Feat/schema validation (#5350)

* Add the Schema type and a function to read it

* Added a function to read a schema from a file

* Check that values.yaml matches schema

This commit uses the gojsonschema package to validate a values.yaml file
against a corresponding values.schema.yaml file.

* Add functionality to generate a schema from a values.yaml

* Add Schema to Chart and loader

* Clean up implementation in chartutil

* Add tests for helm install with schema

* Add schema validation to helm lint

* Clean up "matchSchema"

* Modify error output

* Add documentation

* Fix a linter issue

* Fix a test that broke during a rebase

* Clean up documentation

* Specify JSONSchema spec

Since JSONSchema is still in a draft state as of this commit, we need to
specify a particular version of the JSONSchema spec

* Switch to using builtin functionality for file extensions

* Switch to using a third-party library for JSON conversion

* Use the constants from the gojsonschema package

* Updates to unit tests

* Minor change to avoid string cast

* Remove JSON Schema generation

* Change Schema type from map[string]interface{} to []byte

* Convert all Schema YAML to JSON

* Fix some tests that were broken by a rebase

* Fix up YAML/JSON conversions

* This checks subcharts for schema validation

The final coalesced values for a given chart will be validated against
that chart's schema, as well as any dependent subchart's schema

* Add unit tests for ValidateAgainstSchema

* Remove nonessential test files

* Remove a misleading unit test

The TestReadSchema unit test was simply testing the ReadValues function,
which is already being validated in the TestReadValues unit test

* Update documentation to reflect changes to subchart schemas

Gopkg.lock

@@ -835,6 +835,30 @@
   revision = "ffdc059bfe9ce6a4e144ba849dbedead332c6053"
   version = "v1.3.0"
 
+[[projects]]
+  branch = "master"
+  digest = "1:f4e5276a3b356f4692107047fd2890f2fe534f4feeb6b1fd2f6dfbd87f1ccf54"
+  name = "github.com/xeipuuv/gojsonpointer"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "4e3ac2762d5f479393488629ee9370b50873b3a6"
+
+[[projects]]
+  branch = "master"
+  digest = "1:dc6a6c28ca45d38cfce9f7cb61681ee38c5b99ec1425339bfc1e1a7ba769c807"
+  name = "github.com/xeipuuv/gojsonreference"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "bd5ef7bd5415a7ac448318e64f11a24cd21e594b"
+
+[[projects]]
+  digest = "1:1c898ea6c30c16e8d55fdb6fe44c4bee5f9b7d68aa260cfdfc3024491dcc7bea"
+  name = "github.com/xeipuuv/gojsonschema"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "f971f3cd73b2899de6923801c147f075263e0c50"
+  version = "v1.1.0"
+
 [[projects]]
   digest = "1:340553b2fdaab7d53e63fd40f8ed82203bdd3274253055bdb80a46828482ef81"
   name = "github.com/xenolf/lego"
@@ -1676,6 +1700,7 @@
     "github.com/spf13/pflag",
     "github.com/stretchr/testify/assert",
     "github.com/stretchr/testify/suite",
+    "github.com/xeipuuv/gojsonschema",
     "golang.org/x/crypto/openpgp",
     "golang.org/x/crypto/openpgp/clearsign",
     "golang.org/x/crypto/openpgp/errors",

Gopkg.toml

@@ -107,3 +107,6 @@
   go-tests = true
   unused-packages = true
 
+[[constraint]]
+  name = "github.com/xeipuuv/gojsonschema"
+  version = "1.1.0"

