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Gonfique

Gonfique logo

Gonfique is a CLI tool for Go developers to automatically build exact struct definitions in Go that will match the provided YAML or JSON config. Makes instant to notice when and where a breaking change occurs. Since compiler warns whenever it happens by type-checking, and source control shows where the change exactly is.

TOC

Full example

Say this file is your input:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
  namespace: my-namespace
type: Opaque
data:
  my-key: my-value
  password: cGFzc3dvcmQ=
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  rules:
    - host: myapp.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-service
                port:
                  number: 80
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: my-image
          ports:
            - containerPort: 80
          envFrom:
            - configMapRef:
                name: my-config
            - secretRef:
                name: my-secret

Output with nested declarations

Gonfique creates the most compact type declaration for the provided file when it's not supplied a mapping file or the flag --organize. The file will contain only one declaration with all sub-structs defined inlined. Such as:

package config

import (
  "fmt"
  "os"

  "gopkg.in/yaml.v3"
)

type Config struct {
  ApiVersion string `yaml:"apiVersion"`
  Data       struct {
    MyKey    string `yaml:"my-key"`
    Password string `yaml:"password"`
  } `yaml:"data"`
  Kind     string `yaml:"kind"`
  Metadata struct {
    Name      string `yaml:"name"`
    Namespace string `yaml:"namespace"`
  } `yaml:"metadata"`
  Spec struct {
    Ports []struct {
      Port       int    `yaml:"port"`
      Protocol   string `yaml:"protocol"`
      TargetPort int    `yaml:"targetPort"`
    } `yaml:"ports"`
    Replicas int `yaml:"replicas"`
    Rules    []struct {
      Host string `yaml:"host"`
      Http struct {
        Paths []struct {
          Backend struct {
            Service struct {
              Name string `yaml:"name"`
              Port struct {
                Number int `yaml:"number"`
              } `yaml:"port"`
            } `yaml:"service"`
          } `yaml:"backend"`
          Path     string `yaml:"path"`
          PathType string `yaml:"pathType"`
        } `yaml:"paths"`
      } `yaml:"http"`
    } `yaml:"rules"`
    Selector struct {
      MatchLabels struct {
        App string `yaml:"app"`
      } `yaml:"matchLabels"`
    } `yaml:"selector"`
    Template struct {
      Metadata struct {
        Labels struct {
          App string `yaml:"app"`
        } `yaml:"labels"`
      } `yaml:"metadata"`
      Spec struct {
        Containers []struct {
          EnvFrom []struct {
            ConfigMapRef struct {
              Name string `yaml:"name"`
            } `yaml:"configMapRef"`
            SecretRef struct {
              Name string `yaml:"name"`
            } `yaml:"secretRef"`
          } `yaml:"envFrom"`
          Image string `yaml:"image"`
          Name  string `yaml:"name"`
          Ports []struct {
            ContainerPort int `yaml:"containerPort"`
          } `yaml:"ports"`
        } `yaml:"containers"`
      } `yaml:"spec"`
    } `yaml:"template"`
  } `yaml:"spec"`
  Type string `yaml:"type"`
}

func ReadConfig(path string) (Config, error) {
  file, err := os.Open(path)
  if err != nil {
    return Config{}, fmt.Errorf("opening config file: %w", err)
  }
  defer file.Close()
  c := Config{}
  err = yaml.NewDecoder(file).Decode(&c)
  if err != nil {
    return Config{}, fmt.Errorf("decoding config file: %w", err)
  }
  return c, nil
}

Creating separate (named) type declarations

You can create named declarations for types you want. Just provide a mapping file that contains the "paths" of targets and the typename you pick. Pass the path of this file as an argument (via --mappings <path>) to gonfique. See docs: Mapping file

apiVersion: ApiVersion
metadata.name: Name
spec.rules.[]: Rule
spec.rules.[].http.paths.[]: Path
spec.ports.[]: Port
spec.**.containers: SpecContainers
spec.**.containers.[]: SpecContainer
spec.**.containers.[].name: ContainerName

This time the generated file would contain additional types as the mappings file directs. The main type declaration refers to those type in related substructures.

