Support custom constraint (templates)

acceptance.bats

@@ -23,3 +23,9 @@
   [ "$status" -eq 0 ]
   git diff --quiet -- test/
 }
+
+@test "[CREATE] Creating constraints using --constraint-custom-template-file, --constraint-template-custom-template-file and --output matches expected output" {
+  run ./build/konstraint create test --constraint-custom-template-file internal/commands/constraint_template.tpl --constraint-template-custom-template-file internal/commands/constrainttemplate_template.tpl --partial-constraints --output test/custom
+  [ "$status" -eq 0 ]
+  git diff --quiet -- test/custom
+}

docs/cli/konstraint_create.md

@@ -22,12 +22,14 @@ Create constraints with the Gatekeeper enforcement action set to dryrun
 ### Options
 
 ```
-      --constraint-template-version string   Set the version of ConstraintTemplates (default "v1beta1")
-  -d, --dryrun                               Sets the enforcement action of the constraints to dryrun, overriding the @enforcement tag
-  -h, --help                                 help for create
-  -o, --output string                        Specify an output directory for the Gatekeeper resources
-      --partial-constraints                  Generate partial Constraints for policies with parameters
-      --skip-constraints                     Skip generation of constraints
+      --constraint-custom-template-file string            Path to a custom template file to generate constraints
+      --constraint-template-custom-template-file string   Path to a custom template file to generate constraint templates
+      --constraint-template-version string                Set the version of ConstraintTemplates (default "v1beta1")
+  -d, --dryrun                                            Sets the enforcement action of the constraints to dryrun, overriding the @enforcement tag
+  -h, --help                                              help for create
+  -o, --output string                                     Specify an output directory for the Gatekeeper resources
+      --partial-constraints                               Generate partial Constraints for policies with parameters
+      --skip-constraints                                  Skip generation of constraints
 ```
 
