125 lines
4.3 KiB
Go
125 lines
4.3 KiB
Go
package terraform
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// HookAction is an enum of actions that can be taken as a result of a hook
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// callback. This allows you to modify the behavior of Terraform at runtime.
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type HookAction byte
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const (
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// HookActionContinue continues with processing as usual.
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HookActionContinue HookAction = iota
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// HookActionHalt halts immediately: no more hooks are processed
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// and the action that Terraform was about to take is cancelled.
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HookActionHalt
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)
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// Hook is the interface that must be implemented to hook into various
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// parts of Terraform, allowing you to inspect or change behavior at runtime.
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//
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// There are MANY hook points into Terraform. If you only want to implement
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// some hook points, but not all (which is the likely case), then embed the
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// NilHook into your struct, which implements all of the interface but does
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// nothing. Then, override only the functions you want to implement.
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type Hook interface {
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// PreApply and PostApply are called before and after a single
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// resource is applied. The error argument in PostApply is the
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// error, if any, that was returned from the provider Apply call itself.
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PreApply(*InstanceInfo, *InstanceState, *InstanceDiff) (HookAction, error)
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PostApply(*InstanceInfo, *InstanceState, error) (HookAction, error)
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// PreDiff and PostDiff are called before and after a single resource
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// resource is diffed.
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PreDiff(*InstanceInfo, *InstanceState) (HookAction, error)
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PostDiff(*InstanceInfo, *InstanceDiff) (HookAction, error)
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// Provisioning hooks
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//
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// All should be self-explanatory. ProvisionOutput is called with
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// output sent back by the provisioners. This will be called multiple
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// times as output comes in, but each call should represent a line of
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// output. The ProvisionOutput method cannot control whether the
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// hook continues running.
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PreProvisionResource(*InstanceInfo, *InstanceState) (HookAction, error)
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PostProvisionResource(*InstanceInfo, *InstanceState) (HookAction, error)
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PreProvision(*InstanceInfo, string) (HookAction, error)
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PostProvision(*InstanceInfo, string) (HookAction, error)
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ProvisionOutput(*InstanceInfo, string, string)
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// PreRefresh and PostRefresh are called before and after a single
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// resource state is refreshed, respectively.
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PreRefresh(*InstanceInfo, *InstanceState) (HookAction, error)
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PostRefresh(*InstanceInfo, *InstanceState) (HookAction, error)
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// PostStateUpdate is called after the state is updated.
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PostStateUpdate(*State) (HookAction, error)
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}
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// NilHook is a Hook implementation that does nothing. It exists only to
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// simplify implementing hooks. You can embed this into your Hook implementation
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// and only implement the functions you are interested in.
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type NilHook struct{}
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func (*NilHook) PreApply(*InstanceInfo, *InstanceState, *InstanceDiff) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostApply(*InstanceInfo, *InstanceState, error) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PreDiff(*InstanceInfo, *InstanceState) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostDiff(*InstanceInfo, *InstanceDiff) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PreProvisionResource(*InstanceInfo, *InstanceState) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostProvisionResource(*InstanceInfo, *InstanceState) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PreProvision(*InstanceInfo, string) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostProvision(*InstanceInfo, string) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) ProvisionOutput(
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*InstanceInfo, string, string) {
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}
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func (*NilHook) PreRefresh(*InstanceInfo, *InstanceState) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostRefresh(*InstanceInfo, *InstanceState) (HookAction, error) {
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return HookActionContinue, nil
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}
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func (*NilHook) PostStateUpdate(*State) (HookAction, error) {
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return HookActionContinue, nil
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}
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// handleHook turns hook actions into panics. This lets you use the
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// panic/recover mechanism in Go as a flow control mechanism for hook
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// actions.
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func handleHook(a HookAction, err error) {
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if err != nil {
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// TODO: handle errors
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}
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switch a {
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case HookActionContinue:
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return
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case HookActionHalt:
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panic(HookActionHalt)
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}
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}
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