Serving raster layers on Google Cloud Platform

Serving raster layers on Google Cloud Platform Lastupdated:22December2014

Contents

Introduction1.ConfigureaCloudPlatformprojectforservingrasters2.UploadtilestoGoogleCloudStorage

AccesscontroldecisionsMaptilesUploadingtilesinbulkforpublicaccessUploadingtilesinbulkforprivateaccess

3.UsetilesfromGoogleCloudStoragewiththeGoogleMapsAPIMapsAPIPublictilesexampleMapsAPIGoogleCloudStoragecookieauthexampleMapsAPIGoogleCloudStorageOAuth2.0Example

Howthisdemoworks4.WrapOGCendpointsaroundtilesfromGoogleCloudStoragewithGoogleComputeEngine

CreatingaGoogleComputeEngineVMInstallingandconfiguringMapProxyLoadbalancing

CreateasnapshotofyourworkingMapProxyVMCreateadiskfromthesnapshotCreateanimagefromthediskCreateaninstancetemplateCreateanInstanceGroupCreateanHTTPloadbalancer

Thirdpartyproducts:ThisdocumentdescribeshowGoogleproductsworkwiththirdpartyproductsandtheconfigurationsthatGooglerecommends.Googledoesnotprovidetechnicalsupportforconfiguringthirdpartyproducts.GOOGLEACCEPTSNORESPONSIBILITYFORTHIRDPARTYPRODUCTS.Pleaseconsulttheproduct'swebsiteforthelatestconfigurationandsupportinformation.YoucanalsocontactGooglePartnersforconsultingservices.

GoogleMapsforWork1/35

Introduction ThisdocumentshowsyouhowtoservecustomrasterlayersusingGoogleCloudStorage,GoogleComputeEngine,andtheGoogleMapsAPI.ThisapproachisusefulifyouhavealargequantityofsatelliteoraerialimagerythatyouneedtoserveatscaleontoaGooglemaporotherGIStool.Usingthisdocument,youllcompletethefollowingsteps:

1. ConfigureaGoogleCloudPlatformproject.2. UploadimagerytilestoGoogleCloudStorage.3. DisplaytilesusingtheGoogleMapsAPI.4. ServemaptilesusingOGCstandards.5. Loadbalanceyourapplication.

Note:ThisdocumentdoesnotdescribehowtocreaterastertilesandassumesyoualreadyhaverastertilestouploadandhostinGoogleCloudStorage.Youcanuseoneofmanythirdpartytoolstocreaterastertiles.Beforeyoubegin,makesureyouhaveaGoogleAccount.ConsiderusingasharedGoogleAccountforyourorganization,ratherthanapersonalGoogleAccount.

1. Configure a Cloud Platform project for serving rasters

1. SignintotheGoogleDevelopersConsoleandclickCreateProject.


2. Enablebilling.

FordetailsaboutbillinginGoogleCloudPlatform,seetheGoogleAPIsConsoleHelp.

3. Addacreditcardorbankaccounttotheprojectforhosting(storage)anddownloading

(egress)thesourceimageryforthecontractterm.GoogleCloudPlatformprovidesacalculatorforestimatingmonthlybillingchargesbasedonusage.

4. CreateaGoogleCloudstoragebucket.

Note:Cloudstoragebucketsareglobal,soifthenameyouchooseisalreadyinuse,chooseadifferentname.

5. InstallandauthenticatetheGoogleCloudSDKtoeasilyconductbulkdownloads.

Followtheinstallationinstructionsforyouroperatingsystem.OnceyouinstalltheSDK,youllhavenewsystemcommandslikegcloudandgsutil.


6. UsethefollowingcommandtoauthorizetheCloudSDKtoyourGoogleAccount.UsethesameGoogleAccountyouusedfortheowneroftheCloudPlatformProjectandtheImageryBucket.

$gcloudauthloginprojectyourprojectname

Detailsaboutthiscommand

AnOAuth2authorizationscreenwillopenabrowserwindow,givingtheCloudSDKaccesstoyourproject.


