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appengineでcontextからとれるやつ

Last updated at Posted at 2017-03-28

GAEでcontextの状態で設定を変えたりしたいとき、contextからどんな値がとれるのか覚えられないのでまとめておく。
この記事ではStandard環境のgoのみを対象としている。

手順

go1.9 go111ランタイムでサービスを分けてstandard環境にデプロイ。以下の関数の返り値を比較する。
ソース: https://github.com/crifff/go-context-value/

func handler(w http.ResponseWriter, r *http.Request) {
	ctx := appengine.NewContext(r)

	v := map[string]interface{}{}

	v["AppID"] = appengine.AppID(ctx)
	v["Datacenter"] = appengine.Datacenter(ctx)
	v["DefaultVersionHostname"] = appengine.DefaultVersionHostname(ctx)
	v["ModuleName"] = appengine.ModuleName(ctx)
	v["RequestID"] = appengine.RequestID(ctx)
	v["VersionID"] = appengine.VersionID(ctx)
	v["ServerSoftware"] = appengine.ServerSoftware()
	v["InstanceID"] = appengine.InstanceID()
	v["IsSecondGen"] = appengine.IsSecondGen()
	v["IsFlex"] = appengine.IsFlex()
	v["IsStandard"] = appengine.IsStandard()
	v["IsAppEngine"] = appengine.IsAppEngine()
	v["IsDevAppServer"] = appengine.IsDevAppServer()
	v["ServiceAccount"], _ = appengine.ServiceAccount(ctx)

	b, err := json.Marshal(v)
	if err != nil {
		panic(err)
	}
	w.Header().Add("Content-Type", "text/json")
	fmt.Fprint(w, string(b))
}

それぞれ下記のURLでアクセスできる

go service version URL
go1.9 default v1(default) https://v1-dot-go-context-value.appspot.com
go1.9 default v2 https://v2-dot-go-context-value.appspot.com
go1.11 default go111 https://go111-dot-go-context-value.appspot.com
go1.9 alpha v1(default) https://v1-dot-alpha-dot-go-context-value.appspot.com
go1.9 default v2 https://v2-dot-alpha-dot-go-context-value.appspot.com
go1.11 alpha go111 https://go111-dot-alpha-dot-go-context-value.appspot.com

結果

Local(DevServer/go1.9)

{
AppID: "None",
Datacenter: "us1",
DefaultVersionHostname: "localhost:8080",
InstanceID: "d29a6f03ec0778baf8bc2a0fa774aacc02bb",
IsAppEngine: true,
IsDevAppServer: true,
IsFlex: false,
IsSecondGen: false,
IsStandard: true,
ModuleName: "default",
RequestID: "fedbc794ac72e67fce70bea0eabb781921f3eef6b8c487",
ServerSoftware: "Development/2.0",
ServiceAccount: "test@localhost",
VersionID: "None.364449680094579473"
}

Local(DevServer/go111)

{
AppID: "None",
Datacenter: "",
DefaultVersionHostname: "localhost:8080",
InstanceID: "a11fdc6301ffee05f7689e6b5f2dfe6aadfe",
IsAppEngine: false,
IsDevAppServer: true,
IsFlex: false,
IsSecondGen: false,
IsStandard: false,
ModuleName: "default",
RequestID: "3e5e032f5c5a1eedfe2d05da90cda8c088bf8af6fb7727ea5b71fee52c90c0b86cbc27ebc8ccefce8facfab2dc3cce",
ServerSoftware: "Development/2.0",
ServiceAccount: "test@localhost",
VersionID: "None.449244578024933454"
}

default/v1(go1.9)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117c4208063954f191b68b4874f42a81a4613cb2391f230faf7ff13535dfc90fc7183f",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: false,
IsStandard: true,
ModuleName: "default",
RequestID: "5d2729b600ff0c7ed2bd2a31060001627e676f2d636f6e746578742d76616c756500017631000100",
ServerSoftware: "Google App Engine/1.9.71",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "v1.419522998664490749"
}

