vers

Documentation

Overview

Package vers contains the common versions parsing which is required by all config versions. Two versions are tracked here, namely the configuration files and database schema (and other aspects which may need migration support can be added later). The idea is that versions should be known before trying to obtain and parse the actual data, so the actual data format can be known and verified when loading them and although the format of keeping versions may change too, but it is less likely to change over time.

Index

• type Config
  • func Load(data []byte) (*Config, error)
  • func (vc *Config) Marshal() *Marshalled
  • func (vc *Config) Validate(major, minor uint) error
• type Marshalled
• type Versions

Types

type Config

type Config struct {
	Versions Versions `yaml:"versions"`
}

Config contains the versions of those system components which should be supported in the migration operations. It may be embedded with inline format in the released config struct versions in order to indicate their versions and relevant items format.

func Load

func Load(data []byte) (*Config, error)

Load deserializes the data byte slice into a new instance of Config struct. Of course, data may contain extra fields which will be ignored. The deserialized version fields (in the returned Config) can be used to detect the format of other settings in the data and complete deserialization of the remaining fields.

func (*Config) Marshal

func (vc *Config) Marshal() *Marshalled

Marshal creates and returns a Marshalled instance representing the vc Config instance. It may be serialized instead of vc to YAML format.

func (*Config) Validate

func (vc *Config) Validate(major, minor uint) error

Validate returns an error if the configuration settings version which is stored in the `vc` Config instance is not supported by the given major and minor version arguments. That is, stored major version must match with the major argument and the stored minor version must be at most equal with the given minor version (not newer than it).

type Marshalled

type Marshalled struct {
	Versions struct {
		Database string
		Config   string
	}
}

Marshalled is an alternative form of Config struct which replaces its model.SemVer inner fields by their string representation. The Marshalled is used during the YAML serialization operation instead of the main Config struct.

The yaml.Marshaler interface with MarshalYAML method may be used by a struct in order to provide an alternative value to be serialized instead of the main value at hand. However, MarshalYAML is only used for replacing the most top level value, where the serialization begin from. The Marshalled struct (returned by the Marshal method) allows multiple nested structs to participate in this value replacement during a serialization operation.

type Versions

type Versions struct {
	Database model.SemVer `yaml:"database"`
	Config   model.SemVer `yaml:"config"`
}

Versions contains the configuration file and database schema versions which are used for detecting their relevant formats. Although different versions may be supported by system migration operations, each binary only supports the latest version which is known to that binary for its non-migration operations.