78 lines
2.4 KiB
Go
78 lines
2.4 KiB
Go
// Package env implements encoding and decoding between environment variable and a typed Configuration.
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package env
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import (
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"fmt"
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"regexp"
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"strings"
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"github.com/containous/traefik/v2/pkg/config/parser"
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)
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// DefaultNamePrefix is the default prefix for environment variable names.
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const DefaultNamePrefix = "TRAEFIK_"
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// Decode decodes the given environment variables into the given element.
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// The operation goes through four stages roughly summarized as:
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// env vars -> map
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// map -> tree of untyped nodes
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// untyped nodes -> nodes augmented with metadata such as kind (inferred from element)
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// "typed" nodes -> typed element.
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func Decode(environ []string, prefix string, element interface{}) error {
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if err := checkPrefix(prefix); err != nil {
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return err
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}
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vars := make(map[string]string)
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for _, evr := range environ {
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n := strings.SplitN(evr, "=", 2)
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if strings.HasPrefix(strings.ToUpper(n[0]), prefix) {
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key := strings.ReplaceAll(strings.ToLower(n[0]), "_", ".")
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vars[key] = n[1]
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}
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}
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rootName := strings.ToLower(prefix[:len(prefix)-1])
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return parser.Decode(vars, element, rootName)
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}
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// Encode encodes the configuration in element into the environment variables represented in the returned Flats.
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// The operation goes through three stages roughly summarized as:
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// typed configuration in element -> tree of untyped nodes
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// untyped nodes -> nodes augmented with metadata such as kind (inferred from element)
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// "typed" nodes -> environment variables with default values (determined by type/kind).
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func Encode(element interface{}) ([]parser.Flat, error) {
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if element == nil {
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return nil, nil
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}
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etnOpts := parser.EncoderToNodeOpts{OmitEmpty: false, TagName: parser.TagLabel, AllowSliceAsStruct: true}
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node, err := parser.EncodeToNode(element, parser.DefaultRootName, etnOpts)
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if err != nil {
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return nil, err
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}
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metaOpts := parser.MetadataOpts{TagName: parser.TagLabel, AllowSliceAsStruct: true}
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err = parser.AddMetadata(element, node, metaOpts)
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if err != nil {
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return nil, err
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}
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flatOpts := parser.FlatOpts{Case: "upper", Separator: "_", TagName: parser.TagLabel}
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return parser.EncodeToFlat(element, node, flatOpts)
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}
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func checkPrefix(prefix string) error {
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prefixPattern := `[a-zA-Z0-9]+_`
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matched, err := regexp.MatchString(prefixPattern, prefix)
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if err != nil {
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return err
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}
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if !matched {
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return fmt.Errorf("invalid prefix %q, the prefix pattern must match the following pattern: %s", prefix, prefixPattern)
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}
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return nil
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}
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