2. Upload tiles to Google Cloud Storage

Access control decisions YoucanfindadetaileddescriptionofhowGoogleCloudStoragehandlesAuthenticationandAccessControlintheGoogleCloudStoragedocumentation.Thisdocumentfocusesontheuseofaccesscontrollists(orACLs)forpublicorprivateaccess.Withpublicaccess,thetilesyouplaceonGoogleCloudStorageareaccessibletoanyoneontheInternet.Withprivateaccess,onlythosetowhomyouexplicitlygrantaccesscanviewthetiles.PrivateaccessiscontrolledusingOAuth2.0,andrequiresviewerstopresentcredentialsbasedoneofthefollowing:

AGoogleAccount(suchasGmailorGoogleApps) AGoogleAccountthatisamemberofanapprovedGoogleGroup Accessviaathirdpartyserviceorproxythathandlesauthenticationviaserverside

authentication(awebservicethatacceptsausernameandpasswordandproxiesdatawithaserversideaccesstoken).

Map tiles Maptilescanhavevariousnamingstandardsandcanvarybasedonmapprojection.Thisdocumentfocusesonmaptilesinaz/x/y.pngnamingstandard,where

Zisthecurrentzoomlevel,and XistheXcoordinateandYistheYcoordinate,measuredfromthetopleftofthemap

foreachzoomlevelGoogleMaps,ESRI,Bing,OpenStreetMap,andothersusethistopleftstandard.However,theOGCstandard,calledTMS,startsfromthebottomleft.Youcanseethedifferencesinthetwoexamplesbelow,whichshowatypicaltilesfilestructure(Z/X/Y.png),where,inthe4thXcolumnofzoomlevel4,therearetwoimagesfortheYcoordinates.Notethattheirnamesaredifferentbasedonwhethercountingbeganatthetopleftofbottomleft.


Thefilestructureinwhichyoursoftwareexportedthetileswilldeterminethelogicyouneedtouseinyourapplicationwhenyouwanttoloadaspecifictile.However,thefilestructuredoesntimpacttheactualuploadprocess.Forexamplepurposes,thisdocumentusestheUSGSNationalLandCoverDatabase.

Uploading tiles in bulk for public access TomakethetilespubliclyaccessibletoanyoneontheInternet,setthedefaultACLforthemaspublicread.Inthedirectorywhereyouhaveyourtilesinasubfoldercalledzxy,run:$gsutilmcpapublicreadRzxy/gs://usgslandcoverdemo/

Detailsaboutthiscommand

Themparameterwillmakethecpprocessruninparallelthreads,whichwillgreatlyspeedupyourupload.

Uploading tiles in bulk for private access Tomanageaccesstoprivatetiles,youcanuseGoogleGroups.WithGroups,itseasytograntreadpermissiontoaGoogleCloudStoragebuckettomembersofagroup,andthenmanagewriteaccessforindividualusersusingthestandardGoogleGroupsadministrationtools.Forthisexample,welluseagroupnamedCloudStorageTilesPrivate.Tojointhisgroup,clickJoinonthispage:


https://groups.google.com/forum/#!forum/cloudstoragetilesprivate$gsutilmbpcloudstoragetilesdemogs://usgslandcoverdemoprivate/[email protected]:Rgs://usgslandcoverdemoprivate/

3. Use tiles from Google Cloud Storage with the Google Maps API Maps API Public tiles example

SeethedemoThefollowingcodesnippetshowstheGoogleMapsAPIJavaScriptyouneedtocallthetilesasaGoogleMapsAPIImageMapType.Thesefilesresideinthe/z/x/y.pngstructureinthesamebucketinwhichtheHTMLthatloadstheMapsAPIresides.


varimageMapType=newgoogle.maps.ImageMapType({getTileUrl:function(coord,zoom){varproj=map.getProjection()varz2=Math.pow(2,zoom)vartileXSize=256/z2vartileYSize=256/z2vartileBounds=newgoogle.maps.LatLngBounds(proj.fromPointToLatLng(newgoogle.maps.Point(coord.x*tileXSize,(coord.y+1)*tileYSize)),proj.fromPointToLatLng(newgoogle.maps.Point((coord.x+1)*tileXSize,coord.y*tileYSize)))return"{z}/{x}/{y}.png".replace('{z}',zoom).replace('{x}',coord.x).replace('{y}',coord.y)},tileSize:newgoogle.maps.Size(256,256),minZoom:mapMinZoom,maxZoom:mapMaxZoom,name:'Tiles'})

