521 lines
15 KiB
Go
521 lines
15 KiB
Go
package command
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import (
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"context"
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"errors"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"sort"
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"strings"
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"github.com/hashicorp/terraform/backend"
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"github.com/hashicorp/terraform/command/clistate"
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"github.com/hashicorp/terraform/state"
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"github.com/hashicorp/terraform/terraform"
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)
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// backendMigrateState handles migrating (copying) state from one backend
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// to another. This function handles asking the user for confirmation
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// as well as the copy itself.
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//
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// This function can handle all scenarios of state migration regardless
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// of the existence of state in either backend.
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//
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// After migrating the state, the existing state in the first backend
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// remains untouched.
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//
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// This will attempt to lock both states for the migration.
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func (m *Meta) backendMigrateState(opts *backendMigrateOpts) error {
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// We need to check what the named state status is. If we're converting
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// from multi-state to single-state for example, we need to handle that.
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var oneSingle, twoSingle bool
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oneStates, err := opts.One.States()
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if err == backend.ErrNamedStatesNotSupported {
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oneSingle = true
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err = nil
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}
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if err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateLoadStates), opts.OneType, err)
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}
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_, err = opts.Two.States()
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if err == backend.ErrNamedStatesNotSupported {
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twoSingle = true
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err = nil
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}
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if err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateLoadStates), opts.TwoType, err)
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}
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// Setup defaults
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opts.oneEnv = backend.DefaultStateName
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opts.twoEnv = backend.DefaultStateName
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opts.force = m.forceInitCopy
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// Determine migration behavior based on whether the source/destination
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// supports multi-state.
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switch {
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// Single-state to single-state. This is the easiest case: we just
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// copy the default state directly.
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case oneSingle && twoSingle:
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return m.backendMigrateState_s_s(opts)
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// Single-state to multi-state. This is easy since we just copy
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// the default state and ignore the rest in the destination.
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case oneSingle && !twoSingle:
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return m.backendMigrateState_s_s(opts)
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// Multi-state to single-state. If the source has more than the default
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// state this is complicated since we have to ask the user what to do.
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case !oneSingle && twoSingle:
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// If the source only has one state and it is the default,
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// treat it as if it doesn't support multi-state.
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if len(oneStates) == 1 && oneStates[0] == backend.DefaultStateName {
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return m.backendMigrateState_s_s(opts)
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}
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return m.backendMigrateState_S_s(opts)
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// Multi-state to multi-state. We merge the states together (migrating
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// each from the source to the destination one by one).
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case !oneSingle && !twoSingle:
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// If the source only has one state and it is the default,
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// treat it as if it doesn't support multi-state.
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if len(oneStates) == 1 && oneStates[0] == backend.DefaultStateName {
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return m.backendMigrateState_s_s(opts)
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}
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return m.backendMigrateState_S_S(opts)
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}
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return nil
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}
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//-------------------------------------------------------------------
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// State Migration Scenarios
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//
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// The functions below cover handling all the various scenarios that
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// can exist when migrating state. They are named in an immediately not
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// obvious format but is simple:
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//
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// Format: backendMigrateState_s1_s2[_suffix]
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//
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// When s1 or s2 is lower case, it means that it is a single state backend.
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// When either is uppercase, it means that state is a multi-state backend.
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// The suffix is used to disambiguate multiple cases with the same type of
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// states.
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//
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//-------------------------------------------------------------------
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// Multi-state to multi-state.
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func (m *Meta) backendMigrateState_S_S(opts *backendMigrateOpts) error {
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// Ask the user if they want to migrate their existing remote state
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migrate, err := m.confirm(&terraform.InputOpts{
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Id: "backend-migrate-multistate-to-multistate",
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Query: fmt.Sprintf(
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"Do you want to migrate all workspaces to %q?",
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opts.TwoType),
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Description: fmt.Sprintf(
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strings.TrimSpace(inputBackendMigrateMultiToMulti),
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opts.OneType, opts.TwoType),
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})
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if err != nil {
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return fmt.Errorf(
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"Error asking for state migration action: %s", err)
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}
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if !migrate {
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return fmt.Errorf("Migration aborted by user.")