cmd/helm/install_test.go

@@ -136,6 +136,53 @@ func TestInstall(t *testing.T) {
 			wantError: true,
 			golden:    "output/install-chart-bad-type.txt",
 		},
+		// Install, values from yaml, schematized
+		{
+			name:   "install with schema file",
+			cmd:    "install schema testdata/testcharts/chart-with-schema",
+			golden: "output/schema.txt",
+		},
+		// Install, values from yaml, schematized with errors
+		{
+			name:      "install with schema file, with errors",
+			cmd:       "install schema testdata/testcharts/chart-with-schema-negative",
+			wantError: true,
+			golden:    "output/schema-negative.txt",
+		},
+		// Install, values from yaml, extra values from yaml, schematized with errors
+		{
+			name:      "install with schema file, extra values from yaml, with errors",
+			cmd:       "install schema testdata/testcharts/chart-with-schema -f testdata/testcharts/chart-with-schema/extra-values.yaml",
+			wantError: true,
+			golden:    "output/schema-negative.txt",
+		},
+		// Install, values from yaml, extra values from cli, schematized with errors
+		{
+			name:      "install with schema file, extra values from cli, with errors",
+			cmd:       "install schema testdata/testcharts/chart-with-schema --set age=-5",
+			wantError: true,
+			golden:    "output/schema-negative-cli.txt",
+		},
+		// Install with subchart, values from yaml, schematized with errors
+		{
+			name:      "install with schema file and schematized subchart, with errors",
+			cmd:       "install schema testdata/testcharts/chart-with-schema-and-subchart",
+			wantError: true,
+			golden:    "output/subchart-schema-negative.txt",
+		},
+		// Install with subchart, values from yaml, extra values from cli, schematized with errors
+		{
+			name:   "install with schema file and schematized subchart, extra values from cli",
+			cmd:    "install schema testdata/testcharts/chart-with-schema-and-subchart --set lastname=doe --set subchart-with-schema.age=25",
+			golden: "output/subchart-schema-cli.txt",
+		},
+		// Install with subchart, values from yaml, extra values from cli, schematized with errors
+		{
+			name:      "install with schema file and schematized subchart, extra values from cli, with errors",
+			cmd:       "install schema testdata/testcharts/chart-with-schema-and-subchart --set lastname=doe --set subchart-with-schema.age=-25",
+			wantError: true,
+			golden:    "output/subchart-schema-cli-negative.txt",
+		},
 	}
 
 	runTestActionCmd(t, tests)

cmd/helm/testdata/output/schema-negative-cli.txt

@@ -0,0 +1,4 @@
+Error: values don't meet the specifications of the schema(s) in the following chart(s):
+empty:
+- age: Must be greater than or equal to 0/1
+

cmd/helm/testdata/output/schema-negative.txt

@@ -0,0 +1,5 @@
+Error: values don't meet the specifications of the schema(s) in the following chart(s):
+empty:
+- (root): employmentInfo is required
+- age: Must be greater than or equal to 0/1
+

cmd/helm/testdata/output/schema.txt

@@ -0,0 +1,5 @@
+NAME: schema
+LAST DEPLOYED: 1977-09-02 22:04:05 +0000 UTC
+NAMESPACE: default
+STATUS: deployed
+

cmd/helm/testdata/output/subchart-schema-cli-negative.txt

@@ -0,0 +1,4 @@
+Error: values don't meet the specifications of the schema(s) in the following chart(s):
+subchart-with-schema:
+- age: Must be greater than or equal to 0/1
+

cmd/helm/testdata/output/subchart-schema-cli.txt

@@ -0,0 +1,5 @@
+NAME: schema
+LAST DEPLOYED: 1977-09-02 22:04:05 +0000 UTC
+NAMESPACE: default
+STATUS: deployed
+

cmd/helm/testdata/output/subchart-schema-negative.txt

@@ -0,0 +1,6 @@
+Error: values don't meet the specifications of the schema(s) in the following chart(s):
+chart-without-schema:
+- (root): lastname is required
+subchart-with-schema:
+- (root): age is required
+

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/Chart.yaml

@@ -0,0 +1,6 @@
+apiVersion: v1
+name: chart-without-schema
+description: A Helm chart for Kubernetes
+type: application
+version: 0.1.0
+appVersion: 0.1.0

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/charts/subchart-with-schema/Chart.yaml

@@ -0,0 +1,6 @@
+apiVersion: v1
+name: subchart-with-schema
+description: A Helm chart for Kubernetes
+type: application
+version: 0.1.0
+appVersion: 0.1.0

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/charts/subchart-with-schema/templates/empty.yaml

