example.rconf

////////////////////////////////////////////////////////////////////////////////
// This is an example of a proposed configuration language for restic,
// based on Hashpicorp's HCL.
//
// The main feature of the grammar in this example are:
//
//    - More than one repository can be defined in a single configuration file.
//    - Some aspects of the configuration (i.e. backends definitions) can be
//      shared by different repositories.
//    - Support for multiple backends for a single repository.
//
// More over, using HCL as a base for this configuration language has the
// following intrinsic upsides:
//
//    - Support for comments.
//    - The syntax is very easy to understand (well, at least when not using ).
//    - Relatively easy to implement in Go (the HCL2 module is both powerful
//      and simple to use).
//    - The HCL Go module has a very light dependency tree.
////////////////////////////////////////////////////////////////////////////////


defaults {
    quiet = false
    verbose = 0
}


////////////////////////////////////////////////////////////////////////////////
// Repositories specification

repo "myrepo" {
    backends = [ backends.local1, backends.s3 ]

    backup_options {
        target = [
            "/home/user/",
            "/home/otheruser",
        ]

        exclude = ["*.c"]
    }
}

repo "myrepo" {
    backend = backends.local1
}


////////////////////////////////////////////////////////////////////////////////
// Backends specification

backend "local" "local1" {
    path = "/foo/bar"
}

backend "local" "local2" {
    path = "/foo/bar"
}

backend "sftp" {
    host = "bar"
    port = 2222
    user = "foo"
    password = "secret"
    path = "/foo/bar"
}

backend "s3" {
    user = "foo"
    host = "bar"
    path = "/foo/bar"
}

restic_config_types.go

// This is an outline of Go types required to support the HCL configuration
// proposed above. Anotations are based on HCL2 (see references).
//
// References:
// https://github.com/hashicorp/hcl2/tree/master/guide
// https://godoc.org/github.com/hashicorp/hcl2


type Config struct {
    *Defaults           DefaultRepositoryOptions    `hcl:"defaults,block"`
    Repositories        Repository[]                `hcl:"repo,block"`
    Backends            Backend[]                   `hcl:"backend,block"`
}


type Backend struct {
    Type                string                      `hcl:"type,label"`
    *Name               string                      `hcl:"name,label"`
    
    // This will contain undecoded HCL attributes for this block
    // that are specific to the backend type
    Remain              hcl.Body                    `hcl:",remain"`
    
    // This will contain decoded attributes for this block;
    // the exact struct type will depend on the value of the Type field
    *BackendDetails     interface{}
}


type BackendDetailsLocal struct {
    Path                string                      `hcl:"path"`
}


type BackendDetailsSFTP struct {
    Host                string                      `hcl:"host"`
    *Port               uint16                      `hcl:"port"`
    User                string                      `hcl:"user"`
    *Password           string                      `hcl:"password"`
    Path                string                      `hcl:"path"`
}


type BackendDetailsS3 struct {
    Bucket              string                      `hcl:"bucket"`
    AccessKey           string                      `hcl:"access_key"`
    AccessSecret        string                      `hcl:"access_secret"`
    *Path               string                      `hcl:"path"`
}


type DefaultRepositoryOptions struct {
    BackupOptions       BackupOptions               `hcl:"backup_options"`
    Quiet               bool                        `hcl:"quiet"`
    Verbose             uint8                       `hcl:"verbose"`
}


type Repository struct {
    Backends            []Backend                   `hcl:"backends"`
    BackupOptions       BackupOptions               `hcl:"backup_options"`
    Quiet               bool                        `hcl:"quiet"`
    Verbose             uint8                       `hcl:"verbose"`
}


type BackupOptions struct {
    Target              []string                    `hcl:"target"`
    Excludes            []string                    `hcl:"exclude"`
}