feat: add initial support for cloud native buildpacks

This change adds a new builder - builder-cnb - via the 'DOKKU_CNB_EXPERIMENTAL' environment variable. While support for customizing pack builds is not currently implemented and there may be other missing functionality, this initial implementation allows folks to start playing with CNB.

Future releases of Dokku will provide tighter CNB integration and eventually switch to CNB for default building, as well as allow users to better select builders needed for their applications.

All new code for CNB support should be considered experimental and subject to change as the support evolves over time.

plugins/20_events/post-build-cnb

@@ -0,0 +1 @@
+hook

plugins/20_events/post-release-cnb

@@ -0,0 +1 @@
+hook

plugins/20_events/pre-build-cnb

@@ -0,0 +1 @@
+hook

plugins/20_events/pre-release-cnb

@@ -0,0 +1 @@
+hook

plugins/builder-cnb/builder-build

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+source "$PLUGIN_AVAILABLE_PATH/config/functions"
+
+trigger-builder-cnb-builder-build() {
+  declare desc="builder-cnb builder-build plugin trigger"
+  declare trigger="builder-build"
+  declare BUILDER_TYPE="$1" APP="$2" SOURCECODE_WORK_DIR="$3"
+
+  if [[ "$BUILDER_TYPE" != "cnb" ]]; then
+    return
+  fi
+
+  if ! command -v "pack" &>/dev/null; then
+    dokku_log_fail "Missing pack, install it"
+  fi
+
+  local IMAGE=$(get_app_image_name "$APP")
+
+  pushd "$SOURCECODE_WORK_DIR" &>/dev/null
+
+  local TMP_FILE=$(mktemp "/tmp/dokku-${DOKKU_PID}-${FUNCNAME[0]}.XXXXXX")
+  trap "rm -rf '$TMP_FILE' >/dev/null" RETURN INT TERM
+
+  config_export app "$APP" --format envfile --merged > "$TMP_FILE"
+
+  plugn trigger pre-build-cnb "$APP" "$SOURCECODE_WORK_DIR"
+
+  pack build "$IMAGE" --builder heroku/buildpacks --path "$SOURCECODE_WORK_DIR" --default-process web
+
+  echo "FROM $IMAGE" | suppress_output "$DOCKER_BIN" image build --label=com.dokku.image-stage=build --label=org.label-schema.schema-version=1.0 --label=org.label-schema.vendor=dokku --label=com.dokku.app-name=$APP --label=dokku -t "$IMAGE" -
+
+  plugn trigger post-build-cnb "$APP" "$SOURCECODE_WORK_DIR"
+}
+
+trigger-builder-cnb-builder-build "$@"

plugins/builder-cnb/builder-release

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+
+trigger-builder-cnb-builder-release() {
+  declare desc="builder-cnb builder-release plugin trigger"
+  declare trigger="builder-release"
+  declare BUILDER_TYPE="$1" APP="$2" IMAGE_TAG="$3"
+
+  if [[ "$BUILDER_TYPE" != "cnb" ]]; then
+    return
+  fi
+
+  plugn trigger pre-release-cnb "$APP" "$IMAGE_TAG"
+
+  local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")
+  echo "FROM $IMAGE" | suppress_output "$DOCKER_BIN" image build --label=com.dokku.image-stage=release --label=com.dokku.app-name=$APP --label=org.label-schema.schema-version=1.0 --label=org.label-schema.vendor=dokku --label=dokku -t "$IMAGE" -
+  plugn trigger post-release-cnb "$APP" "$IMAGE_TAG"
+}
+
+trigger-builder-cnb-builder-release "$@"

plugins/builder-cnb/plugin.toml

@@ -0,0 +1,4 @@
+[plugin]
+description = "dokku core builder-cnb plugin"
+version = "0.21.4"
+[plugin.config]

plugins/builder-dockerfile/builder-release

@@ -12,7 +12,6 @@ trigger-builder-dockerfile-builder-release() {
     return
   fi
 
