Add builtin yq support to lima start command

Allows modifying the template inplace for a single instance, if you
don't want to change the default or override for all instances.

Signed-off-by: Anders F Björklund <[email protected]>

Author: afbjorklund

cmd/limactl/start.go

@@ -21,6 +21,7 @@ import (
 	"github.com/lima-vm/lima/pkg/store"
 	"github.com/lima-vm/lima/pkg/store/filenames"
 	"github.com/lima-vm/lima/pkg/templatestore"
+	"github.com/lima-vm/lima/pkg/yqutil"
 	"github.com/mattn/go-isatty"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -36,6 +37,9 @@ $ limactl start
 To create an instance "default" from a template "docker":
 $ limactl start --name=default template://docker
 
+To create an instance "default" with modified parameters:
+$ limactl start --yq '.cpus = 2 | .memory = "2GiB"'
+
 To see the template list:
 $ limactl start --list-templates
 
@@ -56,6 +60,7 @@ $ cat template.yaml | limactl start --name=local -
 	// TODO: "survey" does not support using cygwin terminal on windows yet
 	startCommand.Flags().Bool("tty", isatty.IsTerminal(os.Stdout.Fd()), "enable TUI interactions such as opening an editor, defaults to true when stdout is a terminal")
 	startCommand.Flags().String("name", "", "override the instance name")
+	startCommand.Flags().String("yq", "", "modify the template inplace")
 	startCommand.Flags().Bool("list-templates", false, "list available templates and exit")
 	startCommand.Flags().Duration("timeout", start.DefaultWatchHostAgentEventsTimeout, "duration to wait for the instance to be running before timing out")
 	return startCommand
@@ -82,6 +87,10 @@ func loadOrCreateInstance(cmd *cobra.Command, args []string) (*store.Instance, e
 	if err != nil {
 		return nil, err
 	}
+	st.yq, err = cmd.Flags().GetString("yq")
+	if err != nil {
+		return nil, err
+	}
 	const yBytesLimit = 4 * 1024 * 1024 // 4MiB
 
 	if ok, u := guessarg.SeemsTemplateURL(arg); ok {
@@ -206,6 +215,9 @@ func loadOrCreateInstance(cmd *cobra.Command, args []string) (*store.Instance, e
 		}
 	} else {
 		logrus.Info("Terminal is not available, proceeding without opening an editor")
+		if err := modifyInPlace(st); err != nil {
+			return nil, err
+		}
 	}
 	saveBrokenEditorBuffer := tty
 	return createInstance(st, saveBrokenEditorBuffer)
@@ -261,10 +273,27 @@ func createInstance(st *creatorState, saveBrokenEditorBuffer bool) (*store.Insta
 type creatorState struct {
 	instName string // instance name
 	yBytes   []byte // yaml bytes
+	yq       string // yq expression
+}
+
+func modifyInPlace(st *creatorState) error {
+	if st.yq == "" {
+		return nil
+	}
+	out, err := yqutil.EvaluateExpression(st.yq, st.yBytes)
+	if err != nil {
+		return err
+	}
+	st.yBytes = out
+	return nil
 }
 
 func chooseNextCreatorState(st *creatorState) (*creatorState, error) {
 	for {
+		if err := modifyInPlace(st); err != nil {
+			logrus.WithError(err).Warn("Failed to evaluate yq expression")
+			return st, err
+		}
 		var ans string
 		prompt := &survey.Select{
 			Message: fmt.Sprintf("Creating an instance %q", st.instName),

