Introduction

Currently Cloudstack accepts only URL's to register a template/volume. If the user has a downloaded template/volume available, user has to host it either on dropbox etc. or run web server so as to get downloadable url. It is desirable to be able to upload a template/volume directly through standard web browser.

This feature enables the users to directly upload the template/volume to Cloudstack and eliminates the dependency on an external http server. This will be a complementary functionality and users can continue to register template/volume with URL as well.

Use cases

  1. User wants to upload a template from the browser and launch a vm with it on Cloudstack
  2. User wants to upload a volume from the browser and attach it to a vm on Cloudstack

Functional Requirements

Out of Scope

  1. Support for Http/unencrypted upload

  2. Upload progress during POST request

  3. Splitting of template/volume during upload and merge back

  4. Ability to cancel in-progress uploads by admin

  5. Upload for template/volume with more than one file will not be supported

Process Flow

The browser-based uploading process will have the following steps:

  1. Management Server generates a unique pre-shared key (PSK) and shares it with the SSVM agent. 
  2. New API request "getUploadParamsForVolume/Template" encoded the usual Cloudstack API way using api keys. Request parameters include format, hypervisor, md5 sum etc.
  3. Management Server response to (b) returns post url to upload the file, encrypted metadata to send to the url while uploading the volume/template file and a SHA1 signature generated using PSK.
  4. User should upload the file over https POST request to the url obtained in (c). The signature and metadata returned in (c) should be passed as is.
  5. The Apache web server on the SSVM matches the url, decrypts and passes on to the SSVM java agent as plain HTTP. The SSVM agent checks the signature against the decrypted metadata using the key PSK and SHA1. Once the data is verified, it writes to the NFS storage to the location encoded in the URL.
  6. Once the upload completes, the MD5 checksum is compared (if available from step c).

API changes

New APIs getUploadParamsForVolume/getUploadParamsForTemplate to enable users to upload volume/template from a local or network file share. The API response has a POST URL to which the volume/template needs to be uploaded. These are available to regular and admin users of Cloudstack. The request and response parameters are described below. Required parameters are marked with 'required'. Some of the parameters are exclusive for admin user and are marked 'admin only'.

GetUploadParamsForVolume
GetUploadParamsForTemplate
GetUploadParamsForVolume API call

http://managementip:8080/client/api?command=getUploadParamsForVolume&response=json&sessionkey=TW1GLzPclNGgKtoYN5Xznbw8Nds%3D&name=windows&zoneId=c2bcad2f-1eb1-45ba-bebe-1c21873831b7&format=VHD&apiKey=miVr6X7u6bN_sdahOBpjNejPgEsT35eXq-jB8CG20YI3yaxXcgpyuaIRmFI_EJTVwZ0nUkkJbPmY3y2bciKwFQ&signature=Lxx1DM40AjcXU%2FcaiK8RAP0O1hU%3D

Volume response

{ 
postURL:https://1-2-3-4.xyz.com/upload/C7D351D2-F167-4CC8-A9FF-3BECB0A625C4,
metadata:TKPFeuz2nHmE/kcREEu24mnj1MrLdzOeJIHXR9HLIGgk56bkRJHaD0RRL2lds1rKKhrro4/PuleEh4YhRinhxaAmPpU4e55eprG8gTCX0ItyFAtlZViVdKXMew5Dfp4Qg8W9I1/IsDJd2Kas9/ftDQLiemAlPt0uS7Ou6asOCpifnBaKvhM4UGEjHSnni1KhBzjgEyDW3Y42HKJSSv58Sgmxl9LCewBX8vtn9tXKr+j4afj7Jlh7DFhyo9HOPC5ogR4hPBKqP7xF9tHxAyq6YqfBzsng3Xwe+Pb8TU1kFHg1l2DM4tY6ooW2h8lOhWUkrJu4hOAOeTeRtCjW3H452NKoeA1M8pKWuqMo5zRMti2u2hNZs0YY2yOy8oWMMG+lG0hvIlajqEU=,
signature:de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9,
expires: 2014-10-17T12:00:00+0530,
uuid:C7D351D2-F167-4CC8-A9FF-3BECB0A625C4
}