-  # buildstep plugins don't necessarily make sense for dockerfiles. call the new breed!!!
   plugn trigger pre-release-dockerfile "$APP" "$IMAGE_TAG"
 
   local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")

plugins/common/functions

@@ -293,20 +293,41 @@ get_running_image_tag() {
   echo "$RUNNING_IMAGE_TAG"
 }
 
+is_image_cnb_based() {
+  declare desc="returns true if app image is based on cnb"
+  declare IMAGE="$1"
+
+  if [[ -z "$IMAGE" ]]; then
+    return 1
+  fi
+
+  CNB_STACK_ID="$("$DOCKER_BIN" image inspect --format '{{ index .Config.Labels "io.buildpacks.stack.id" }}' "$IMAGE")"
+  if [[ -n "$CNB_STACK_ID" ]]; then
+    return 0
+  fi
+
+  return 1
+}
+
 is_image_herokuish_based() {
-  declare desc="returns true if app image is based on herokuish"
+  declare desc="returns true if app image is based on herokuish or a buildpack-like env"
   declare IMAGE="$1" APP="$2"
   local DOKKU_APP_USER
-  if [[ -n "$APP" ]]; then
-    DOKKU_APP_USER=$(config_get "$APP" DOKKU_APP_USER || true)
-  fi
-  DOKKU_APP_USER=${DOKKU_APP_USER:="herokuishuser"}
   local USER_VALUE
 
   if [[ -z "$IMAGE" ]]; then
     return 1
   fi
 
+  if is_image_cnb_based "$IMAGE"; then
+    return 0
+  fi
+
+  if [[ -n "$APP" ]]; then
+    DOKKU_APP_USER=$(config_get "$APP" DOKKU_APP_USER || true)
+  fi
+  DOKKU_APP_USER=${DOKKU_APP_USER:="herokuishuser"}
+
   # due to how the build process works, all herokuish images have the Environment variable USER=$DOKKU_APP_USER
   USER_VALUE="$("$DOCKER_BIN" image inspect --format '{{range .Config.Env}}{{if eq . "USER='"$DOKKU_APP_USER"'"}}{{println .}}{{end}}{{end}}' "$IMAGE")"
   [[ "$USER_VALUE" == "" ]] && return 1
@@ -566,6 +587,11 @@ dokku_release() {
   declare desc="release phase"
   declare APP="$1" IMAGE_SOURCE_TYPE="$2" IMAGE_TAG="$3"
 
+  local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")
+  if is_image_cnb_based "$IMAGE"; then
+    IMAGE_SOURCE_TYPE="cnb"
+  fi
+
   plugn trigger builder-release "$IMAGE_SOURCE_TYPE" "$APP" "$IMAGE_TAG"
 }
 
@@ -630,9 +656,17 @@ dokku_receive() {
   local IMAGE=$(get_app_image_name "$APP")
   local IMAGE_SOURCE_TYPE="$2"
   local TMP_WORK_DIR="$3"
-  local DOKKU_SKIP_CLEANUP="$(config_get "$APP" DOKKU_SKIP_CLEANUP || true)"
+
   docker_cleanup "$APP"
-  dokku_log_info1 "Building $APP from $IMAGE_SOURCE_TYPE..."
+
+  local DOKKU_CNB_EXPERIMENTAL="$(config_get "$APP" DOKKU_CNB_EXPERIMENTAL || true)"
+  if [[ "$DOKKU_CNB_EXPERIMENTAL" == "1" ]]; then
+    IMAGE_SOURCE_TYPE="cnb"
+    dokku_log_info1 "Building $APP from $IMAGE_SOURCE_TYPE (experimental)..."
+  else
+    dokku_log_info1 "Building $APP from $IMAGE_SOURCE_TYPE..."
+  fi
+
   DOKKU_QUIET_OUTPUT=1 config_set --no-restart "$APP" DOKKU_APP_TYPE="$IMAGE_SOURCE_TYPE"
   dokku_build "$APP" "$IMAGE_SOURCE_TYPE" "$TMP_WORK_DIR"
   plugn trigger release-and-deploy "$APP"

plugins/scheduler-docker-local/scheduler-enter

@@ -72,7 +72,8 @@ trigger-scheduler-docker-local-scheduler-enter() {
   local EXEC_CMD=""
   has_tty && local DOKKU_RUN_OPTS+=" -i -t"
   local IMAGE="$("$DOCKER_BIN" container inspect --format '{{ .Config.Image }}' "$CONTAINER_ID")"
-  is_image_herokuish_based "$IMAGE" "$APP" && local EXEC_CMD="/exec"
+  is_image_herokuish_based "$IMAGE" "$APP" && EXEC_CMD="/exec"
+  is_image_cnb_based "$IMAGE" && EXEC_CMD="" && DOKKU_RUN_OPTS+=" -w /app"
   # shellcheck disable=SC2086
   "$DOCKER_BIN" container exec $DOKKU_RUN_OPTS "$CONTAINER_ID" $EXEC_CMD "${@:-$DOKKU_APP_SHELL}"
 }