open-consul/api/api.go

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package api
import (
"bytes"
"crypto/tls"
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"crypto/x509"
"encoding/json"
"fmt"
"io"
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"io/ioutil"
"log"
"net"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"time"
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"github.com/hashicorp/go-cleanhttp"
)
// QueryOptions are used to parameterize a query
type QueryOptions struct {
// Providing a datacenter overwrites the DC provided
// by the Config
Datacenter string
// AllowStale allows any Consul server (non-leader) to service
// a read. This allows for lower latency and higher throughput
AllowStale bool
// RequireConsistent forces the read to be fully consistent.
// This is more expensive but prevents ever performing a stale
// read.
RequireConsistent bool
// WaitIndex is used to enable a blocking query. Waits
// until the timeout or the next index is reached
WaitIndex uint64
// WaitTime is used to bound the duration of a wait.
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// Defaults to that of the Config, but can be overridden.
WaitTime time.Duration
// Token is used to provide a per-request ACL token
// which overrides the agent's default token.
Token string
// Near is used to provide a node name that will sort the results
// in ascending order based on the estimated round trip time from
// that node. Setting this to "_agent" will use the agent's node
// for the sort.
Near string
}
// WriteOptions are used to parameterize a write
type WriteOptions struct {
// Providing a datacenter overwrites the DC provided
// by the Config
Datacenter string
// Token is used to provide a per-request ACL token
// which overrides the agent's default token.
Token string
}
// QueryMeta is used to return meta data about a query
type QueryMeta struct {
// LastIndex. This can be used as a WaitIndex to perform
// a blocking query
LastIndex uint64
// Time of last contact from the leader for the
// server servicing the request
LastContact time.Duration
// Is there a known leader
KnownLeader bool
// How long did the request take
RequestTime time.Duration
// Is address translation enabled for HTTP responses on this agent
AddressTranslationEnabled bool
}
// WriteMeta is used to return meta data about a write
type WriteMeta struct {
// How long did the request take
RequestTime time.Duration
}
// HttpBasicAuth is used to authenticate http client with HTTP Basic Authentication
type HttpBasicAuth struct {
// Username to use for HTTP Basic Authentication
Username string
// Password to use for HTTP Basic Authentication
Password string
}
// Config is used to configure the creation of a client
type Config struct {
// Address is the address of the Consul server
Address string
// Scheme is the URI scheme for the Consul server
Scheme string
// Datacenter to use. If not provided, the default agent datacenter is used.
Datacenter string
// HttpClient is the client to use. Default will be
// used if not provided.
HttpClient *http.Client
// HttpAuth is the auth info to use for http access.
HttpAuth *HttpBasicAuth
// WaitTime limits how long a Watch will block. If not provided,
// the agent default values will be used.
WaitTime time.Duration
// Token is used to provide a per-request ACL token
// which overrides the agent's default token.
Token string
}
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// TLSConfig is used to generate a TLSClientConfig that's useful for talking to
// Consul using TLS.
type TLSConfig struct {
// Address is the optional address of the Consul server. The port, if any
// will be removed from here and this will be set to the ServerName of the
// resulting config.
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Address string
// CAFile is the optional path to the CA certificate used for Consul
// communication, defaults to the system bundle if not specified.
CAFile string
// CertFile is the optional path to the certificate for Consul
// communication. If this is set then you need to also set KeyFile.
CertFile string
// KeyFile is the optional path to the private key for Consul communication.
// If this is set then you need to also set CertFile.
KeyFile string
// InsecureSkipVerify if set to true will disable TLS host verification.
