github.com/jd3nn1s/terraform@v0.9.6-0.20170906225847-13878347b7a1/backend/init/init.go (about)

     1  // Package init contains the list of backends that can be initialized and
     2  // basic helper functions for initializing those backends.
     3  package init
     4  
     5  import (
     6  	"sync"
     7  
     8  	"github.com/hashicorp/terraform/backend"
     9  	"github.com/hashicorp/terraform/terraform"
    10  
    11  	backendatlas "github.com/hashicorp/terraform/backend/atlas"
    12  	backendlegacy "github.com/hashicorp/terraform/backend/legacy"
    13  	backendlocal "github.com/hashicorp/terraform/backend/local"
    14  	backendAzure "github.com/hashicorp/terraform/backend/remote-state/azure"
    15  	backendconsul "github.com/hashicorp/terraform/backend/remote-state/consul"
    16  	backendinmem "github.com/hashicorp/terraform/backend/remote-state/inmem"
    17  	backendS3 "github.com/hashicorp/terraform/backend/remote-state/s3"
    18  	backendSwift "github.com/hashicorp/terraform/backend/remote-state/swift"
    19  )
    20  
    21  // backends is the list of available backends. This is a global variable
    22  // because backends are currently hardcoded into Terraform and can't be
    23  // modified without recompilation.
    24  //
    25  // To read an available backend, use the Backend function. This ensures
    26  // safe concurrent read access to the list of built-in backends.
    27  //
    28  // Backends are hardcoded into Terraform because the API for backends uses
    29  // complex structures and supporting that over the plugin system is currently
    30  // prohibitively difficult. For those wanting to implement a custom backend,
    31  // they can do so with recompilation.
    32  var backends map[string]func() backend.Backend
    33  var backendsLock sync.Mutex
    34  
    35  func init() {
    36  	// Our hardcoded backends. We don't need to acquire a lock here
    37  	// since init() code is serial and can't spawn goroutines.
    38  	backends = map[string]func() backend.Backend{
    39  		"atlas":  func() backend.Backend { return &backendatlas.Backend{} },
    40  		"local":  func() backend.Backend { return &backendlocal.Local{} },
    41  		"consul": func() backend.Backend { return backendconsul.New() },
    42  		"inmem":  func() backend.Backend { return backendinmem.New() },
    43  		"swift":  func() backend.Backend { return backendSwift.New() },
    44  		"s3":     func() backend.Backend { return backendS3.New() },
    45  		"azure": deprecateBackend(backendAzure.New(),
    46  			`Warning: "azure" name is deprecated, please use "azurerm"`),
    47  		"azurerm": func() backend.Backend { return backendAzure.New() },
    48  	}
    49  
    50  	// Add the legacy remote backends that haven't yet been convertd to
    51  	// the new backend API.
    52  	backendlegacy.Init(backends)
    53  }
    54  
    55  // Backend returns the initialization factory for the given backend, or
    56  // nil if none exists.
    57  func Backend(name string) func() backend.Backend {
    58  	backendsLock.Lock()
    59  	defer backendsLock.Unlock()
    60  	return backends[name]
    61  }
    62  
    63  // Set sets a new backend in the list of backends. If f is nil then the
    64  // backend will be removed from the map. If this backend already exists
    65  // then it will be overwritten.
    66  //
    67  // This method sets this backend globally and care should be taken to do
    68  // this only before Terraform is executing to prevent odd behavior of backends
    69  // changing mid-execution.
    70  func Set(name string, f func() backend.Backend) {
    71  	backendsLock.Lock()
    72  	defer backendsLock.Unlock()
    73  
    74  	if f == nil {
    75  		delete(backends, name)
    76  		return
    77  	}
    78  
    79  	backends[name] = f
    80  }
    81  
    82  // deprecatedBackendShim is used to wrap a backend and inject a deprecation
    83  // warning into the Validate method.
    84  type deprecatedBackendShim struct {
    85  	backend.Backend
    86  	Message string
    87  }
    88  
    89  // Validate the Backend then add the deprecation warning.
    90  func (b deprecatedBackendShim) Validate(c *terraform.ResourceConfig) ([]string, []error) {
    91  	warns, errs := b.Backend.Validate(c)
    92  	warns = append(warns, b.Message)
    93  	return warns, errs
    94  }
    95  
    96  // DeprecateBackend can be used to wrap a backend to retrun a deprecation
    97  // warning during validation.
    98  func deprecateBackend(b backend.Backend, message string) func() backend.Backend {
    99  	// Since a Backend wrapped by deprecatedBackendShim can no longer be
   100  	// asserted as an Enhanced or Local backend, disallow those types here
   101  	// entirely.  If something other than a basic backend.Backend needs to be
   102  	// deprecated, we can add that functionality to schema.Backend or the
   103  	// backend itself.
   104  	if _, ok := b.(backend.Enhanced); ok {
   105  		panic("cannot use DeprecateBackend on an Enhanced Backend")
   106  	}
   107  
   108  	if _, ok := b.(backend.Local); ok {
   109  		panic("cannot use DeprecateBackend on a Local Backend")
   110  	}
   111  
   112  	return func() backend.Backend {
   113  		return deprecatedBackendShim{
   114  			Backend: b,
   115  			Message: message,
   116  		}
   117  	}
   118  }