Parallelize Docker builds

Log output to docker/logs.

docker/.gitignore

@@ -0,0 +1,3 @@
+logs/*.log
+packages/
+unstable/*/bootstrap.ps1

docker/launch.sh

@@ -21,12 +21,18 @@ if [[ -z $DISTROS ]]; then
 fi
 
 for build in $BUILDS; do
-    # cd so $distro is only the distro name
-    pushd "$build"
+    # each distro can be done in parallel; but stable must be done before unstable
     for distro in $DISTROS; do
+        logfile="$build-$distro.log"
+        if [[ "$TEST" -eq 1 ]]; then logfile="test-$logfile"; fi
+        mkdir -p logs
+        logfile="logs/$logfile"
+        echo "Logging to docker/$logfile"
+        (
             image="powershell/powershell:$build-$distro"
+            cd "$build"
             if [[ "$TEST" -eq 1 ]]; then
-            echo "Testing $image"
+                echo "LOG: testing $image"
                 command="cd PowerShell; Import-Module ./build.psm1; Install-Dotnet -NoSudo; Start-PSPester -powershell powershell -Pester ./src/Modules/Shared/Pester"
                 # clone repo for stable images because it's not already done
                 if [[ "$build" = stable ]]; then
@@ -34,9 +40,9 @@ for build in $BUILDS; do
                 fi
                 # run Pester tests inside container
                 # RUNARGS can be set in the environment
-            docker run -it $RUNARGS "$image" -c "$command"
+                docker run $RUNARGS "$image" -c "$command"
             else
-            echo "Building $image"
+                echo "LOG: building $image"
                 # copy the common script because it lives outside the docker build context
                 if [[ "$build" = unstable ]]; then
                     cp bootstrap.ps1 "$distro"
@@ -46,6 +52,8 @@ for build in $BUILDS; do
                 # BUILDARGS can be set in the environment
                 docker build $buildargs $BUILDARGS -t "$image" "$distro"
             fi
+        ) &>> "$logfile" &
     done
-    popd
+    echo "Waiting for $build containers to finish; tail the logs for more information."
+    wait
 done

docker/unstable/.gitignore

@@ -1 +0,0 @@
-*/bootstrap.ps1