releases/latest"
return json.loads(sub.check_output(["curl", url]))
# fetch the latest nixos unstable version
def curl_latest_nixos_unstable():
url = "https://nixos.org/channels/nixos-unstable/git-revision"
return sub.check_output(["curl", "--location", url]).strip().decode()
def update_nixpkgs(lockfile_path, new_hash):
# --unpack produces the hash required by `builtins.fetchTarball`
github_archive = "https://github.com/NixOS/nixpkgs/archive/{}.tar.gz".format(new_hash)
hash = sub.check_output([
"nix-prefetch-url", '--unpack', github_archive
]).strip().decode()
date = sub.check_output([
"date", "--iso-8601=minutes"
]).strip().decode()
with open(lockfile_path, 'w') as f:
json.dump({
"comment": "autogenerated by fetch.py",
"url": github_archive,
"sha256": hash,
"date": date
}, f, indent=2)
# call nix-prefetch-url on each asset to get their hashes
def prefetch_binaries(release):
res = []
for a in release['assets']:
if "linux" in a['name'] or "macos" in a['name']:
print(a['name'], file=sys.stderr)
hash = sub.check_output([
"nix-prefetch-url", a['browser_download_url']
]).strip().decode()
res += [{
'name': a['name'],
'url': a['browser_download_url'],
'hash': hash
}]
return res
# convert the list of binaries to an object we can address
def postprocess(fetched):
obj = {}
for i in fetched:
# split on the first digit ("dhall-foo-bar-1.2.3")
name = re.split(r'-\d', i['name'])[0]
post = "-linux" if "linux" in i['name'] else "-darwin"
obj[name + post] = i
return(obj)
if __name__ == "__main__":
print("updating nixpkgs to latest unstable", file=sys.stderr)
nixos_hash = curl_latest_nixos_unstable()
update_nixpkgs("./nixpkgs.json", nixos_hash)
release = curl_latest_release()
version = release['tag_name']
print("updating to release {}".format(version), file=sys.stderr)
fetched = prefetch_binaries(release)
res = postprocess(fetched)
print("writing ./release.json", file=sys.stderr)
with open("./release.json", mode='w') as f:
json.dump(res, f, indent=2)