terraform/backend/backend.go

281 lines
11 KiB
Go

// Package backend provides interfaces that the CLI uses to interact with
// Terraform. A backend provides the abstraction that allows the same CLI
// to simultaneously support both local and remote operations for seamlessly
// using Terraform in a team environment.
package backend
import (
"context"
"errors"
"time"
"github.com/zclconf/go-cty/cty"
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/command/clistate"
"github.com/hashicorp/terraform/configs/configschema"
"github.com/hashicorp/terraform/configs"
"github.com/hashicorp/terraform/configs/configload"
"github.com/hashicorp/terraform/state"
"github.com/hashicorp/terraform/terraform"
"github.com/hashicorp/terraform/tfdiags"
)
// DefaultStateName is the name of the default, initial state that every
// backend must have. This state cannot be deleted.
const DefaultStateName = "default"
// This must be returned rather than a custom error so that the Terraform
// CLI can detect it and handle it appropriately.
var (
// ErrDefaultStateNotSupported is returned when an operation does not support
// using the default state, but requires a named state to be selected.
ErrDefaultStateNotSupported = errors.New("default state not supported\n" +
"You can create a new workspace with the \"workspace new\" command.")
// ErrNamedStatesNotSupported is returned when a named state operation
// isn't supported.
ErrNamedStatesNotSupported = errors.New("named states not supported")
// ErrOperationNotSupported is returned when an unsupported operation
// is detected by the configured backend.
ErrOperationNotSupported = errors.New("operation not supported")
)
// InitFn is used to initialize a new backend.
type InitFn func() Backend
// Backend is the minimal interface that must be implemented to enable Terraform.
type Backend interface {
// ConfigSchema returns a description of the expected configuration
// structure for the receiving backend.
//
// This method does not have any side-effects for the backend and can
// be safely used before configuring.
ConfigSchema() *configschema.Block
// ValidateConfig checks the validity of the values in the given
// configuration, assuming that its structure has already been validated
// per the schema returned by ConfigSchema.
//
// This method does not have any side-effects for the backend and can
// be safely used before configuring. It also does not consult any
// external data such as environment variables, disk files, etc. Validation
// that requires such external data should be deferred until the
// Configure call.
//
// If error diagnostics are returned then the configuration is not valid
// and must not subsequently be passed to the Configure method.
//
// This method may return configuration-contextual diagnostics such
// as tfdiags.AttributeValue, and so the caller should provide the
// necessary context via the diags.InConfigBody method before returning
// diagnostics to the user.
ValidateConfig(cty.Value) tfdiags.Diagnostics
// Configure uses the provided configuration to set configuration fields
// within the backend.
//
// The given configuration is assumed to have already been validated
// against the schema returned by ConfigSchema and passed validation
// via ValidateConfig.
//
// This method may be called only once per backend instance, and must be
// called before all other methods except where otherwise stated.
//
// If error diagnostics are returned, the internal state of the instance
// is undefined and no other methods may be called.
Configure(cty.Value) tfdiags.Diagnostics
// State returns the current state for this environment. This state may
// not be loaded locally: the proper APIs should be called on state.State
// to load the state. If the state.State is a state.Locker, it's up to the
// caller to call Lock and Unlock as needed.
//
// If the named state doesn't exist it will be created. The "default" state
// is always assumed to exist.
State(name string) (state.State, error)
// DeleteState removes the named state if it exists. It is an error
// to delete the default state.
//
// DeleteState does not prevent deleting a state that is in use. It is the
// responsibility of the caller to hold a Lock on the state when calling
// this method.
DeleteState(name string) error
// States returns a list of configured named states.
States() ([]string, error)
}
// Enhanced implements additional behavior on top of a normal backend.
//
// Enhanced backends allow customizing the behavior of Terraform operations.
// This allows Terraform to potentially run operations remotely, load
// configurations from external sources, etc.
type Enhanced interface {
Backend
// Operation performs a Terraform operation such as refresh, plan, apply.
// It is up to the implementation to determine what "performing" means.
// This DOES NOT BLOCK. The context returned as part of RunningOperation
// should be used to block for completion.
// If the state used in the operation can be locked, it is the
// responsibility of the Backend to lock the state for the duration of the
// running operation.
Operation(context.Context, *Operation) (*RunningOperation, error)
}
// Local implements additional behavior on a Backend that allows local
// operations in addition to remote operations.
//
// This enables more behaviors of Terraform that require more data such
// as `console`, `import`, `graph`. These require direct access to
// configurations, variables, and more. Not all backends may support this
// so we separate it out into its own optional interface.
type Local interface {
// Context returns a runnable terraform Context. The operation parameter
// doesn't need a Type set but it needs other options set such as Module.
