Enable TLS based communication with Zookeeper Backend (#4856)
* The added method customTLSDial() creates a tls connection to the zookeeper backend when 'tls_enabled' is set to true in config * Update to the document for TLS configuration that is required to enable TLS connection to Zookeeper backend * Minor formatting update * Minor update to the description for example config * As per review comments from @kenbreeman, additional property description indicating support for multiple Root CAs in a single file has been added * minor formatting
This commit is contained in:
Saurabh Pal
Brian Kassouf
parent
5f34bbbe6d
commit
77e635f7e1
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@ -2,7 +2,11 @@ package zookeeper
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import (
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"context"
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"crypto/tls"
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"crypto/x509"
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"fmt"
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"io/ioutil"
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"net"
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"path/filepath"
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"sort"
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"strings"
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@ -11,9 +15,11 @@ import (
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"github.com/hashicorp/errwrap"
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log "github.com/hashicorp/go-hclog"
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"github.com/hashicorp/vault/helper/parseutil"
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"github.com/hashicorp/vault/physical"
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metrics "github.com/armon/go-metrics"
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"github.com/hashicorp/vault/helper/tlsutil"
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"github.com/samuel/go-zookeeper/zk"
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)
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@ -119,7 +125,7 @@ func NewZooKeeperBackend(conf map[string]string, logger log.Logger) (physical.Ba
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}
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// We have all of the configuration in hand - let's try and connect to ZK
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client, _, err := zk.Connect(strings.Split(machines, ","), time.Second)
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client, _, err := createClient(conf, machines, time.Second)
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if err != nil {
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return nil, errwrap.Wrapf("client setup failed: {{err}}", err)
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}
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@ -142,6 +148,162 @@ func NewZooKeeperBackend(conf map[string]string, logger log.Logger) (physical.Ba
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return c, nil
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}
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func caseInsenstiveContains(superset, val string) bool {
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return strings.Contains(strings.ToUpper(superset), strings.ToUpper(val))
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}
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// Returns a client for ZK connection. Config value 'tls_enabled' determines if TLS is enabled or not.
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func createClient(conf map[string]string, machines string, timeout time.Duration) (*zk.Conn, <-chan zk.Event, error) {
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// 'tls_enabled' defaults to false
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isTlsEnabled := false
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isTlsEnabledStr, ok := conf["tls_enabled"]
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if ok && isTlsEnabledStr != "" {
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parsedBoolval, err := parseutil.ParseBool(isTlsEnabledStr)
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if err != nil {
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return nil, nil, errwrap.Wrapf("failed parsing tls_enabled parameter: {{err}}", err)
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}
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isTlsEnabled = parsedBoolval
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}
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if isTlsEnabled {
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// Create a custom Dialer with cert configuration for TLS handshake.
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tlsDialer := customTLSDial(conf, machines)
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options := zk.WithDialer(tlsDialer)
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return zk.Connect(strings.Split(machines, ","), timeout, options)
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} else {
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return zk.Connect(strings.Split(machines, ","), timeout)
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}
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}
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// Vault config file properties:
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// 1. tls_skip_verify: skip host name verification.
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// 2. tls_min_version: minimum supported/acceptable tls version
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// 3. tls_cert_file: Cert file Absolute path
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// 4. tls_key_file: Key file Absolute path
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// 5. tls_ca_file: ca file absolute path
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// 6. tls_verify_ip: If set to true, server's IP is verified in certificate if tls_skip_verify is false.
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func customTLSDial(conf map[string]string, machines string) zk.Dialer {
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return func(network, addr string, timeout time.Duration) (net.Conn, error) {
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// Sets the serverName. *Note* the addr field comes in as an IP address
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serverName, _, sParseErr := net.SplitHostPort(addr)
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if sParseErr != nil {
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// If the address is only missing port, assign the full address anyway
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if strings.Contains(sParseErr.Error(), "missing port") {
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serverName = addr
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} else {
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return nil, errwrap.Wrapf("failed parsing the server address for 'serverName' setting {{err}}", sParseErr)
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}
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}
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insecureSkipVerify := false
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tlsSkipVerify, ok := conf["tls_skip_verify"]
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if ok && tlsSkipVerify != "" {
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b, err := parseutil.ParseBool(tlsSkipVerify)
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if err != nil {
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return nil, errwrap.Wrapf("failed parsing tls_skip_verify parameter: {{err}}", err)
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}
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insecureSkipVerify = b
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}
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if !insecureSkipVerify {
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// If tls_verify_ip is set to false, Server's DNS name is verified in the CN/SAN of the certificate.
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// if tls_verify_ip is true, Server's IP is verified in the CN/SAN of the certificate.
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// These checks happen only when tls_skip_verify is set to false.
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// This value defaults to false
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ipSanCheck := false
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configVal, lookupOk := conf["tls_verify_ip"]
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if lookupOk && configVal != "" {
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parsedIpSanCheck, ipSanErr := parseutil.ParseBool(configVal)
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if ipSanErr != nil {
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return nil, errwrap.Wrapf("failed parsing tls_verify_ip parameter: {{err}}", ipSanErr)
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}
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ipSanCheck = parsedIpSanCheck
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}
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// The addr/serverName parameter to this method comes in as an IP address.
