internal: propose custom types for image types, arches, etc.
We currently use strings for passing arches and image types around, which is not ideal. We should have a finite set of supported image types and architectures as well as upload targets. This PR introduces custom types to make the code base more readable and possibly also more correct. I considered some alternatives like a struct with private fields, but struct cannot be const, so that does not help either. Eventually I think this is the "get s**t done" solution. The package also includes unit-tests which try to convert string to structure and the other way around to make sure it all works properly.
This commit is contained in:
Martin Sehnoutka
msehnout
parent
aab8a4d305
commit
8dac72f4fd
2 changed files with 313 additions and 0 deletions
212
internal/common/types.go
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212
internal/common/types.go
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@ -0,0 +1,212 @@
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package common
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import (
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"encoding/json"
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"fmt"
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"github.com/google/uuid"
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)
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// CustomJsonConversionError is thrown when parsing strings into enumerations
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type CustomJsonConversionError struct {
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reason string
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}
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func (err *CustomJsonConversionError) Error() string {
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return err.reason
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}
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func unmarshalHelper(data []byte, jsonError, typeConversionError string, mapping map[string]int) (int, error) {
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var stringInput string
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err := json.Unmarshal(data, &stringInput)
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if err != nil {
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return 0, &CustomJsonConversionError{string(data) + jsonError}
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}
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value, exists := mapping[stringInput]
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if !exists {
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return 0, &CustomJsonConversionError{stringInput + typeConversionError}
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}
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return value, nil
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}
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func marshalHelper(input int, mapping map[string]int, errorMessage string) ([]byte, error) {
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for k, v := range mapping {
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if v == input {
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return json.Marshal(k)
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}
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}
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return nil, &CustomJsonConversionError{fmt.Sprintf("%d %s", input, errorMessage)}
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}
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// Architecture represents one of the supported CPU architectures available for images
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// produced by osbuild-composer. It is represented as an integer because if it
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// was a string it would unmarshal from JSON just fine even in case that the architecture
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// was unknown.
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type Architecture int
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// A list of supported architectures. As the comment above suggests the type system does
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// not allow to create a type with a custom set of values, so it is possible to use e.g.
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// 56 instead of an architecture, but as opposed to a string it should be obvious that
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// hardcoding a number instead of an architecture is just wrong.
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//
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// NOTE: If you want to add more constants here, don't forget to add a mapping below
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const (
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X86_64 Architecture = iota
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Aarch64
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Armv7hl
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I686
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Ppc64le
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S390x
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)
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// getArchMapping is a helper function that defines the conversion from JSON string value
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// to Architecture.
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func getArchMapping() map[string]int {
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mapping := map[string]int{
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"x86_64": int(X86_64),
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"aarch64": int(Aarch64),
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"armv7hl": int(Armv7hl),
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"i686": int(I686),
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"ppc64le": int(Ppc64le),
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"s390x": int(S390x),
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}
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return mapping
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}
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// UnmarshalJSON is a custom unmarshaling function to limit the set of allowed values
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// in case the input is JSON.
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func (arch Architecture) UnmarshalJSON(data []byte) error {
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value, err := unmarshalHelper(data, " is not a valid JSON value", " is not a valid architecture", getArchMapping())
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if err != nil {
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return err
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}
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arch = Architecture(value)
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return nil
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}
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// MarshalJSON is a custom marshaling function for our custom Architecture type
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func (arch Architecture) MarshalJSON() ([]byte, error) {
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return marshalHelper(int(arch), getArchMapping(), "is not a valid architecture tag")
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}
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type ImageType int
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// NOTE: If you want to add more constants here, don't forget to add a mapping below
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const (
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Alibaba ImageType = iota
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Azure
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Aws
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GoogleCloud
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HyperV
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LiveISO
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OpenStack
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Qcow2Generic
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Vmware
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)
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// getArchMapping is a helper function that defines the conversion from JSON string value
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// to ImageType.
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func getImageTypeMapping() map[string]int {
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mapping := map[string]int{
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"Alibaba": int(Alibaba),
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"Azure": int(Azure),
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"AWS": int(Aws),
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"Google Cloud": int(GoogleCloud),
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"Hyper-V": int(HyperV),
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"LiveISO": int(LiveISO),
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"OpenStack": int(OpenStack),
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"qcow2": int(Qcow2Generic),
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"VMWare": int(Vmware),
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}
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return mapping
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}
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func (imgType ImageType) UnmarshalJSON(data []byte) error {
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value, err := unmarshalHelper(data, " is not a valid JSON value", " is not a valid image type", getImageTypeMapping())
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if err != nil {
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return err
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}
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imgType = ImageType(value)
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return nil
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}
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func (imgType ImageType) MarshalJSON() ([]byte, error) {
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return marshalHelper(int(imgType), getImageTypeMapping(), "is not a valid image type tag")
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}
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type Distribution int
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// NOTE: If you want to add more constants here, don't forget to add a mapping below
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const (
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Fedora30 Distribution = iota
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Fedora31
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RHEL82
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)
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// getArchMapping is a helper function that defines the conversion from JSON string value
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// to Distribution.
