providers: add initial zVM hypervisor support

doc/supported-platforms.md

@@ -10,6 +10,7 @@ Ignition is currently only supported for the following platforms:
 * [Packet] - Ignition will read its configuration from the instance userdata. SSH keys are handled by coreos-metadata.
 * [QEMU] - Ignition will read its configuration from the 'opt/com.coreos/config' key on the QEMU Firmware Configuration Device (available in QEMU 2.4.0 and higher).
 * [DigitalOcean] - Ignition will read its configuration from the droplet userdata. SSH keys and network configuration are handled by coreos-metadata.
+* [zVM] - Ignition will read its configuration from the reader device directly.The vmur program is necessary,which requires the vmcp and vmur kernel module as prerequisite, and the corresponding z/VM virtual unit record devices (in most cases 000c as reader, 000d as punch) must be set online.
 
 Ignition is under active development so expect this list to expand in the coming months.
 

internal/platform/platform.go

@@ -31,6 +31,7 @@ import (
 	"github.com/coreos/ignition/v2/internal/providers/qemu"
 	"github.com/coreos/ignition/v2/internal/providers/virtualbox"
 	"github.com/coreos/ignition/v2/internal/providers/vmware"
+	"github.com/coreos/ignition/v2/internal/providers/zvm"
 	"github.com/coreos/ignition/v2/internal/registry"
 	"github.com/coreos/ignition/v2/internal/resource"
 )
@@ -127,6 +128,10 @@ func init() {
 		name:  "metal",
 		fetch: noop.FetchConfig,
 	})
+	configs.Register(Config{
+		name:  "zvm",
+		fetch: zvm.FetchConfig,
+	})
 }
 
 func Get(name string) (config Config, ok bool) {

internal/providers/zvm/zvm.go

@@ -0,0 +1,102 @@
+// Copyright 2019 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.
+
+// The zVM provider fetches a local configuration from the virtual unit
+// record devices.
+
+package zvm
+
+import (
+	"io/ioutil"
+	"os/exec"
+	"strings"
+
+	"github.com/coreos/ignition/v2/config/shared/errors"
+	"github.com/coreos/ignition/v2/config/v3_1_experimental/types"
+	"github.com/coreos/ignition/v2/internal/log"
+	"github.com/coreos/ignition/v2/internal/providers/util"
+	"github.com/coreos/ignition/v2/internal/resource"
+	"github.com/coreos/vcontext/report"
+)
+
+const readerDevice string = "000c"
+const configFile string = "config.ign"
+
+func FetchConfig(f *resource.Fetcher) (types.Config, report.Report, error) {
+	// Fetch config files directly from reader device.
+	_, err := f.Logger.LogCmd(exec.Command("modprobe", "vmur"), "loading zVM control program module")
+	if err != nil {
+		f.Logger.Err("couldn't install vmur module: %v", err)
+		return types.Config{}, report.Report{}, err
+	}
+	// Online the reader device.
+	logger := f.Logger
+	rc := onlineDevice(logger)
+	if !rc {
+		return types.Config{}, report.Report{}, err
+	}
+	// Read files from the z/VM reader queue.
+	var comm string = "vmur li | tail -n +2 | cut -c 1-80 | awk '{print $1,$2,$3,$10,$11}'"
+	cmd := exec.Command("/bin/sh", "-c", comm)
+	out, err := cmd.Output()
+	if err != nil {
+		f.Logger.Err("Can not get reader device: %v", err)
+	}
+	items := strings.Split(string(out), "\n")
+	for _, records := range items {
+		record := strings.Split(records, " ")
+		if len(record) == 1 {
+			break
+		}
+		spoolid := record[1]
+		filename := record[3]
+		types := record[4]
+		var file string
+		if types == "" {
+			file = filename
+		} else {
+			file = filename + "." + types
+		}
+		// Receive the spool file.
+		if filename == "ignition" {
+			_, err := f.Logger.LogCmd(exec.Command("vmur", "re", "-f", spoolid, file), "Receive the spool file")
+			if err == nil {
+				f.Logger.Info("using config file at %q", file)
+				_, err := f.Logger.LogCmd(exec.Command("tar", "-xzvf", file), "Extract the spool file")
+				rawConfig, err := ioutil.ReadFile(configFile)
+				if err != nil {
+					f.Logger.Err("couldn't read config %q: %v", filename, err)
+					break
+				}
+				return util.ParseConfig(f.Logger, rawConfig)
+			}
+		}
+		_ = file
+	}
+	return types.Config{}, report.Report{}, errors.ErrEmpty
+}
+
+func onlineDevice(logger *log.Logger) bool {
+	_, err := logger.LogCmd(exec.Command("chccwdev", "-e", readerDevice), "Brings a Linux device online")
+	if err != nil {
+		_, err = logger.LogCmd(exec.Command("cio_ignore", "-r", readerDevice), "Expose reader device")
+		_, err = logger.LogCmd(exec.Command("chccwdev", "-e", readerDevice), "Brings a Linux device online")
+		if err != nil {
+			logger.Err("Couldn't online reader device")
+			return (err == nil)
+		}
+	}
+	_, err = logger.LogCmd(exec.Command("udevadm", "settle", "||", "udevsettle"), "Settle udev device")
+	return (err == nil)
+}