open-consul/api/kv.go

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package api
import (
"bytes"
"fmt"
"io"
"net/http"
"strconv"
"strings"
)
// KVPair is used to represent a single K/V entry
type KVPair struct {
// Key is the name of the key. It is also part of the URL path when accessed
// via the API.
Key string
// CreateIndex holds the index corresponding the creation of this KVPair. This
// is a read-only field.
CreateIndex uint64
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// ModifyIndex is used for the Check-And-Set operations and can also be fed
// back into the WaitIndex of the QueryOptions in order to perform blocking
// queries.
ModifyIndex uint64
// LockIndex holds the index corresponding to a lock on this key, if any. This
// is a read-only field.
LockIndex uint64
// Flags are any user-defined flags on the key. It is up to the implementer
// to check these values, since Consul does not treat them specially.
Flags uint64
// Value is the value for the key. This can be any value, but it will be
// base64 encoded upon transport.
Value []byte
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// Session is a string representing the ID of the session. Any other
// interactions with this key over the same session must specify the same
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// session ID.
Session string
}
// KVPairs is a list of KVPair objects
type KVPairs []*KVPair
// KVOp constants give possible operations available in a KVTxn.
type KVOp string
const (
KVSet KVOp = "set"
KVDelete = "delete"
KVDeleteCAS = "delete-cas"
KVDeleteTree = "delete-tree"
KVCAS = "cas"
KVLock = "lock"
KVUnlock = "unlock"
KVGet = "get"
KVGetTree = "get-tree"
KVCheckSession = "check-session"
KVCheckIndex = "check-index"
)
// KVTxnOp defines a single operation inside a transaction.
type KVTxnOp struct {
Verb string
Key string
Value []byte
Flags uint64
Index uint64
Session string
}
// KVTxnOps defines a set of operations to be performed inside a single
// transaction.
type KVTxnOps []*KVTxnOp
// KVTxnResponse has the outcome of a transaction.
type KVTxnResponse struct {
Results []*KVPair
Errors TxnErrors
}
// KV is used to manipulate the K/V API
type KV struct {
c *Client
}
// KV is used to return a handle to the K/V apis
func (c *Client) KV() *KV {
return &KV{c}
}
// Get is used to lookup a single key. The returned pointer
// to the KVPair will be nil if the key does not exist.
func (k *KV) Get(key string, q *QueryOptions) (*KVPair, *QueryMeta, error) {
resp, qm, err := k.getInternal(key, nil, q)
if err != nil {
return nil, nil, err
}
if resp == nil {
return nil, qm, nil
}
defer resp.Body.Close()
var entries []*KVPair
if err := decodeBody(resp, &entries); err != nil {
return nil, nil, err
}
if len(entries) > 0 {
return entries[0], qm, nil
}
return nil, qm, nil
}
// List is used to lookup all keys under a prefix
func (k *KV) List(prefix string, q *QueryOptions) (KVPairs, *QueryMeta, error) {
resp, qm, err := k.getInternal(prefix, map[string]string{"recurse": ""}, q)
if err != nil {
return nil, nil, err
}
if resp == nil {
return nil, qm, nil
}
defer resp.Body.Close()
var entries []*KVPair
if err := decodeBody(resp, &entries); err != nil {
return nil, nil, err
}
return entries, qm, nil
}
// Keys is used to list all the keys under a prefix. Optionally,
// a separator can be used to limit the responses.
func (k *KV) Keys(prefix, separator string, q *QueryOptions) ([]string, *QueryMeta, error) {
params := map[string]string{"keys": ""}
if separator != "" {
params["separator"] = separator
}
resp, qm, err := k.getInternal(prefix, params, q)
if err != nil {
return nil, nil, err
}
if resp == nil {
return nil, qm, nil
}
defer resp.Body.Close()
var entries []string
if err := decodeBody(resp, &entries); err != nil {
return nil, nil, err
}
return entries, qm, nil
}
func (k *KV) getInternal(key string, params map[string]string, q *QueryOptions) (*http.Response, *QueryMeta, error) {
r := k.c.newRequest("GET", "/v1/kv/"+key)
r.setQueryOptions(q)
for param, val := range params {
r.params.Set(param, val)
}
rtt, resp, err := k.c.doRequest(r)
if err != nil {
return nil, nil, err
}
qm := &QueryMeta{}
parseQueryMeta(resp, qm)
qm.RequestTime = rtt
if resp.StatusCode == 404 {
resp.Body.Close()
return nil, qm, nil
} else if resp.StatusCode != 200 {
resp.Body.Close()
return nil, nil, fmt.Errorf("Unexpected response code: %d", resp.StatusCode)
}
return resp, qm, nil
}
// Put is used to write a new value. Only the
// Key, Flags and Value is respected.