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}
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// Read all the states
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oneStates, err := opts.One.States()
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if err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateLoadStates), opts.OneType, err)
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}
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// Sort the states so they're always copied alphabetically
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sort.Strings(oneStates)
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// Go through each and migrate
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for _, name := range oneStates {
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// Copy the same names
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opts.oneEnv = name
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opts.twoEnv = name
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// Force it, we confirmed above
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opts.force = true
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// Perform the migration
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if err := m.backendMigrateState_s_s(opts); err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateMulti), name, opts.OneType, opts.TwoType, err)
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}
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}
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return nil
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}
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// Multi-state to single state.
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func (m *Meta) backendMigrateState_S_s(opts *backendMigrateOpts) error {
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currentEnv := m.Workspace()
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migrate := opts.force
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if !migrate {
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var err error
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// Ask the user if they want to migrate their existing remote state
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migrate, err = m.confirm(&terraform.InputOpts{
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Id: "backend-migrate-multistate-to-single",
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Query: fmt.Sprintf(
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"Destination state %q doesn't support workspaces.\n"+
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"Do you want to copy only your current workspace?",
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opts.TwoType),
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Description: fmt.Sprintf(
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strings.TrimSpace(inputBackendMigrateMultiToSingle),
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opts.OneType, opts.TwoType, currentEnv),
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})
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if err != nil {
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return fmt.Errorf(
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"Error asking for state migration action: %s", err)
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}
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}
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if !migrate {
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return fmt.Errorf("Migration aborted by user.")
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}
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// Copy the default state
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opts.oneEnv = currentEnv
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// now switch back to the default env so we can acccess the new backend
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m.SetWorkspace(backend.DefaultStateName)
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return m.backendMigrateState_s_s(opts)
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}
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// Single state to single state, assumed default state name.
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func (m *Meta) backendMigrateState_s_s(opts *backendMigrateOpts) error {
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stateOne, err := opts.One.State(opts.oneEnv)
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if err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.OneType, err)
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}
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if err := stateOne.RefreshState(); err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.OneType, err)
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}
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stateTwo, err := opts.Two.State(opts.twoEnv)
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if err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.TwoType, err)
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}
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if err := stateTwo.RefreshState(); err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.TwoType, err)
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}
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// Check if we need migration at all.
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// This is before taking a lock, because they may also correspond to the same lock.
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one := stateOne.State()
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two := stateTwo.State()
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// no reason to migrate if the state is already there
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if one.Equal(two) {
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// Equal isn't identical; it doesn't check lineage.
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if one != nil && two != nil && one.Lineage == two.Lineage {
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return nil
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}
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}
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if m.stateLock {
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lockCtx, cancel := context.WithTimeout(context.Background(), m.stateLockTimeout)
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defer cancel()
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lockInfoOne := state.NewLockInfo()
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lockInfoOne.Operation = "migration"
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lockInfoOne.Info = "source state"
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lockIDOne, err := clistate.Lock(lockCtx, stateOne, lockInfoOne, m.Ui, m.Colorize())
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if err != nil {
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return fmt.Errorf("Error locking source state: %s", err)
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}
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defer clistate.Unlock(stateOne, lockIDOne, m.Ui, m.Colorize())
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lockInfoTwo := state.NewLockInfo()
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lockInfoTwo.Operation = "migration"
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lockInfoTwo.Info = "destination state"
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lockIDTwo, err := clistate.Lock(lockCtx, stateTwo, lockInfoTwo, m.Ui, m.Colorize())
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if err != nil {
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return fmt.Errorf("Error locking destination state: %s", err)
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}
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defer clistate.Unlock(stateTwo, lockIDTwo, m.Ui, m.Colorize())
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// We now own a lock, so double check that we have the version
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// corresponding to the lock.
