terraform/backend/init/init.go

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// Package init contains the list of backends that can be initialized and
// basic helper functions for initializing those backends.
package init
import (
"sync"
"github.com/hashicorp/terraform/backend"
backendatlas "github.com/hashicorp/terraform/backend/atlas"
backendlegacy "github.com/hashicorp/terraform/backend/legacy"
backendlocal "github.com/hashicorp/terraform/backend/local"
backendconsul "github.com/hashicorp/terraform/backend/remote-state/consul"
backendinmem "github.com/hashicorp/terraform/backend/remote-state/inmem"
backendS3 "github.com/hashicorp/terraform/backend/remote-state/s3"
)
// backends is the list of available backends. This is a global variable
// because backends are currently hardcoded into Terraform and can't be
// modified without recompilation.
//
// To read an available backend, use the Backend function. This ensures
// safe concurrent read access to the list of built-in backends.
//
// Backends are hardcoded into Terraform because the API for backends uses
// complex structures and supporting that over the plugin system is currently
// prohibitively difficult. For those wanting to implement a custom backend,
// they can do so with recompilation.
var backends map[string]func() backend.Backend
var backendsLock sync.Mutex
func init() {
// Our hardcoded backends. We don't need to acquire a lock here
// since init() code is serial and can't spawn goroutines.
backends = map[string]func() backend.Backend{
"atlas": func() backend.Backend { return &backendatlas.Backend{} },
"local": func() backend.Backend { return &backendlocal.Local{} },
"consul": func() backend.Backend { return backendconsul.New() },
"inmem": func() backend.Backend { return backendinmem.New() },
"s3": func() backend.Backend { return backendS3.New() },
}
// Add the legacy remote backends that haven't yet been convertd to
// the new backend API.
backendlegacy.Init(backends)
}
// Backend returns the initialization factory for the given backend, or
// nil if none exists.
func Backend(name string) func() backend.Backend {
backendsLock.Lock()
defer backendsLock.Unlock()
return backends[name]
}
// Set sets a new backend in the list of backends. If f is nil then the
// backend will be removed from the map. If this backend already exists
// then it will be overwritten.
//
// This method sets this backend globally and care should be taken to do
// this only before Terraform is executing to prevent odd behavior of backends
// changing mid-execution.
func Set(name string, f func() backend.Backend) {
backendsLock.Lock()
defer backendsLock.Unlock()
if f == nil {
delete(backends, name)
return
}
backends[name] = f
}