YoucanalsohosttheHTMLpageonGoogleAppEngine,GoogleComputeEngine,oryourownwebserverandstillpointtotilesinaGoogleCloudstoragebucket.Todothis,justmodifytheURLfromalocalreferencetoaremotereference,asfollows:return"{z}/{x}/{y}.png".replace('{z}',zoom).replace('{x}',coord.x).replace('{y}',coord.y)toreturn"http://storage.googleapis.com/usgslandcoverdemo/zxy/{z}/{x}/{y}.png".replace('{z}',zoom).replace('{x}',coord.x).replace('{y}',coord.y)ForTMStiles,youneedtofliptheYcoordinate,asshowninthefollowingcodesample:varimageMapType=newgoogle.maps.ImageMapType({getTileUrl:function(coord,zoom){varproj=map.getProjection()varz2=Math.pow(2,zoom)vartileXSize=256/z2vartileYSize=256/z2vartileBounds=newgoogle.maps.LatLngBounds(proj.fromPointToLatLng(newgoogle.maps.Point(coord.x*tileXSize,(coord.y+1)*tileYSize)),proj.fromPointToLatLng(newgoogle.maps.Point((coord.x+1)*tileXSize,coord.y*tileYSize)))//FliptheYvaluevarymax=1

},tileSize:newgoogle.maps.Size(256,256),minZoom:mapMinZoom,maxZoom:mapMaxZoom,name:'Tiles'})Seeademo

Maps API Google Cloud Storage cookie auth example Forthisexample,wellusetheGooglegroupnamedCloudStorageTilesPrivate.Tojointhisgroup,clickJoinonthispage:https://groups.google.com/forum/#!forum/cloudstoragetilesprivateYoumustbeamemberofthisgrouptoviewthetilesinthefollowingdemo:https://storage.cloud.google.com/usgslandcoverdemo/zxy/cookiezxy.htmlFromtheGoogleCloudStorageDocumentation:

GoogleCloudStorageletsyouprovidebrowserbasedauthenticateddownloadstouserswhodonothaveGoogleCloudStorageaccounts.Todothis,applyGoogleAccountbasedACLstotheobjectandthenprovideuserswithaURLthatisscopedtotheobject.TheURLforbrowserbasedauthenticateddownloadsis:https://storage.cloud.google.com/bucket/objectNote:ThisURLbaseisslightlydifferentthanthehttp://storage.googleapis.com/basethisdocumentusesforthepublicmapexamples.

OnceyouveuploadedyourHTMLfile,youcanaddormodifythepermissions.MakesureyouveappliedthegroupyoureusingforthebucketsdefaultreaderACL.


WhenauservisitstheprivatewebpageURLintheirbrowser,theuserisautomaticallypromptedtosignintotheirGoogleAccount(ifnotalreadysignedin).Aftertheuserisauthenticatedandthebrowserhasacquiredacookiewithanencapsulatedidentitytoken,theuserisredirectedtothepageintheGoogleCloudStoragerepository.GoogleCloudStoragethenverifiesthattheuserisallowedtoreadthepage,andthenloadsthepageintothebrowser.Inthecodesamplebelow,notethatitisarequirementthattheabsolute,andnotlocalizedURLpattern,begivenforthetiles:varimageMapType=newgoogle.maps.ImageMapType({getTileUrl:function(coord,zoom){varproj=map.getProjection()varz2=Math.pow(2,zoom)vartileXSize=256/z2vartileYSize=256/z2vartileBounds=newgoogle.maps.LatLngBounds(proj.fromPointToLatLng(newgoogle.maps.Point(coord.x*tileXSize,(coord.y+1)*tileYSize)),proj.fromPointToLatLng(newgoogle.maps.Point((coord.x+1)*tileXSize,coord.y*tileYSize)))return"https://storage.cloud.google.com/usgslandcoverdemo/zxy/{z}/{x}/{y}.png".replace('{z}',zoom).replace('{x}',coord.x).replace('{y}',coord.y)},tileSize:newgoogle.maps.Size(256,256),minZoom:mapMinZoom,maxZoom:mapMaxZoom,name:'Tiles'})