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if err := stateOne.RefreshState(); err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.OneType, err)
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}
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if err := stateTwo.RefreshState(); err != nil {
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return fmt.Errorf(strings.TrimSpace(
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errMigrateSingleLoadDefault), opts.OneType, err)
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}
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one = stateOne.State()
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two = stateTwo.State()
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}
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// Clear the legacy remote state in both cases. If we're at the migration
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// step then this won't be used anymore.
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if one != nil {
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one.Remote = nil
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}
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if two != nil {
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two.Remote = nil
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}
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var confirmFunc func(state.State, state.State, *backendMigrateOpts) (bool, error)
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switch {
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// No migration necessary
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case one.Empty() && two.Empty():
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return nil
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// No migration necessary if we're inheriting state.
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case one.Empty() && !two.Empty():
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return nil
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// We have existing state moving into no state. Ask the user if
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// they'd like to do this.
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case !one.Empty() && two.Empty():
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confirmFunc = m.backendMigrateEmptyConfirm
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// Both states are non-empty, meaning we need to determine which
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// state should be used and update accordingly.
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case !one.Empty() && !two.Empty():
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confirmFunc = m.backendMigrateNonEmptyConfirm
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}
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if confirmFunc == nil {
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panic("confirmFunc must not be nil")
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}
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if !opts.force {
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// Abort if we can't ask for input.
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if !m.input {
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return errors.New("error asking for state migration action: input disabled")
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}
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// Confirm with the user whether we want to copy state over
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confirm, err := confirmFunc(stateOne, stateTwo, opts)
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if err != nil {
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return err
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}
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if !confirm {
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return nil
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}
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}
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// Confirmed! Write.
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if err := stateTwo.WriteState(one); err != nil {
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return fmt.Errorf(strings.TrimSpace(errBackendStateCopy),
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opts.OneType, opts.TwoType, err)
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}
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if err := stateTwo.PersistState(); err != nil {
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return fmt.Errorf(strings.TrimSpace(errBackendStateCopy),
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opts.OneType, opts.TwoType, err)
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}
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// And we're done.
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return nil
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}
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func (m *Meta) backendMigrateEmptyConfirm(one, two state.State, opts *backendMigrateOpts) (bool, error) {
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inputOpts := &terraform.InputOpts{
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Id: "backend-migrate-copy-to-empty",
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Query: fmt.Sprintf(
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"Do you want to copy state from %q to %q?",
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opts.OneType, opts.TwoType),
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Description: fmt.Sprintf(
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strings.TrimSpace(inputBackendMigrateEmpty),
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opts.OneType, opts.TwoType),
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}
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// Confirm with the user that the copy should occur
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for {
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v, err := m.UIInput().Input(inputOpts)
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if err != nil {
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return false, fmt.Errorf(
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"Error asking for state copy action: %s", err)
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}
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switch strings.ToLower(v) {
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case "no":
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return false, nil
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case "yes":
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return true, nil
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}
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}
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}
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func (m *Meta) backendMigrateNonEmptyConfirm(
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stateOne, stateTwo state.State, opts *backendMigrateOpts) (bool, error) {
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// We need to grab both states so we can write them to a file
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one := stateOne.State()
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two := stateTwo.State()
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// Save both to a temporary
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td, err := ioutil.TempDir("", "terraform")
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if err != nil {
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return false, fmt.Errorf("Error creating temporary directory: %s", err)
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}
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defer os.RemoveAll(td)
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// Helper to write the state
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saveHelper := func(n, path string, s *terraform.State) error {
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f, err := os.Create(path)
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if err != nil {
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return err
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}
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defer f.Close()
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return terraform.WriteState(s, f)
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}
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// Write the states
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onePath := filepath.Join(td, fmt.Sprintf("1-%s.tfstate", opts.OneType))
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twoPath := filepath.Join(td, fmt.Sprintf("2-%s.tfstate", opts.TwoType))
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if err := saveHelper(opts.OneType, onePath, one); err != nil {
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return false, fmt.Errorf("Error saving temporary state: %s", err)
