# Copyright 2020 Authors of Cilium
# SPDX-License-Identifier: Apache-2.0

ifdef DOCKER_BUILDKIT

# Export with value expected by docker
export DOCKER_BUILDKIT=1

# Clean the build directory and cache
clean-build:
	-$(QUIET) rm -rf $(BUILD_DIR)
	-$(QUIET) docker builder prune --filter type=exec.cachemount -f

veryclean: clean-build

# Overrides for the main Dockerfile
DOCKER_BUILD_DIR := $(BUILD_DIR)/context
CILIUM_DOCKERFILE := $(BUILD_DIR)/cilium.Dockerfile
OPERATOR_DOCKERFILE := $(BUILD_DIR)/cilium-operator.Dockerfile
DOCKER_PLUGIN_DOCKERFILE := $(BUILD_DIR)/cilium-docker-plugin.Dockerfile
HUBBLE_RELAY_DOCKERFILE := $(BUILD_DIR)/hubble-relay.Dockerfile

BUILDKIT_DOCKERFILE_FILTER := | sed -e "1s|^\#.*|\# syntax = docker/dockerfile:experimental|" -e "s|^RUN\(.*\)make|RUN --mount=type=cache,target=/root/.cache/go-build\1make|"

# _build/.git is a shallow bare clone of the main repo
$(BUILD_DIR)/.git:
	-mkdir -p $(dir $@)
	git clone --bare --no-local --depth 1 . $@
	@cd $(dir $@) && git remote set-url origin "$(shell realpath --relative-to $(dir $@) $(ROOT_DIR))"

#
# Create _build context:
# $(DOCKER_BUILD_DIR)/.git will be a file (rather than directory) that contains git specific
# symbolic link to _build/.git (--separate-git-dir)
#
$(DOCKER_BUILD_DIR): $(BUILD_DIR)/.git
	git init --separate-git-dir=$(BUILD_DIR)/.git $@

#
# Update the docker build context by:
# 1. shallow fetch from the main repo to _build/.git
# 2. check out FETCH_HEAD into _build/context. Hard reset seems to be a best way of doing this.
# 3. remove the .git file from _build/context/.git so that make running in docker knows this is
#    no a git repo (as _build/.git is NOT part of the docker context)
#
# Dependencies:
# - check that git status is clean
# - make sure docker build context exists
# - update GIT_VERSION in the build context if needed
# - update BPF_SRCFILES in the build context if needed
#
build-context-update: check-status $(DOCKER_BUILD_DIR) $(DOCKER_BUILD_DIR)/GIT_VERSION $(DOCKER_BUILD_DIR)/BPF_SRCFILES
	@echo "gitdir: ../.git" > $(DOCKER_BUILD_DIR)/.git
	cd $(BUILD_DIR) && git fetch --depth=1 --no-tags
	cd $(DOCKER_BUILD_DIR) && git reset --hard FETCH_HEAD && git clean -fd
	@rm $(DOCKER_BUILD_DIR)/.git

#
# Docker build context does not contain the actual git repo, so we need to pass
# GIT_VERSION and/or BPF_SRCFILES to the build context separately.
#
$(DOCKER_BUILD_DIR)/GIT_VERSION: GIT_VERSION $(DOCKER_BUILD_DIR)
	cp $< $@
$(DOCKER_BUILD_DIR)/BPF_SRCFILES: BPF_SRCFILES $(DOCKER_BUILD_DIR)
	cp $< $@

# Bare 'Dockerfile' needs a special rule
$(CILIUM_DOCKERFILE): Dockerfile force
	@-mkdir -p $(dir $@)
	@cat $< $(BUILDKIT_DOCKERFILE_FILTER) > $@

# Generic rule for '*.Dockerfile'
$(BUILD_DIR)/%.Dockerfile: %.Dockerfile force
	@-mkdir -p $(dir $@)
	@cat $< $(BUILDKIT_DOCKERFILE_FILTER) > $@

check-status:
	@if [ -n "`git status --porcelain`" ] ; then git status && echo "These changes will not be included in build, aborting. Define IGNORE_GIT_STATUS to build anyway." && test $(IGNORE_GIT_STATUS); fi

endif