go.mod

@@ -25,6 +25,7 @@ require (
 	github.com/mattn/go-isatty v0.0.17
 	github.com/mattn/go-shellwords v1.0.12
 	github.com/miekg/dns v1.1.50
+	github.com/mikefarah/yq/v4 v4.30.8
 	github.com/norouter/norouter v0.6.3
 	github.com/nxadm/tail v1.4.8
 	github.com/opencontainers/go-digest v1.0.0
@@ -41,18 +42,25 @@ require (
 require (
 	github.com/Microsoft/go-winio v0.5.2 // indirect
 	github.com/VividCortex/ewma v1.1.1 // indirect
+	github.com/a8m/envsubst v1.3.0 // indirect
+	github.com/alecthomas/participle/v2 v2.0.0-beta.5 // indirect
 	github.com/apparentlymart/go-cidr v1.1.0 // indirect
 	github.com/digitalocean/go-libvirt v0.0.0-20201209184759-e2a69bcd5bd1 // indirect
+	github.com/dimchansky/utfbom v1.1.1 // indirect
+	github.com/elliotchance/orderedmap v1.5.0 // indirect
 	github.com/fatih/color v1.13.0 // indirect
 	github.com/fsnotify/fsnotify v1.5.1 // indirect
+	github.com/goccy/go-json v0.10.0 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/google/btree v1.0.1 // indirect
 	github.com/google/gopacket v1.1.19 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/inconshreveable/mousetrap v1.0.1 // indirect
 	github.com/insomniacslk/dhcp v0.0.0-20220504074936-1ca156eafb9f // indirect
+	github.com/jinzhu/copier v0.3.5 // indirect
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
 	github.com/kr/fs v0.1.0 // indirect
+	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mattn/go-colorable v0.1.12 // indirect
 	github.com/mattn/go-runewidth v0.0.12 // indirect
 	github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b // indirect
@@ -75,6 +83,8 @@ require (
 	google.golang.org/grpc v1.47.0 // indirect
 	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/djherbis/times.v1 v1.2.0 // indirect
+	gopkg.in/op/go-logging.v1 v1.0.0-20160211212156-b2cb9fa56473 // indirect
 	gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 	gvisor.dev/gvisor v0.0.0-20220908032458-edc830a43ba6 // indirect
 )

