1 files changed, 163 insertions, 0 deletions
diff --git a/nixpkgs/pkgs/servers/web-apps/lemmy/update.py b/nixpkgs/pkgs/servers/web-apps/lemmy/update.py
new file mode 100755
index 000000000000..4e867553b790
--- /dev/null
+++ b/nixpkgs/pkgs/servers/web-apps/lemmy/update.py
@@ -0,0 +1,163 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i python3 -p python3 python3.pkgs.semver nix-prefetch-github
+from urllib.request import Request, urlopen
+import dataclasses
+import subprocess
+import os.path
+import semver
+from typing import (
+    Optional,
+    Dict,
+    List,
+)
+import json
+import os
+
+
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+NIXPKGS = os.path.abspath(os.path.join(SCRIPT_DIR, "../../../../"))
+
+
+OWNER = "LemmyNet"
+UI_REPO = "lemmy-ui"
+SERVER_REPO = "lemmy"
+
+
+@dataclasses.dataclass
+class Pin:
+    serverVersion: str
+    uiVersion: str
+    serverHash: str = ""
+    serverCargoHash: str = ""
+    uiHash: str = ""
+    uiYarnDepsHash: str = ""
+
+    filename: Optional[str] = None
+
+    def write(self) -> None:
+        if not self.filename:
+            raise ValueError("No filename set")
+
+        with open(self.filename, "w") as fd:
+            pin = dataclasses.asdict(self)
+            del pin["filename"]
+            json.dump(pin, fd, indent=2)
+            fd.write("\n")
+
+
+def github_get(path: str) -> Dict:
+    """Send a GET request to GitHub, optionally adding GITHUB_TOKEN auth header"""
+    url = f"https://api.github.com/{path.lstrip('/')}"
+    print(f"Retrieving {url}")
+
+    req = Request(url)
+
+    if "GITHUB_TOKEN" in os.environ:
+        req.add_header("authorization", f"Bearer {os.environ['GITHUB_TOKEN']}")
+
+    with urlopen(req) as resp:
+        return json.loads(resp.read())
+
+
+def get_latest_release(owner: str, repo: str) -> str:
+    return github_get(f"/repos/{owner}/{repo}/releases/latest")["tag_name"]
+
+
+def prefetch_github(owner: str, repo: str, rev: str) -> str:
+    """Prefetch GitHub rev and return SRI hash"""
+    print(f"Prefetching {owner}/{repo}({rev})")
+
+    proc = subprocess.run(
+        ["nix-prefetch-github", owner, repo, "--rev", rev, "--fetch-submodules"],
+        check=True,
+        stdout=subprocess.PIPE,
+    )
+
+    return json.loads(proc.stdout)["hash"]
+
+
+def get_latest_tag(owner: str, repo: str, prerelease: bool = False) -> str:
+    """Get the latest tag from a GitHub Repo"""
+    tags: List[str] = []
+
+    # As the GitHub API doesn't have any notion of "latest" for tags we need to
+    # collect all of them and sort so we can figure out the latest one.
+    i = 0
+    while i <= 100:  # Prevent infinite looping
+        i += 1
+        resp = github_get(f"/repos/{owner}/{repo}/tags?page={i}")
+        if not resp:
+            break
+
+        # Filter out unparseable tags
+        for tag in resp:
+            try:
+                parsed = semver.Version.parse(tag["name"])
+                if (
+                    semver.Version.parse(tag["name"])
+                    and not prerelease
+                    and parsed.prerelease
+                ):  # Filter out release candidates
+                    continue
+            except ValueError:
+                continue
+            else:
+                tags.append(tag["name"])
+
+    # Sort and return latest
+    return sorted(tags, key=lambda name: semver.Version.parse(name))[-1]
+
+
+def get_fod_hash(attr: str) -> str:
+    """
+    Get fixed output hash for attribute.
+    This depends on a fixed output derivation with an empty hash.
+    """
+
+    print(f"Getting fixed output hash for {attr}")
+
+    proc = subprocess.run(["nix-build", NIXPKGS, "-A", attr], stderr=subprocess.PIPE)
+    if proc.returncode != 1:
+        raise ValueError("Expected nix-build to fail")
+
+    # Iterate list in reverse order so we get the "got:" line early
+    for line in proc.stderr.decode().split("\n")[::-1]:
+        cols = line.split()
+        if cols and cols[0] == "got:":
+            return cols[1]
+
+    raise ValueError("No fixed output hash found")
+
+
+def make_server_pin(pin: Pin, attr: str) -> None:
+    pin.serverHash = prefetch_github(OWNER, SERVER_REPO, pin.serverVersion)
+    pin.write()
+    pin.serverCargoHash = get_fod_hash(attr)
+    pin.write()
+
+
+def make_ui_pin(pin: Pin, package_json: str, attr: str) -> None:
+    # Save a copy of package.json
+    print("Getting package.json")
+    with urlopen(
+        f"https://raw.githubusercontent.com/{OWNER}/{UI_REPO}/{pin.uiVersion}/package.json"
+    ) as resp:
+        with open(os.path.join(SCRIPT_DIR, package_json), "wb") as fd:
+            fd.write(resp.read())
+
+    pin.uiHash = prefetch_github(OWNER, UI_REPO, pin.uiVersion)
+    pin.write()
+    pin.uiYarnDepsHash = get_fod_hash(attr)
+    pin.write()
+
+
+if __name__ == "__main__":
+    # Get server version
+    server_version = get_latest_tag(OWNER, SERVER_REPO)
+
+    # Get UI version (not always the same as lemmy-server)
+    ui_version = get_latest_tag(OWNER, UI_REPO)
+
+    pin = Pin(server_version, ui_version, filename=os.path.join(SCRIPT_DIR, "pin.json"))
+    make_server_pin(pin, "lemmy-server")
+    make_ui_pin(pin, "package.json", "lemmy-ui")