GetUploadParamsForTemplate API call

http://managementip:8080/client/api?command=getUploadParamsForTemplate&type=template&response=json&name=centos 64 64bit&displayText=centos 64 64bit&zoneid=-1&format=VHD&isextractable=false&passwordEnabled=false&isdynamicallyscalable=false&osTypeId=1b510c30-3352-11e4-aaca-a5c7f57670d0&hypervisor=XenServer&requireshvm=false&apiKey=miVr6X7u6bN_sdahOBpjNejPgEsT35eXq-jB8CG20YI3yaxXcgpyuaIRmFI_EJTVwZ0nUkkJbPmY3y2bciKwFQ&signature=Lxx1DM40AjcXU%2FcaiK8RAP0O1hU%3D

Template response

{ 
postURL:https://1-2-3-4.xyz.com/upload/DD0A9FC6-C17E-4180-963C-870B9D03A80A,
metadata:TKPFeuz2nHmE/kcREEu24mnj1MrLdzOeJIHXR9HLIGgk56bkRJHaD0RRL2lds1rKKhrro4/PuleEh4YhRinhxaAmPpU4e55eprG8gTCX0ItyFAtlZViVdKXMew5Dfp4Qg8W9I1/IsDJd2Kas9/ftDQLiemAlPt0uS7Ou6asOCpifnBaKvhM4UGEjHSnni1KhBzjgEyDW3Y42HKJSSv58Sgmxl9LCewBX8vtn9tXKr+j4afj7Jlh7DFhyo9HOPC5ogR4hPBKqP7xF9tHxAyq6YqfBzsng3Xwe+Pb8TU1kFHg1l2DM4tY6ooW2h8lOhWUkrJu4hOAOeTeRtCjW3H452NKoeA1M8pKWuqMo5zRMti2u2hNZs0YY2yOy8oWMMG+lG0hvIlajqEU=,
signature:de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9,
expires: 2014-10-17T12:00:00+0530,
uuid:DD0A9FC6-C17E-4180-963C-870B9D03A80A
}

POST URL to post the data on to SSVM. This post url is returned from the getUploadParamsForVolume/Template api calls

Ex: https://1-2-3-4.xyz.com/upload/uuid

As seen in the example, the URL has a domain name (in this case xyz.com) and a prefix (in this case 1-2-3-4). The reason for having a domain name is that SSL certs can only issued for a domain and not any IP address. The domain name to be used is configured using the global config "secstorage.ssl.cert.domain". The prefix is to identify the SSVM based on its public IP address. So if the public IP is 1.2.3.4 then the prefix is 1-2-3-4. This approach for generating the URL is already present in Cloudstack. Refer (1) and (2) for more details.

Volume upload request

curl -X POST "https://1-2-3-4.xyz.com/upload/C7D351D2-F167-4CC8-A9FF-3BECB0A625C4" -F "file=@volume.vhd" -F "signature=de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9" -F "metadata=TKPFeuz2nHmE/kcREEu24mnj1MrLdzOeJIHXR9HLIGgk56bkRJHaD0RRL2lds1rKKhrro4/PuleEh4YhRinhxaAmPpU4e55eprG8gTCX0ItyFAtlZViVdKXMew5Dfp4Qg8W9I1/IsDJd2Kas9/ftDQLiemAlPt0uS7Ou6asOCpifnBaKvhM4UGEjHSnni1KhBzjgEyDW3Y42HKJSSv58Sgmxl9LCewBX8vtn9tXKr+j4afj7Jlh7DFhyo9HOPC5ogR4hPBKqP7xF9tHxAyq6YqfBzsng3Xwe+Pb8TU1kFHg1l2DM4tY6ooW2h8lOhWUkrJu4hOAOeTeRtCjW3H452NKoeA1M8pKWuqMo5zRMti2u2hNZs0YY2yOy8oWMMG+lG0hvIlajqEU=" -F "expires=2014-10-17T12:00:00+0530" -v