Context(*Operation) (*terraform.Context, state.State, tfdiags.Diagnostics)
}
// An operation represents an operation for Terraform to execute.
//
// Note that not all fields are supported by all backends and can result
// in an error if set. All backend implementations should show user-friendly
// errors explaining any incorrectly set values. For example, the local
// backend doesn't support a PlanId being set.
//
// The operation options are purposely designed to have maximal compatibility
// between Terraform and Terraform Servers (a commercial product offered by
// HashiCorp). Therefore, it isn't expected that other implementation support
// every possible option. The struct here is generalized in order to allow
// even partial implementations to exist in the open, without walling off
// remote functionality 100% behind a commercial wall. Anyone can implement
// against this interface and have Terraform interact with it just as it
// would with HashiCorp-provided Terraform Servers.
type Operation struct {
// Type is the operation to perform.
Type OperationType
// PlanId is an opaque value that backends can use to execute a specific
// plan for an apply operation.
//
// PlanOutBackend is the backend to store with the plan. This is the
// backend that will be used when applying the plan.
PlanId string
PlanRefresh bool // PlanRefresh will do a refresh before a plan
PlanOutPath string // PlanOutPath is the path to save the plan
PlanOutBackend *terraform.BackendState
// ConfigDir is the path to the directory containing the configuration's
// root module.
ConfigDir string
// ConfigLoader is a configuration loader that can be used to load
// configuration from ConfigDir.
ConfigLoader *configload.Loader
// Plan is a plan that was passed as an argument. This is valid for
// plan and apply arguments but may not work for all backends.
Plan *terraform.Plan
// The options below are more self-explanatory and affect the runtime
// behavior of the operation.
AutoApprove bool
Destroy bool
Targets []addrs.Targetable
Variables map[string]UnparsedVariableValue
AutoApprove bool
DestroyForce bool
// Input/output/control options.
UIIn terraform.UIInput
UIOut terraform.UIOutput
// If LockState is true, the Operation must Lock any
// state.Lockers for its duration, and Unlock when complete.
LockState bool
// StateLocker is used to lock the state while providing UI feedback to the
// user. This will be supplied by the Backend itself.
StateLocker clistate.Locker
// The duration to retry obtaining a State lock.
StateLockTimeout time.Duration
// Workspace is the name of the workspace that this operation should run
// in, which controls which named state is used.
Workspace string
}
// HasConfig returns true if and only if the operation has a ConfigDir value
// that refers to a directory containing at least one Terraform configuration
// file.
func (o *Operation) HasConfig() bool {
return o.ConfigLoader.IsConfigDir(o.ConfigDir)
}
// Config loads the configuration that the operation applies to, using the
// ConfigDir and ConfigLoader fields within the receiving operation.
func (o *Operation) Config() (*configs.Config, tfdiags.Diagnostics) {
var diags tfdiags.Diagnostics
config, hclDiags := o.ConfigLoader.LoadConfig(o.ConfigDir)
diags = diags.Append(hclDiags)
return config, diags
}
// RunningOperation is the result of starting an operation.
type RunningOperation struct {
// For implementers of a backend, this context should not wrap the
// passed in context. Otherwise, cancelling the parent context will
// immediately mark this context as "done" but those aren't the semantics
// we want: we want this context to be done only when the operation itself
// is fully done.
context.Context
// Stop requests the operation to complete early, by calling Stop on all
// the plugins. If the process needs to terminate immediately, call Cancel.
Stop context.CancelFunc
// Cancel is the context.CancelFunc associated with the embedded context,
// and can be called to terminate the operation early.
// Once Cancel is called, the operation should return as soon as possible
// to avoid running operations during process exit.
Cancel context.CancelFunc
// Result is the exit status of the operation, populated only after the
// operation has completed.
Result OperationResult
// ExitCode can be used to set a custom exit code. This enables enhanced
// backends to set specific exit codes that miror any remote exit codes.
ExitCode int
// PlanEmpty is populated after a Plan operation completes without error
// to note whether a plan is empty or has changes.
PlanEmpty bool
// State is the final state after the operation completed. Persisting
// this state is managed by the backend. This should only be read
// after the operation completes to avoid read/write races.
State *terraform.State
}
// OperationResult describes the result status of an operation.
type OperationResult int
const (
// OperationSuccess indicates that the operation completed as expected.
OperationSuccess OperationResult = 0
// OperationFailure indicates that the operation encountered some sort
// of error, and thus may have been only partially performed or not
// performed at all.
OperationFailure OperationResult = 1
)
func (r OperationResult) ExitStatus() int {
return int(r)
}