@@ -0,0 +1 @@
+# This file is intentionally blank

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/charts/subchart-with-schema/values.schema.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Values",
+  "type": "object",
+  "properties": {
+    "age": {
+      "description": "Age",
+      "minimum": 0,
+      "type": "integer"
+    }
+  },
+  "required": [
+    "age"
+  ]
+}

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/templates/empty.yaml

@@ -0,0 +1 @@
+# This file is intentionally blank

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/values.schema.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Values",
+  "type": "object",
+  "properties": {
+    "firstname": {
+      "description": "First name",
+      "type": "string"
+    },
+    "lastname": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "firstname",
+    "lastname"
+  ]
+}

cmd/helm/testdata/testcharts/chart-with-schema-and-subchart/values.yaml

@@ -0,0 +1 @@
+firstname: "John"

cmd/helm/testdata/testcharts/chart-with-schema-negative/Chart.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+description: Empty testing chart
+home: https://k8s.io/helm
+name: empty
+sources:
+- https://github.com/kubernetes/helm
+version: 0.1.0

cmd/helm/testdata/testcharts/chart-with-schema-negative/templates/empty.yaml

@@ -0,0 +1 @@
+# This file is intentionally blank

cmd/helm/testdata/testcharts/chart-with-schema-negative/values.schema.json

@@ -0,0 +1,67 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "properties": {
+    "addresses": {
+      "description": "List of addresses",
+      "items": {
+        "properties": {
+          "city": {
+            "type": "string"
+          },
+          "number": {
+            "type": "number"
+          },
+          "street": {
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "age": {
+      "description": "Age",
+      "minimum": 0,
+      "type": "integer"
+    },
+    "employmentInfo": {
+      "properties": {
+        "salary": {
+          "minimum": 0,
+          "type": "number"
+        },
+        "title": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "salary"
+      ],
+      "type": "object"
+    },
+    "firstname": {
+      "description": "First name",
+      "type": "string"
+    },
+    "lastname": {
+      "type": "string"
+    },
+    "likesCoffee": {
+      "type": "boolean"
+    },
+    "phoneNumbers": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "firstname",
+    "lastname",
+    "addresses",
+    "employmentInfo"
+  ],
+  "title": "Values",
+  "type": "object"
+}

cmd/helm/testdata/testcharts/chart-with-schema-negative/values.yaml

@@ -0,0 +1,14 @@
+firstname: John
+lastname: Doe
+age: -5
+likesCoffee: true
+addresses:
+  - city: Springfield
+    street: Main
+    number: 12345
+  - city: New York
+    street: Broadway
+    number: 67890
+phoneNumbers:
+  - "(888) 888-8888"
+  - "(555) 555-5555"

cmd/helm/testdata/testcharts/chart-with-schema/Chart.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+description: Empty testing chart
+home: https://k8s.io/helm
+name: empty
+sources:
+- https://github.com/kubernetes/helm
+version: 0.1.0

cmd/helm/testdata/testcharts/chart-with-schema/extra-values.yaml

@@ -0,0 +1,2 @@
+age: -5
+employmentInfo: null

cmd/helm/testdata/testcharts/chart-with-schema/templates/empty.yaml

@@ -0,0 +1 @@
+# This file is intentionally blank

cmd/helm/testdata/testcharts/chart-with-schema/values.schema.json

@@ -0,0 +1,67 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "properties": {
+    "addresses": {
+      "description": "List of addresses",
+      "items": {
+        "properties": {
+          "city": {
+            "type": "string"
+          },
+          "number": {
+            "type": "number"
+          },
+          "street": {
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "age": {
+      "description": "Age",
+      "minimum": 0,
+      "type": "integer"
+    },
+    "employmentInfo": {
+      "properties": {
+        "salary": {
+          "minimum": 0,
+          "type": "number"
+        },
+        "title": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "salary"
+      ],
+      "type": "object"
+    },
+    "firstname": {
+      "description": "First name",
+      "type": "string"
+    },
+    "lastname": {
+      "type": "string"
+    },
+    "likesCoffee": {
+      "type": "boolean"
+    },
+    "phoneNumbers": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "firstname",
+    "lastname",
+    "addresses",
+    "employmentInfo"
+  ],
+  "title": "Values",
+  "type": "object"
+}