go.sum

@@ -62,6 +62,10 @@ github.com/PuerkitoBio/purell v1.0.0/go.mod h1:c11w/QuzBsJSee3cPx9rAFu61PvFxuPbt
 github.com/PuerkitoBio/urlesc v0.0.0-20160726150825-5bd2802263f2/go.mod h1:uGdkoq3SwY9Y+13GIhn11/XLaGBb4BfwItxLd5jeuXE=
 github.com/VividCortex/ewma v1.1.1 h1:MnEK4VOv6n0RSY4vtRe3h11qjxL3+t0B8yOL8iMXdcM=
 github.com/VividCortex/ewma v1.1.1/go.mod h1:2Tkkvm3sRDVXaiyucHiACn4cqf7DpdyLvmxzcbUokwA=
+github.com/a8m/envsubst v1.3.0 h1:GmXKmVssap0YtlU3E230W98RWtWCyIZzjtf1apWWyAg=
+github.com/a8m/envsubst v1.3.0/go.mod h1:MVUTQNGQ3tsjOOtKCNd+fl8RzhsXcDvvAEzkhGtlsbY=
+github.com/alecthomas/participle/v2 v2.0.0-beta.5 h1:y6dsSYVb1G5eK6mgmy+BgI3Mw35a3WghArZ/Hbebrjo=
+github.com/alecthomas/participle/v2 v2.0.0-beta.5/go.mod h1:RC764t6n4L8D8ITAJv0qdokritYSNR3wV5cVwmIEaMM=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alessio/shellescape v1.4.1 h1:V7yhSDDn8LP4lc4jS8pFkt0zCnzVJlG5JXy9BVKJUX0=
@@ -160,6 +164,8 @@ github.com/digitalocean/go-libvirt v0.0.0-20201209184759-e2a69bcd5bd1 h1:j6vGfla
 github.com/digitalocean/go-libvirt v0.0.0-20201209184759-e2a69bcd5bd1/go.mod h1:QS1XzqZLcDniNYrN7EZefq3wIyb/M2WmJbql4ZKoc1Q=
 github.com/digitalocean/go-qemu v0.0.0-20210326154740-ac9e0b687001 h1:WAg57gnaAWWjMAELcwHjc2xy0PoXQ5G+vn3+XS6s1jI=
 github.com/digitalocean/go-qemu v0.0.0-20210326154740-ac9e0b687001/go.mod h1:IetBE52JfFxK46p2n2Rqm+p5Gx1gpu2hRHsrbnPOWZQ=
+github.com/dimchansky/utfbom v1.1.1 h1:vV6w1AhK4VMnhBno/TPVCoK9U/LP0PkLCS9tbxHdi/U=
+github.com/dimchansky/utfbom v1.1.1/go.mod h1:SxdoEBH5qIqFocHMyGOXVAybYJdr71b1Q/j0mACtrfE=
 github.com/diskfs/go-diskfs v1.3.0 h1:D3IVe1y7ybB5SjCO0pOmkWThL9lZEWeanp8rRa0q0sk=
 github.com/diskfs/go-diskfs v1.3.0/go.mod h1:3pUpCAz75Q11om5RsGpVKUgXp2Z+ATw1xV500glmCP0=
 github.com/docker/distribution v2.7.1-0.20190205005809-0d3efadf0154+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
@@ -177,6 +183,8 @@ github.com/elastic/go-libaudit/v2 v2.3.2/go.mod h1:+ZE0czqmbqtnRkl0fNgpI+HvVVRo/
 github.com/elazarl/goproxy v0.0.0-20170405201442-c4fc26588b6e/go.mod h1:/Zj4wYkgs4iZTTu3o/KG3Itv/qCCa8VVMlb3i9OVuzc=
 github.com/elazarl/goproxy v0.0.0-20210110162100-a92cc753f88e/go.mod h1:Ro8st/ElPeALwNFlcTpWmkr6IoMFfkjXAvTHpevnDsM=
 github.com/elazarl/goproxy/ext v0.0.0-20190711103511-473e67f1d7d2/go.mod h1:gNh8nYJoAm43RfaxurUnxr+N1PwuFV3ZMl/efxlIlY8=
+github.com/elliotchance/orderedmap v1.5.0 h1:1IsExUsjv5XNBD3ZdC7jkAAqLWOOKdbPTmkHx63OsBg=
+github.com/elliotchance/orderedmap v1.5.0/go.mod h1:wsDwEaX5jEoyhbs7x93zk2H/qv0zwuhg4inXhDkYqys=
 github.com/emicklei/go-restful v0.0.0-20170410110728-ff4f55a20633/go.mod h1:otzb+WCGbkyDHkqmQmT5YD2WR4BBwUdeQoFo8l/7tVs=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
@@ -225,6 +233,8 @@ github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/me
 github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0/go.mod h1:fyg7847qk6SyHyPtNmDHnmrv/HOrqktSC+C9fM+CJOE=
 github.com/go-test/deep v1.0.8 h1:TDsG77qcSprGbC6vTN8OuXp5g+J+b5Pcguhf7Zt61VM=
 github.com/go-test/deep v1.0.8/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
+github.com/goccy/go-json v0.10.0 h1:mXKd9Qw4NuzShiRlOXKews24ufknHO7gx30lsDyokKA=
+github.com/goccy/go-json v0.10.0/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
