github.com/SigNoz/golang-migrate/v4@v4.0.0-20231005133642-7493dbaf5f5b/template.go (about)

     1  package migrate
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  	"os"
     7  	"strings"
     8  	"text/template"
     9  )
    10  
    11  var envMapCache map[string]string
    12  
    13  func envMap() map[string]string {
    14  	if envMapCache != nil {
    15  		return envMapCache
    16  	}
    17  	envMapCache = make(map[string]string)
    18  	for _, kvp := range os.Environ() {
    19  		kvParts := strings.SplitN(kvp, "=", 2)
    20  		envMapCache[kvParts[0]] = kvParts[1]
    21  	}
    22  	return envMapCache
    23  }
    24  
    25  func applyEnvironmentTemplate(body io.ReadCloser) (io.ReadCloser, error) {
    26  	bodyBytes, err := io.ReadAll(body)
    27  	if err != nil {
    28  		return nil, fmt.Errorf("reading body: %w", err)
    29  	}
    30  	defer func() {
    31  		_ = body.Close()
    32  	}()
    33  
    34  	tmpl, err := template.New("migration").Parse(string(bodyBytes))
    35  	if err != nil {
    36  		return nil, fmt.Errorf("parsing template: %w", err)
    37  	}
    38  
    39  	r, w := io.Pipe()
    40  
    41  	go func() {
    42  		_ = tmpl.Execute(w, envMap())
    43  		_ = w.Close()
    44  	}()
    45  
    46  	return r, nil
    47  }