cmd/helm/testdata/testcharts/chart-with-schema/values.yaml

@@ -0,0 +1,17 @@
+firstname: John
+lastname: Doe
+age: 25
+likesCoffee: true
+employmentInfo:
+  title: Software Developer
+  salary: 100000
+addresses:
+  - city: Springfield
+    street: Main
+    number: 12345
+  - city: New York
+    street: Broadway
+    number: 67890
+phoneNumbers:
+  - "(888) 888-8888"
+  - "(555) 555-5555"

docs/charts.md

@@ -26,6 +26,7 @@ wordpress/
   LICENSE             # OPTIONAL: A plain text file containing the license for the chart
   README.md           # OPTIONAL: A human-readable README file
   values.yaml         # The default configuration values for this chart
+  values.schema.json  # OPTIONAL: A JSON Schema for imposing a structure on the values.yaml file
   charts/             # A directory containing any charts upon which this chart depends.
   templates/          # A directory of templates that, when combined with values,
                       # will generate valid Kubernetes manifest files.
@@ -763,14 +764,98 @@ parent chart.
 
 Also, global variables of parent charts take precedence over the global variables from subcharts.
 
+### Schema Files
+
+Sometimes, a chart maintainer might want to define a structure on their values.
+This can be done by defining a schema in the `values.schema.json` file. A
+schema is represented as a [JSON Schema](https://json-schema.org/).
+It might look something like this:
+
+```json
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "properties": {
+    "image": {
+      "description": "Container Image",
+      "properties": {
+        "repo": {
+          "type": "string"
+        },
+        "tag": {
+          "type": "string"
+        }
+      },
+      "type": "object"
+    },
+    "name": {
+      "description": "Service name",
+      "type": "string"
+    },
+    "port": {
+      "description": "Port",
+      "minimum": 0,
+      "type": "integer"
+    },
+    "protocol": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "protocol",
+    "port"
+  ],
+  "title": "Values",
+  "type": "object"
+}
+```
+
+This schema will be applied to the values to validate it. Validation occurs
+when any of the following commands are invoked:
+
+* `helm install`
+* `helm upgrade`
+* `helm lint`
+* `helm template`
+
+An example of a
+`values.yaml` file that meets the requirements of this schema might look
+something like this:
+
+```yaml
+name: frontend
+protocol: https
+port: 443
+```
+
+Note that the schema is applied to the final `.Values` object, and not just to
+the `values.yaml` file. This means that the following `yaml` file is valid,
+given that the chart is installed with the appropriate `--set` option shown
+below.
+
+```yaml
+name: frontend
+protocol: https
+```
+
+````
+helm install --set port=443
+````
+
+Furthermore, the final `.Values` object is checked against *all* subchart
+schemas. This means that restrictions on a subchart can't be circumvented by a
+parent chart. This also works backwards - if a subchart has a requirement that
+is not met in the subchart's `values.yaml` file, the parent chart *must*
+satisfy those restrictions in order to be valid.
+
 ### References
 
-When it comes to writing templates and values files, there are several
+When it comes to writing templates, values, and schema files, there are several
 standard references that will help you out.
 
 - [Go templates](https://godoc.org/text/template)
 - [Extra template functions](https://godoc.org/github.com/Masterminds/sprig)
 - [The YAML format](http://yaml.org/spec/)
+- [JSON Schema](https://json-schema.org/)
 
 ## Using Helm to Manage Charts
 

pkg/action/lint_test.go

@@ -29,6 +29,8 @@ var (
 	invalidArchivedChartPath     = "../../cmd/helm/testdata/testcharts/invalidcompressedchart0.1.0.tgz"
 	chartDirPath                 = "../../cmd/helm/testdata/testcharts/decompressedchart/"
 	chartMissingManifest         = "../../cmd/helm/testdata/testcharts/chart-missing-manifest"
+	chartSchema                  = "../../cmd/helm/testdata/testcharts/chart-with-schema"
+	chartSchemaNegative          = "../../cmd/helm/testdata/testcharts/chart-with-schema-negative"
 )
 