 github.com/goccy/go-yaml v1.9.8 h1:5gMyLUeU1/6zl+WFfR1hN7D2kf+1/eRGa7DFtToiBvQ=
 github.com/goccy/go-yaml v1.9.8/go.mod h1:JubOolP3gh0HpiBc4BLRD4YmjEjHAmIIB2aaXKkTfoE=
 github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
@@ -348,6 +358,8 @@ github.com/inconshreveable/mousetrap v1.0.1 h1:U3uMjPSQEBMNp1lFxmllqCPM6P5u/Xq7P
 github.com/inconshreveable/mousetrap v1.0.1/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/insomniacslk/dhcp v0.0.0-20220504074936-1ca156eafb9f h1:l1QCwn715k8nYkj4Ql50rzEog3WnMdrd4YYMMwemxEo=
 github.com/insomniacslk/dhcp v0.0.0-20220504074936-1ca156eafb9f/go.mod h1:h+MxyHxRg9NH3terB1nfRIUaQEcI0XOVkdR9LNBlp8E=
+github.com/jinzhu/copier v0.3.5 h1:GlvfUwHk62RokgqVNvYsku0TATCF7bAHVwEXoBh3iJg=
+github.com/jinzhu/copier v0.3.5/go.mod h1:DfbEm0FYsaqBcKcFuvmOZb218JkPGtvSHsKg8S8hyyg=
 github.com/jonboulle/clockwork v0.1.0/go.mod h1:Ii8DK3G1RaLaWxj9trq07+26W01tbo22gdxWY5EU2bo=
 github.com/jsimonetti/rtnetlink v0.0.0-20190606172950-9527aa82566a/go.mod h1:Oz+70psSo5OFh8DBl0Zv2ACw7Esh6pPUphlvZG9x7uw=
 github.com/jsimonetti/rtnetlink v0.0.0-20200117123717-f846d4f6c1f4/go.mod h1:WGuG/smIU4J/54PblvSbh+xvCZmpJnFgr3ds6Z55XMQ=
@@ -381,6 +393,8 @@ github.com/lima-vm/sshocker v0.3.1 h1:MxqWJVsNZ2AKw/mWJ3n2DBNxFABZpaR79olLIjAQK8
 github.com/lima-vm/sshocker v0.3.1/go.mod h1:Pv7KiykFCequiWTPMytCbAC92ZT2TSFPgmMqGgh3vm0=
 github.com/linuxkit/virtsock v0.0.0-20220523201153-1a23e78aa7a2/go.mod h1:SWzULI85WerrFt3u+nIm5F9l7EvxZTKQvd0InF3nmgM=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
+github.com/magiconair/properties v1.8.7 h1:IeQXZAiQcpL9mgcAe1Nu6cX9LLw6ExEHKjN0VQdvPDY=
+github.com/magiconair/properties v1.8.7/go.mod h1:Dhd985XPs7jluiymwWYZ0G4Z61jb3vdS329zhj2hYo0=
 github.com/mailru/easyjson v0.0.0-20160728113105-d5b7844b561a/go.mod h1:C1wdFJiN94OJF2b5HbByQZoLdCWB1Yqtg26g4irojpc=
 github.com/mattbaird/jsonpatch v0.0.0-20171005235357-81af80346b1a/go.mod h1:M1qoD/MqPgTZIk0EWKB38wE28ACRfVcn+cU08jyArI0=
 github.com/mattn/go-colorable v0.1.2/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
@@ -415,6 +429,8 @@ github.com/miekg/dns v1.1.25/go.mod h1:bPDLeHnStXmXAq1m/Ch/hvfNHr14JKNPMBo3VZKju
 github.com/miekg/dns v1.1.41/go.mod h1:p6aan82bvRIyn+zDIv9xYNUpwa73JcSh9BKwknJysuI=
 github.com/miekg/dns v1.1.50 h1:DQUfb9uc6smULcREF09Uc+/Gd46YWqJd5DbpPE9xkcA=
 github.com/miekg/dns v1.1.50/go.mod h1:e3IlAVfNqAllflbibAZEWOXOQ+Ynzk/dDozDxY7XnME=
+github.com/mikefarah/yq/v4 v4.30.8 h1:EHovseqMJs9kvE25/2k6VnDs4CrBZN+DFbybUhpPAGM=
+github.com/mikefarah/yq/v4 v4.30.8/go.mod h1:8D30GDxhu3+KXll0aFV5msGcdgYRZSPOPVBTbgUQ7Dc=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -1009,6 +1025,8 @@ gopkg.in/djherbis/times.v1 v1.2.0/go.mod h1:AQlg6unIsrsCEdQYhTzERy542dz6SFdQFZFv
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
 gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
+gopkg.in/op/go-logging.v1 v1.0.0-20160211212156-b2cb9fa56473 h1:6D+BvnJ/j6e222UW8s2qTSe3wGBtvo0MbVQG/c5k8RE=
+gopkg.in/op/go-logging.v1 v1.0.0-20160211212156-b2cb9fa56473/go.mod h1:N1eN2tsCx0Ydtgjl4cqmbRCsY4/+z4cYDeqwZTk6zog=
 gopkg.in/resty.v1 v1.12.0/go.mod h1:mDo4pnntr5jdWRML875a/NmxYqAlA73dVijT2AXvQQo=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=

