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3 secrets
to build web APIs in Go
Matt Aimonetti - splice.com - @mattetti
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Matt Aimonetti
splice:
Go, Ruby, JS, Obj-C, C#, C++, C
golangbootcamp.com
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Splice
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Splice
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Architecture
clients
APIs / core logic
web rendering
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Architecture
Web API:
Synchronization
File upload
File download
Notifications
Obj-C C#
C
Go
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Architecture
file parsing/analysis
(sessions, media)
deduplication/storage
intermediate representation
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Architecture
internal/private API
(application logic)
“public” API
(states
retrieval/change)
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Architecture
HTTP
Message Bus
Long running async
tasks
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Go vs Ruby
10-20%
slower to write
20-100x
faster to run
60-80%
less maintenance
required
batteries included
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• Deployment
• Routing
• Monitoring
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Deployment
Zero downtime deployments
bitbucket.org/splice/go.grace
careful with goroutines
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Deployment
Version
Control
CI Storage
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Deployment
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Deployment
2014-06-23-183000/api 2014-06-23-204500/api
current/api
symlink
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Deployment
2014-06-23-183000/api 2014-06-23-204500/api
current/api
$ kill -USR2 {api PID}
symlink
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Routing
var V42Routes = Endpoints{
// create Ableton Live session
{
Verb: "POST",
Path: "/v42/live/sessions",
Handler: handlers.AlsUpload,
RequiredParams: handlers.AlsUploadReqParams,
Auth: splice.ClientAuth,
},
// create Logic session
{
Verb: "POST",
Path: "/v42/logic/sessions",
Handler: handlers.LogicUpload,
RequiredParams: handlers.LogicUploadReqParams,
Auth: splice.ClientAuth,
},
}
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Routing
package router
type Endpoint struct {
Verb string
Path string
RequiredParams []string
Auth func(*splice.ReqEnv, bool) bool
Handler splice.Handler
}
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Routing
type Endpoints []Endpoint
// Activate all the endpoint API routes.
func (es Endpoints) Activate(p *pat.PatternServeMux)
{
for _, e := range es {
// [..] set authentication calls
// [..] check param requirements
handler := splice.ReqWrap(e.Handler, e.Auth)
p.Add(e.Verb, e.Path, handler)
// [..] collect all CORS verbs accepted for
this endpoint so we can create OPTIONS routes.
}
}
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Routing
func ReqWrap(handler *Handler,
checkAuthFn func(*ReqEnv, bool) bool) http.Handler {
!
return http.HandlerFunc(func(w http.ResponseWriter,
r *http.Request) {
start := time.Now()
defer reportRequest(req, start, handler.Metrics)
reqUuid := uuid.GenUUID()
req := &ReqEnv{
ReqUuid: reqUuid,
Request: r,
Response: &statusResponseWriter{w, 0},
}
// [..] set headers (content type, req ID, build)
if !checkAuthFn(req, checkAuth) {
return
}
!
!
!
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Routing
!
!
!
// We must return a 400 and stop here if there was a problem
// parsing the request.
err := req.ParseParams()
if err != nil {
// […]return 400
return
}
// convert a panic into a 500
defer req.handlePanic()
handler.Handle(req)
})
}
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Monitoring
Monitor all the things!
runtime.ReadMemStats
http://golang.org/pkg/runtime/#MemStats
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Lessons learned
low memory usage
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Lessons learned
detect issues
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Lessons learned
detect issues
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Low memory usage
use streaming
io.Reader/io.Writer
io.Copy
Encoder/Decoder
instead of ReadAll and Unmarshal
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Monitoring
Monitor all the things!
Per endpoint:
• # of requests
• Status codes
• Response times
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@mattetti
http://matt.aimonetti.net