envexpand

envexpand is replace placeholders in strings recursively with environment variables.

install

$ go get -u github.com/nissy/envexpand

example

environment variable placeholder.

${VARIABLE_NAME}

package main

import "github.com/nissy/envexpand"

type (
    ABC struct {
        A string
        B []string
        C map[int]string
        D *D
    }
    D struct {
        E string
        F *F
    }
    F struct {
        G int
        H string
        I []*I
    }
    I struct {
        J string
        K []map[int]string
        L []string
    }
)

func main() {
    data := ABC{
        A: "${A}",
        B: []string{
            "${B}",
            "${B}",
            "${B}",
        },
        D: &D{
            F: &F{
                I: []*I{
                    {
                        J: "${J}",
                    },
                    {
                        J: "${J}",
                        K: []map[int]string{
                            {
                                1: "${K}",
                                2: "${K}",
                            },
                        },
                        L: []string{
                            "${L}",
                            "${L}",
                        },
                    },
                },
            },
        },
    }

    if err := envexpand.Do(&data); err != nil {
        panic(err)
    }
}

$ echo A=$A B=$B J=$J K=$K L=$L
A=AAAAA B=BBBBB J=JJJJJ K=KKKKK L=LLLLL

main.ABC{
    A: "AAAAA",
    B: []string{
        "BBBBB",
        "BBBBB",
        "BBBBB",
    },
    C: map[int]string{},
    D: &main.D{
        E: "",
        F: &main.F{
            G: 0,
            H: "",
            I: []*main.I{
                &main.I{
                    J: "JJJJJ",
                    K: []map[int]string{},
                    L: []string{},
                },
                &main.I{
                    J: "JJJJJ",
                    K: []map[int]string{
                        map[int]string{
                            1: "KKKKK",
                            2: "KKKKK",
                        },
                    },
                    L: []string{
                        "LLLLL",
                        "LLLLL",
                    },
                },
            },
        },
    },
}