pkg/yqutil/yqutil.go

@@ -0,0 +1,65 @@
+package yqutil
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+
+	"github.com/mikefarah/yq/v4/pkg/yqlib"
+	"github.com/sirupsen/logrus"
+	logging "gopkg.in/op/go-logging.v1"
+)
+
+// EvaluateExpression evaluates the yq expression, and returns the modified yaml.
+func EvaluateExpression(expression string, content []byte) ([]byte, error) {
+	tmpYAMLFile, err := os.CreateTemp("", "lima-yq-*.yaml")
+	if err != nil {
+		return nil, err
+	}
+	tmpYAMLPath := tmpYAMLFile.Name()
+	defer os.RemoveAll(tmpYAMLPath)
+	err = os.WriteFile(tmpYAMLPath, content, 0o600)
+	if err != nil {
+		return nil, err
+	}
+
+	memory := logging.NewMemoryBackend(0)
+	backend := logging.AddModuleLevel(memory)
+	logging.SetBackend(backend)
+	yqlib.InitExpressionParser()
+
+	indent := 2
+	encoder := yqlib.NewYamlEncoder(indent, false, yqlib.ConfiguredYamlPreferences)
+	out := new(bytes.Buffer)
+	printer := yqlib.NewPrinter(encoder, yqlib.NewSinglePrinterWriter(out))
+	decoder := yqlib.NewYamlDecoder(yqlib.ConfiguredYamlPreferences)
+
+	streamEvaluator := yqlib.NewStreamEvaluator()
+	files := []string{tmpYAMLPath}
+	err = streamEvaluator.EvaluateFiles(expression, files, printer, decoder)
+	if err != nil {
+		logger := logrus.StandardLogger()
+		for node := memory.Head(); node != nil; node = node.Next() {
+			entry := logrus.NewEntry(logger).WithTime(node.Record.Time)
+			prefix := fmt.Sprintf("[%s] ", node.Record.Module)
+			message := prefix + node.Record.Message()
+			switch node.Record.Level {
+			case logging.CRITICAL:
+				entry.Fatal(message)
+			case logging.ERROR:
+				entry.Error(message)
+			case logging.WARNING:
+				entry.Warn(message)
+			case logging.NOTICE:
+			case logging.INFO:
+				entry.Info(message)
+			case logging.DEBUG:
+				entry.Debug(message)
+			}
+		}
+		return nil, err
+	}
+
+	return out.Bytes(), nil
+
+}

pkg/yqutil/yqutil_test.go

@@ -0,0 +1,28 @@
+package yqutil
+
+import (
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestEvaluateExpression(t *testing.T) {
+	expression := `.cpus = 2 | .memory = "2GiB"`
+	content := `
+# CPUs
+cpus: null
+
+# Memory size
+memory: null
+`
+	// Note: yq currently removes empty lines, but not comments
+	expected := `
+# CPUs
+cpus: 2
+# Memory size
+memory: 2GiB
+`
+	out, err := EvaluateExpression(expression, []byte(content))
+	assert.NilError(t, err)
+	assert.Equal(t, expected, string(out))
+}