Maps API Google Cloud Storage OAuth 2.0 Example OAuth2.0isanopenauthenticationprotocolusedfrequentlyinGoogleprojects.Itoffersauthenticationforbothclientandserverbasedapplications.ItsusefulformanagingquotausageforAPIsthathavedailylimitsorcostsassociatedwiththem,andforrestrictingquotausageanddataconsumptiontospecificdomains.Forthisexample,wellagainusetheGooglegroupnamedCloudStorageTilesPrivate.Tojointhisgroup,clickJoinonthispage:https://groups.google.com/forum/#!forum/cloudstoragetilesprivateYoumustbeamemberofthisgrouptoviewthetilesinthefollowingdemo:


http://storage.googleapis.com/usgslandcoverdemoprivate/zxy/privatezxy.htmlAsamemberofthegroup,youllfirstseeapagethatasksyoutoauthorize.ClicktheAuthorizebuttontoprovidetherequiredclientsideOAuth2.0credentialstoaccessthetiles.Next,youllseeascreenthatasksyoutogranttheapplicationpermissiontoaccessfilesinGoogleCloudStorageonyourbehalf.

ClickAccept.AmapwillappearandloadtheprivatelyACLdtiles.


How this demo works ThetopofthesourcecodeforthedemoaboveisablockofJavaScript: //TheClientIDforyourapplication,asconfiguredontheGoogleAPIsconsole.varclientId='237898814327hacml4d6ii16ekeopho52vepp5cq6e5o.apps.googleusercontent.com'//TheoauthscopefordisplayingGoogleCloudStoragedata.varscopes='https://www.googleapis.com/auth/devstorage.read_only'varaccess_token=''functioninitialize(){authorizationFlow(authorizationComplete,refreshComplete)}functionauthorizationComplete(authResult){access_token=authResult.access_tokeninitMap()}

ThiscodeconfigurestheOAuth2.0Workflowparameters.ThefirstdefinedvariableisanOAuth2.0ClientID.TocreateaClientID:

1. FromtheAPIs&AuthlistintheDevelopersConsoleproject,clickCredentials.


2. ClickCreatenewClientID:

3. OntheCreateClientIDscreen,selectWebapplication(default)fortheApplication

Type.(Thisapplicationisaccessedbyawebbrowseroveranetwork,andisnotaserversideorinstalledapplication.)

4. ClickConfigureconsentscreen.


Theuserseestheconsentscreenafterinvokingthefunctiontoauthorizetheapplication.Werecommendthatyouprovidelogosandlinksforyourapplication,toencourageuserstotrusttheapplicationtowhichtheyaregrantingpermissionstoaccesstheirdata.

5. Ataminimum,enteryourcontactemailaddressandaprojectname.ThenclickSave.

6. OntheCreateClientIDscreen,providetheAuthorizedJavaScriptOriginsandthe

AuthorizedRedirectURIs.


ThisinformationpreventssomeonefromcopyingyourHTML/JavaScriptandhostingitonaninsecureorthirdpartyserver,tointerceptuserdataoruseyourprojectsquotas.Inthisexample,wewanttohostaprivatemaponGoogleCloudStorage,soweneedtosettheAuthorizedJavaScriptOriginstohttp://storage.gooogleapis.com.WealsoneedtosettheAuthorizedRedirectURIstothefinalURLatwhichtheHTMLpagewillbehosted.Oncetheuserisauthorized,theOAuthworfklowredirectstheuserbacktotheoriginalpage,thistimewithaURLparameterthatistheiraccesstoken.Whentheapplicationseesthattheresanaccesstoken,itwillthenreplacetheblankpagewiththeAuthorizebuttonbyinitializingtheGoogleMapsAPI.

Finally,auniqueClientIDentrywillbecreated.YoulladdthisClientIDtotheJavaScriptforthevariableclientIDintheexample.


