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Config module

This module provides features to read and merge Flamingo configurations. Also it provides template functions to access configurations in your template.

Configurations are defined and used by the individual modules. The modules should come with a documentation which configurations/feature-flags they support.

Basics

Configurations are yml files located in config folder.

The configuration syntax is to specify sections either with . or as yaml maps:

foo:
  bar: x

is the same as

foo.bar: x

Configuration values can also be read from environment variables during the loading process with the syntax:

auth.secret: '%%ENV:KEYCLOAK_SECRET%%'

or

auth.secret: '%%ENV:KEYCLOAK_SECRET%%default_value%%'

In the second case, Flamingo falls back to default_value if the environment variable is not set or empty.

Configuration can be used:

  • either by the config() templatefunction in your template
  • or via dependency injection from Dingo

Loaded Configuration files

The following configuration files will be loaded from config folder:

  • config.yml
  • routes.yml
  • optional: config_($CONTEXT).yml
  • optional: routes_($CONTEXT).yml
  • config_local.yml
  • routes_local.yml

You can set different contexts with the environment variable CONTEXT and this will cause Flamingo to load additional configuration files.

e.g. starting Flamingo with

CONTEXT="dev" go run project.go serve

Will cause Flamingo to additionally load the config file config/config_dev.yml

You can also load multiple extra configuration files - e.g. starting Flamingo with

CONTEXT="dev:testdata" go run project.go serve

Will cause Flamingo to additionally load the config files "config/config_dev.yml" and "config/config_testdata.yml" in the given order.

Additional configuration files from outside

Flamingo can load multiple additional yaml files, which must be given in the environment variable CONTEXTFILE, separated by :.

The files can be given by using relative paths from the working directory or absolute paths.

CONTEXTFILE="../../myCfg.yml:/var/flamingo/cfg/main.yml" go run project.go serve

Additional temporary configuration

You can set any configuration value within the run command by using the --flamingo-config flag:

go run project.go serve --flamingo-config "auth.secret: mySecret" --flamingo-config "other.secret: mySecret"

The flag's values are expected to be valid yaml. The flag can be used multiple times.

Configurations provided via --flamingo-config flag overwrite all values provided in yaml files.

Priority of configuration

If multiple sources define the same configuration key, the value from the last loaded source is taken. The order of loading is:

  1. All files from config directory
  2. config.yml
  3. routes.yml
  4. All context files given in the environment variable CONTEXT
    1. config_($CONTEXT).yml
    2. routes_($CONTEXT).yml
  5. config_local.yml
  6. routes_local.yml
  7. All files given in the environment variable CONTEXTFILE
  8. All values given via --flamingo-config flag

Debugging configuration loading

By stating --flamingo-config-log, you can enable the configuration loader's debug log, which prints all handled files to the output using go's log package, because the flamingo.Logger is not available yet in this early state of bootstrapping.

Injecting configurations

Asking for either a concrete value via e.g. foo.bar is possible, as well as getting a whole config.Map instance by a partially-selector, e.g. foo. This would be a Map with element bar.

All configuration values are registered as Dingo annotated binding and can be requested using the inject tag. To get this in the arguments of the Inject function or a dingo provider, you will have to wrap it by an anonymous struct.

For example:

// Inject dependencies
func (m *Module) Inject(
    cfg *struct {
    CompleteConfig config.Map `inject:"config:mymodule"`
    Title          string     `inject:"config:mymodule.title"`
    Amount         float64    `inject:"config:mymodule.amount"`
    Flag           bool       `inject:"config:mymodule.flag"`
},
) *Module {
    if cfg != nil {
        m.title = cfg.Title
        m.amount = cfg.Amount
        m.flag = cfg.Flag
        m.cfg = cfg.CompleteConfig
    }

    return m
}

Note, that a number injection will always be delivered as float64 type. This is the default behaviour of the underlying yaml unmarshaller github.com/ghodss/yaml.

Deeply nested config maps can be marshaled into structs for convenience.

The result struct must match exactly the structure and types of the config map and all fields must be exported.

err := m.MarshalTo(&result)

Using multiple configuration areas:

A Flamingo application can have multiple config.Area - that is essentially useful for localisation. See Flamingo Bootstrap