diff options
Diffstat (limited to 'vendor/github.com/hashicorp/vault/api/renewer.go')
-rw-r--r-- | vendor/github.com/hashicorp/vault/api/renewer.go | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/vendor/github.com/hashicorp/vault/api/renewer.go b/vendor/github.com/hashicorp/vault/api/renewer.go new file mode 100644 index 0000000..a2a4b66 --- /dev/null +++ b/vendor/github.com/hashicorp/vault/api/renewer.go @@ -0,0 +1,302 @@ +package api + +import ( + "errors" + "math/rand" + "sync" + "time" +) + +var ( + ErrRenewerMissingInput = errors.New("missing input to renewer") + ErrRenewerMissingSecret = errors.New("missing secret to renew") + ErrRenewerNotRenewable = errors.New("secret is not renewable") + ErrRenewerNoSecretData = errors.New("returned empty secret data") + + // DefaultRenewerGrace is the default grace period + DefaultRenewerGrace = 15 * time.Second + + // DefaultRenewerRenewBuffer is the default size of the buffer for renew + // messages on the channel. + DefaultRenewerRenewBuffer = 5 +) + +// Renewer is a process for renewing a secret. +// +// renewer, err := client.NewRenewer(&RenewerInput{ +// Secret: mySecret, +// }) +// go renewer.Renew() +// defer renewer.Stop() +// +// for { +// select { +// case err := <-renewer.DoneCh(): +// if err != nil { +// log.Fatal(err) +// } +// +// // Renewal is now over +// case renewal := <-renewer.RenewCh(): +// log.Printf("Successfully renewed: %#v", renewal) +// } +// } +// +// +// The `DoneCh` will return if renewal fails or if the remaining lease duration +// after a renewal is less than or equal to the grace (in number of seconds). In +// both cases, the caller should attempt a re-read of the secret. Clients should +// check the return value of the channel to see if renewal was successful. +type Renewer struct { + l sync.Mutex + + client *Client + secret *Secret + grace time.Duration + random *rand.Rand + doneCh chan error + renewCh chan *RenewOutput + + stopped bool + stopCh chan struct{} +} + +// RenewerInput is used as input to the renew function. +type RenewerInput struct { + // Secret is the secret to renew + Secret *Secret + + // Grace is a minimum renewal before returning so the upstream client + // can do a re-read. This can be used to prevent clients from waiting + // too long to read a new credential and incur downtime. + Grace time.Duration + + // Rand is the randomizer to use for underlying randomization. If not + // provided, one will be generated and seeded automatically. If provided, it + // is assumed to have already been seeded. + Rand *rand.Rand + + // RenewBuffer is the size of the buffered channel where renew messages are + // dispatched. + RenewBuffer int +} + +// RenewOutput is the metadata returned to the client (if it's listening) to +// renew messages. +type RenewOutput struct { + // RenewedAt is the timestamp when the renewal took place (UTC). + RenewedAt time.Time + + // Secret is the underlying renewal data. It's the same struct as all data + // that is returned from Vault, but since this is renewal data, it will not + // usually include the secret itself. + Secret *Secret +} + +// NewRenewer creates a new renewer from the given input. +func (c *Client) NewRenewer(i *RenewerInput) (*Renewer, error) { + if i == nil { + return nil, ErrRenewerMissingInput + } + + secret := i.Secret + if secret == nil { + return nil, ErrRenewerMissingSecret + } + + grace := i.Grace + if grace == 0 { + grace = DefaultRenewerGrace + } + + random := i.Rand + if random == nil { + random = rand.New(rand.NewSource(int64(time.Now().Nanosecond()))) + } + + renewBuffer := i.RenewBuffer + if renewBuffer == 0 { + renewBuffer = DefaultRenewerRenewBuffer + } + + return &Renewer{ + client: c, + secret: secret, + grace: grace, + random: random, + doneCh: make(chan error, 1), + renewCh: make(chan *RenewOutput, renewBuffer), + + stopped: false, + stopCh: make(chan struct{}), + }, nil +} + +// DoneCh returns the channel where the renewer will publish when renewal stops. +// If there is an error, this will be an error. +func (r *Renewer) DoneCh() <-chan error { + return r.doneCh +} + +// RenewCh is a channel that receives a message when a successful renewal takes +// place and includes metadata about the renewal. +func (r *Renewer) RenewCh() <-chan *RenewOutput { + return r.renewCh +} + +// Stop stops the renewer. +func (r *Renewer) Stop() { + r.l.Lock() + if !r.stopped { + close(r.stopCh) + r.stopped = true + } + r.l.Unlock() +} + +// Renew starts a background process for renewing this secret. When the secret +// is has auth data, this attempts to renew the auth (token). When the secret +// has a lease, this attempts to renew the lease. +func (r *Renewer) Renew() { + var result error + if r.secret.Auth != nil { + result = r.renewAuth() + } else { + result = r.renewLease() + } + + select { + case r.doneCh <- result: + case <-r.stopCh: + } +} + +// renewAuth is a helper for renewing authentication. +func (r *Renewer) renewAuth() error { + if !r.secret.Auth.Renewable || r.secret.Auth.ClientToken == "" { + return ErrRenewerNotRenewable + } + + client, token := r.client, r.secret.Auth.ClientToken + + for { + // Check if we are stopped. + select { + case <-r.stopCh: + return nil + default: + } + + // Renew the auth. + renewal, err := client.Auth().Token().RenewTokenAsSelf(token, 0) + if err != nil { + return err + } + + // Push a message that a renewal took place. + select { + case r.renewCh <- &RenewOutput{time.Now().UTC(), renewal}: + default: + } + + // Somehow, sometimes, this happens. + if renewal == nil || renewal.Auth == nil { + return ErrRenewerNoSecretData + } + + // Do nothing if we are not renewable + if !renewal.Auth.Renewable { + return ErrRenewerNotRenewable + } + + // Grab the lease duration and sleep duration - note that we grab the auth + // lease duration, not the secret lease duration. + leaseDuration := time.Duration(renewal.Auth.LeaseDuration) * time.Second + sleepDuration := r.sleepDuration(leaseDuration) + + // If we are within grace, return now. + if leaseDuration <= r.grace || sleepDuration <= r.grace { + return nil + } + + select { + case <-r.stopCh: + return nil + case <-time.After(sleepDuration): + continue + } + } +} + +// renewLease is a helper for renewing a lease. +func (r *Renewer) renewLease() error { + if !r.secret.Renewable || r.secret.LeaseID == "" { + return ErrRenewerNotRenewable + } + + client, leaseID := r.client, r.secret.LeaseID + + for { + // Check if we are stopped. + select { + case <-r.stopCh: + return nil + default: + } + + // Renew the lease. + renewal, err := client.Sys().Renew(leaseID, 0) + if err != nil { + return err + } + + // Push a message that a renewal took place. + select { + case r.renewCh <- &RenewOutput{time.Now().UTC(), renewal}: + default: + } + + // Somehow, sometimes, this happens. + if renewal == nil { + return ErrRenewerNoSecretData + } + + // Do nothing if we are not renewable + if !renewal.Renewable { + return ErrRenewerNotRenewable + } + + // Grab the lease duration and sleep duration + leaseDuration := time.Duration(renewal.LeaseDuration) * time.Second + sleepDuration := r.sleepDuration(leaseDuration) + + // If we are within grace, return now. + if leaseDuration <= r.grace || sleepDuration <= r.grace { + return nil + } + + select { + case <-r.stopCh: + return nil + case <-time.After(sleepDuration): + continue + } + } +} + +// sleepDuration calculates the time to sleep given the base lease duration. The +// base is the resulting lease duration. It will be reduced to 1/3 and +// multiplied by a random float between 0.0 and 1.0. This extra randomness +// prevents multiple clients from all trying to renew simultaneously. +func (r *Renewer) sleepDuration(base time.Duration) time.Duration { + sleep := float64(base) + + // Renew at 1/3 the remaining lease. This will give us an opportunity to retry + // at least one more time should the first renewal fail. + sleep = sleep / 3.0 + + // Use a randomness so many clients do not hit Vault simultaneously. + sleep = sleep * (r.random.Float64() + 1) / 2.0 + + return time.Duration(sleep) +} |