Volume response

200 OK

Template upload request

curl -X POST "https://1-2-3-4.xyz.com/upload/DD0A9FC6-C17E-4180-963C-870B9D03A80A" -F "file=@templatelocation.vhd" -F "signature=de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9" -F "metadata=TKPFeuz2nHmE/kcREEu24mnj1MrLdzOeJIHXR9HLIGgk56bkRJHaD0RRL2lds1rKKhrro4/PuleEh4YhRinhxaAmPpU4e55eprG8gTCX0ItyFAtlZViVdKXMew5Dfp4Qg8W9I1/IsDJd2Kas9/ftDQLiemAlPt0uS7Ou6asOCpifnBaKvhM4UGEjHSnni1KhBzjgEyDW3Y42HKJSSv58Sgmxl9LCewBX8vtn9tXKr+j4afj7Jlh7DFhyo9HOPC5ogR4hPBKqP7xF9tHxAyq6YqfBzsng3Xwe+Pb8TU1kFHg1l2DM4tY6ooW2h8lOhWUkrJu4hOAOeTeRtCjW3H452NKoeA1M8pKWuqMo5zRMti2u2hNZs0YY2yOy8oWMMG+lG0hvIlajqEU=" -F "expires=2014-10-17T12:00:00+0530" -v

Template response

200 OK

Query status of uploaded template/volume

User should be able to query the status of uploaded template/volume by calling listtemplates/listvolumes API with unique uuid obtained as part of the getUploadParams response (present in POST URL as mentioned above). The polling for status should start on successful completion of the POST request.

Volume status check request

http://managementip:8080/client/api?command=listVolumes&id=C7D351D2-F167-4CC8-A9FF-3BECB0A625C4&response=json&apiKey=miVr6X7u6bN_sdahOBpjNejPgEsT35eXq-jB8CG20YI3yaxXcgpyuaIRmFI_EJTVwZ0nUkkJbPmY3y2bciKwFQ&signature=Lxx1DM40AjcXU%2FcaiK8RAP0O1hU%3D

Volume status response

{ "listvolumesresponse" : { "count":1 ,"volume" : [  {"id":"C7D351D2-F167-4CC8-A9FF-3BECB0A625C4","name":"windows","zoneid":"c2bcad2f-1eb1-45ba-bebe-1c21873831b7","zonename":"zone","type":"DATADISK","provisioningtype":"thin","size":0,"created":"2014-10-17T15:24:06+0530","state":"Uploading","account":"admin","domainid":"fad51d88-449b-11e4-9cf2-2d5524b62490","domain":"ROOT","storagetype":"shared","hypervisor":"XenServer","diskofferingid":"a1bb6667-780c-47ad-91cb-b98aed589c18","diskofferingname":"Custom","diskofferingdisplaytext":"Custom Disk","destroyed":false,"isextractable":true,"status":"1% Uploaded","tags":[],"displayvolume":true,"quiescevm":false} ] } }

Template status check request

http://managementip:8080/client/api?command=listTemplates&response=json&templatefilter=self&id=DD0A9FC6-C17E-4180-963C-870B9D03A80A&apiKey=miVr6X7u6bN_sdahOBpjNejPgEsT35eXq-jB8CG20YI3yaxXcgpyuaIRmFI_EJTVwZ0nUkkJbPmY3y2bciKwFQ&signature=Lxx1DM40AjcXU%2FcaiK8RAP0O1hU%3D

Template status response

{ "listtemplatesresponse" : { "count":1 ,"template" : [  {"id":"DD0A9FC6-C17E-4180-963C-870B9D03A80A","name":"centos 64 64bit","displaytext":"centos 64 64bit","ispublic":false,"created":"2014-10-17T10:54:40+0530","isready":false,"passwordenabled":false,"format":"tar","isfeatured":false,"crossZones":false,"ostypeid":"1b510c30-3352-11e4-aaca-a5c7f57670d0","ostypename":"CentOS 6.2 (64-bit)","account":"admin","zoneid":"c2bcad2f-1eb1-45ba-bebe-1c21873831b7","zonename":"zone","status":"8% Downloaded","templatetype":"USER","hypervisor":"XenServer","domain":"ROOT","domainid":"fad51d88-449b-11e4-9cf2-2d5524b62490","isextractable":true,"details":{"hypervisortoolsversion":"xenserver61"},"tags":[],"sshkeyenabled":false,"isdynamicallyscalable":false} ] } }

Failed uploads

If the template/volume fails to upload (HTTP code other than 200 OK), the user should request for a new upload url and upload it again. The same upload URL shouldn't be reused.