// ...

type ApiVersion string
type ContainerName string
type Name string
type Path struct {
  Backend struct {
    Service struct {
      Name string `yaml:"name"`
      Port struct {
        Number int `yaml:"number"`
      } `yaml:"port"`
    } `yaml:"service"`
  } `yaml:"backend"`
  Path     string `yaml:"path"`
  PathType string `yaml:"pathType"`
}
type Port struct {
  Port       int    `yaml:"port"`
  Protocol   string `yaml:"protocol"`
  TargetPort int    `yaml:"targetPort"`
}
type Rule struct {
  Host string `yaml:"host"`
  Http struct {
    Paths []Path `yaml:"paths"`
  } `yaml:"http"`
}
type SpecContainer struct {
  EnvFrom []struct {
    ConfigMapRef struct {
      Name string `yaml:"name"`
    } `yaml:"configMapRef"`
    SecretRef struct {
      Name string `yaml:"name"`
    } `yaml:"secretRef"`
  } `yaml:"envFrom"`
  Image string        `yaml:"image"`
  Name  ContainerName `yaml:"name"`
  Ports []struct {
    ContainerPort int `yaml:"containerPort"`
  } `yaml:"ports"`
}
type SpecContainers []SpecContainer
type Config struct {
  ApiVersion ApiVersion `yaml:"apiVersion"`
  Data       struct {
    MyKey    string `yaml:"my-key"`
    Password string `yaml:"password"`
  } `yaml:"data"`
  Kind     string `yaml:"kind"`
  Metadata struct {
    Name      Name   `yaml:"name"`
    Namespace string `yaml:"namespace"`
  } `yaml:"metadata"`
  Spec struct {
    Ports    []Port `yaml:"ports"`
    Replicas int    `yaml:"replicas"`
    Rules    []Rule `yaml:"rules"`
    Selector struct {
      MatchLabels struct {
        App string `yaml:"app"`
      } `yaml:"matchLabels"`
    } `yaml:"selector"`
    Template struct {
      Metadata struct {
        Labels struct {
          App string `yaml:"app"`
        } `yaml:"labels"`
      } `yaml:"metadata"`
      Spec struct {
        Containers SpecContainers `yaml:"containers"`
      } `yaml:"spec"`
    } `yaml:"template"`
  } `yaml:"spec"`
  Type string `yaml:"type"`
}

// ...

See outputs for different flag combinations:

Install

Use version tags to avoid development versions as such:

go install github.com/ufukty/[email protected]

Usage

gonfique -in config.yml -out config.go -pkg main [-type-name "Config"] [-use "use.go"] [-organize] [-mappings "mappings.yml"]

Run gonfique --help for parameter details.

Features

  • Works offline
  • Specify names for detected types via -mapping flag to export safely. More
  • Defines named or inline types depending on user choice (-organize flag).
  • Reuses user-defined types provided in a file when schemas match via -use flag
  • Supports arrays:
    • When all array items share same schema; array types are generated as []<item type>.
    • When all array items don't share same schema, but all items are compatible; array types are generated as []<combined item types>.
  • Supports dictionaries:
    • Implements .Range() method on those dictionaries that all values share same schema, so they can be iterable via for loops. Such as for service, details := range cfg.Services.Range() { ... }
  • Supports time.Duration values such as 200ms or 1µs.
  • Supports JSON and YAML config files.

Docs

Limitations

  • Multidocument YAML files are not supported.
  • Mapping file is for generating an exported type definition with the given name and detected type; not to specify type.
  • Type of keys with value of null gets assigned as any.

Contribution

Issues are open for discussions and rest.

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License

Apache2. See LICENSE file.