 ### SEE ALSO

docs/constraint_creation.md

@@ -103,6 +103,11 @@ violation[{"msg": msg}] {
 }
 ```
 
+### Custom templates for Constraint and/or ConstraintTemplate resources
+
+In some cases there might be the need to further customize the rendered Constraint and ConstraintTemplates. This is particularly helpful, if you want to create e.g. template for Helm charts, where certain values are additional fields to be rendered through Helm. 
+You can provide custom templates through the `--constraint-template-custom-template-file` and `--constraint-custom-template-file` command line flags. 
+
 ### Skipping generation of the Constraint and/or ConstraintTemplate resource
 
 In some scenarios, you may wish for Konstraint to skip the generation of the `Constraint` resource for a policy and manage that externally. To do so, add the `skipConstraint: true` annotation in the custom metadata section.

go.mod

@@ -1,8 +1,10 @@
 module github.com/plexsystems/konstraint
 
-go 1.23.0
+go 1.23.4
 
 require (
+	github.com/go-sprout/sprout v1.0.0
+	github.com/google/go-cmp v0.6.0
 	github.com/open-policy-agent/frameworks/constraint v0.0.0-20220218180203-c2a0d8cdf85a
 	github.com/open-policy-agent/opa v1.1.0
 	github.com/sirupsen/logrus v1.9.3
@@ -16,6 +18,8 @@ require (
 
 require (
 	cel.dev/expr v0.19.0 // indirect
+	dario.cat/mergo v1.0.1 // indirect
+	github.com/Masterminds/semver/v3 v3.3.1 // indirect
 	github.com/OneOfOne/xxhash v1.2.8 // indirect
 	github.com/antlr4-go/antlr/v4 v4.13.0 // indirect
 	github.com/asaskevich/govalidator v0.0.0-20210307081110-f21760c49a8d // indirect
@@ -34,14 +38,17 @@ require (
 	github.com/google/cel-go v0.22.0 // indirect
 	github.com/google/gnostic-models v0.6.8 // indirect
 	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/compress v1.17.11 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
@@ -55,7 +62,7 @@ require (
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
-	github.com/spf13/cast v1.6.0 // indirect
+	github.com/spf13/cast v1.7.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/stoewer/go-strcase v1.3.0 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
@@ -65,9 +72,9 @@ require (
 	go.opentelemetry.io/otel v1.34.0 // indirect
 	go.opentelemetry.io/otel/trace v1.34.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
+	golang.org/x/crypto v0.32.0 // indirect
 	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
 	golang.org/x/net v0.34.0 // indirect
-	golang.org/x/oauth2 v0.24.0 // indirect
 	golang.org/x/sync v0.11.0 // indirect
 	golang.org/x/sys v0.29.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20250115164207-1a7da9e5054f // indirect

go.sum

@@ -1,5 +1,9 @@
 cel.dev/expr v0.19.0 h1:lXuo+nDhpyJSpWxpPVi5cPUwzKb+dsdOiw6IreM5yt0=
 cel.dev/expr v0.19.0/go.mod h1:MrpN08Q+lEBs+bGYdLxxHkZoUSsCp0nSKTs0nTymJgw=
+dario.cat/mergo v1.0.1 h1:Ra4+bf83h2ztPIQYNP99R6m+Y7KfnARDfID+a+vLl4s=
+dario.cat/mergo v1.0.1/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
+github.com/Masterminds/semver/v3 v3.3.1 h1:QtNSWtVZ3nBfk8mAOu/B6v7FMJ+NHTIgUPi7rj+4nv4=
+github.com/Masterminds/semver/v3 v3.3.1/go.mod h1:4V+yj/TJE1HU9XfppCwVMZq3I84lprf4nC11bSS5beM=
 github.com/OneOfOne/xxhash v1.2.8 h1:31czK/TI9sNkxIKfaUfGlU47BAxQ0ztGgd9vPyqimf8=
 github.com/OneOfOne/xxhash v1.2.8/go.mod h1:eZbhyaAYD41SGSSsnmcpxVoRiQ/MPUTjUdIIOT9Um7Q=
 github.com/antlr4-go/antlr/v4 v4.13.0 h1:lxCg3LAv+EUK6t1i0y1V6/SLeUi0eKEKdhQAlS8TVTI=
@@ -54,6 +58,8 @@ github.com/go-openapi/jsonreference v0.20.2/go.mod h1:Bl1zwGIM8/wsvqjsOQLJ/SH+En
 github.com/go-openapi/swag v0.22.3/go.mod h1:UzaqsxGiab7freDnrUUra0MwWfN/q7tE4j+VcZ0yl14=
 github.com/go-openapi/swag v0.23.0 h1:vsEVJDUo2hPJ2tu0/Xc+4noaxyEffXNIs3cOULZ+GrE=
 github.com/go-openapi/swag v0.23.0/go.mod h1:esZ8ITTYEsH1V2trKHjAN8Ai7xHb8RV+YSZ577vPjgQ=
+github.com/go-sprout/sprout v1.0.0 h1:4uxG1fZbUxfXB2OsjwzyIOK4lZQEhsksib17vVAZqOs=
+github.com/go-sprout/sprout v1.0.0/go.mod h1:I6ifgKakZI/NOkFyZueoS5N0qENvI5ZWcWT7oM34vsE=
 github.com/gobwas/glob v0.2.3 h1:A4xDbljILXROh+kObIiy5kIaPYD8e96x1tgBhUI5J+Y=