Design

Pre-shared key management

This section covers when and how the pre-shared key is generated by management server, how is it stored, how is it passed to SSVM

  1. On start of management server, if the key doesn't exist, it auto-generates one using SHA1 and stores it in db
  2. Key is saved in encrypted form (if db encryption is enabled) in the configuration table as hidden configuration with name upload.post.secret.key
  3. During SSVM start-up, the key is passed on to it by management server 
  4. SSVM stores this key in a file at /etc/cloudstack/agent/ms-psk
  5. If the key sharing fails SSVM agent would shut itself down
  6. Updating the PSK would involve the following:
    1. Delete the upload.secret.key config from configuration table in db (manual step)
    2. Restart the MS, so that it gets regenerated again (manual step)
    3. Destroy all the existing SSVMs (manual step)
    4. When the new SSVMs starts up the key is copied to it
    5. There will be a window when the key is not in sync between management server and SSVMs

Signature generation and verification

The signature returned from the management server in the response of getUploadParams will be validated on the SSVM Agent.

  1. The signature is generated using SHA1 and the PSK on the metadata, expires and postURL
  2. Management server and SSVM machines should be in time sync for the verification to work
  3. On the SSVM agent, it first checks if the expires has crossed
  4. It computes hash on metadata, expires and postURL using SHA1 and PSK and rejects the request if they do not match.
  5. The postURL, expires and metadata returned from getUploadParamsForVolume/Template shouldn't be tampered by the user. Else, signature validation would fail.

Encryption and decryption of 'metadata'

The PSK will also be used to encrypt and decrypt the metadata sent from the management server in the api response and received on the SSVM agent in the api request.

  1. jasypt library with PBEWITHSHA1ANDDESEDE algorithm and the initial PSK will be used to encrypt and decrypt the metadata.
  2. Management server encrypts the data using the method in #1 and returns the encrypted string in the response
  3. SSVM Agent, after receiving the metadata, decrypts it using the method in #1 and then does signature validation.

Unencrypted metadata

The unencrypted metadata is a JSON string having all the necessary information to store the uploaded volume/template to secondary store. For a template it looks something like below.

{"store":{"com.cloud.agent.api.to.NfsTO":"nfs://10.147.28.7/export/home/rajani/lxc/secondary"},"hvm":false,"description":"lxc1","maxDownloadSizeInBytes":53687091200,"id":207,"resourceType":"TEMPLATE","installPath":"template/tmpl/2/207","format":"TAR","accountId":2,"name":"207-2-09c78adc-065f-3dc8-9621-9e7a036d7dc9"}

Sequence Diagram

Management server and SSVM agent interaction

When the management server receives getUploadParams api call, it selects SSVM and secondary store in the zone requested by the user and returns a POST url to that SSVM. There can be multiple SSVMs in the same zone. Management servers decides which SSVM to handle this based on the load.

SSVM agent will keep track of all upload status assigned to it and sends it to management server (based on management server initiated polling). If the template/volume is selected to be cross-zone, it will uploaded to one zone and then copied to other zones from it (already existing functionality).

Management server owns the lifecycle of volume/template (initially gets created with upload state as "NOT_UPLOADED"). It polls the SSVM agent (using an already existing agent command) to get the status and triggers appropriate state transitions. Polling starts after the successful completion of the getUploadParams API. The polling 'interval' and 'timeout' are determined by global configuration parameters.

Failure at any point during the upload process to SSVM would result in upload state getting transitioned to "UPLOAD_ERROR" (refer to the state machine below). Also if the upload is not completed within 'timeout' configuration the state transitions to "UPLOAD_ERROR". This will take care of SSVM agent failure/SSVM failure scenarios.

If the management server itself goes down during the upload, the polling is resumed by the new management server that takes ownership of the SSVM. The 'timeout' is always taken in account from the time template entry gets created in db.

SSVM selection logic

TBD - check existing code and reuse

SSVM agent and SSVM apache interaction

The SSVM agent will listen for any connections from Apache web server (using the NioServer utility). It will be using the localhost and port number (come from a configuration) to listen.

SSVM apache proxies the data from https to http url on localhost:port using ProxyPass.

All the http events and data will be proxied by apache to agent. SSL validation only happens at apache layer.

Upload lifecycle

Upload failures

The below failures can happen while SSVM agent is receiving the template. When management server polls for the status of the template/volume, if any of these below errors happen, the agent returns appropriate information and management server transitions the state accordingly.

Upload success

The process is considered success If the volume/template upload is successfully completes (and installed in case of template) within the polling timeout. In this case agent returns a success status to management server during the polling.

