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"
"github.com/hashicorp/terraform/svchost/disco"
"github.com/hashicorp/terraform/tfdiags"
backendatlas "github.com/hashicorp/terraform/backend/atlas"
backendlocal "github.com/hashicorp/terraform/backend/local"
backendartifactory "github.com/hashicorp/terraform/backend/remote-state/artifactory"
backendAzure "github.com/hashicorp/terraform/backend/remote-state/azure"
backendconsul "github.com/hashicorp/terraform/backend/remote-state/consul"
backendetcdv2 "github.com/hashicorp/terraform/backend/remote-state/etcdv2"
backendetcdv3 "github.com/hashicorp/terraform/backend/remote-state/etcdv3"
backendGCS "github.com/hashicorp/terraform/backend/remote-state/gcs"
backendhttp "github.com/hashicorp/terraform/backend/remote-state/http"
backendinmem "github.com/hashicorp/terraform/backend/remote-state/inmem"
backendManta "github.com/hashicorp/terraform/backend/remote-state/manta"
backendS3 "github.com/hashicorp/terraform/backend/remote-state/s3"
backendSwift "github.com/hashicorp/terraform/backend/remote-state/swift"
"github.com/zclconf/go-cty/cty"
)
// 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(services *disco.Disco) {
// 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{
"artifactory": func() backend.Backend { return backendartifactory.New() },
"atlas": func() backend.Backend { return &backendatlas.Backend{} },
"http": func() backend.Backend { return backendhttp.New() },
"local": func() backend.Backend { return &backendlocal.Local{} },
"consul": func() backend.Backend { return backendconsul.New() },
"inmem": func() backend.Backend { return backendinmem.New() },
"swift": func() backend.Backend { return backendSwift.New() },
"s3": func() backend.Backend { return backendS3.New() },
"azurerm": func() backend.Backend { return backendAzure.New() },
"etcd": func() backend.Backend { return backendetcdv2.New() },
"etcdv3": func() backend.Backend { return backendetcdv3.New() },
"gcs": func() backend.Backend { return backendGCS.New() },
"manta": func() backend.Backend { return backendManta.New() },
"azure": func() backend.Backend {
return deprecateBackend(
backendAzure.New(),
`Warning: "azure" name is deprecated, please use "azurerm"`,
)
},
}
}
// 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
}
// deprecatedBackendShim is used to wrap a backend and inject a deprecation
// warning into the Validate method.
type deprecatedBackendShim struct {
backend.Backend
Message string
}
// ValidateConfig delegates to the wrapped backend to validate its config
// and then appends shim's deprecation warning.
func (b deprecatedBackendShim) ValidateConfig(obj cty.Value) tfdiags.Diagnostics {
diags := b.Backend.ValidateConfig(obj)
return diags.Append(tfdiags.SimpleWarning(b.Message))
}
// DeprecateBackend can be used to wrap a backend to retrun a deprecation
// warning during validation.
func deprecateBackend(b backend.Backend, message string) backend.Backend {
// Since a Backend wrapped by deprecatedBackendShim can no longer be
// asserted as an Enhanced or Local backend, disallow those types here
// entirely. If something other than a basic backend.Backend needs to be
// deprecated, we can add that functionality to schema.Backend or the
// backend itself.
if _, ok := b.(backend.Enhanced); ok {
panic("cannot use DeprecateBackend on an Enhanced Backend")
}
if _, ok := b.(backend.Local); ok {
panic("cannot use DeprecateBackend on a Local Backend")
}
return deprecatedBackendShim{
Backend: b,
Message: message,
}
}