func (k *KV) Put(p *KVPair, q *WriteOptions) (*WriteMeta, error) {
params := make(map[string]string, 1)
if p.Flags != 0 {
params["flags"] = strconv.FormatUint(p.Flags, 10)
}
_, wm, err := k.put(p.Key, params, p.Value, q)
return wm, err
}
// CAS is used for a Check-And-Set operation. The Key,
// ModifyIndex, Flags and Value are respected. Returns true
// on success or false on failures.
func (k *KV) CAS(p *KVPair, q *WriteOptions) (bool, *WriteMeta, error) {
params := make(map[string]string, 2)
if p.Flags != 0 {
params["flags"] = strconv.FormatUint(p.Flags, 10)
}
params["cas"] = strconv.FormatUint(p.ModifyIndex, 10)
return k.put(p.Key, params, p.Value, q)
}
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// Acquire is used for a lock acquisition operation. The Key,
// Flags, Value and Session are respected. Returns true
// on success or false on failures.
func (k *KV) Acquire(p *KVPair, q *WriteOptions) (bool, *WriteMeta, error) {
params := make(map[string]string, 2)
if p.Flags != 0 {
params["flags"] = strconv.FormatUint(p.Flags, 10)
}
params["acquire"] = p.Session
return k.put(p.Key, params, p.Value, q)
}
// Release is used for a lock release operation. The Key,
// Flags, Value and Session are respected. Returns true
// on success or false on failures.
func (k *KV) Release(p *KVPair, q *WriteOptions) (bool, *WriteMeta, error) {
params := make(map[string]string, 2)
if p.Flags != 0 {
params["flags"] = strconv.FormatUint(p.Flags, 10)
}
params["release"] = p.Session
return k.put(p.Key, params, p.Value, q)
}
func (k *KV) put(key string, params map[string]string, body []byte, q *WriteOptions) (bool, *WriteMeta, error) {
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if len(key) > 0 && key[0] == '/' {
return false, nil, fmt.Errorf("Invalid key. Key must not begin with a '/': %s", key)
}
r := k.c.newRequest("PUT", "/v1/kv/"+key)
r.setWriteOptions(q)
for param, val := range params {
r.params.Set(param, val)
}
r.body = bytes.NewReader(body)
rtt, resp, err := requireOK(k.c.doRequest(r))
if err != nil {
return false, nil, err
}
defer resp.Body.Close()
qm := &WriteMeta{}
qm.RequestTime = rtt
var buf bytes.Buffer
if _, err := io.Copy(&buf, resp.Body); err != nil {
return false, nil, fmt.Errorf("Failed to read response: %v", err)
}
res := strings.Contains(string(buf.Bytes()), "true")
return res, qm, nil
}
// Delete is used to delete a single key
func (k *KV) Delete(key string, w *WriteOptions) (*WriteMeta, error) {
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_, qm, err := k.deleteInternal(key, nil, w)
return qm, err
}
// DeleteCAS is used for a Delete Check-And-Set operation. The Key
// and ModifyIndex are respected. Returns true on success or false on failures.
func (k *KV) DeleteCAS(p *KVPair, q *WriteOptions) (bool, *WriteMeta, error) {
params := map[string]string{
"cas": strconv.FormatUint(p.ModifyIndex, 10),
}
return k.deleteInternal(p.Key, params, q)
}
// DeleteTree is used to delete all keys under a prefix
func (k *KV) DeleteTree(prefix string, w *WriteOptions) (*WriteMeta, error) {
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_, qm, err := k.deleteInternal(prefix, map[string]string{"recurse": ""}, w)
return qm, err
}
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func (k *KV) deleteInternal(key string, params map[string]string, q *WriteOptions) (bool, *WriteMeta, error) {
r := k.c.newRequest("DELETE", "/v1/kv/"+key)
r.setWriteOptions(q)
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for param, val := range params {
r.params.Set(param, val)
}
rtt, resp, err := requireOK(k.c.doRequest(r))
if err != nil {
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return false, nil, err
}
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defer resp.Body.Close()
qm := &WriteMeta{}
qm.RequestTime = rtt
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var buf bytes.Buffer
if _, err := io.Copy(&buf, resp.Body); err != nil {
return false, nil, fmt.Errorf("Failed to read response: %v", err)
}
res := strings.Contains(string(buf.Bytes()), "true")
return res, qm, nil
}
// TxnOp is the internal format we send to Consul. It's not specific to KV,
// though currently only KV operations are supported.