State machine 

Template/Volume go through below state machine transitions, when it goes through the browser based upload.

States:

NOT_UPLOADED: getUploadParams API was successful and the template is registered. But, upload hasn't started yet (agent has no data about this upload)

UPLOAD_IN_PROGRESS: User has initiated the POST request on SSVM Apache and the validation/upload is in progress

UPLOADED: SSVM agent successfully copied the template/volume to secondary storage

UPLOAD_ERROR: Any failure in between user initiating the POST request and template being downloaded OR failure to complete within configured timeout

ABANDONED: the POST request isn't initiated within the configured timeout. In this case the SSVM agent has no record of the upload (TBD: Do we really need to distinguish ERROR and ABANDONED?)

State Transitions:

Cleanup

A cleanup thread will be running at regular intervals (configurable, provide details). It will pick up all volume/template with upload state as "UPLOAD_ERROR" and "ABANDONED" and send agent command to cleanup any partial data from secondary store. The cleanup will be a best-effort approach.

Recovery mechanisms

There isn't any recovery or retry mechanism as this is a POST request. Once error happens user gets notified with a clear error message as part of the response. The template/volume will remain in the error state and admin will be able to troubleshoot it based on the appropriate log messages in management server log, agent log, apache access/error log files. This failed entries will eventually get be cleaned by the cleanup process. The user has to reinitiate the upload by calling getUploadParams API again.

One time POST url and parallel uploads

The POST url returned by the management server to upload template/volume is expected to be used only once. If there is a download in-progress/error/success state for template/volume in the URL and the SSVM agent gets a new request for the same URL, the agent rejects this request saying there is another download in progress (409 conflict).

Open item: The limitation here is that if the template/volume cleanup happened and the template is cleaned, agent would start accepting the url again. This will be fixed later. 

DB Changes

No schema changes. Some configuration items will be created.

Configurations

The following new configurations will be added

Security

Performance

UI Changes

UI to upload volume/template which should be able to accept "browse and upload" file. Existing UI for volume/template upload will be extended with the browser-based upload functionality.

UI flow for Templates:

  1. User navigates to the Templates page then clicks on "Register template" (existing screen)
  2. Register template form pops up (existing screen)
  3. User has now the choice to provide URL of the template (existing functionality) or Upload File from Browser (new functionality)
  4. Selects File Upload from Browser then specifies the template file (Browse...) to be uploaded
  5. User fills in other existing form fields
  6. User clicks OK to submit the form
  7. Browser UI requests an unique upload URL using the getUploadParamsForTemplate api call
  8. Management server returns an upload url, encrypted metadata string which should be passed on to the upload url while doing the upload
  9. Browser starts uploading using POST request to the upload URL
  10. The post request completes once the template is uploaded or there was an error uploading.
  11. The user can close the dialog (POST request should still be active) and use list templates API result to check the status of it

 

UI flow for Volume/ISO:

  1. User navigates to the Templates page then switches to ISO using the "Select view" selector, then the user clicks on "Register ISO" (existing screen)
  2. Register ISO form pops up (existing screen)
  3. User has now the choice to provide URL of the volume/ISO (existing functionality) or Upload File from Browser (new functionality)
  4. Selects File Upload from Browser then specifies the volume/ISO file (Browse...) to be uploaded
  5. User fills in other existing form fields
  6. User clicks OK to submit the form
  7. Browser UI requests an unique upload URL using the getUploadParamsForVolume api call
  8. Management server returns an upload url, encrypted metadata string which should be passed on to the upload url while doing the upload
  9. Browser starts uploading using POST request to the upload URL
  10. The post request completes once the template is uploaded or there was an error uploading.
  11. The user can close the dialog (POST request should still be active) and use listvolumes API result to check the status of it

Open Issues

  1. PSK length - for now it can be a fixed length, later on it can be made configurable.

  2. Upload url should be active only for one call - Its partially handled now. The limitation needs to be addressed.

  3. Recommended configuration of SSVM and apache web server

Reference

  1. Procedure to Replace realhostip.com with Your Own Domain Name
  2. Implementation details and troubleshooting - uploading custom domain certificate instead of using realhostip.com

Bug Reference & Branch

CLOUDSTACK-....

volume-upload branch off master