80 lines
2.0 KiB
Go
80 lines
2.0 KiB
Go
package mcfg
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import (
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"os"
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"strings"
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"github.com/mediocregopher/mediocre-go-lib/mcmp"
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"github.com/mediocregopher/mediocre-go-lib/mctx"
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"github.com/mediocregopher/mediocre-go-lib/merr"
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)
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// SourceEnv is a Source which will parse configuration from the process
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// environment.
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//
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// Possible Env options are generated by joining a Param's Path and Name with
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// underscores and making all characters uppercase, as well as changing all
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// dashes to underscores.
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//
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// cmp := new(mcmp.Component)
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// cmpFoo := cmp.Child("foo")
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// cmpFooBar := cmp.Child("bar")
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// addr := mcfg.String(cmpFooBar, "srv-addr", "", "Some address")
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// // the Env option to fill addr will be "FOO_BAR_SRV_ADDR"
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//
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type SourceEnv struct {
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// In the format key=value. Defaults to os.Environ() if nil.
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Env []string
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// If set then all expected Env options must be prefixed with this string,
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// which will be uppercased and have dashes replaced with underscores like
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// all the other parts of the option names.
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Prefix string
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}
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var _ Source = new(SourceEnv)
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func (env *SourceEnv) expectedName(path []string, name string) string {
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out := strings.Join(append(path, name), "_")
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if env.Prefix != "" {
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out = env.Prefix + "_" + out
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}
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out = strings.Replace(out, "-", "_", -1)
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out = strings.ToUpper(out)
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return out
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}
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// Parse implements the method for the Source interface.
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func (env *SourceEnv) Parse(cmp *mcmp.Component) ([]ParamValue, error) {
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kvs := env.Env
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if kvs == nil {
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kvs = os.Environ()
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}
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params := CollectParams(cmp)
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pM := map[string]Param{}
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for _, p := range params {
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name := env.expectedName(p.Component.Path(), p.Name)
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pM[name] = p
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}
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pvs := make([]ParamValue, 0, len(kvs))
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for _, kv := range kvs {
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split := strings.SplitN(kv, "=", 2)
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if len(split) != 2 {
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return nil, merr.New("malformed environment key/value pair",
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mctx.Annotated("kv", kv))
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}
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k, v := split[0], split[1]
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if p, ok := pM[k]; ok {
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pvs = append(pvs, ParamValue{
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Name: p.Name,
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Path: p.Component.Path(),
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Value: p.fuzzyParse(v),
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})
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}
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}
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return pvs, nil
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}
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