ci/request-reviews: share code to request reviewers from gh api

This makes it easier to add ofborg's request-1-by-1 logic, where failed
requests are OK for edge cases.

.github/workflows/eval.yml

@@ -294,14 +294,7 @@ jobs:
           # There appears to be no API to request reviews based on GitHub IDs
           jq -r 'keys[]' comparison/maintainers.json \
             | while read -r id; do gh api /user/"$id" --jq .login; done \
-            | GH_TOKEN=${{ steps.app-token.outputs.token }} result/bin/process-reviewers.sh "$REPOSITORY" "$NUMBER" "$AUTHOR" \
-            > reviewers.json
-
-          # Request reviewers from maintainers of changed output paths
-          GH_TOKEN=${{ steps.app-token.outputs.token }} gh api \
-            --method POST \
-            /repos/"$REPOSITORY"/pulls/"$NUMBER"/requested_reviewers \
-            --input reviewers.json
+            | GH_TOKEN=${{ steps.app-token.outputs.token }} result/bin/request-reviewers.sh "$REPOSITORY" "$NUMBER" "$AUTHOR"
 
         env:
           GH_TOKEN: ${{ github.token }}

ci/request-reviews/default.nix

@@ -15,7 +15,7 @@ stdenvNoCC.mkDerivation {
     root = ./.;
     fileset = lib.fileset.unions [
       ./get-code-owners.sh
-      ./process-reviewers.sh
+      ./request-reviewers.sh
       ./request-code-owner-reviews.sh
       ./verify-base-branch.sh
       ./dev-branches.txt

ci/request-reviews/request-code-owner-reviews.sh

@@ -77,20 +77,6 @@ if ! "$SCRIPT_DIR"/verify-base-branch.sh "$tmp/nixpkgs.git" "$headRef" "$baseRep
     exit 1
 fi
 
-log "Getting code owners to request reviews from"
+log "Requesting reviews from code owners"
 "$SCRIPT_DIR"/get-code-owners.sh "$tmp/nixpkgs.git" "$ownersFile" "$baseBranch" "$headRef" | \
-    "$SCRIPT_DIR"/process-reviewers.sh "$baseRepo" "$prNumber" "$prAuthor" > "$tmp/reviewers.json"
-
-log "Requesting reviews from: $(<"$tmp/reviewers.json")"
-
-if ! response=$(effect gh api \
-    --method POST \
-    -H "Accept: application/vnd.github+json" \
-    -H "X-GitHub-Api-Version: 2022-11-28" \
-    "/repos/$baseRepo/pulls/$prNumber/requested_reviewers" \
-    --input "$tmp/reviewers.json"); then
-    log "Failed to request reviews: $response"
-    exit 1
-fi
-
-log "Successfully requested reviews"
+    "$SCRIPT_DIR"/request-reviewers.sh "$baseRepo" "$prNumber" "$prAuthor"

ci/request-reviews/request-reviewers.sh

@@ -1,15 +1,26 @@
 #!/usr/bin/env bash
 
-# Process reviewers for a PR, reading line-separated usernames on stdin,
-# returning a JSON suitable to be consumed by the API endpoint to request reviews:
+# Request reviewers for a PR, reading line-separated usernames on stdin,
+# filtering for valid reviewers before using the API endpoint to request reviews:
 # https://docs.github.com/en/rest/pulls/review-requests?apiVersion=2022-11-28#request-reviewers-for-a-pull-request
 
 set -euo pipefail
 
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' exit
+
 log() {
     echo "$@" >&2
 }
 
+effect() {
+    if [[ -n "${DRY_MODE:-}" ]]; then
+        log "Skipping in dry mode:" "${@@Q}"
+    else
+        "$@"
+    fi
+}
+
 if (( "$#" < 3 )); then
     log "Usage: $0 BASE_REPO PR_NUMBER PR_AUTHOR"
     exit 1
@@ -62,4 +73,18 @@ jq -n \
     --arg users "${!users[*]}" \
     '{
       reviewers: $users | split(" "),
-    }'
+    }' > "$tmp/reviewers.json"
+
+log "Requesting reviews from: $(<"$reviewersFile")"
+
+if ! response=$(effect gh api \
+    --method POST \
+    -H "Accept: application/vnd.github+json" \
+    -H "X-GitHub-Api-Version: 2022-11-28" \
+    "/repos/$baseRepo/pulls/$prNumber/requested_reviewers" \
+    --input "$tmp/reviewers.json"); then
+    log "Failed to request reviews: $response"
+    exit 1
+fi
+
+log "Successfully requested reviews"