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// Here we lookup the DNS name and assign it to serverName if ipSanCheck is set to false
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if !ipSanCheck {
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lookupAddressMany, lookupErr := net.LookupAddr(serverName)
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if lookupErr == nil {
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for _, lookupAddress := range lookupAddressMany {
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// strip the trailing '.' from lookupAddr
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if lookupAddress[len(lookupAddress)-1] == '.' {
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lookupAddress = lookupAddress[:len(lookupAddress)-1]
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}
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// Allow serverName to be replaced only if the lookupname is part of the
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// supplied machine names
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// If there is no match, the serverName will continue to be an IP value.
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if caseInsenstiveContains(machines, lookupAddress) {
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serverName = lookupAddress
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break
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}
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}
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}
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}
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}
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tlsMinVersionStr, ok := conf["tls_min_version"]
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if !ok {
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// Set the default value
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tlsMinVersionStr = "tls12"
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}
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tlsMinVersion, ok := tlsutil.TLSLookup[tlsMinVersionStr]
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if !ok {
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return nil, fmt.Errorf("invalid 'tls_min_version'")
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}
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tlsClientConfig := &tls.Config{
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MinVersion: tlsMinVersion,
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InsecureSkipVerify: insecureSkipVerify,
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ServerName: serverName,
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}
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_, okCert := conf["tls_cert_file"]
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_, okKey := conf["tls_key_file"]
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if okCert && okKey {
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tlsCert, err := tls.LoadX509KeyPair(conf["tls_cert_file"], conf["tls_key_file"])
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if err != nil {
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return nil, errwrap.Wrapf("client tls setup failed for ZK: {{err}}", err)
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}
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tlsClientConfig.Certificates = []tls.Certificate{tlsCert}
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}
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if tlsCaFile, ok := conf["tls_ca_file"]; ok {
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caPool := x509.NewCertPool()
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data, err := ioutil.ReadFile(tlsCaFile)
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if err != nil {
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return nil, errwrap.Wrapf("failed to read ZK CA file: {{err}}", err)
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}
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if !caPool.AppendCertsFromPEM(data) {
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return nil, fmt.Errorf("failed to parse ZK CA certificate")
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}
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tlsClientConfig.RootCAs = caPool
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}
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if network != "tcp" {
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return nil, fmt.Errorf("unsupported network %q", network)
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}
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tcpConn, err := net.DialTimeout("tcp", addr, timeout)
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if err != nil {
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return nil, err
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}
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conn := tls.Client(tcpConn, tlsClientConfig)
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if err := conn.Handshake(); err != nil {
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return nil, fmt.Errorf("Handshake failed with Zookeeper : %v", err)
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}
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return conn, nil
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}
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}
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// ensurePath is used to create each node in the path hierarchy.
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// We avoid calling this optimistically, and invoke it when we get
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// an error during an operation
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@ -66,6 +66,30 @@ znodes and, potentially, take Vault out of service.
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ip:70.95.0.0/16
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```
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- `tls_enabled` `(bool: false)` – Specifies if TLS communication with the Zookeeper
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backend has to be enabled.
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- `tls_ca_file` `(string: "")` – Specifies the path to the CA certificate file used
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for Zookeeper communication. Multiple CA certificates can be provided in the same file.
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- `tls_cert_file` `(string: "")` (optional) – Specifies the path to the
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client certificate for Zookeeper communication.
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- `tls_key_file` `(string: "")` – Specifies the path to the private key for
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Zookeeper communication.
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- `tls_min_version` `(string: "tls12")` – Specifies the minimum TLS version to
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use. Accepted values are `"tls10"`, `"tls11"` or `"tls12"`.
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- `tls_skip_verify` `(bool: false)` – Specifies if the TLS host verification
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should be disabled. It is highly discouraged that you disable this option.
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- `tls_verify_ip` `(bool: false)` - This property comes into play only when
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'tls_skip_verify' is set to false. When 'tls_verify_ip' is set to 'true', the
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zookeeper server's IP is verified in the presented certificates CN/SAN entry.
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When set to 'false' the server's DNS name is verified in the certificates CN/SAN entry.
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## `zookeeper` Examples
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### Custom Address and Path
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@ -105,4 +129,25 @@ storage "zookeeper" {
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}
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```
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### zNode connection over TLS.
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This example instructs Vault to connect to Zookeeper using the provided TLS configuration. The host verification will happen with the presented certificate using the servers IP because 'tls_verify_ip' is set to true.
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```hcl
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storage "zookeeper" {
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address = "host1.com:5200,host2.com:5200,host3.com:5200"
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path = "vault_path_on_zk/"
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znode_owner = "digest:vault_user:digestvalueforpassword="
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auth_info = "digest:vault_user:thisisthepassword"
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redirect_addr = "http://localhost:8200"
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tls_verify_ip = "true"
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tls_enabled= "true"
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tls_min_version= "tls12"
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tls_cert_file = "/path/to/the/cert/file/zkcert.pem"
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tls_key_file = "/path/to/the/key/file/zkkey.pem"
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tls_skip_verify= "false"
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tls_ca_file= "/path/to/the/ca/file/ca.pem"
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}
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```
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[zk]: https://zookeeper.apache.org/
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