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}
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if err := saveHelper(opts.TwoType, twoPath, two); err != nil {
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return false, fmt.Errorf("Error saving temporary state: %s", err)
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}
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// Ask for confirmation
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inputOpts := &terraform.InputOpts{
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Id: "backend-migrate-to-backend",
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Query: fmt.Sprintf(
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"Do you want to copy state from %q to %q?",
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opts.OneType, opts.TwoType),
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Description: fmt.Sprintf(
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strings.TrimSpace(inputBackendMigrateNonEmpty),
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opts.OneType, opts.TwoType, onePath, twoPath),
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}
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// Confirm with the user that the copy should occur
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for {
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v, err := m.UIInput().Input(inputOpts)
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if err != nil {
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return false, fmt.Errorf(
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"Error asking for state copy action: %s", err)
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}
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switch strings.ToLower(v) {
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case "no":
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return false, nil
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case "yes":
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return true, nil
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}
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}
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}
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type backendMigrateOpts struct {
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OneType, TwoType string
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One, Two backend.Backend
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// Fields below are set internally when migrate is called
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oneEnv string // source env
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twoEnv string // dest env
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force bool // if true, won't ask for confirmation
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}
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const errMigrateLoadStates = `
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Error inspecting state in %q: %s
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Prior to changing backends, Terraform inspects the source and destination
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states to determine what kind of migration steps need to be taken, if any.
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Terraform failed to load the states. The data in both the source and the
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destination remain unmodified. Please resolve the above error and try again.
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`
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const errMigrateSingleLoadDefault = `
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Error loading state from %q: %s
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Terraform failed to load the default state from %[1]q.
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State migration cannot occur unless the state can be loaded. Backend
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modification and state migration has been aborted. The state in both the
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source and the destination remain unmodified. Please resolve the
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above error and try again.
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`
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const errMigrateMulti = `
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Error migrating the workspace %q from %q to %q:
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%s
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Terraform copies workspaces in alphabetical order. Any workspaces
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alphabetically earlier than this one have been copied. Any workspaces
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later than this haven't been modified in the destination. No workspaces
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in the source state have been modified.
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Please resolve the error above and run the initialization command again.
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This will attempt to copy (with permission) all workspaces again.
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`
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const errBackendStateCopy = `
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Error copying state from %q to %q: %s
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The state in %[1]q remains intact and unmodified. Please resolve the
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error above and try again.
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`
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const inputBackendMigrateEmpty = `
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Pre-existing state was found in %q while migrating to %q. No existing
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state was found in %[2]q. Do you want to copy the state from %[1]q to
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%[2]q? Enter "yes" to copy and "no" to start with an empty state.
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`
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const inputBackendMigrateNonEmpty = `
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Pre-existing state was found in %q while migrating to %q. An existing
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non-empty state exists in %[2]q. The two states have been saved to temporary
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files that will be removed after responding to this query.
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One (%[1]q): %[3]s
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Two (%[2]q): %[4]s
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Do you want to copy the state from %[1]q to %[2]q? Enter "yes" to copy
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and "no" to start with the existing state in %[2]q.
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`
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const inputBackendMigrateMultiToSingle = `
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The existing backend %[1]q supports workspaces and you currently are
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using more than one. The target backend %[2]q doesn't support workspaces.
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If you continue, Terraform will offer to copy your current workspace
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%[3]q to the default workspace in the target. Your existing workspaces
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in the source backend won't be modified. If you want to switch workspaces,
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back them up, or cancel altogether, answer "no" and Terraform will abort.
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`
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const inputBackendMigrateMultiToMulti = `
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Both the existing backend %[1]q and the target backend %[2]q support
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workspaces. When migrating between backends, Terraform will copy all
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workspaces (with the same names). THIS WILL OVERWRITE any conflicting
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states in the destination.
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Terraform initialization doesn't currently migrate only select workspaces.
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If you want to migrate a select number of workspaces, you must manually
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pull and push those states.
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If you answer "yes", Terraform will migrate all states. If you answer
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"no", Terraform will abort.
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`
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