ThefollowinglinedefinestheOAuth2.0Scope,whichprovidesthedataaccessrightsthattheapplicationneedstheusertogranttotheapplication:

varscopes='https://www.googleapis.com/auth/devstorage.read_only'AtGoogle,thesescopesaretiedtoindividualservices.Inthiscase,wearecallingthedevstoragescope(GoogleCloudStorage),andbecausetheuserjustneedstoaccess(notwrite)tiles,theapplicationonlyneedsread_onlyaccess.Itsbesttokeepscopesasnarrowandconservativeaspossible,bothforsecurityandusertrust.Forexample,youwouldntwanttograntawebpagethatissupposedtoshowyourmaptilestheabilitytoposttoyourGoogle+profileorreadyourGmailcontactslist.BecausewewanttoallowuserstoaccessthewebpagebeforetheusersprovidetheircredentialstoinitiatetheOAuth2.0workflow,weneedtomaketheactualwebpagepublicallyaccessible.Dontworry,userswillnotbeabletoaccesstheprivatelyACLdtilesinthebucket,becausewearenotgoingtomodifytheirACLshowever,wellmaketheHTMLpageinthebucketpublicallyaccessible.


NotethatOAuth2.0credentialsexpireafteragivenamountoftime.AtGoogle,thedefaulttimeoutis60minutes.Thetimeoutisasecurityfeaturethatpreventssomeonewhomayhavenefariouslyinterceptedanaccesstokenfromusingthattokenforaprolongedperiodoftime.Thisapplicationrefresheseveryhourtoretrieveafreshaccesstoken:functionhandleAuthResult(authResult){varauthorizeButton=document.getElementById('authorize_button')//Hastheuserauthorizedthisapplication?if(authResult&&!authResult.error){//Theapplicationisauthorized.Hidethe'Authorization'button.authorizeButton.style.display='none'authorization_complete(authResult)//Wemustrefreshthetokenafteritexpires.window.setTimeout(refreshToken,authResult.expires_in*1000)Finally,unlikethepublicexamples,theprivateexamplesappendaqueryparametertothetileURL,?access_token={access_token}.WhenrequestingdatathatsprotectedbyprivateACLsfromGoogleCloudStorage,youmustpasstheaccess_tokenqueryparameterwithavalidandproperlyscopedaccesstoken.return"{z}/{x}/{y}.png?access_token={access_token}".replace('{z}',zoom).replace('{x}',coord.x).replace('{y}',coord.y).replace('{access_token}',access_token)


4. Wrap OGC endpoints around tiles from Google Cloud Storage with Google Compute Engine

Creating a Google Compute Engine VM ToenableOGCcompliantendpoints,youcanhostaccesstotheimagerytilesfromtheopensourceapplicationMapProxy.Inthissection,youllcreateaLinuxvirtualmachinewithinGoogleComputeEnginetohostMapProxy,andalsocreateacustomfirewallconfigurationtopermitincomingtraffictoMapProxy. TheGoogleComputeEngineDevelopersCenterhasseveralresourcestohelpyougetstartedrunningvirtualmachines,andindepthinformationforconfiguringfirewallrules.

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickNetworks.

2. UnderAllnetworks,clickdefaulttoaddanewfirewallrule.Thisruleletsyoutestthedevelopmentserveronport8080.

3. Createafirewallrule.


4. Enableport80byclickingonAllowHTTPtraffic.

Installing and configuring MapProxy

1. CreateanewUbuntu14.04ComputeEngineinstanceinyourproject:

gcloudcomputeinstancescreatemapproxyimageubuntu1404trustyv20141031aimageprojectubuntuoscloudzoneuscentral1a

2. ConnectviaSSH,usingaterminalortheDevelopersConsolebrowserterminal.

$sudoaptgetupdate$sudoaptgetinstallpythonvirtualenv$sudomkdir/mapproxy$sudochmod777/mapproxy$cd/mapproxy$virtualenvsystemsitepackagesmapproxy$sudoaptgetinstallpythonimagingpythonyamllibproj0$sudoaptgetinstalllibgeosdevpythonlxmllibgdaldevpythonshapely