 github.com/gobwas/glob v0.2.3/go.mod h1:d3Ez4x06l9bZtSvzIay5+Yzi0fmZzPgnTbPcKjJAkT8=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
@@ -108,8 +114,12 @@ github.com/magiconair/properties v1.8.7 h1:IeQXZAiQcpL9mgcAe1Nu6cX9LLw6ExEHKjN0V
 github.com/magiconair/properties v1.8.7/go.mod h1:Dhd985XPs7jluiymwWYZ0G4Z61jb3vdS329zhj2hYo0=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
+github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa15WveJJGw=
+github.com/mitchellh/copystructure v1.2.0/go.mod h1:qLl+cE2AmVv+CoeAwDPye/v+N2HKCj9FbZEVFJRxO9s=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
+github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zxSIeXaQ=
+github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -157,8 +167,8 @@ github.com/sourcegraph/conc v0.3.0 h1:OQTbbt6P72L20UqAkXXuLOj79LfEanQ+YQFNpLA9yS
 github.com/sourcegraph/conc v0.3.0/go.mod h1:Sdozi7LEKbFPqYX2/J+iBAM6HpqSLTASQIKqDmF7Mt0=
 github.com/spf13/afero v1.11.0 h1:WJQKhtpdm3v2IzqG8VMqrr6Rf3UYpEF239Jy9wNepM8=
 github.com/spf13/afero v1.11.0/go.mod h1:GH9Y3pIexgf1MTIWtNGyogA5MwRIDXGUr+hbWNoBjkY=
-github.com/spf13/cast v1.6.0 h1:GEiTHELF+vaR5dhz3VqZfFSzZjYbgeKDpBxQVS4GYJ0=
-github.com/spf13/cast v1.6.0/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
+github.com/spf13/cast v1.7.1 h1:cuNEagBQEHWN1FnbGEjCXL2szYEXqfJPbP2HNUaca9Y=
+github.com/spf13/cast v1.7.1/go.mod h1:ancEpBxwJDODSW/UG4rDrAqiKolqNNh2DX3mk86cAdo=
 github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
 github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
@@ -170,6 +180,7 @@ github.com/stoewer/go-strcase v1.3.0/go.mod h1:fAH5hQ5pehh+j3nZfvwdk2RgEgQjAoM8w
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
 github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -227,6 +238,8 @@ go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
+golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
 golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 h1:2dVuKD2vS7b0QIHQbpyTISPd0LeHDbnYEryqj5Q1ug8=
 golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56/go.mod h1:M4RDyNAINzryxdtnbRXRL/OHtkFuWGRjvuhBJpk2IlY=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -237,8 +250,8 @@ golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.34.0 h1:Mb7Mrk043xzHgnRM88suvJFwzVrRfHEHJEl5/71CKw0=
 golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
-golang.org/x/oauth2 v0.24.0 h1:KTBBxWqUa0ykRPLtV69rRto9TLXcqYkeswu48x/gvNE=
-golang.org/x/oauth2 v0.24.0/go.mod h1:XYTD2NtWslqkgxebSiOHnXEap4TF09sJSc7H1sXbhtI=
+golang.org/x/oauth2 v0.23.0 h1:PbgcYx2W7i4LvjJWEbf0ngHV6qJYr86PkAV3bXdLEbs=
+golang.org/x/oauth2 v0.23.0/go.mod h1:XYTD2NtWslqkgxebSiOHnXEap4TF09sJSc7H1sXbhtI=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=

internal/commands/constraint_template.tpl

@@ -0,0 +1,21 @@
+# This is a custom template for constraints
+apiVersion: constraints.gatekeeper.sh/v1beta1
+kind: {{ .Kind }}
+metadata:
+  {{- if .Annotations }}
+  annotations: {{- .Annotations | toIndentYAML 2 | nindent 4 }}
+  {{- end }}
+  {{- if .Labels }}
+  labels: {{ .Labels | toIndentYAML 2 | nindent 4 }}
+  {{- end }}
+  name: {{ .Name }}
+spec:
+  {{- if .Matchers }}
+  match: {{- .GetAnnotation "matchers" | toIndentYAML 2 | nindent 4 }}
+  {{- end }}
+  {{- if ne .Enforcement "deny" }}
+  enforcementAction: {{ .Enforcement }}
+  {{- end -}}
+  {{- if .AnnotationParameters }}
+  parameters: {{- .AnnotationParameters | toIndentYAML 2 | nindent 4 }}
+  {{- end }}

internal/commands/constrainttemplate_template.tpl

@@ -0,0 +1,21 @@
+# This is a custom template for a constraint template
+apiVersion: templates.gatekeeper.sh/v1
+kind: ConstraintTemplate
+metadata:
+  name: {{ .Name }}
+spec:
+  crd:
+    spec:
+      names:
+        kind: {{ .Kind }}
+      {{- if .AnnotationParameters }}
+      validation:
+        openAPIV3Schema:
+          properties: {{- .AnnotationParameters | toJSON | fromJSON | toIndentYAML 2 | nindent 12 }}
+      {{- end }}
+  targets:
+  - libs: {{- range .Dependencies }}
+    - |- {{- . | nindent 6 -}}
+    {{ end }}
+    rego: |- {{- .Source | nindent 6 }}
+    target: admission.k8s.gatekeeper.sh