README
¶
gentleman-consul 
gentleman's v2 plugin for easy service discovery using Consul.
Provides transparent retry/backoff support for resilient and reactive HTTP client capabilities.
It also allows you to use custom retry strategies, such as constant or exponential retries.
Installation
go get -u gopkg.in/h2non/gentleman-consul.v2
Versions
API
See godoc reference for detailed API documentation.
Examples
See examples directory for featured examples.
Simple request
package main
import (
"fmt"
"gopkg.in/h2non/gentleman.v2"
"gopkg.in/h2non/gentleman-consul.v2"
)
func main() {
// Create a new client
cli := gentleman.New()
// Register Consul's plugin at client level
cli.Use(consul.New(consul.NewConfig("demo.consul.io", "web")))
// Create a new request based on the current client
req := cli.Request()
// Set a new header field
req.SetHeader("Client", "gentleman")
// Perform the request
res, err := req.Send()
if err != nil {
fmt.Printf("Request error: %s\n", err)
return
}
if !res.Ok {
fmt.Printf("Invalid server response: %d\n", res.StatusCode)
return
}
// Print response info
fmt.Printf("Server URL: %s\n", res.RawRequest.URL.String())
fmt.Printf("Response status: %d\n", res.StatusCode)
fmt.Printf("Server header: %s\n", res.Header.Get("Server"))
}
Custom retry strategy
package main
import (
"fmt"
"time"
"gopkg.in/h2non/gentleman.v2"
"gopkg.in/h2non/gentleman-consul.v1"
"gopkg.in/eapache/go-resiliency.v1/retrier"
)
func main() {
// Create a new client
cli := gentleman.New()
// Configure Consul plugin
config := consul.NewConfig("demo.consul.io", "web")
// Use a custom retrier strategy with max 10 retry attempts
config.Retrier = retrier.New(retrier.ConstantBackoff(10, time.Duration(25*time.Millisecond)), nil)
// Register Consul's plugin at client level
cli.Use(consul.New(config))
// Create a new request based on the current client
req := cli.Request()
// Set a new header field
req.SetHeader("Client", "gentleman")
// Perform the request
res, err := req.Send()
if err != nil {
fmt.Printf("Request error: %s\n", err)
return
}
if !res.Ok {
fmt.Printf("Invalid server response: %d\n", res.StatusCode)
return
}
// Print response info
fmt.Printf("Server URL: %s\n", res.RawRequest.URL.String())
fmt.Printf("Response status: %d\n", res.StatusCode)
fmt.Printf("Server header: %s\n", res.Header.Get("Server"))
}
License
MIT - Tomas Aparicio
Documentation
¶
Index ¶
- Constants
- Variables
- func New(config *Config) plugin.Plugin
- type Config
- type Consul
- func (c *Consul) GetBestCandidateNode(ctx *context.Context) (string, error)
- func (c *Consul) GetNodes() ([]string, error)
- func (c *Consul) IsUpdated() bool
- func (c *Consul) OnBeforeDial(ctx *context.Context, h context.Handler)
- func (c *Consul) Plugin() plugin.Plugin
- func (c *Consul) SetServerURL(ctx *context.Context, host string)
- func (c *Consul) UpdateCache(nodes []string)
- func (c *Consul) UseBestCandidateNode(ctx *context.Context) error
- type Retrier
Constants ¶
const Version = "2.0.1"
Version defines the package semantic version
Variables ¶
var CacheTTL = 10 * time.Minute
CacheTTL stores the default Consul catalog refresh cycle TTL. Default to 10 minutes.
var DefaultConfig = api.DefaultConfig
DefaultConfig provides a custom
var DefaultRetrier = retry.ConstantBackoff
DefaultRetrier stores the default retry strategy used by the plugin. By default will use a constant retry strategy with a maximum of 3 retry attempts.
var Scheme = "http"
Scheme represents the URI scheme used by default.
Functions ¶
Types ¶
type Config ¶
type Config struct {
// Retry enables/disables HTTP request retry policy. Defaults to true.
Retry bool
// Cache enables/disables the Consul catalog internal cache
// avoiding recurrent request to Consul server.
Cache bool
// Service stores the Consul's service name identifier. E.g: web.
Service string
// Tag stores the optional Consul's service tag to use when asking to Consul server.
Tag string
// Scheme stores the default HTTP URI scheme to be used when asking to Consul server.
// Defaults to: http.
Scheme string
// Retrier stores the retry strategy to be used.
// Defaults to: ContanstBackOff with max 3 retries.
Retrier retry.Retrier
// CacheTTL stores the max Consul catalog cache TTL.
CacheTTL time.Duration
// Client stores the official Consul client Config instance.
Client *api.Config
// Query stores the official Consul client query options when asking to Consul server.
Query *api.QueryOptions
}
Config represents the plugin supported settings.
func NewBasicConfig ¶
NewBasicConfig creates a new basic default config with the given Consul server hostname.
type Consul ¶
type Consul struct {
// mutex is used internallt to avoid race coditions for multithread scenarios.
sync.Mutex
// Config stores the Consul's plugin specific settings.
Config *Config
// Client stores the official Consul client.
Client *api.Client
// contains filtered or unexported fields
}
Consul represents the Consul plugin adapter for gentleman, which encapsulates the official Consul client and plugin specific settings.
func (*Consul) GetBestCandidateNode ¶
GetBestCandidateNode retrieves and returns the best service node candidate asking to Consul server catalog or reading catalog from cache.
func (*Consul) GetNodes ¶
GetNodes returns a list of nodes for the current service from Consul server or from cache (if enabled and not expired).
func (*Consul) IsUpdated ¶
IsUpdated returns true if the current list of catalog services is up-to-date, based on the cache TTL.
func (*Consul) OnBeforeDial ¶
OnBeforeDial is a middleware function handler that replaces the outgoing request URL and provides a new http.RoundTripper if necessary in order to handle request failures and retry it accordingly.
func (*Consul) SetServerURL ¶
SetServerURL sets the request URL fields based on the given Consul service instance.
func (*Consul) UpdateCache ¶
UpdateCache updates the list of catalog services.
type Retrier ¶
type Retrier struct {
// Consul stores the Consul client wrapper instance.
Consul *Consul
// Context stores the HTTP current gentleman context.
Context *context.Context
// Retry stores the retry strategy to be used.
Retry retry.Retrier
}
Retrier provides a retry.Retrier capable interface that encapsulates Consul client and user defined strategy.
func NewRetrier ¶
NewRetrier creates a default retrier for the given Consul client and context.
Source Files
Directories