Allow running helmfile against a subset of releases (#30)

This adds `releases[].labels` in which you can set arbitrary number of key-value pairs, so that commands like `helmfile sync --selector key=value` can be used to run the helmfile subcommand against a subnet of declared releases.

`labels` and `selector` are named as such on purpose of being consistent with terminology of Kubernetes and other tools in the K8S ecosystem, including kubectl, stern, helm, and so on.

Resolves #8

.gitignore

@@ -1,2 +1,3 @@
 dist/
 .idea/
+helmfile

README.md

@@ -31,6 +31,8 @@ releases:
   # Published chart example
   - name: vault                            # name of this release
     namespace: vault                       # target namespace
+    labels:                                  # Arbitrary key value pairs for filtering releases
+      foo: bar
     chart: roboll/vault-secret-manager     # the chart being installed to create this release, referenced by `repository/chart` syntax
     values: [ vault.yaml ]                 # value files (--values)
     secrets:
@@ -104,6 +106,11 @@ COMMANDS:
 GLOBAL OPTIONS:
    --file FILE, -f FILE         load config from FILE (default: "helmfile.yaml")
    --quiet, -q                  silence output
+   --namespace value, -n value  Set namespace. Uses the namespace set in the context by default
+   --selector,l value           Only run using the releases that match labels. Labels can take the form of foo=bar or foo!=bar.
+	                              A release must match all labels in a group in order to be used. Multiple groups can be specified at once.
+	                              --selector tier=frontend,tier!=proxy --selector tier=backend. Will match all frontend, non-proxy releases AND all backend releases.
+	                              The name of a release can be used as a label. --selector name=myrelease
    --kube-context value         Set kubectl context. Uses current context by default
    --help, -h                   show help
    --version, -v                print the version
@@ -142,3 +149,13 @@ A few rules to clear up this ambiguity:
 - Relative paths referenced on the command line are relative to the current working directory the user is in
 
 For additional context, take a look at [paths examples](PATHS.md)
+## Labels Overview
+A selector can be used to only target a subset of releases when running helmfile. This is useful for large helmfiles with releases that are logically grouped together.
+
+Labels are simple key value pairs that are an optional field of the release spec. When selecting by label, the search can be inverted. `tier!=backend` would match all releases that do NOT have the `tier: backend` label. `tier=fronted` would only match releases with the `tier: frontend` label.
+
+Multiple labels can be specified using `,` as a separator. A release must match all selectors in order to be selected for the final helm command. 
+
+The `selector` parameter can be specified multiple times. Each parameter is resolved independently so a release that matches any parameter will be used. 
+
+`--selector tier=frontend --selector tier=backend` will select all the charts

main.go

@@ -45,6 +45,13 @@ func main() {
 			Name:  "namespace, n",
 			Usage: "Set namespace. Uses the namespace set in the context by default",
 		},
+		cli.StringSliceFlag{
+			Name: "selector, l",
+			Usage: `Only run using the releases that match labels. Labels can take the form of foo=bar or foo!=bar.
+	A release must match all labels in a group in order to be used. Multiple groups can be specified at once.
+	--selector tier=frontend,tier!=proxy --selector tier=backend. Will match all frontend, non-proxy releases AND all backend releases.
+	The name of a release can be used as a label. --selector name=myrelease`,
+		},
 	}
 
 	app.Commands = []cli.Command{
@@ -215,6 +222,7 @@ func before(c *cli.Context) (*state.HelmState, helmexec.Interface, error) {
 	quiet := c.GlobalBool("quiet")
 	kubeContext := c.GlobalString("kube-context")
 	namespace := c.GlobalString("namespace")
+	labels := c.GlobalStringSlice("selector")
 
 	st, err := state.ReadFromFile(file)
 	if err != nil && strings.Contains(err.Error(), fmt.Sprintf("open %s:", DefaultHelmfile)) {
@@ -239,6 +247,13 @@ func before(c *cli.Context) (*state.HelmState, helmexec.Interface, error) {
 		}
 		st.Namespace = namespace
 	}
+	if len(labels) > 0 {
+		err = st.FilterReleases(labels)
+		if err != nil {
+			log.Print(err)
+			os.Exit(1)
+		}
+	}
 	var writer io.Writer
 	if !quiet {
 		writer = os.Stdout
@@ -249,7 +264,7 @@ func before(c *cli.Context) (*state.HelmState, helmexec.Interface, error) {
 	go func() {
 		sig := <-sigs
 