 func TestLintChart(t *testing.T) {
@@ -47,4 +49,10 @@ func TestLintChart(t *testing.T) {
 	if _, err := lintChart(chartMissingManifest, values, namespace, strict); err == nil {
 		t.Error("Expected a chart parsing error")
 	}
+	if _, err := lintChart(chartSchema, values, namespace, strict); err != nil {
+		t.Error(err)
+	}
+	if _, err := lintChart(chartSchemaNegative, values, namespace, strict); err != nil {
+		t.Error(err)
+	}
 }

pkg/chart/chart.go

@@ -31,6 +31,8 @@ type Chart struct {
 	RawValues []byte
 	// Values are default config for this template.
 	Values map[string]interface{}
+	// Schema is an optional JSON schema for imposing structure on Values
+	Schema []byte
 	// Files are miscellaneous files in a chart archive,
 	// e.g. README, LICENSE, etc.
 	Files []*File

pkg/chart/loader/load.go

@@ -90,6 +90,8 @@ func LoadFiles(files []*BufferedFile) (*chart.Chart, error) {
 				return c, errors.Wrap(err, "cannot load values.yaml")
 			}
 			c.RawValues = f.Data
+		case f.Name == "values.schema.json":
+			c.Schema = f.Data
 		case strings.HasPrefix(f.Name, "templates/"):
 			c.Templates = append(c.Templates, &chart.File{Name: f.Name, Data: f.Data})
 		case strings.HasPrefix(f.Name, "charts/"):

pkg/chart/loader/load_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package loader
 
 import (
+	"bytes"
 	"testing"
 
 	"helm.sh/helm/pkg/chart"
@@ -78,6 +79,10 @@ icon: https://example.com/64x64.png
 			Name: "values.yaml",
 			Data: []byte("var: some values"),
 		},
+		{
+			Name: "values.schema.json",
+			Data: []byte("type: Values"),
+		},
 		{
 			Name: "templates/deployment.yaml",
 			Data: []byte("some deployment"),
@@ -101,6 +106,10 @@ icon: https://example.com/64x64.png
 		t.Error("Expected chart values to be populated with default values")
 	}
 
+	if !bytes.Equal(c.Schema, []byte("type: Values")) {
+		t.Error("Expected chart schema to be populated with default values")
+	}
+
 	if len(c.Templates) != 2 {
 		t.Errorf("Expected number of templates == 2, got %d", len(c.Templates))
 	}

pkg/chartutil/testdata/test-values-negative.yaml

@@ -0,0 +1,14 @@
+firstname: John
+lastname: Doe
+age: -5
+likesCoffee: true
+addresses:
+  - city: Springfield
+    street: Main
+    number: 12345
+  - city: New York
+    street: Broadway
+    number: 67890
+phoneNumbers:
+  - "(888) 888-8888"
+  - "(555) 555-5555"

pkg/chartutil/testdata/test-values.schema.json

@@ -0,0 +1,67 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "properties": {
+    "addresses": {
+      "description": "List of addresses",
+      "items": {
+        "properties": {
+          "city": {
+            "type": "string"
+          },
+          "number": {
+            "type": "number"
+          },
+          "street": {
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "age": {
+      "description": "Age",
+      "minimum": 0,
+      "type": "integer"
+    },
+    "employmentInfo": {
+      "properties": {
+        "salary": {
+          "minimum": 0,
+          "type": "number"
+        },
+        "title": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "salary"
+      ],
+      "type": "object"
+    },
+    "firstname": {
+      "description": "First name",
+      "type": "string"
+    },
+    "lastname": {
+      "type": "string"
+    },
+    "likesCoffee": {
+      "type": "boolean"
+    },
+    "phoneNumbers": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "firstname",
+    "lastname",
+    "addresses",
+    "employmentInfo"
+  ],
+  "title": "Values",
+  "type": "object"
+}

pkg/chartutil/testdata/test-values.yaml

@@ -0,0 +1,17 @@
+firstname: John
+lastname: Doe
+age: 25
+likesCoffee: true
+employmentInfo:
+  title: Software Developer
+  salary: 100000
+addresses:
+  - city: Springfield
+    street: Main
+    number: 12345
+  - city: New York
+    street: Broadway
+    number: 67890
+phoneNumbers:
+  - "(888) 888-8888"
+  - "(555) 555-5555"

pkg/chartutil/values.go

@@ -17,6 +17,7 @@ limitations under the License.
 package chartutil
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -25,6 +26,7 @@ import (
 