default/v2(go1.9)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117c9ca8a71316870ce43989f5b9191979daae14874331e8df0c0bbccde1b5ee7fe269",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: false,
IsStandard: true,
ModuleName: "default",
RequestID: "5d2729c200ff0e992090f0456d0001627e676f2d636f6e746578742d76616c756500017632000100",
ServerSoftware: "Google App Engine/1.9.71",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "v2.419523017757684430"
}

default/go111(go1.11)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117c9602f1817444427716f2f9a42f11dc0a7eadedb977e814a3c7abd2c8678a90975b",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: true,
IsStandard: true,
ModuleName: "default",
RequestID: "5d2729d100ff0361c42aa165df0001627e676f2d636f6e746578742d76616c75650001676f313131000100",
ServerSoftware: "standard",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "go111.419522942073841896"
}

alpha/v1(go1.9)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117c486572bdd3d8471df1650b2b6687c501a1ae8b3f6ebcfb3f85d069ef1e42b96db0",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: false,
IsStandard: true,
ModuleName: "alpha",
RequestID: "5d2729fd00ff0c6827e7d0795d0001627e676f2d636f6e746578742d76616c75650001616c7068613a7631000100",
ServerSoftware: "Google App Engine/1.9.71",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "v1.419523038922272815"
}

alpha/v2(go1.9)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117cd83d41491a86632082d3fafb8f58e7edef707922a03b181a8addf116aad79ac1e6",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: false,
IsStandard: true,
ModuleName: "alpha",
RequestID: "5d2729fe00ff082562e2c9b5cd0001627e676f2d636f6e746578742d76616c75650001616c7068613a7632000100",
ServerSoftware: "Google App Engine/1.9.71",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "v2.419523046912807332"
}

alpha/go111(go1.11)

{
AppID: "go-context-value",
Datacenter: "asia-northeast1-2",
DefaultVersionHostname: "go-context-value.appspot.com",
InstanceID: "00c61b117ca653f6fcc15941dabb4167698307fa5e2a632c0f3a93aeea51e59da3eddc238997",
IsAppEngine: true,
IsDevAppServer: false,
IsFlex: false,
IsSecondGen: true,
IsStandard: true,
ModuleName: "alpha",
RequestID: "5d2729fe00ff0efb11ff0034ad970001627e676f2d636f6e746578742d76616c75650001616c7068613a676f313131000100",
ServerSoftware: "standard",
ServiceAccount: "go-context-value@appspot.gserviceaccount.com",
VersionID: "go111.419523079476164322"
}

まとめ

AppID

常にアプリケーション名(プロジェクトID)を返す。
アプリケーション名(プロジェクトID)はデプロイ時に必須なので必ず任意の値が入る。
ただしローカル環境でアプリケーション名(プロジェクトID)の指定がない場合は None

Datacenter

常に作成時のリージョンを返す

IsAppEngine

LocalでもAppEngine上でも常に真

IsDevAppServer

Localのみ真

IsFlex

今回はStandardでしか検証していない全て偽

IsSecondGen

go111ランタイムで真

IsStandard

今回はStandardでしか検証していないので全て真

DefaultVersionHostname

バージョン、モジュールによらず常に基本となるホスト名を返す [アプリケーションID].appspot.com

ModuleName

常に現在のモジュール名を返す。
指定がない場合は default

RequestID

リクエストに対し一意なIDを返す。

ServerSoftware

go1.9以前はSDKのバージョンを含む文字列を返すがgo111ランタイムでは standard しか返さない。 IsSecondGenはこれで判別されている。ローカルは Development/2.0 を返す。

ServiceAccount

デフォルトのサービスアカウント名を返す。ローカルは test@localhost を返す。

VersionID

現在のバージョンとデプロイ毎に変化するバージョン番号が結合した文字列を返す [現在のバージョン名].[バージョン番号]
バージョン名はデプロイ時に必須なので必ず任意の値が入る。
ただしローカル環境で指定しない場合は None

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