-		errs := []error{fmt.Errorf("Recived [%s] to shutdown ", sig)}
+		errs := []error{fmt.Errorf("Received [%s] to shutdown ", sig)}
 		clean(st, errs)
 	}()
 

state/release_filters.go

@@ -0,0 +1,64 @@
+package state
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// ReleaseFilter is used to determine if a given release should be used during helmfile execution
+type ReleaseFilter interface {
+	// Match returns true if the ReleaseSpec matches the Filter
+	Match(r ReleaseSpec) bool
+}
+
+// LabelFilter matches a release with the given positive lables. Negative labels
+// invert the match for cases such as tier!=backend
+type LabelFilter struct {
+	positiveLabels map[string]string
+	negativeLabels map[string]string
+}
+
+// Match will match a release that has the same labels as the filter
+func (l LabelFilter) Match(r ReleaseSpec) bool {
+	if len(l.positiveLabels) > 0 {
+		for k, v := range l.positiveLabels {
+			if rVal, ok := r.Labels[k]; !ok {
+				return false
+			} else if rVal != v {
+				return false
+			}
+		}
+	}
+	if len(l.negativeLabels) > 0 {
+		for k, v := range l.negativeLabels {
+			if rVal, ok := r.Labels[k]; !ok {
+				return true
+			} else if rVal == v {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// ParseLabels takes a label in the form foo=bar,baz!=bat and returns a LabelFilter that will match the labels
+func ParseLabels(l string) (LabelFilter, error) {
+	lf := LabelFilter{}
+	lf.positiveLabels = map[string]string{}
+	lf.negativeLabels = map[string]string{}
+	var err error
+	labels := strings.Split(l, ",")
+	for _, label := range labels {
+		if match, _ := regexp.MatchString("^[a-zA-Z0-9_-]+!=[a-zA-Z0-9_-]+$", label); match == true { // k!=v case
+			kv := strings.Split(label, "!=")
+			lf.negativeLabels[kv[0]] = kv[1]
+		} else if match, _ := regexp.MatchString("^[a-zA-Z0-9_-]+=[a-zA-Z0-9_-]+$", label); match == true { // k=v case
+			kv := strings.Split(label, "=")
+			lf.positiveLabels[kv[0]] = kv[1]
+		} else { // malformed case
+			err = fmt.Errorf("Malformed label: %s. Expected label in form k=v or k!=v", label)
+		}
+	}
+	return lf, err
+}

state/state.go

@@ -44,6 +44,7 @@ type ReleaseSpec struct {
 	// Name is the name of this release
 	Name      string            `yaml:"name"`
 	Namespace string            `yaml:"namespace"`
+	Labels    map[string]string `yaml:"labels"`
 	Values    []string          `yaml:"values"`
 	Secrets   []string          `yaml:"secrets"`
 	SetValues []SetValue        `yaml:"set"`
@@ -148,7 +149,7 @@ func (state *HelmState) SyncRepos(helm helmexec.Interface) []error {
 	return nil
 }
 
-func (state *HelmState) SyncReleases(helm helmexec.Interface, additonalValues []string, workerLimit int) []error {
+func (state *HelmState) SyncReleases(helm helmexec.Interface, additionalValues []string, workerLimit int) []error {
 	errs := []error{}
 	jobQueue := make(chan ReleaseSpec)
 	doneQueue := make(chan bool)
@@ -169,7 +170,7 @@ func (state *HelmState) SyncReleases(helm helmexec.Interface, additonalValues []
 				}
 
 				haveValueErr := false
-				for _, value := range additonalValues {
+				for _, value := range additionalValues {
 					valfile, err := filepath.Abs(value)
 					if err != nil {
 						errQueue <- err
@@ -214,7 +215,7 @@ func (state *HelmState) SyncReleases(helm helmexec.Interface, additonalValues []
 	return nil
 }
 
-func (state *HelmState) DiffReleases(helm helmexec.Interface, additonalValues []string) []error {
+func (state *HelmState) DiffReleases(helm helmexec.Interface, additionalValues []string) []error {
 	var wg sync.WaitGroup
 	errs := []error{}
 
@@ -229,7 +230,7 @@ func (state *HelmState) DiffReleases(helm helmexec.Interface, additonalValues []
 				errs = append(errs, flagsErr)
 			}
 
-			for _, value := range additonalValues {
+			for _, value := range additionalValues {
 				valfile, err := filepath.Abs(value)
 				if err != nil {
 					errs = append(errs, err)
@@ -295,6 +296,41 @@ func (state *HelmState) Clean() []error {
 	return nil
 }
 
