pomerium: add update script

pkgs/servers/http/pomerium/default.nix

@@ -111,9 +111,12 @@ buildGoModule rec {
     install -Dm0755 $GOPATH/bin/pomerium $out/bin/pomerium
   '';
 
-  passthru.tests = {
-    inherit (nixosTests) pomerium;
-    inherit pomerium-cli;
+  passthru = {
+    tests = {
+      inherit (nixosTests) pomerium;
+      inherit pomerium-cli;
+    };
+    updateScript = ./updater.sh;
   };
 
   meta = with lib; {

pkgs/servers/http/pomerium/updater.sh

@@ -0,0 +1,23 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p gnugrep coreutils curl wget jq nix-update prefetch-yarn-deps
+
+set -euo pipefail
+pushd "$(dirname "${BASH_SOURCE[0]}")"
+
+owner="pomerium"
+repo="pomerium"
+version=`curl -s "https://api.github.com/repos/$owner/$repo/tags" | jq -r .[0].name | grep -oP "^v\K.*"`
+url="https://raw.githubusercontent.com/$owner/$repo/v$version/"
+
+if [[ "$UPDATE_NIX_OLD_VERSION" == "$version" ]]; then
+    echo "Already up to date!"
+    exit 0
+fi
+
+rm -f package.json yarn.lock
+wget "$url/ui/yarn.lock" "$url/ui/package.json"
+echo $(prefetch-yarn-deps) > yarn-hash
+rm -f yarn.lock
+
+popd
+nix-update pomerium --version $version