InsecureSkipVerify bool
}
// DefaultConfig returns a default configuration for the client. By default this
// will pool and reuse idle connections to Consul. If you have a long-lived
// client object, this is the desired behavior and should make the most efficient
// use of the connections to Consul. If you don't reuse a client object , which
// is not recommended, then you may notice idle connections building up over
// time. To avoid this, use the DefaultNonPooledConfig() instead.
func DefaultConfig() *Config {
return defaultConfig(cleanhttp.DefaultPooledTransport)
}
// DefaultNonPooledConfig returns a default configuration for the client which
// does not pool connections. This isn't a recommended configuration because it
// will reconnect to Consul on every request, but this is useful to avoid the
// accumulation of idle connections if you make many client objects during the
// lifetime of your application.
func DefaultNonPooledConfig() *Config {
return defaultConfig(cleanhttp.DefaultTransport)
}
// defaultConfig returns the default configuration for the client, using the
// given function to make the transport.
func defaultConfig(transportFn func() *http.Transport) *Config {
config := &Config{
Address: "127.0.0.1:8500",
Scheme: "http",
HttpClient: &http.Client{
Transport: transportFn(),
},
}
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if addr := os.Getenv("CONSUL_HTTP_ADDR"); addr != "" {
config.Address = addr
}
if token := os.Getenv("CONSUL_HTTP_TOKEN"); token != "" {
config.Token = token
}
if auth := os.Getenv("CONSUL_HTTP_AUTH"); auth != "" {
var username, password string
if strings.Contains(auth, ":") {
split := strings.SplitN(auth, ":", 2)
username = split[0]
password = split[1]
} else {
username = auth
}
config.HttpAuth = &HttpBasicAuth{
Username: username,
Password: password,
}
}
if ssl := os.Getenv("CONSUL_HTTP_SSL"); ssl != "" {
enabled, err := strconv.ParseBool(ssl)
if err != nil {
log.Printf("[WARN] client: could not parse CONSUL_HTTP_SSL: %s", err)
}
if enabled {
config.Scheme = "https"
}
}
if verify := os.Getenv("CONSUL_HTTP_SSL_VERIFY"); verify != "" {
doVerify, err := strconv.ParseBool(verify)
if err != nil {
log.Printf("[WARN] client: could not parse CONSUL_HTTP_SSL_VERIFY: %s", err)
}
if !doVerify {
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tlsClientConfig, err := SetupTLSConfig(&TLSConfig{
InsecureSkipVerify: true,
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})
// We don't expect this to fail given that we aren't
// parsing any of the input, but we panic just in case
// since this doesn't have an error return.
if err != nil {
panic(err)
}
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transport := transportFn()
transport.TLSClientConfig = tlsClientConfig
config.HttpClient.Transport = transport
}
}
return config
}
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// TLSConfig is used to generate a TLSClientConfig that's useful for talking to
// Consul using TLS.
func SetupTLSConfig(tlsConfig *TLSConfig) (*tls.Config, error) {
tlsClientConfig := &tls.Config{
InsecureSkipVerify: tlsConfig.InsecureSkipVerify,
}
if tlsConfig.Address != "" {
server := tlsConfig.Address
hasPort := strings.LastIndex(server, ":") > strings.LastIndex(server, "]")
if hasPort {
var err error
server, _, err = net.SplitHostPort(server)
if err != nil {
return nil, err
}
}
tlsClientConfig.ServerName = server
}
if tlsConfig.CertFile != "" && tlsConfig.KeyFile != "" {
tlsCert, err := tls.LoadX509KeyPair(tlsConfig.CertFile, tlsConfig.KeyFile)
if err != nil {
return nil, err
}
tlsClientConfig.Certificates = []tls.Certificate{tlsCert}
}
if tlsConfig.CAFile != "" {
data, err := ioutil.ReadFile(tlsConfig.CAFile)
if err != nil {
return nil, fmt.Errorf("failed to read CA file: %v", err)
}
caPool := x509.NewCertPool()
if !caPool.AppendCertsFromPEM(data) {
return nil, fmt.Errorf("failed to parse CA certificate")
}
tlsClientConfig.RootCAs = caPool
}
return tlsClientConfig, nil
}
// Client provides a client to the Consul API
type Client struct {
config Config
}
// NewClient returns a new client
func NewClient(config *Config) (*Client, error) {
// bootstrap the config
defConfig := DefaultConfig()
