templatefile/pkg/utils/templates.go

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package utils
import (
"bytes"
"encoding/json"
"fmt"
"os"
"text/template"
"github.com/hashicorp/hcl/v2"
"github.com/hashicorp/hcl/v2/hclsyntax"
"github.com/zclconf/go-cty/cty"
ctyjson "github.com/zclconf/go-cty/cty/json"
)
// The actual template processing for Go templates
func ProcessGoTemplate(file string, configValues []byte) (string, error) {
// The JSON configuration
var confData map[string]interface{}
var res bytes.Buffer
err := json.Unmarshal(configValues, &confData)
CheckErr(err)
// Read the template
templateData, err := os.ReadFile(file)
CheckErr(err)
tpl, err := template.New("conf").Parse(string(templateData))
CheckErr(err)
CheckErr(tpl.Execute(&res, confData))
return res.String(), nil
}
// The actual template processing for HCL templates
func ProcessHCLTemplate(file string, config []byte) (string, error) {
fct, err := os.ReadFile(file)
CheckErr(err)
expr, diags := hclsyntax.ParseTemplate(fct, file, hcl.Pos{Line: 0, Column: 1})
CheckDiags(diags)
// Retrieve values from JSON
var varsVal cty.Value
ctyType, err := ctyjson.ImpliedType(config)
if err != nil {
return "", err
/* Maybe one day
cexpr, diags := hclsyntax.ParseExpression(config, "", hcl.Pos{Line: 0, Column: 1})
if diags.HasErrors() {
panic(diags.Error())
}
varsVal, diags = cexpr.Value(&hcl.EvalContext{})
fmt.Println(cexpr.Variables())
checkDiags(diags)
*/
} else {
varsVal, err = ctyjson.Unmarshal(config, ctyType)
CheckErr(err)
}
ctx := &hcl.EvalContext{
Variables: varsVal.AsValueMap(),
}
for n := range ctx.Variables {
if !hclsyntax.ValidIdentifier(n) {
return "", fmt.Errorf("invalid template variable name %q: must start with a letter, followed by zero or more letters, digits, and underscores", n)
}
}
for _, traversal := range expr.Variables() {
root := traversal.RootName()
if _, ok := ctx.Variables[root]; !ok {
return "", fmt.Errorf("vars map does not contain key %q, referenced at %s", root, traversal[0].SourceRange())
}
}
val, diags := expr.Value(ctx)
if diags.HasErrors() {
return "", diags
}
return val.AsString(), nil
}