Skip CI run if commit only documentation changes (#1282)

.circleci/config.yml

@@ -13,6 +13,22 @@ commands:
             docker buildx create --name ci-builder --use
 
 jobs:
+  short-if-irrelevant:
+    docker:
+      - image: cimg/base:stable
+    steps:
+      - checkout
+      - run: 
+          name: Bootstrap Babashka
+          command: |
+            curl -sLO https://raw.githubusercontent.com/babashka/babashka/master/install
+            sudo bash install --dir /tmp
+      - run:
+          name: Rename bb binary
+          command: mv /tmp/bb /tmp/bbb
+      - run:
+          name: Short CI if only irrelevant changes
+          command: /tmp/bbb  .circleci/script/short.clj
   jvm:
     docker:
       - image: circleci/clojure:openjdk-11-lein-2.9.8-bullseye
@@ -468,12 +484,25 @@ workflows:
   version: 2
   ci:
     jobs:
-      - jvm
-      - linux
-      - linux-static
-      - mac
-      - linux-aarch64
-      - linux-aarch64-static
+      - short-if-irrelevant
+      - jvm: 
+          requires:
+             - short-if-irrelevant
+      - linux: 
+          requires:
+             - short-if-irrelevant
+      - linux-static: 
+          requires:
+             - short-if-irrelevant
+      - mac: 
+          requires:
+             - short-if-irrelevant
+      - linux-aarch64: 
+          requires:
+             - short-if-irrelevant
+      - linux-aarch64-static: 
+          requires:
+             - short-if-irrelevant
       - deploy:
           filters:
             branches:

.circleci/script/short.clj

@@ -0,0 +1,42 @@
+(require '[babashka.process :as proc]
+         '[clojure.string :as str])
+
+(def config
+  {:skip-if-only [#".*.md$"]})
+
+(defn exec [cmd]
+  (-> cmd
+      (proc/process)
+      (proc/check)))
+
+(defn get-changes []
+  (-> "git diff --name-only HEAD~1"
+      (exec)
+      (:out)
+      slurp
+      (str/split-lines)))
+
+(defn irrelevant-change? [change regexes]
+  (some? (some #(re-matches % change) regexes)))
+
+(defn relevant? [change-set regexes]
+  (some? (some  #(not (irrelevant-change? % regexes)) change-set)))
+
+(defn main []
+  (let [{:keys [skip-if-only]} config
+        changed-files (get-changes)]
+    (if (relevant? changed-files skip-if-only)
+      (println "Proceeding with CI run")
+      (do
+        (println "Irrelevant changes - skipping CI run")
+        (exec "circleci task halt")))))
+
+(when (= *file* (System/getProperty "babashka.file"))
+  (main))
+
+(comment
+  (def regexes [#".*.md$"
+                #".*.clj"]) ;ignore clojure files
+  (irrelevant-change? "src/file.png" regexes)
+  (re-matches #".*.clj$" "src/file.clj.dfff")
+  (relevant? ["src/file.clj"] regexes))