Implement config parser.

cmd/config.go

@@ -0,0 +1,224 @@
+package main
+
+import (
+	yaml "gopkg.in/yaml.v2"
+	"io/ioutil"
+	"github.com/mitchellh/mapstructure"
+	"github.com/zrepl/zrepl/zfs"
+	"errors"
+	"strings"
+)
+
+type Pool struct {
+	Name 	string
+	Url 	string
+}
+type Push struct {
+	To 		 string
+	Datasets []zfs.DatasetPath
+}
+type Pull struct {
+	From     string
+	Mapping  zfs.DatasetMapping
+}
+type Sink struct {
+	From 	 string
+	Mapping  zfs.DatasetMapping
+}
+
+type Config struct {
+	Pools []Pool
+	Pushs []Push
+	Pulls []Pull
+	Sinks []Sink
+}
+
+func ParseConfig(path string) (config Config, err error) {
+
+	c := make(map[string]interface{}, 0)
+
+	var bytes []byte
+
+	if bytes, err = ioutil.ReadFile(path); err != nil {
+		return
+	}
+
+	if err = yaml.Unmarshal(bytes, &c); err != nil {
+		return
+	}
+
+	return parseMain(c)
+}
+
+func parseMain(root map[string]interface{}) (c Config, err error) {
+	if c.Pools, err = parsePools(root["pools"]); err != nil {
+		return
+	}
+	if c.Pushs, err = parsePushs(root["pushs"]); err != nil {
+		return
+	}
+	if c.Pulls, err = parsePulls(root["pulls"]); err != nil {
+		return
+	}
+	if c.Sinks, err = parseSinks(root["sinks"]); err != nil {
+		return
+	}
+	return
+}
+
+func parsePools(v interface{}) (p []Pool, err error) {
+	p = make([]Pool, 0)
+	err = mapstructure.Decode(v, &p)
+	return
+}
+
+func parsePushs(v interface{}) (p []Push, err error) {
+
+	asList := make([]struct{
+		To 		 string
+		Datasets []string
+	}, 0)
+
+	if err = mapstructure.Decode(v, &asList); err != nil {
+		return
+	}
+
+	p = make([]Push, len(asList))
+
+	for _, e := range asList {
+		push := Push{
+			To: e.To,
+			Datasets: make([]zfs.DatasetPath, len(e.Datasets)),
+		}
+
+		for i, ds := range e.Datasets {
+			if push.Datasets[i], err = zfs.NewDatasetPath(ds); err != nil {
+				return
+			}
+		}
+
+		p = append(p, push)
+	}
+
+	return
+}
+
+func parsePulls(v interface{}) (p []Pull, err error) {
+
+	asList := make([]struct{
+		From 	string
+		Mapping map[string]string
+	}, 0)
+
+
+	if err = mapstructure.Decode(v, &asList); err != nil {
+		return
+	}
+
+	p = make([]Pull, len(asList))
+
+	for _, e := range asList {
+		pull := Pull{
+			From: e.From,
+		}
+		if pull.Mapping, err = parseComboMapping(e.Mapping); err != nil {
+			return
+		}
+		p = append(p, pull)
+	}
+
+	return
+}
+
+func parseSinks(v interface{}) (s []Sink, err error) {
+
+	var asList []interface{}
+	var ok bool
+	if asList, ok  = v.([]interface{}); !ok {
+		return nil, errors.New("expected list")
+	}
+
+	s = make([]Sink, len(asList))
+
+	for _, i := range asList {
+		var sink Sink
+		if sink, err = parseSink(i); err != nil {
+			return
+		}
+		s = append(s, sink)
+	}
+
+	return
+}
+
+func parseSink(v interface{}) (s Sink, err error) {
+	t := struct {
+		From string
+		Mapping map[string]string
+	}{}
+	if err = mapstructure.Decode(v, &t); err != nil {
+		return
+	}
+
+	s.From = t.From
+	s.Mapping, err = parseComboMapping(t.Mapping)
+	return
+}
+
+func parseComboMapping(m map[string]string) (c zfs.ComboMapping, err error) {
+
+	c.Mappings = make([]zfs.DatasetMapping, len(m))
+
+	for lhs,rhs := range m {
+
+		if lhs[0] == '|' {
+
+			if len(m) != 1 {
+				err = errors.New("non-recursive mapping must be the only mapping for a sink")
+			}
+
+			m := zfs.DirectMapping{
+				 Source: nil,
+			}
+
+			if m.Target, err = zfs.NewDatasetPath(rhs); err != nil {
+				return
+			}
+
+			c.Mappings = append(c.Mappings, m)
+
+		} else if lhs[0] == '*' {
+
+			m := zfs.ExecMapping{}
+			fields := strings.Fields(strings.TrimPrefix(rhs, "!"))
+			if len(fields) < 1 {
+				err = errors.New("ExecMapping without acceptor path")
+				return
+			}
+			m.Name = fields[0]
+			m.Args = fields[1:]
+
+			c.Mappings = append(c.Mappings, m)
+
+		} else if strings.HasSuffix(lhs, "*") {
+
+			m := zfs.GlobMapping{}
+
+			m.PrefixPath, err = zfs.NewDatasetPath(strings.TrimSuffix(lhs, "*"))
+			if err != nil {
+				return
+			}
+
+			if m.TargetRoot, err = zfs.NewDatasetPath(rhs); err != nil {
+				return
+			}
+
+			c.Mappings = append(c.Mappings, m)
+
+		}
+
+	}
+
+	return
+
+}