providers/qemu: support Ignition block device on s390x and ppc64le

Makefile

@@ -1,7 +1,23 @@
+# Canonical version of this in https://github.com/coreos/coreos-assembler/blob/6eb97016f4dab7d13aa00ae10846f26c1cd1cb02/Makefile#L19
+GOARCH:=$(shell uname -m)
+ifeq ($(GOARCH),x86_64)
+	GOARCH=amd64
+else ifeq ($(GOARCH),aarch64)
+	GOARCH=arm64
+endif
+
 .PHONY: all
 all:
 	./build
 
+# This currently assumes you're using https://github.com/coreos/ignition-dracut/
+# If in the future any other initramfs integration appears, feel free to add a PR
+# to make this configurable.
+.PHONY: install
+install: all
+	install -m 0755 -D -t $(DESTDIR)/usr/lib/dracut/modules.d/30ignition bin/$(GOARCH)/ignition
+	install -m 0755 -D -t $(DESTDIR)/usr/bin bin/$(GOARCH)/ignition-validate
+
 .PHONY: vendor
 vendor:
 	@glide --quiet update --strip-vendor

internal/providers/qemu/qemu_blockdev.go

@@ -0,0 +1,89 @@
+// Copyright 2020 Red Hat, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build s390x ppc64le
+
+// The QEMU provider on s390x and ppc64le fetches a configuration file from an
+// attached block device with id 'virtio-ignition'.
+
+package qemu
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"time"
+
+	"github.com/coreos/ignition/config/validate/report"
+	"github.com/coreos/ignition/internal/config/types"
+	"github.com/coreos/ignition/internal/log"
+	"github.com/coreos/ignition/internal/providers/util"
+	"github.com/coreos/ignition/internal/resource"
+)
+
+const (
+	ignitionBlockDevicePath    = "/dev/disk/by-id/virtio-ignition"
+	blockDeviceTimeout         = 5 * time.Minute
+	blockDevicePollingInterval = 5 * time.Second
+)
+
+func FetchConfig(f *resource.Fetcher) (types.Config, report.Report, error) {
+	f.Logger.Warning("Fetching the Ignition config via the Virtio block driver is currently experimental and subject to change.")
+
+	_, err := f.Logger.LogCmd(exec.Command("modprobe", "virtio_blk"), "loading Virtio block driver module")
+	if err != nil {
+		return types.Config{}, report.Report{}, err
+	}
+
+	data, err := fetchConfigFromBlockDevice(f.Logger)
+	if err != nil {
+		return types.Config{}, report.Report{}, err
+	}
+
+	return util.ParseConfig(f.Logger, data)
+}
+
+func fetchConfigFromBlockDevice(logger *log.Logger) ([]byte, error) {
+	var data []byte
+	c := make(chan error)
+	go func() {
+		var err error
+		for {
+			if data, err = ioutil.ReadFile(ignitionBlockDevicePath); err != nil {
+				if !os.IsNotExist(err) {
+					break
+				}
+				logger.Debug("block device (%q) not found. Waiting...", ignitionBlockDevicePath)
+				time.Sleep(blockDevicePollingInterval)
+			} else {
+				err = nil
+				break
+			}
+		}
+		c <- err
+	}()
+
+	select {
+	case err := <-c:
+		if err != nil {
+			return nil, err
+		}
+	case <-time.After(blockDeviceTimeout):
+		return nil, fmt.Errorf("timed out after %v waiting for block device %q to appear", blockDeviceTimeout, ignitionBlockDevicePath)
+	}
+
+	return bytes.TrimRight(data, "\x00"), nil
+}

internal/providers/qemu/qemu.go → internal/providers/qemu/qemu_fwcfg.go

@@ -12,8 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// The QEMU provider fetches a local configuration from the firmware config
-// interface (opt/com.coreos/config).
+// +build amd64 arm64
+
+// The QEMU provider on amd64 and arm64 fetches a local configuration from the
+// firmware config interface (opt/com.coreos/config).
 
 package qemu