terraform/backend/backend.go

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// 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"
"io/ioutil"
"log"
"os"
terraform: ugly huge change to weave in new HCL2-oriented types Due to how deeply the configuration types go into Terraform Core, there isn't a great way to switch out to HCL2 gradually. As a consequence, this huge commit gets us from the old state to a _compilable_ new state, but does not yet attempt to fix any tests and has a number of known missing parts and bugs. We will continue to iterate on this in forthcoming commits, heading back towards passing tests and making Terraform fully-functional again. The three main goals here are: - Use the configuration models from the "configs" package instead of the older models in the "config" package, which is now deprecated and preserved only to help us write our migration tool. - Do expression inspection and evaluation using the functionality of the new "lang" package, instead of the Interpolator type and related functionality in the main "terraform" package. - Represent addresses of various objects using types in the addrs package, rather than hand-constructed strings. This is not critical to support the above, but was a big help during the implementation of these other points since it made it much more explicit what kind of address is expected in each context. Since our new packages are built to accommodate some future planned features that are not yet implemented (e.g. the "for_each" argument on resources, "count"/"for_each" on modules), and since there's still a fair amount of functionality still using old-style APIs, there is a moderate amount of shimming here to connect new assumptions with old, hopefully in a way that makes it easier to find and eliminate these shims later. I apologize in advance to the person who inevitably just found this huge commit while spelunking through the commit history.
2018-04-30 19:33:53 +02:00
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/command/clistate"
2021-02-17 19:01:30 +01:00
"github.com/hashicorp/terraform/command/views"
terraform: ugly huge change to weave in new HCL2-oriented types Due to how deeply the configuration types go into Terraform Core, there isn't a great way to switch out to HCL2 gradually. As a consequence, this huge commit gets us from the old state to a _compilable_ new state, but does not yet attempt to fix any tests and has a number of known missing parts and bugs. We will continue to iterate on this in forthcoming commits, heading back towards passing tests and making Terraform fully-functional again. The three main goals here are: - Use the configuration models from the "configs" package instead of the older models in the "config" package, which is now deprecated and preserved only to help us write our migration tool. - Do expression inspection and evaluation using the functionality of the new "lang" package, instead of the Interpolator type and related functionality in the main "terraform" package. - Represent addresses of various objects using types in the addrs package, rather than hand-constructed strings. This is not critical to support the above, but was a big help during the implementation of these other points since it made it much more explicit what kind of address is expected in each context. Since our new packages are built to accommodate some future planned features that are not yet implemented (e.g. the "for_each" argument on resources, "count"/"for_each" on modules), and since there's still a fair amount of functionality still using old-style APIs, there is a moderate amount of shimming here to connect new assumptions with old, hopefully in a way that makes it easier to find and eliminate these shims later. I apologize in advance to the person who inevitably just found this huge commit while spelunking through the commit history.
2018-04-30 19:33:53 +02:00
"github.com/hashicorp/terraform/configs"
"github.com/hashicorp/terraform/configs/configload"
"github.com/hashicorp/terraform/configs/configschema"
"github.com/hashicorp/terraform/plans"
"github.com/hashicorp/terraform/plans/planfile"
"github.com/hashicorp/terraform/states"
"github.com/hashicorp/terraform/states/statemgr"
"github.com/hashicorp/terraform/terraform"
"github.com/hashicorp/terraform/tfdiags"
"github.com/mitchellh/go-homedir"
"github.com/zclconf/go-cty/cty"
)
// DefaultStateName is the name of the default, initial state that every
// backend must have. This state cannot be deleted.
const DefaultStateName = "default"
var (
// ErrDefaultWorkspaceNotSupported is returned when an operation does not
// support using the default workspace, but requires a named workspace to
// be selected.
ErrDefaultWorkspaceNotSupported = errors.New("default workspace not supported\n" +
"You can create a new workspace with the \"workspace new\" command.")
// ErrWorkspacesNotSupported is an error returned when a caller attempts
// to perform an operation on a workspace other than "default" for a
// backend that doesn't support multiple workspaces.
//
// The caller can detect this to do special fallback behavior or produce
// a specific, helpful error message.