type TxnOp struct {
KV *KVTxnOp
}
// TxnOps is a list of transaction operations.
type TxnOps []*TxnOp
// TxnResult is the internal format we receive from Consul.
type TxnResult struct {
KV *KVPair
}
// TxnResults is a list of TxnResult objects.
type TxnResults []*TxnResult
// TxnError is used to return information about an operation in a transaction.
type TxnError struct {
OpIndex int
What string
}
// TxnErrors is a list of TxnError objects.
type TxnErrors []*TxnError
// TxnResponse is the internal format we receive from Consul.
type TxnResponse struct {
Results TxnResults
Errors TxnErrors
}
// Txn is used to apply multiple KV operations in a single, atomic transaction.
//
// Note that Go will perform the required base64 encoding on the values
// automatically because the type is a byte slice. Transactions are defined as a
// list of operations to perform, using the KVOp constants and KVTxnOp structure
// to define operations. If any operation fails, none of the changes are applied
// to the state store. Note that this hides the internal raw transaction interface
// and munges the input and output types into KV-specific ones for ease of use.
// If there are more non-KV operations in the future we may break out a new
// transaction API client, but it will be easy to keep this KV-specific variant
// supported.
//
// Even though this is generally a write operation, we take a QueryOptions input
// and return a QueryMeta output. If the transaction contains only read ops, then
// Consul will fast-path it to a different endpoint internally which supports
// consistency controls, but not blocking. If there are write operations then
// the request will always be routed through raft and any consistency settings
// will be ignored.
//
// Here's an example:
//
// ops := KVTxnOps{
// &KVTxnOp{
// Verb: KVLock,
// Key: "test/lock",
// Session: "adf4238a-882b-9ddc-4a9d-5b6758e4159e",
// Value: []byte("hello"),
// },
// &KVTxnOp{
// Verb: KVGet,
// Key: "another/key",
// },
// }
// ok, response, _, err := kv.Txn(&ops, nil)
//
// If there is a problem making the transaction request then an error will be
// returned. Otherwise, the ok value will be true if the transaction succeeded
// or false if it was rolled back. The response is a structured return value which
// will have the outcome of the transaction. Its Results member will have entries
// for each operation. Deleted keys will have a nil entry in the, and to save
// space, the Value of each key in the Results will be nil unless the operation
// is a KVGet. If the transaction was rolled back, the Errors member will have
// entries referencing the index of the operation that failed along with an error
// message.
func (k *KV) Txn(txn KVTxnOps, q *QueryOptions) (bool, *KVTxnResponse, *QueryMeta, error) {
r := k.c.newRequest("PUT", "/v1/txn")
r.setQueryOptions(q)
// Convert into the internal format since this is an all-KV txn.
ops := make(TxnOps, 0, len(txn))
for _, kvOp := range txn {
ops = append(ops, &TxnOp{KV: kvOp})
}
r.obj = ops
rtt, resp, err := k.c.doRequest(r)
if err != nil {
return false, nil, nil, err
}
defer resp.Body.Close()
qm := &QueryMeta{}
parseQueryMeta(resp, qm)
qm.RequestTime = rtt
if resp.StatusCode == http.StatusOK || resp.StatusCode == http.StatusConflict {
var txnResp TxnResponse
if err := decodeBody(resp, &txnResp); err != nil {
return false, nil, nil, err
}
// Convert from the internal format.
kvResp := KVTxnResponse{
Errors: txnResp.Errors,
}
for _, result := range txnResp.Results {
kvResp.Results = append(kvResp.Results, result.KV)
}
return resp.StatusCode == http.StatusOK, &kvResp, qm, nil
}
var buf bytes.Buffer
if _, err := io.Copy(&buf, resp.Body); err != nil {
return false, nil, nil, fmt.Errorf("Failed to read response: %v", err)
}
return false, nil, nil, fmt.Errorf("Failed request: %s", buf.String())
}