feat(diff,apply): --context=N for limiting diff context (#849)

Resolves #787

main.go

@@ -187,6 +187,11 @@ func main() {
 					Value: 0,
 					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
 				},
+				cli.IntFlag{
+					Name:  "context",
+					Value: 0,
+					Usage: "output NUM lines of context around changes",
+				},
 			},
 			Action: action(func(run *app.App, c configImpl) error {
 				return run.Diff(c)
@@ -290,6 +295,11 @@ func main() {
 					Value: 0,
 					Usage: "maximum number of concurrent helm processes to run, 0 is unlimited",
 				},
+				cli.IntFlag{
+					Name:  "context",
+					Value: 0,
+					Usage: "output NUM lines of context around changes",
+				},
 				cli.StringFlag{
 					Name:  "args",
 					Value: "",
@@ -545,6 +555,10 @@ func (c configImpl) NoColor() bool {
 	return c.c.GlobalBool("no-color")
 }
 
+func (c configImpl) Context() int {
+	return c.c.Int("context")
+}
+
 func (c configImpl) Logger() *zap.SugaredLogger {
 	return c.c.App.Metadata["logger"].(*zap.SugaredLogger)
 }

pkg/app/config.go

@@ -41,6 +41,7 @@ type ApplyConfigProvider interface {
 	SuppressSecrets() bool
 
 	NoColor() bool
+	Context() int
 
 	concurrencyConfig
 	interactive
@@ -67,6 +68,7 @@ type DiffConfigProvider interface {
 
 	DetailedExitcode() bool
 	NoColor() bool
+	Context() int
 
 	concurrencyConfig
 }

pkg/app/run.go

@@ -139,6 +139,7 @@ func (r *Run) Apply(c ApplyConfigProvider) []error {
 
 	diffOpts := &state.DiffOpts{
 		NoColor: c.NoColor(),
+		Context: c.Context(),
 	}
 
 	releases, errs := st.DiffReleases(helm, c.Values(), c.Concurrency(), detailedExitCode, c.SuppressSecrets(), false, diffOpts)

pkg/state/state.go

@@ -776,6 +776,10 @@ func (st *HelmState) prepareDiffReleases(helm helmexec.Interface, additionalValu
 					flags = append(flags, "--no-color")
 				}
 
+				if opts.Context > 0 {
+					flags = append(flags, "--context", fmt.Sprintf("%d", opts.Context))
+				}
+
 				if len(errs) > 0 {
 					rsErrs := make([]*ReleaseError, len(errs))
 					for i, e := range errs {
@@ -823,6 +827,7 @@ func (st *HelmState) createHelmContext(spec *ReleaseSpec, workerIndex int) helme
 
 type DiffOpts struct {
 	NoColor bool
+	Context int
 }
 
 func (o *DiffOpts) Apply(opts *DiffOpts) {

test/integration/run.sh

@@ -63,6 +63,9 @@ bash -c "${helmfile} -f ${dir}/happypath.yaml diff --detailed-exitcode; code="'$
 info "Diffing ${dir}/happypath.yaml without color"
 bash -c "${helmfile} -f ${dir}/happypath.yaml --no-color diff --detailed-exitcode; code="'$?'"; [ "'${code}'" -eq 2 ]" || fail "unexpected exit code returned by helmfile diff"
 
+info "Diffing ${dir}/happypath.yaml with limited context"
+bash -c "${helmfile} -f ${dir}/happypath.yaml diff --context 3 --detailed-exitcode; code="'$?'"; [ "'${code}'" -eq 2 ]" || fail "unexpected exit code returned by helmfile diff"
+
 info "Templating ${dir}/happypath.yaml"
 ${helmfile} -f ${dir}/happypath.yaml template
 code=$?