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if len(config.Address) == 0 {
config.Address = defConfig.Address
}
if len(config.Scheme) == 0 {
config.Scheme = defConfig.Scheme
}
if config.HttpClient == nil {
config.HttpClient = defConfig.HttpClient
}
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if parts := strings.SplitN(config.Address, "unix://", 2); len(parts) == 2 {
trans := cleanhttp.DefaultTransport()
trans.Dial = func(_, _ string) (net.Conn, error) {
return net.Dial("unix", parts[1])
}
config.HttpClient = &http.Client{
Transport: trans,
}
config.Address = parts[1]
}
client := &Client{
config: *config,
}
return client, nil
}
// request is used to help build up a request
type request struct {
config *Config
method string
url *url.URL
params url.Values
body io.Reader
header http.Header
obj interface{}
}
// setQueryOptions is used to annotate the request with
// additional query options
func (r *request) setQueryOptions(q *QueryOptions) {
if q == nil {
return
}
if q.Datacenter != "" {
r.params.Set("dc", q.Datacenter)
}
if q.AllowStale {
r.params.Set("stale", "")
}
if q.RequireConsistent {
r.params.Set("consistent", "")
}
if q.WaitIndex != 0 {
r.params.Set("index", strconv.FormatUint(q.WaitIndex, 10))
}
if q.WaitTime != 0 {
r.params.Set("wait", durToMsec(q.WaitTime))
}
if q.Token != "" {
r.header.Set("X-Consul-Token", q.Token)
}
if q.Near != "" {
r.params.Set("near", q.Near)
}
}
// durToMsec converts a duration to a millisecond specified string. If the
// user selected a positive value that rounds to 0 ms, then we will use 1 ms
// so they get a short delay, otherwise Consul will translate the 0 ms into
// a huge default delay.
func durToMsec(dur time.Duration) string {
ms := dur / time.Millisecond
if dur > 0 && ms == 0 {
ms = 1
}
return fmt.Sprintf("%dms", ms)
}
// serverError is a string we look for to detect 500 errors.
const serverError = "Unexpected response code: 500"
// IsServerError returns true for 500 errors from the Consul servers, these are
// usually retryable at a later time.
func IsServerError(err error) bool {
if err == nil {
return false
}
// TODO (slackpad) - Make a real error type here instead of using
// a string check.
return strings.Contains(err.Error(), serverError)
}
// setWriteOptions is used to annotate the request with
// additional write options
func (r *request) setWriteOptions(q *WriteOptions) {
if q == nil {
return
}
if q.Datacenter != "" {
r.params.Set("dc", q.Datacenter)
}
if q.Token != "" {
r.header.Set("X-Consul-Token", q.Token)
}
}
// toHTTP converts the request to an HTTP request
func (r *request) toHTTP() (*http.Request, error) {
// Encode the query parameters
r.url.RawQuery = r.params.Encode()
// Check if we should encode the body
if r.body == nil && r.obj != nil {
if b, err := encodeBody(r.obj); err != nil {
return nil, err
} else {
r.body = b
}
}
// Create the HTTP request
req, err := http.NewRequest(r.method, r.url.RequestURI(), r.body)
if err != nil {
return nil, err
}
req.URL.Host = r.url.Host
req.URL.Scheme = r.url.Scheme
req.Host = r.url.Host
req.Header = r.header
// Setup auth
if r.config.HttpAuth != nil {
req.SetBasicAuth(r.config.HttpAuth.Username, r.config.HttpAuth.Password)
}
return req, nil
}
// newRequest is used to create a new request
func (c *Client) newRequest(method, path string) *request {
r := &request{
config: &c.config,
method: method,
url: &url.URL{
Scheme: c.config.Scheme,
Host: c.config.Address,
Path: path,
},
params: make(map[string][]string),
header: make(http.Header),
}
if c.config.Datacenter != "" {
r.params.Set("dc", c.config.Datacenter)
}
if c.config.WaitTime != 0 {
r.params.Set("wait", durToMsec(r.config.WaitTime))
}
if c.config.Token != "" {
r.header.Set("X-Consul-Token", r.config.Token)
}
return r
}
// doRequest runs a request with our client
func (c *Client) doRequest(r *request) (time.Duration, *http.Response, error) {
req, err := r.toHTTP()
if err != nil {
return 0, nil, err
}
start := time.Now()
resp, err := c.config.HttpClient.Do(req)
diff := time.Now().Sub(start)
return diff, resp, err
}
// Query is used to do a GET request against an endpoint
// and deserialize the response into an interface using
// standard Consul conventions.
