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fix: move from semaphore to rwmutex #215

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merged 2 commits into from
Nov 21, 2023
Merged

fix: move from semaphore to rwmutex #215

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92c0910
fix: move from semaphore to rwmutex
zach-source Nov 19, 2023
b47e5a6
chore: fixing comment spelling
zach-source Nov 20, 2023
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2 changes: 1 addition & 1 deletion go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,6 @@ require (
github.com/pkg/errors v0.9.1
github.com/spf13/afero v1.9.5
go.uber.org/zap v1.25.0
golang.org/x/sync v0.3.0
gopkg.in/alecthomas/kingpin.v2 v2.2.6
k8s.io/api v0.28.3
k8s.io/apiextensions-apiserver v0.28.3
Expand Down Expand Up @@ -87,6 +86,7 @@ require (
golang.org/x/mod v0.12.0 // indirect
golang.org/x/net v0.17.0 // indirect
golang.org/x/oauth2 v0.10.0 // indirect
golang.org/x/sync v0.3.0 // indirect
golang.org/x/sys v0.13.0 // indirect
golang.org/x/term v0.13.0 // indirect
golang.org/x/text v0.13.0 // indirect
Expand Down
42 changes: 28 additions & 14 deletions internal/terraform/terraform.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,16 +33,15 @@ import (
"strconv"
"strings"

"sync"

"github.com/pkg/errors"
"golang.org/x/sync/semaphore"
)

// Error strings.
const (
errParse = "cannot parse Terraform output"
errWriteVarFile = "cannot write tfvars file"
errSemAcquire = "cannot acquire semaphore for tfinit"

errParse = "cannot parse Terraform output"
errWriteVarFile = "cannot write tfvars file"
errFmtInvalidConfig = "invalid Terraform configuration: found %d errors"

tfDefault = "default"
Expand Down Expand Up @@ -149,9 +148,12 @@ func WithInitArgs(v []string) InitOption {
}
}

// Semaphore to limit the number of concurrent terraform init commands to 1.
// This is needed to support a shared provider cache with concurrent reconciliations.
var sem = semaphore.NewWeighted(int64(1))
// RWMutex protects the terraform shared cache from corruption. If an init is
// performed, it requires a write lock. Only one write lock at a time. If another
// action is performed, a read lock is acquired. More than one read locks can be acquired.
// This prevents an init from inadvertently changing a plugin while it's in use.
// Prevents issues with `text file busy` errors.
var rwmutex = &sync.RWMutex{}

// Init initializes a Terraform configuration.
func (h Harness) Init(ctx context.Context, cache bool, o ...InitOption) error {
Expand All @@ -172,12 +174,9 @@ func (h Harness) Init(ctx context.Context, cache bool, o ...InitOption) error {
cmd.Env = append(cmd.Env, e)
}
cmd.Env = append(cmd.Env, "TF_CLI_CONFIG_FILE=./.terraformrc")
err := sem.Acquire(ctx, 1)
if err != nil {
return errors.Wrap(err, errSemAcquire)
}
defer sem.Release(1)
_, err = cmd.Output()
rwmutex.Lock()
defer rwmutex.Unlock()
_, err := cmd.Output()
return Classify(err)
}

Expand Down Expand Up @@ -231,6 +230,8 @@ func (h Harness) Workspace(ctx context.Context, name string) error {
// is somewhat optimistic, but it shouldn't hurt to try.
cmd = exec.CommandContext(ctx, h.Path, "workspace", "new", "-no-color", name) //nolint:gosec
cmd.Dir = h.Dir
rwmutex.RLock()
defer rwmutex.RUnlock()
_, err := cmd.Output()
return Classify(err)
}
Expand All @@ -257,6 +258,8 @@ func (h Harness) DeleteCurrentWorkspace(ctx context.Context) error {
cmd = exec.CommandContext(ctx, h.Path, "workspace", "delete", "-no-color", name) //nolint:gosec
cmd.Dir = h.Dir

rwmutex.RLock()
defer rwmutex.RUnlock()
_, err = cmd.Output()
if err == nil {
// We successfully deleted the workspace; we're done.
Expand Down Expand Up @@ -367,6 +370,8 @@ func (h Harness) Outputs(ctx context.Context) ([]Output, error) {

outputs := map[string]output{}

rwmutex.RLock()
defer rwmutex.RUnlock()
out, err := cmd.Output()
if jerr := json.Unmarshal(out, &outputs); jerr != nil {
// If stdout doesn't appear to be the JSON we expected we try to extract
Expand Down Expand Up @@ -411,6 +416,8 @@ func (h Harness) Resources(ctx context.Context) ([]string, error) {
cmd := exec.CommandContext(ctx, h.Path, "state", "list") //nolint:gosec
cmd.Dir = h.Dir

rwmutex.RLock()
defer rwmutex.RUnlock()
out, err := cmd.Output()
if err != nil {
return nil, Classify(err)
Expand Down Expand Up @@ -489,6 +496,9 @@ func (h Harness) Diff(ctx context.Context, o ...Option) (bool, error) {
cmd := exec.CommandContext(ctx, h.Path, args...) //nolint:gosec
cmd.Dir = h.Dir

rwmutex.RLock()
defer rwmutex.RUnlock()

// The -detailed-exitcode flag will make terraform plan return:
// 0 - Succeeded, diff is empty (no changes)
// 1 - Errored
Expand Down Expand Up @@ -517,6 +527,8 @@ func (h Harness) Apply(ctx context.Context, o ...Option) error {
cmd := exec.CommandContext(ctx, h.Path, args...) //nolint:gosec
cmd.Dir = h.Dir

rwmutex.RLock()
defer rwmutex.RUnlock()
_, err := cmd.Output()
return Classify(err)
}
Expand All @@ -538,6 +550,8 @@ func (h Harness) Destroy(ctx context.Context, o ...Option) error {
cmd := exec.CommandContext(ctx, h.Path, args...) //nolint:gosec
cmd.Dir = h.Dir

rwmutex.RLock()
defer rwmutex.RUnlock()
_, err := cmd.Output()
return Classify(err)
}
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