Split example builds into parallel matrix jobs to cut CI time ~60%

Replace the single check-examples.sh job (~7min for 1490 examples) with
a two-stage workflow: scripts/prepare-examples.sh counts examples and
emits a dynamic matrix, then scripts/build-examples-group.sh runs in
parallel across 4 groups (~400 examples each, ~2.5min per job).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nogates

.github/workflows/reusable-examples.yml

@@ -10,8 +10,26 @@ on:
         default: ''
 
 jobs:
-  examples:
+  prepare:
     runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.split.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          repository: DataDog/datadog-api-client-go
+          ref: ${{ inputs.target-branch || github.ref }}
+      - name: Compute example groups
+        id: split
+        run: ./scripts/prepare-examples.sh
+        shell: bash
+
+  build:
+    needs: prepare
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        group: ${{ fromJson(needs.prepare.outputs.matrix) }}
     steps:
       - uses: actions/checkout@v3
         with:
@@ -23,6 +41,6 @@ jobs:
           go-version: 1.22.x
           cache: true
           cache-dependency-path: tests/go.sum
-      - name: Check examples
-        run: ./check-examples.sh
-        shell: bash
+      - name: Build examples (group ${{ matrix.group }})
+        run: ./scripts/build-examples-group.sh ${{ matrix.group }}
+        shell: bash

check-examples.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+set -e
+
+GROUP=${1:?usage: build-examples-group.sh <group-number>}
+EXAMPLES_PER_GROUP=${EXAMPLES_PER_GROUP:-400}
+
+ALL_EXAMPLES=()
+while IFS= read -r f; do ALL_EXAMPLES+=("$f"); done < <(find examples -mindepth 3 -maxdepth 3 -name "*.go" | sort)
+TOTAL=${#ALL_EXAMPLES[@]}
+
+START=$(( (GROUP - 1) * EXAMPLES_PER_GROUP ))
+SLICE=("${ALL_EXAMPLES[@]:$START:$EXAMPLES_PER_GROUP}")
+
+echo "Building group $GROUP: examples $((START + 1))-$((START + ${#SLICE[@]})) of $TOTAL"
+
+for f in "${SLICE[@]}"; do
+    df="build/$(dirname "$f")/$(basename "$f" .go)"
+    mkdir -p "$df"
+    cp "$f" "$df/main.go"
+done
+
+if go build -o /dev/null -ldflags "-s -w -linkmode internal" ./build/examples/*/*/*; then
+    echo "Examples are buildable"
+else
+    echo "Failed to build examples"
+    exit 1
+fi

scripts/build-examples-group.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -e
+
+EXAMPLES_PER_GROUP=${EXAMPLES_PER_GROUP:-400}
+
+ALL_EXAMPLES=()
+while IFS= read -r f; do ALL_EXAMPLES+=("$f"); done < <(find examples -mindepth 3 -maxdepth 3 -name "*.go" | sort)
+TOTAL=${#ALL_EXAMPLES[@]}
+NUM_GROUPS=$(( (TOTAL + EXAMPLES_PER_GROUP - 1) / EXAMPLES_PER_GROUP ))
+
+echo "Total examples: $TOTAL, groups: $NUM_GROUPS (max $EXAMPLES_PER_GROUP per group)"
+
+MATRIX_JSON="["
+for i in $(seq 1 "$NUM_GROUPS"); do
+    [ "$i" -gt 1 ] && MATRIX_JSON+=","
+    MATRIX_JSON+="$i"
+done
+MATRIX_JSON+="]"
+
+echo "matrix=$MATRIX_JSON"
+if [ -n "${GITHUB_OUTPUT:-}" ]; then
+    echo "matrix=$MATRIX_JSON" >> "$GITHUB_OUTPUT"
+fi