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plan.go
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plan.go
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package plans
import (
"sort"
"github.com/snyk/policy-engine/pkg/internal/terraform/addrs"
"github.com/snyk/policy-engine/pkg/internal/terraform/configs/configschema"
"github.com/snyk/policy-engine/pkg/internal/terraform/lang/globalref"
"github.com/snyk/policy-engine/pkg/internal/terraform/states"
"github.com/zclconf/go-cty/cty"
)
// Plan is the top-level type representing a planned set of changes.
//
// A plan is a summary of the set of changes required to move from a current
// state to a goal state derived from configuration. The described changes
// are not applied directly, but contain an approximation of the final
// result that will be completed during apply by resolving any values that
// cannot be predicted.
//
// A plan must always be accompanied by the configuration it was built from,
// since the plan does not itself include all of the information required to
// make the changes indicated.
type Plan struct {
// Mode is the mode under which this plan was created.
//
// This is only recorded to allow for UI differences when presenting plans
// to the end-user, and so it must not be used to influence apply-time
// behavior. The actions during apply must be described entirely by
// the Changes field, regardless of how the plan was created.
//
// FIXME: destroy operations still rely on DestroyMode being set, because
// there is no other source of this information in the plan. New behavior
// should not be added based on this flag, and changing the flag should be
// checked carefully against existing destroy behaviors.
UIMode Mode
VariableValues map[string]DynamicValue
Changes *Changes
DriftedResources []*ResourceInstanceChangeSrc
TargetAddrs []addrs.Targetable
ForceReplaceAddrs []addrs.AbsResourceInstance
Backend Backend
// Checks captures a snapshot of the (probably-incomplete) check results
// at the end of the planning process.
//
// If this plan is applyable (that is, if the planning process completed
// without errors) then the set of checks here should be complete even
// though some of them will likely have StatusUnknown where the check
// condition depends on values we won't know until the apply step.
Checks *states.CheckResults
// RelevantAttributes is a set of resource instance addresses and
// attributes that are either directly affected by proposed changes or may
// have indirectly contributed to them via references in expressions.
//
// This is the result of a heuristic and is intended only as a hint to
// the UI layer in case it wants to emphasize or de-emphasize certain
// resources. Don't use this to drive any non-cosmetic behavior, especially
// including anything that would be subject to compatibility constraints.
RelevantAttributes []globalref.ResourceAttr
// PrevRunState and PriorState both describe the situation that the plan
// was derived from:
//
// PrevRunState is a representation of the outcome of the previous
// Terraform operation, without any updates from the remote system but
// potentially including some changes that resulted from state upgrade
// actions.
//
// PriorState is a representation of the current state of remote objects,
// which will differ from PrevRunState if the "refresh" step returned
// different data, which might reflect drift.
//
// PriorState is the main snapshot we use for actions during apply.
// PrevRunState is only here so that we can diff PriorState against it in
// order to report to the user any out-of-band changes we've detected.
PrevRunState *states.State
PriorState *states.State
}
// CanApply returns true if and only if the recieving plan includes content
// that would make sense to apply. If it returns false, the plan operation
// should indicate that there's nothing to do and Terraform should exit
// without prompting the user to confirm the changes.
//
// This function represents our main business logic for making the decision
// about whether a given plan represents meaningful "changes", and so its
// exact definition may change over time; the intent is just to centralize the
// rules for that rather than duplicating different versions of it at various
// locations in the UI code.
func (p *Plan) CanApply() bool {
switch {
case !p.Changes.Empty():
// "Empty" means that everything in the changes is a "NoOp", so if
// not empty then there's at least one non-NoOp change.
return true
case !p.PriorState.ManagedResourcesEqual(p.PrevRunState):
// If there are no changes planned but we detected some
// outside-Terraform changes while refreshing then we consider
// that applyable in isolation only if this was a refresh-only
// plan where we expect updating the state to include these
// changes was the intended goal.
//
// (We don't treat a "refresh only" plan as applyable in normal
// planning mode because historically the refresh result wasn't
// considered part of a plan at all, and so it would be
// a disruptive breaking change if refreshing alone suddenly
// became applyable in the normal case and an existing configuration
// was relying on ignore_changes in order to be convergent in spite
// of intentional out-of-band operations.)
return p.UIMode == RefreshOnlyMode
default:
// Otherwise, there are either no changes to apply or they are changes
// our cases above don't consider as worthy of applying in isolation.
return false
}
}
// ProviderAddrs returns a list of all of the provider configuration addresses
// referenced throughout the receiving plan.
//
// The result is de-duplicated so that each distinct address appears only once.
func (p *Plan) ProviderAddrs() []addrs.AbsProviderConfig {
if p == nil || p.Changes == nil {
return nil
}
m := map[string]addrs.AbsProviderConfig{}
for _, rc := range p.Changes.Resources {
m[rc.ProviderAddr.String()] = rc.ProviderAddr
}
if len(m) == 0 {
return nil
}
// This is mainly just so we'll get stable results for testing purposes.
keys := make([]string, 0, len(m))
for k := range m {
keys = append(keys, k)
}
sort.Strings(keys)
ret := make([]addrs.AbsProviderConfig, len(keys))
for i, key := range keys {
ret[i] = m[key]
}
return ret
}
// Backend represents the backend-related configuration and other data as it
// existed when a plan was created.
type Backend struct {
// Type is the type of backend that the plan will apply against.
Type string
// Config is the configuration of the backend, whose schema is decided by
// the backend Type.
Config DynamicValue
// Workspace is the name of the workspace that was active when the plan
// was created. It is illegal to apply a plan created for one workspace
// to the state of another workspace.
// (This constraint is already enforced by the statefile lineage mechanism,
// but storing this explicitly allows us to return a better error message
// in the situation where the user has the wrong workspace selected.)
Workspace string
}
func NewBackend(typeName string, config cty.Value, configSchema *configschema.Block, workspaceName string) (*Backend, error) {
dv, err := NewDynamicValue(config, configSchema.ImpliedType())
if err != nil {
return nil, err
}
return &Backend{
Type: typeName,
Config: dv,
Workspace: workspaceName,
}, nil
}