 	"github.com/ghodss/yaml"
 	"github.com/pkg/errors"
+	"github.com/xeipuuv/gojsonschema"
 
 	"helm.sh/helm/pkg/chart"
 )
@@ -133,6 +135,64 @@ func ReadValuesFile(filename string) (Values, error) {
 	return ReadValues(data)
 }
 
+// ValidateAgainstSchema checks that values does not violate the structure laid out in schema
+func ValidateAgainstSchema(chrt *chart.Chart, values map[string]interface{}) error {
+	var sb strings.Builder
+	if chrt.Schema != nil {
+		err := ValidateAgainstSingleSchema(values, chrt.Schema)
+		if err != nil {
+			sb.WriteString(fmt.Sprintf("%s:\n", chrt.Name()))
+			sb.WriteString(err.Error())
+		}
+	}
+
+	// For each dependency, recurively call this function with the coalesced values
+	for _, subchrt := range chrt.Dependencies() {
+		subchrtValues := values[subchrt.Name()].(map[string]interface{})
+		if err := ValidateAgainstSchema(subchrt, subchrtValues); err != nil {
+			sb.WriteString(err.Error())
+		}
+	}
+
+	if sb.Len() > 0 {
+		return errors.New(sb.String())
+	}
+
+	return nil
+}
+
+// ValidateAgainstSingleSchema checks that values does not violate the structure laid out in this schema
+func ValidateAgainstSingleSchema(values Values, schemaJSON []byte) error {
+	valuesData, err := yaml.Marshal(values)
+	if err != nil {
+		return err
+	}
+	valuesJSON, err := yaml.YAMLToJSON(valuesData)
+	if err != nil {
+		return err
+	}
+	if bytes.Equal(valuesJSON, []byte("null")) {
+		valuesJSON = []byte("{}")
+	}
+	schemaLoader := gojsonschema.NewBytesLoader(schemaJSON)
+	valuesLoader := gojsonschema.NewBytesLoader(valuesJSON)
+
+	result, err := gojsonschema.Validate(schemaLoader, valuesLoader)
+	if err != nil {
+		return err
+	}
+
+	if !result.Valid() {
+		var sb strings.Builder
+		for _, desc := range result.Errors() {
+			sb.WriteString(fmt.Sprintf("- %s\n", desc))
+		}
+		return errors.New(sb.String())
+	}
+
+	return nil
+}
+
 // CoalesceValues coalesces all of the values in a chart (and its subcharts).
 //
 // Values are coalesced together using the following rules:
@@ -331,6 +391,11 @@ func ToRenderValues(chrt *chart.Chart, chrtVals map[string]interface{}, options
 		return top, err
 	}
 
+	if err := ValidateAgainstSchema(chrt, vals); err != nil {
+		errFmt := "values don't meet the specifications of the schema(s) in the following chart(s):\n%s"
+		return top, fmt.Errorf(errFmt, err.Error())
+	}
+
 	top["Values"] = vals
 	return top, nil
 }

pkg/chartutil/values_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"testing"
 	"text/template"
 
@@ -160,6 +161,125 @@ func TestReadValuesFile(t *testing.T) {
 	matchValues(t, data)
 }
 