func (c *Client) query(endpoint string, out interface{}, q *QueryOptions) (*QueryMeta, error) {
r := c.newRequest("GET", endpoint)
r.setQueryOptions(q)
rtt, resp, err := requireOK(c.doRequest(r))
if err != nil {
return nil, err
}
defer resp.Body.Close()
qm := &QueryMeta{}
parseQueryMeta(resp, qm)
qm.RequestTime = rtt
if err := decodeBody(resp, out); err != nil {
return nil, err
}
return qm, nil
}
// write is used to do a PUT request against an endpoint
// and serialize/deserialized using the standard Consul conventions.
func (c *Client) write(endpoint string, in, out interface{}, q *WriteOptions) (*WriteMeta, error) {
r := c.newRequest("PUT", endpoint)
r.setWriteOptions(q)
r.obj = in
rtt, resp, err := requireOK(c.doRequest(r))
if err != nil {
return nil, err
}
defer resp.Body.Close()
wm := &WriteMeta{RequestTime: rtt}
if out != nil {
if err := decodeBody(resp, &out); err != nil {
return nil, err
}
}
return wm, nil
}
// parseQueryMeta is used to help parse query meta-data
func parseQueryMeta(resp *http.Response, q *QueryMeta) error {
header := resp.Header
// Parse the X-Consul-Index
index, err := strconv.ParseUint(header.Get("X-Consul-Index"), 10, 64)
if err != nil {
return fmt.Errorf("Failed to parse X-Consul-Index: %v", err)
}
q.LastIndex = index
// Parse the X-Consul-LastContact
last, err := strconv.ParseUint(header.Get("X-Consul-LastContact"), 10, 64)
if err != nil {
return fmt.Errorf("Failed to parse X-Consul-LastContact: %v", err)
}
q.LastContact = time.Duration(last) * time.Millisecond
// Parse the X-Consul-KnownLeader
switch header.Get("X-Consul-KnownLeader") {
case "true":
q.KnownLeader = true
default:
q.KnownLeader = false
}
// Parse X-Consul-Translate-Addresses
switch header.Get("X-Consul-Translate-Addresses") {
case "true":
q.AddressTranslationEnabled = true
default:
q.AddressTranslationEnabled = false
}
return nil
}
// decodeBody is used to JSON decode a body
func decodeBody(resp *http.Response, out interface{}) error {
dec := json.NewDecoder(resp.Body)
return dec.Decode(out)
}
// encodeBody is used to encode a request body
func encodeBody(obj interface{}) (io.Reader, error) {
buf := bytes.NewBuffer(nil)
enc := json.NewEncoder(buf)
if err := enc.Encode(obj); err != nil {
return nil, err
}
return buf, nil
}
// requireOK is used to wrap doRequest and check for a 200
func requireOK(d time.Duration, resp *http.Response, e error) (time.Duration, *http.Response, error) {
if e != nil {
if resp != nil {
resp.Body.Close()
}
return d, nil, e
}
if resp.StatusCode != 200 {
var buf bytes.Buffer
io.Copy(&buf, resp.Body)
resp.Body.Close()
return d, nil, fmt.Errorf("Unexpected response code: %d (%s)", resp.StatusCode, buf.Bytes())
}
return d, resp, nil
}