/
kong.go
268 lines (228 loc) · 7.18 KB
/
kong.go
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package kong
import (
"bytes"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"reflect"
"github.com/google/go-querystring/query"
)
const (
contentType = "Content-Type"
applicationJson = "application/json"
)
// Client manages communication with the Kong API.
// New client objects should be created using the NewClient function.
// The BaseURL field must be defined and pointed at an instance of the
// Kong Admin API.
//
// Kong resources can be access using the Service objects.
// client.Apis.Get("id") -> GET /apis/id
// client.Consumers.Patch(consumer) -> PATCH /consumers/id
type Client struct {
client *http.Client // HTTP client used to communicate with the API
// Base URL for API requests.
// BaseURL should always be specified with a trailing slash
BaseURL *url.URL
// Reuse a single struct instead of allocating one for each service on the heap
common service
// Services used for talking to different parts of the Kong API
Node *NodeService
Cluster *ClusterService
Apis *ApisService
Upstreams *UpstreamsService
Targets *TargetsService
Consumers *ConsumersService
Plugins *PluginsService
}
// Each service representing a Kong resource type will be of this type
type service struct {
client *Client
}
// addOptions is used to convert the opt struct passed to the
// various Service.GetAll(opt) methods to query string parameters
// on the end of the resource URI passed for s. It is assumed that
// the struct fields passed in for opt are tagged with `url:""` tags.
//
// i.e &ApisGetAllOptions{RequestPath: "service"} -> /apis?request_path=service
func addOptions(s string, opt interface{}) (string, error) {
v := reflect.ValueOf(opt)
if v.Kind() == reflect.Ptr && v.IsNil() {
return s, nil
}
u, err := url.Parse(s)
if err != nil {
return s, err
}
qs, err := query.Values(opt)
if err != nil {
return s, err
}
u.RawQuery = qs.Encode()
return u.String(), nil
}
// NewClient creates a new kong.Client object.
// This should be the primary way a kong.Client object is constructed.
//
// If an httpClient object is specified it will be used instead of the
// default http.DefaultClient.
//
// baseURLStr should point to an instance a Kong Admin API and must
// contain the trailing slash. i.e. http://kong:8001/
func NewClient(httpClient *http.Client, baseURLStr string) (*Client, error) {
if httpClient == nil {
httpClient = http.DefaultClient
}
baseURL, err := url.Parse(baseURLStr)
if err != nil {
return nil, err
}
c := &Client{client: httpClient, BaseURL: baseURL}
c.common.client = c
// Share a single client among all of the services
c.Node = (*NodeService)(&c.common)
c.Cluster = (*ClusterService)(&c.common)
c.Apis = &ApisService{
service: &c.common,
Plugins: (*ApisPluginsService)(&c.common),
}
c.Upstreams = &UpstreamsService{
service: &c.common,
}
c.Targets = &TargetsService{
service: &c.common,
}
c.Consumers = &ConsumersService{
service: &c.common,
Plugins: &ConsumersPlugins{
ACL: (*ConsumersACLService)(&c.common),
JWT: (*ConsumersJWTService)(&c.common),
KeyAuth: (*ConsumersKeyAuthService)(&c.common),
},
}
c.Plugins = (*PluginsService)(&c.common)
return c, nil
}
// NewRequest is used to construct a new *http.Request object
// Generally speaking the returned *http.Request object will be
// used in a subsequent Client.Do to execute the actual REST call
// against Kong.
//
// If body is provided, it will be JSON encoded and used as the request
// body.
func (c *Client) NewRequest(method, urlStr string, body interface{}) (*http.Request, error) {
rel, err := url.Parse(urlStr)
if err != nil {
return nil, err
}
u := c.BaseURL.ResolveReference(rel)
// Kong does not like empty bodies
if method == "POST" || method == "PATCH" {
if reflect.ValueOf(body).IsNil() {
body = struct{}{}
}
}
var buf io.ReadWriter
if body != nil {
buf = new(bytes.Buffer)
err := json.NewEncoder(buf).Encode(body)
if err != nil {
return nil, err
}
}
req, err := http.NewRequest(method, u.String(), buf)
if err != nil {
return nil, err
}
if body != nil {
req.Header.Set("Content-Type", "application/json")
}
req.Header.Set("Accept", "application/json")
return req, nil
}
// Do executes the actual REST call against Kong. The API response is
// JSON decoded and stored in the value pointed to by v, or returned as an
// error if an API error has occurred. If v implements the io.Writer
// interface, the raw response body will be written to v, without attempting to
// first decode it.
//
// The *http.Response object returned by Do should eventually get
// passed back to the caller. If Kong returns a status code outside
// of the 200 range, the caller can inspect the *http.Response to
// get more information. Additionally the err returned in this case
// will be of type ErrorResponse.
func (c *Client) Do(req *http.Request, v interface{}) (*http.Response, error) {
resp, err := c.client.Do(req)
if err != nil {
return nil, err
}
err = CheckResponse(req, resp)
if err != nil {
// even though there was an error, we still return the response
// in case the caller wants to inspect it further
return resp, err
}
if v != nil {
if w, ok := v.(io.Writer); ok {
io.Copy(w, resp.Body)
} else {
err = json.NewDecoder(resp.Body).Decode(v)
if err == io.EOF {
err = nil // ignore EOF errors caused by empty response body
}
}
}
return resp, err
}
// ErrorResponse is returned from Client.Do if Kong returns a status
// code outside the 200 range.
type ErrorResponse struct {
Request *http.Request // HTTP request object used for the failed request
Response *http.Response // HTTP response that caused this error
KongMessage string `json:"message,omitempty"`
KongError string `json:"error,omitempty"`
}
func (r *ErrorResponse) Error() string {
return fmt.Sprintf("%v %v: %d %v %v",
r.Response.Request.Method, r.Response.Request.URL,
r.Response.StatusCode, r.KongMessage, r.KongError)
}
// ConflictError occurs when trying to create a resource that already exists.
// CheckResponse will return this type of error when Kong returns a 409 status code.
type ConflictError ErrorResponse
func (r *ConflictError) Error() string {
return (*ErrorResponse)(r).Error()
}
// NotFoundError occurs when trying to access a resource that does not exist.
// CheckResponse will return this type of error when Kong returns a 404 status code.
type NotFoundError ErrorResponse
func (r *NotFoundError) Error() string {
return (*ErrorResponse)(r).Error()
}
// CheckResponse looks at the response from a Kong API call
// and determines what type of error needs to be returned, if any.
func CheckResponse(req *http.Request, r *http.Response) error {
if c := r.StatusCode; 200 <= c && c <= 299 {
return nil
}
errorResponse := &ErrorResponse{Response: r}
data, err := ioutil.ReadAll(r.Body)
if err == nil && data != nil {
json.Unmarshal(data, errorResponse)
}
// Attach request to error
errorResponse.Request = req
// Restore r.Body to its original state after reading
r.Body = ioutil.NopCloser(bytes.NewBuffer(data))
switch r.StatusCode {
case 404:
return (*NotFoundError)(errorResponse)
case 409:
return (*ConflictError)(errorResponse)
default:
return errorResponse
}
}