+func TestValidateAgainstSingleSchema(t *testing.T) {
+	values, err := ReadValuesFile("./testdata/test-values.yaml")
+	if err != nil {
+		t.Fatalf("Error reading YAML file: %s", err)
+	}
+	schema, err := ioutil.ReadFile("./testdata/test-values.schema.json")
+	if err != nil {
+		t.Fatalf("Error reading YAML file: %s", err)
+	}
+
+	if err := ValidateAgainstSingleSchema(values, schema); err != nil {
+		t.Errorf("Error validating Values against Schema: %s", err)
+	}
+}
+
+func TestValidateAgainstSingleSchemaNegative(t *testing.T) {
+	values, err := ReadValuesFile("./testdata/test-values-negative.yaml")
+	if err != nil {
+		t.Fatalf("Error reading YAML file: %s", err)
+	}
+	schema, err := ioutil.ReadFile("./testdata/test-values.schema.json")
+	if err != nil {
+		t.Fatalf("Error reading YAML file: %s", err)
+	}
+
+	var errString string
+	if err := ValidateAgainstSingleSchema(values, schema); err == nil {
+		t.Fatalf("Expected an error, but got nil")
+	} else {
+		errString = err.Error()
+	}
+
+	expectedErrString := `- (root): employmentInfo is required
+- age: Must be greater than or equal to 0/1
+`
+	if errString != expectedErrString {
+		t.Errorf("Error string :\n`%s`\ndoes not match expected\n`%s`", errString, expectedErrString)
+	}
+}
+
+const subchrtSchema = `{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Values",
+  "type": "object",
+  "properties": {
+    "age": {
+      "description": "Age",
+      "minimum": 0,
+      "type": "integer"
+    }
+  },
+  "required": [
+    "age"
+  ]
+}
+`
+
+func TestValidateAgainstSchema(t *testing.T) {
+	subchrtJSON := []byte(subchrtSchema)
+	subchrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "subchrt",
+		},
+		Schema: subchrtJSON,
+	}
+	chrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "chrt",
+		},
+	}
+	chrt.AddDependency(subchrt)
+
+	vals := map[string]interface{}{
+		"name": "John",
+		"subchrt": map[string]interface{}{
+			"age": 25,
+		},
+	}
+
+	if err := ValidateAgainstSchema(chrt, vals); err != nil {
+		t.Errorf("Error validating Values against Schema: %s", err)
+	}
+}
+
+func TestValidateAgainstSchemaNegative(t *testing.T) {
+	subchrtJSON := []byte(subchrtSchema)
+	subchrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "subchrt",
+		},
+		Schema: subchrtJSON,
+	}
+	chrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "chrt",
+		},
+	}
+	chrt.AddDependency(subchrt)
+
+	vals := map[string]interface{}{
+		"name":    "John",
+		"subchrt": map[string]interface{}{},
+	}
+
+	var errString string
+	if err := ValidateAgainstSchema(chrt, vals); err == nil {
+		t.Fatalf("Expected an error, but got nil")
+	} else {
+		errString = err.Error()
+	}
+
+	expectedErrString := `subchrt:
+- (root): age is required
+`
+	if errString != expectedErrString {
+		t.Errorf("Error string :\n`%s`\ndoes not match expected\n`%s`", errString, expectedErrString)
+	}
+}
+
 func ExampleValues() {
 	doc := `
 title: "Moby Dick"
@@ -399,6 +519,7 @@ func TestCoalesceTables(t *testing.T) {
 		t.Errorf("Expected boat string, got %v", dst["boat"])
 	}
 }
+
 func TestPathValue(t *testing.T) {
 	doc := `
 title: "Moby Dick"

pkg/lint/rules/values.go

@@ -17,6 +17,7 @@ limitations under the License.
 package rules
 
 import (
+	"io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -48,6 +49,19 @@ func validateValuesFileExistence(valuesPath string) error {
 }
 
 func validateValuesFile(valuesPath string) error {
-	_, err := chartutil.ReadValuesFile(valuesPath)
+	values, err := chartutil.ReadValuesFile(valuesPath)
-	return errors.Wrap(err, "unable to parse YAML")
+	if err != nil {
+		return errors.Wrap(err, "unable to parse YAML")
+	}
+
+	ext := filepath.Ext(valuesPath)
+	schemaPath := valuesPath[:len(valuesPath)-len(ext)] + ".schema.json"
+	schema, err := ioutil.ReadFile(schemaPath)
+	if len(schema) == 0 {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	return chartutil.ValidateAgainstSingleSchema(values, schema)
 }