$sudoaptgetinstallbuildessentialpythondevlibjpegdevzlib1gdevlibfreetype6dev$sourcemapproxy/bin/activate$pipinstallMapProxy$nanogcs.yaml

3. CopyandpastethefollowingMapProxyconfigurationfileintothenanoeditor.Note

thatyoullneedtochangetheURLparametertomatchyourGCSbucket.

services:demo:tms:use_grid_names:true#originfor/tilesserviceorigin:'nw'kml:use_grid_names:truewmts:wms:md:title:MapProxyGoogleCloudStorageabstract:ThisisaminimalMapProxyexample.layers:name:gcstitle:GoogleCloudStoragesources:[gcs_cache]caches:gcs_cache:grids:[webmercator]sources:[gcs]sources:gcs:type:tilegrid:webmercatorurl:http://storage.googleapis.com/usgslandcoverdemo/zxy/%(z)s/%(x)s/%(y)s.pngcoverage:srs:'EPSG:4326'bbox:[125.850,24.530,66.800,50.289]grids:webmercator:base:GLOBAL_WEBMERCATOR

4. Savethefile(Ctrl+O)andexit(Ctrl+X)Youcannowtesttheconfiguration.

$mapproxyutilservedevelopb0.0.0.0:8080gcs.yaml


5. Visitthedevelopmentserverat:

http://YourIP:8080/demo/

Therewillbeseveraldifferentservices,basedontheconfigurationfilethatyouused.

6. ClickanyofthePNGorJPEGlinkstotryouttheOGCservices.


7. Onceeverythingappearstobeworking,configureMapProxytoworkwithApacheviaWSGI.

$Ctrl+Ctokillthedevelopmentserver$rmrfcache_data$mapproxyutilcreatetwsgiappfgcs.yamlconfig.py$deactivate$sudoaptgetinstallapache2apache2mpmpreforkapache2utilslibexpat1sslcert$sudoaptitudeinstalllibapache2modwsgi$sudonano/etc/apache2/apache2.conf

8. Scrolldowntotheendofthefileandaddthefollowingcodeblock.Thensave

thefileandexit.

WSGIScriptAlias/mapproxy/mapproxy/config.pyWSGIDaemonProcessmapproxywsgidaemonprocesses=4threads=8WSGIProcessGroupmapproxywsgidaemonWSGIPythonHome/mapproxy/mapproxyWSGIApplicationGroup%{GLOBAL}OptionsAllAllowOverrideAll


Requireallgranted

$sudoserviceapache2restart

9. AccessMapProxyviatheApachewebserverlisteningonport80:

http://YourIP/mapproxy/demo

Load balancing WrappingservicessuchasWMSandWMTStotilesstoredonGoogleCloudstorageintroducesoverhead.WhenaWMSrequestcomesin,MapProxyhastodownloadthetilesfromCloudStoragethatintersectwiththerequestedboundingbox,compositethem,andthencutthemintoasinglenewimage.UnlikeCloudStorage,MapProxyrunningonaComputeEngineVMis,bydefault,notdesignedtohandleveryhighQPSorsupportnumeroususerssimultaneously.Forthisreason,werecommendthatyouincorporateloadbalancing.


ForafewuserswhooccasionallyuseyourOGCservices,youmightbeabletohavejustoneVMrunninghowever,youllneedtheabilitytoscaletohandlehigherdemand.ComputeEngineoffersmanywaystoconfigureloadbalancingthisdocumentshowsanetworkloadbalancedapproachwithautoscaling.

Create a snapshot of your working MapProxy VM

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickSnapshots.

2. ClickNewsnapshot.

3. Givethesnapshotaname,andchoseyourworkingVMasthesourcedisk.Thenclick

Create.

Create a disk from the snapshot

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickDisks.

2. ClickNewdisk.


3. Givethenewdiskaname,andchosethezoneinwhichyoudlikethedisktoreside.ThisshouldbethesameasthezonewhereyoudliketorunyourVMs.FortheSourceType,choseSnapshot,andthenchosethesnapshotyoucreatedinthepreviousstepasthesource.ThenclickCreate.