+// FilterReleases allows for the execution of helm commands against a subset of the releases in the helmfile.
+func (state *HelmState) FilterReleases(labels []string) error {
+	var filteredReleases []ReleaseSpec
+	releaseSet := map[string]ReleaseSpec{}
+	filters := []ReleaseFilter{}
+	for _, label := range labels {
+		f, err := ParseLabels(label)
+		if err != nil {
+			return err
+		}
+		filters = append(filters, f)
+	}
+	for _, r := range state.Releases {
+		if r.Labels == nil {
+			r.Labels = map[string]string{}
+		}
+		// Let the release name be used as a tag
+		r.Labels["name"] = r.Name
+		for _, f := range filters {
+			if r.Labels == nil {
+				r.Labels = map[string]string{}
+			}
+			if f.Match(r) {
+				releaseSet[r.Name] = r
+				continue
+			}
+		}
+	}
+	for _, r := range releaseSet {
+		filteredReleases = append(filteredReleases, r)
+	}
+	state.Releases = filteredReleases
+	return nil
+}
+
 // normalizeChart allows for the distinction between a file path reference and repository references.
 // - Any single (or double character) followed by a `/` will be considered a local file reference and
 // 	 be constructed relative to the `base path`.

state/state_test.go

@@ -62,6 +62,73 @@ releases:
 	}
 }
 
+func TestReadFromYaml_FilterReleasesOnLabels(t *testing.T) {
+	yamlFile := "example/path/to/yaml/file"
+	yamlContent := []byte(`releases:
+- name: myrelease1
+  chart: mychart1
+  labels:
+    tier: frontend
+    foo: bar
+- name: myrelease2
+  chart: mychart2
+  labels:
+    tier: frontend
+- name: myrelease3
+  chart: mychart3
+  labels:
+    tier: backend
+`)
+	cases := []struct {
+		filter  LabelFilter
+		results []bool
+	}{
+		{LabelFilter{positiveLabels: map[string]string{"tier": "frontend"}},
+			[]bool{true, true, false}},
+		{LabelFilter{positiveLabels: map[string]string{"tier": "frontend", "foo": "bar"}},
+			[]bool{true, false, false}},
+		{LabelFilter{negativeLabels: map[string]string{"tier": "frontend"}},
+			[]bool{false, false, true}},
+		{LabelFilter{positiveLabels: map[string]string{"tier": "frontend"}, negativeLabels: map[string]string{"foo": "bar"}},
+			[]bool{false, true, false}},
+	}
+	state, err := readFromYaml(yamlContent, yamlFile)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	for idx, c := range cases {
+		for idx2, expected := range c.results {
+			if f := c.filter.Match(state.Releases[idx2]); f != expected {
+				t.Errorf("[case: %d][outcome: %d] Unexpected outcome wanted %t, got %t", idx, idx2, expected, f)
+			}
+		}
+	}
+}
+
+func TestLabelParsing(t *testing.T) {
+	cases := []struct {
+		labelString    string
+		expectedFilter LabelFilter
+		errorExected   bool
+	}{
+		{"foo=bar", LabelFilter{positiveLabels: map[string]string{"foo": "bar"}, negativeLabels: map[string]string{}}, false},
+		{"foo!=bar", LabelFilter{positiveLabels: map[string]string{}, negativeLabels: map[string]string{"foo": "bar"}}, false},
+		{"foo!=bar,baz=bat", LabelFilter{positiveLabels: map[string]string{"baz": "bat"}, negativeLabels: map[string]string{"foo": "bar"}}, false},
+		{"foo", LabelFilter{positiveLabels: map[string]string{}, negativeLabels: map[string]string{}}, true},
+		{"foo!=bar=baz", LabelFilter{positiveLabels: map[string]string{}, negativeLabels: map[string]string{}}, true},
+		{"=bar", LabelFilter{positiveLabels: map[string]string{}, negativeLabels: map[string]string{}}, true},
+	}
+	for idx, c := range cases {
+		filter, err := ParseLabels(c.labelString)
+		if err != nil && !c.errorExected {
+			t.Errorf("[%d] Didn't expect an error parsing labels: %s", idx, err)
+		} else if err == nil && c.errorExected {
+			t.Errorf("[%d] Expected %s to result in an error but got none", idx, c.labelString)
+		} else if !reflect.DeepEqual(filter, c.expectedFilter) {
+			t.Errorf("[%d] parsed label did not result in expected filter: %v", idx, filter)
+		}
+	}
+}
 func TestHelmState_applyDefaultsTo(t *testing.T) {
 	type fields struct {
 		BaseChartPath      string