ErrWorkspacesNotSupported = errors.New("workspaces 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
// PrepareConfig checks the validity of the values in the given
// configuration, and inserts any missing defaults, 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.
PrepareConfig(cty.Value) (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 PrepareConfig.
//
// 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
// StateMgr returns the state manager for the given workspace name.
//
// If the returned state manager also implements statemgr.Locker then
// it's the caller's responsibility to call Lock and Unlock as appropriate.
//
// If the named workspace doesn't exist, or if it has no state, it will
// be created either immediately on this call or the first time
// PersistState is called, depending on the state manager implementation.
StateMgr(workspace string) (statemgr.Full, error)
// DeleteWorkspace removes the workspace with the given name if it exists.
//
// DeleteWorkspace cannot prevent deleting a state that is in use. It is
// the responsibility of the caller to hold a Lock for the state manager
// belonging to this workspace before calling this method.
DeleteWorkspace(name string) error
// States returns a list of the names of all of the workspaces that exist
// in this backend.
Workspaces() ([]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, statemgr.Full, 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 *plans.Backend
// 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
// Hooks can be used to perform actions triggered by various events during
// the operation's lifecycle.
Hooks []terraform.Hook
// 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.
PlanFile *planfile.Reader
// The options below are more self-explanatory and affect the runtime
// behavior of the operation.
PlanMode plans.Mode
AutoApprove bool
Parallelism int
Targets []addrs.Targetable
ForceReplace []addrs.AbsResourceInstance
Variables map[string]UnparsedVariableValue
// Some operations use root module variables only opportunistically or
// don't need them at all. If this flag is set, the backend must treat
// all variables as optional and provide an unknown value for any required
// variables that aren't set in order to allow partial evaluation against
// the resulting incomplete context.
//
// This flag is honored only if PlanFile isn't set. If PlanFile is set then
// the variables set in the plan are used instead, and they must be valid.
AllowUnsetVariables bool
2021-02-17 19:01:30 +01:00
// View implements the logic for all UI interactions.
View views.Operation
// Input/output/control options.
UIIn terraform.UIInput
UIOut terraform.UIOutput
// StateLocker is used to lock the state while providing UI feedback to the
// user. This will be replaced by the Backend to update the context.
//
// If state locking is not necessary, this should be set to a no-op
// implementation of clistate.Locker.
StateLocker clistate.Locker
// 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
}
// ReportResult is a helper for the common chore of setting the status of
// a running operation and showing any diagnostics produced during that
// operation.
//
// If the given diagnostics contains errors then the operation's result
// will be set to backend.OperationFailure. It will be set to
// backend.OperationSuccess otherwise. It will then use o.View.Diagnostics
// to show the given diagnostics before returning.
//
// Callers should feel free to do each of these operations separately in
// more complex cases where e.g. diagnostics are interleaved with other
// output, but terminating immediately after reporting error diagnostics is
// common and can be expressed concisely via this method.
func (o *Operation) ReportResult(op *RunningOperation, diags tfdiags.Diagnostics) {
if diags.HasErrors() {
op.Result = OperationFailure
} else {
op.Result = OperationSuccess
}
if o.View != nil {
o.View.Diagnostics(diags)
} else {
// Shouldn't generally happen, but if it does then we'll at least
// make some noise in the logs to help us spot it.
if len(diags) != 0 {
log.Printf(
"[ERROR] Backend needs to report diagnostics but View is not set:\n%s",
diags.ErrWithWarnings(),
)
}
}
}
// 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
// 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 *states.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)
}
// If the argument is a path, Read loads it and returns the contents,
// otherwise the argument is assumed to be the desired contents and is simply
// returned.
func ReadPathOrContents(poc string) (string, error) {
if len(poc) == 0 {
return poc, nil
}
path := poc
if path[0] == '~' {
var err error
path, err = homedir.Expand(path)
if err != nil {
return path, err
}
}
if _, err := os.Stat(path); err == nil {
contents, err := ioutil.ReadFile(path)
if err != nil {
return string(contents), err
}
return string(contents), nil
}
return poc, nil
}