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func getDistributionMapping() map[string]int {
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mapping := map[string]int{
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"fedora-30": int(Fedora30),
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"fedora-31": int(Fedora31),
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"rhel-8.2": int(RHEL82),
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}
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return mapping
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}
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func (distro Distribution) UnmarshalJSON(data []byte) error {
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value, err := unmarshalHelper(data, " is not a valid JSON value", " is not a valid distribution", getDistributionMapping())
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if err != nil {
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return err
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}
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distro = Distribution(value)
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return nil
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}
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func (distro Distribution) MarshalJSON() ([]byte, error) {
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return marshalHelper(int(distro), getDistributionMapping(), "is not a valid distribution tag")
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}
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type UploadTarget int
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// NOTE: If you want to add more constants here, don't forget to add a mapping below
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const (
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EC2 UploadTarget = iota
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AzureStorage // I mention "storage" explicitly because we might want to support gallery as well
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)
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// getArchMapping is a helper function that defines the conversion from JSON string value
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// to UploadTarget.
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func getUploadTargetMapping() map[string]int {
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mapping := map[string]int{
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"AWS EC2": int(EC2),
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"Azure storage": int(AzureStorage),
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}
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return mapping
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}
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func (ut UploadTarget) UnmarshalJSON(data []byte) error {
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value, err := unmarshalHelper(data, " is not a valid JSON value", " is not a valid upload target", getUploadTargetMapping())
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if err != nil {
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return err
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}
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ut = UploadTarget(value)
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return nil
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}
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func (ut UploadTarget) MarshalJSON() ([]byte, error) {
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return marshalHelper(int(ut), getUploadTargetMapping(), "is not a valid upload target tag")
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}
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type ImageRequest struct {
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ImgType ImageType `json:"image_type"`
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UpTarget []UploadTarget `json:"upload_targets"`
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}
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// ComposeRequest is used to submit a new compose to the store
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type ComposeRequest struct {
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BlueprintName string `json:"blueprint_name"`
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ComposeID uuid.UUID `json:"uuid"`
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Distro Distribution `json:"distro"`
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Arch Architecture `json:"arch"`
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RequestedImages []ImageRequest `json:"requested_images"`
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}
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101
internal/common/types_test.go
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101
internal/common/types_test.go
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@ -0,0 +1,101 @@
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package common
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import (
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"encoding/json"
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"github.com/google/uuid"
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"reflect"
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"testing"
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)
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func TestJSONConversionsComposeRequest(t *testing.T) {
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cases := []struct{
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input string
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expectedConversionResult ComposeRequest
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}{
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// 1st case
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{
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`
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{
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"blueprint_name": "foo",
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"uuid": "789b4d42-da1a-49c9-a20c-054da3bb6c82",
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"distro": "fedora-31",
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"arch": "x86_64",
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"requested_images": [
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{
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"image_type": "AWS",
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"upload_targets": ["AWS EC2"]
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}
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]
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}
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`,
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ComposeRequest{
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BlueprintName: "foo",
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ComposeID: uuid.UUID{},
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Distro: Fedora31,
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Arch: X86_64,
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RequestedImages: []ImageRequest{{
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ImgType: Aws,
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UpTarget: []UploadTarget{EC2},
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}},
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},
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},
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// 2nd case
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{
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`
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{
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"blueprint_name": "bar",
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"uuid": "789b4d42-da1a-49c9-a20c-054da3bb6c82",
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"distro": "rhel-8.2",
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"arch": "aarch64",
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"requested_images": [
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{
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"image_type": "Azure",
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"upload_targets": ["Azure storage", "AWS EC2"]
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}
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]
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}
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`,
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ComposeRequest{
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BlueprintName: "bar",
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ComposeID: uuid.UUID{},
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Distro: RHEL82,
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Arch: Aarch64,
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RequestedImages: []ImageRequest{{
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ImgType: Azure,
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UpTarget: []UploadTarget{AzureStorage, EC2},
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}},
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},
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},
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}
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for _, c := range cases {
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// Test unmashaling the JSON from the string above
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var inputStringAsStruct *ComposeRequest
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err := json.Unmarshal([]byte(c.input), &inputStringAsStruct)
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if err != nil {
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t.Fatal("Failed ot unmarshal ComposeRequest:", err)
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}
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if reflect.DeepEqual(inputStringAsStruct, c.expectedConversionResult) {
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t.Error("Unmarshaled compose request is not the one expected")
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}
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// Test marshaling the expected structure into JSON byte array, but since JSON package in golang std lib
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// does not have a canonical form (a 3rd party library is necessary) I convert it back to struct and
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// compare the resulting structure with the input one
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data, err := json.Marshal(c.expectedConversionResult)
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if err != nil {
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t.Fatal("Failed ot marshal ComposeRequest:", err)
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}
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var expectedResultAfterMarshaling *ComposeRequest
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err = json.Unmarshal(data, &expectedResultAfterMarshaling)
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if err != nil {
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t.Fatal("Failed ot unmarshal ComposeRequest:", err, ", input:", string(data))
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}
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if reflect.DeepEqual(expectedResultAfterMarshaling, c.expectedConversionResult) {
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t.Error("Marshaled compose request is not the one expected")
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}
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}
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}
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