Extract website version from a file instead of sbt stdout

.github/workflows/website-deploy.yml

@@ -45,8 +45,11 @@ jobs:
       - name: Build
         run: |
           cd ../
-          sbt -batch -error 'print stableVersion' # something unexpected gets added to stdout on first run
-          export CHATOPS4S_VERSION=$(sbt -batch -error 'print stableVersion' | head -n 1)
+          # sbt stdout is not machine-readable (ANSI escapes, progress lines), so the
+          # version is written to a file by the build instead of being parsed from stdout.
+          sbt -batch writeStableVersion
+          export CHATOPS4S_VERSION=$(cat target/stable-version.txt)
+          echo "Building website for chatops4s $CHATOPS4S_VERSION"
           cd website
           yarn build
       - name: Setup Pages

build.sbt

@@ -60,6 +60,18 @@ stableVersion := {
   else previousStableVersion.value.getOrElse("unreleased")
 }
 
+lazy val stableVersionFile = settingKey[File]("File that writeStableVersion writes to")
+stableVersionFile := (ThisBuild / baseDirectory).value / "target" / "stable-version.txt"
+
+// Writing to a file instead of printing, because sbt's stdout is not machine-readable
+// (ANSI escapes, progress lines, launcher output). Consumed by the website build.
+lazy val writeStableVersion = taskKey[Unit]("Writes stableVersion to stableVersionFile")
+writeStableVersion := {
+  val target = stableVersionFile.value
+  IO.write(target, stableVersion.value)
+  streams.value.log.info(s"Wrote stable version to $target")
+}
+
 lazy val commonSettings = Seq(
   scalaVersion  := "3.8.1",
   scalacOptions ++= Seq(