Create an image from the disk

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickImages.

2. ClickNewimage.


3. Givetheimageaname,andchoseDiskastheSourceType.Selectthediskyoucreatedinthepreviousstepasthesourcedisk.ThenclickCreate.

Create an instance template

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickInstancetemplates.

2. ClickCreateaninstancetemplate.


3. Givetheinstancetemplateaname,andsetthefirewalltoallowHTTPtraffic.

4. Chosethemachinetype.A2CPUmachineisagoodbalancebetweenpriceandperformance.ItshouldallowyourloadbalancedVMstohandleseveralsimultaneousconnectionspermachine,whilealsobeinglessexpensivethanahighCPUmachine.

5. ForImageforthetemplate,choosetheimageyoucreatedinthepreviousstep.For

theDisktype,choseastandardpersistentdisk.


Create an Instance Group

1. FromtheComputeEnginelistintheDevelopersConsole,clickInstancegroups.

2. ClickCreateanewinstancegroup.

3. Givetheinstancegroupaname,andchosetheinstancegrouptemplateyoupreviouslyconfigured.

4. TurnonAutoscaling,andchosetoautoscalebasedonHTTPloadbalancingusage.Acceptthedefaultvalueof80%.Later,wellconfiguretheRateofRequestspersecond(RPS/QPS),whichsays,Whenmyloadbalancerisreceiving80%oftheRPSthatthecurrentnumberofinstancescansupport,spinupanewinstance.

5. Configureaminimumof1instance,andsetalimitforthemaximumamountofinstancesyourewillingtoallowtobecreated.Formostcases,10to20issufficient.


Create an HTTP load balancer

1. FromtheComputeEnginelistintheDevelopersConsoleproject,clickHTTPloadbalancing.

2. ClickCreateanHTTPloadbalancer.

3. Givetheloadbalanceraname.ThenclickCreate.

4. Oncetheloadbalanceriscreated,clickthedefaultbackendservicetoeditit.


5. Forthebackendservice,chosetheinstancegroupyoupreviouslycreated.Forthebalancingmode,choseRate,andforMapProxy,5RPSisappropriateforeachofourn1standard2virtualmachines.Becauseyoupreviouslyselected80%asourHTTPLoadBalancingUtilizationthreshold,onceyourfirstinstancestartsreceivingasustained4RPS,anewinstancewillbecreated.Oncethetwoinstancesreach8RPS,athirdinstancewillbecreated,andsoon,untiltheupperlimitofthenumberofinstancesyouveconfigured.

6. Oncethebackendserviceisconfigured,clickthedefaulthealthchecklink.


TheHTTPLoadBalancerwillrunahealthchecktomakesurethatallyourinstancegroupsarehealthyandrespondingtorequests.Bydefault,itwilljustloadtherootofyourwebservers.

7. TomakesurethatthehealthcheckisactuallyinvokingtheWSGIapplicationofMapProxy,changethePathto/mapproxy/demo/Also,changetheIntervalto20seconds.


8. ClickSaveandreturntotheHTTPLoadBalancerUI.ThenclickAddaglobalforwardingrule.


9. Givetheruleaname,andchoseeitheranEphemeralorStaticIP.Werecommend

choosingStaticIP,becauseyoullsharethisIPaddresswithusersormapittoacustomURL.

10. ClickCreate.YourHTTPloadbalancerandinstancegroupswillbepushedtoproduction.Astheserviceisbeingturnedon,youllseea404erroratyourephemeralorstaticIPaddress/mapproxy/demo/.

Shortlyafter,youllstarttosee500errorsduringtheDNSpropagationphase.


Afterabout5minutes,theserviceandDNSpropagationshouldbecomplete,andyoullseeyourliveGoogleComputeEngineMapProxyService.YourservicereadytoserveatGooglescale,withHTTPloadbalancing,autoscaling,andtheabilitytocreateOGCendpointsaroundtilesservedfromGoogleCloudStorage.

Seethedemo


Serving raster layers on Google Cloud Platform

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Transcript of Serving raster layers on Google Cloud Platform