api/api.go
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package api import ( "bytes" "context" "encoding/json" "fmt" "io" "io/ioutil" "net" "net/http" "net/url" "strconv" "strings" "sync" "time" "git.j3s.sh/cascade/lib/cleanhttp" ) // 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 // Transport is the Transport to use for the http client. Transport *http.Transport // HttpClient is the client to use. Default will be // used if not provided. HttpClient *http.Client // WaitTime limits how long a Watch will block. If not provided, // the agent default values will be used. WaitTime time.Duration } // DefaultConfig returns a default configuration for the client. By default this // will pool and reuse idle connections to cascade. If you have a long-lived // client object, this is the desired behavior and should make the most efficient // use of the connections to cascade. 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 cascade 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", Transport: transportFn(), } return config } // Client provides a client to the Consul API type Client struct { modifyLock sync.RWMutex headers http.Header config Config } // Headers gets the current set of headers used for requests. This returns a // copy; to modify it call AddHeader or SetHeaders. func (c *Client) Headers() http.Header { c.modifyLock.RLock() defer c.modifyLock.RUnlock() if c.headers == nil { return nil } ret := make(http.Header) for k, v := range c.headers { for _, val := range v { ret[k] = append(ret[k], val) } } return ret } // AddHeader allows a single header key/value pair to be added // in a race-safe fashion. func (c *Client) AddHeader(key, value string) { c.modifyLock.Lock() defer c.modifyLock.Unlock() c.headers.Add(key, value) } // SetHeaders clears all previous headers and uses only the given // ones going forward. func (c *Client) SetHeaders(headers http.Header) { c.modifyLock.Lock() defer c.modifyLock.Unlock() c.headers = headers } // NewClient returns a new client func NewClient(config *Config) (*Client, error) { // bootstrap the config defConfig := DefaultConfig() if config.Address == "" { config.Address = defConfig.Address } if config.Scheme == "" { config.Scheme = defConfig.Scheme } if config.Transport == nil { config.Transport = defConfig.Transport } if config.HttpClient == nil { config.HttpClient = NewHttpClient(config.Transport) } parts := strings.SplitN(config.Address, "://", 2) if len(parts) == 2 { switch parts[0] { case "http": config.Scheme = "http" // TODO: unix socket support? do i care? no??? default: return nil, fmt.Errorf("Unknown protocol scheme: %s", parts[0]) } config.Address = parts[1] } return &Client{config: *config, headers: make(http.Header)}, nil } // NewHttpClient returns an http client configured with the given Transport func NewHttpClient(transport *http.Transport) *http.Client { client := &http.Client{ Transport: transport, } return client } // 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{} ctx context.Context } // 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 // LastContentHash. This can be used as a WaitHash to perform a blocking query // for endpoints that support hash-based blocking. Endpoints that do not // support it will return an empty hash. LastContentHash string // How long did the request take RequestTime time.Duration // Is address translation enabled for HTTP responses on this agent AddressTranslationEnabled bool } // QueryOptions are used to parameterize a query type QueryOptions struct { // WaitIndex is used to enable a blocking query. Waits // until the timeout or the next index is reached WaitIndex uint64 // WaitHash is used by some endpoints instead of WaitIndex to perform blocking // on state based on a hash of the response rather than a monotonic index. // This is required when the state being blocked on is not stored in Raft, for // example agent-local proxy configuration. WaitHash string // WaitTime is used to bound the duration of a wait. // Defaults to that of the Config, but can be overridden. WaitTime time.Duration // 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 // NodeMeta is used to filter results by nodes with the given // metadata key/value pairs. Currently, only one key/value pair can // be provided for filtering. NodeMeta map[string]string // ctx is an optional context pass through to the underlying HTTP // request layer. Use Context() and WithContext() to manage this. ctx context.Context // Filter requests filtering data prior to it being returned. The string // is a go-bexpr compatible expression. Filter string } // setQueryOptions is used to annotate the request with // additional query options func (r *request) setQueryOptions(q *QueryOptions) { if q == nil { return } 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.WaitHash != "" { r.params.Set("hash", q.WaitHash) } if q.Near != "" { r.params.Set("near", q.Near) } if q.Filter != "" { r.params.Set("filter", q.Filter) } if len(q.NodeMeta) > 0 { for key, value := range q.NodeMeta { r.params.Add("node-meta", key+":"+value) } } r.ctx = q.ctx } // 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" // IsRetryableError returns true for 500 errors from the Consul servers, and // network connection errors. These are usually retryable at a later time. // This applies to reads but NOT to writes. This may return true for errors // on writes that may have still gone through, so do not use this to retry // any write operations. func IsRetryableError(err error) bool { if err == nil { return false } if _, ok := err.(net.Error); ok { return true } // TODO (slackpad) - Make a real error type here instead of using // a string check. return strings.Contains(err.Error(), serverError) } // 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 { b, err := encodeBody(r.obj) if err != nil { return nil, err } 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 // Content-Type must always be set when a body is present // See https://github.com/hashicorp/consul/issues/10011 if req.Body != nil && req.Header.Get("Content-Type") == "" { req.Header.Set("Content-Type", "application/json") } if r.ctx != nil { return req.WithContext(r.ctx), nil } 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: c.Headers(), } if c.config.WaitTime != 0 { r.params.Set("wait", durToMsec(r.config.WaitTime)) } 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.Since(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 cascade conventions. func (c *Client) query(endpoint string, out interface{}, q *QueryOptions) (*QueryMeta, error) { r := c.newRequest("GET", endpoint) r.setQueryOptions(q) rtt, resp, err := c.doRequest(r) if err != nil { return nil, err } defer closeResponseBody(resp) qm := &QueryMeta{} err = parseQueryMeta(resp, qm) if err != nil { return nil, err } qm.RequestTime = rtt if err := decodeBody(resp, out); err != nil { return nil, err } return qm, 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 (if it's set - hash based blocking queries don't // set this) // if indexStr := header.Get("X-Consul-Index"); indexStr != "" { // index, err := strconv.ParseUint(indexStr, 10, 64) // if err != nil { // return fmt.Errorf("Failed to parse X-Consul-Index: %v", err) // } // q.LastIndex = index // } // q.LastContentHash = header.Get("X-Consul-ContentHash") // 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 { closeResponseBody(resp) } return d, nil, e } if resp.StatusCode != 200 { return d, nil, generateUnexpectedResponseCodeError(resp) } return d, resp, nil } // closeResponseBody reads resp.Body until EOF, and then closes it. The read // is necessary to ensure that the http.Client's underlying RoundTripper is able // to re-use the TCP connection. See godoc on net/http.Client.Do. func closeResponseBody(resp *http.Response) error { _, _ = io.Copy(ioutil.Discard, resp.Body) return resp.Body.Close() } func (req *request) filterQuery(filter string) { if filter == "" { return } req.params.Set("filter", filter) } // generateUnexpectedResponseCodeError consumes the rest of the body, closes // the body stream and generates an error indicating the status code was // unexpected. func generateUnexpectedResponseCodeError(resp *http.Response) error { var buf bytes.Buffer io.Copy(&buf, resp.Body) closeResponseBody(resp) return fmt.Errorf("Unexpected response code: %d (%s)", resp.StatusCode, buf.Bytes()) } func requireNotFoundOrOK(d time.Duration, resp *http.Response, e error) (bool, time.Duration, *http.Response, error) { if e != nil { if resp != nil { closeResponseBody(resp) } return false, d, nil, e } switch resp.StatusCode { case 200: return true, d, resp, nil case 404: return false, d, resp, nil default: return false, d, nil, generateUnexpectedResponseCodeError(resp) } }