Lua script to support resumable upload in nginx.
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README.md
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README.md

Nginx Resumable Upload

Nginx Lua module to support resumable upload in nginx. With the help of this module, you can upload a file chunk by chunk, which means one http request uploads one chunk. This is especially useful while uploading big files.

Contents

Get Started

  1. Install Nginx with lua support and other tools if you haven't done this before. On Ubuntu 16.04:
$ sudo apt-get install nginx-extras lua5.1 luarocks
  1. Download this module. You have two ways to do this. Choose the one you prefer.
  • By luarocks (recommended)
$ luarocks install nginx-resumable-upload
  • By git clone directly
$ cd your_desired_dir
$ git clone https://github.com/shuaicj/nginx-resumable-upload.git
  1. Configure your nginx.
http {

    # You must set this lua_package_path if you choose install by `git clone`.
    # Remove this line when installing by luarocks.
    lua_package_path 'your_desired_dir/nginx-resumable-upload/lib/?.lua;;';
  
    init_by_lua_block {
        require("shuaicj.upload").init({
            directory = "./upload_files/"
        })  
    }

    server {
        listen        8080;
        server_name   localhost;
        default_type  application/octet-stream;

        client_max_body_size  100m; # set as needed

        location ~ "^/files/([^/]+)$" {
            content_by_lua_block {
                require("shuaicj.upload").upload(ngx.var[1])
            }
        }
    }
}

Optionally, you can turn on some kind of checksum validation, e.g.

init_by_lua_block {
    require("shuaicj.upload").init({
        directory = "./upload_files/",
        checksum = "md5"
    })
}

A possible scenario is that your client app may want to check the size of the file before it start resumable upload. So another size api is preferred and your will get the size number in response body with status code 200. It is safe if the file doesn't exist and of course you got 0 in body but with status code 404.

location ~ "^/files/([^/]+)/size$" {
    content_by_lua_block {
        require("shuaicj.upload").size(ngx.var[1])
    }
}

Lua APIs

require("shuaicj.upload").init(config)

Init this lua module. If anything wrong happens, nginx will fail to start. The param config is a lua table, and can contains:

  • directory
    • type: string
    • description: the directory where to store the uploading files.
    • e.g. "./uploaded_files/"
    • required: yes
  • checksum
    • type: string or table
    • description: checksums to turn on.
    • constraints: only "crc32", "md5", "sha1" supported for now.
    • e.g. "crc32" or {"crc32", "sha1"}
    • required: no
    • default: none is turned on.
  • timeout
    • type: number
    • description: socket timeout in milliseconds.
    • constraints: must be greater than 0.
    • required: no
    • default: 20000

require("shuaicj.upload").upload(filename)

The core api for uploading.

  • filename
    • type: string
    • description: the filename to save.
    • constraints: can only contains alphanumerics [0-9a-zA-Z] and three special characters - _ . or it will be considered invalid.
    • e.g. "Test-12_345.txt"
    • required: yes

require("shuaicj.upload").size(filename)

Return the file size in byte as http response body. The status code will be 200 if file exists, or else 404. The param filename is the same as above.

Upload Request

Request Method

  • POST : append mode, can only append to the end of file.
  • PUT : idempotent write, can replace existing part of file.

Request URL

A graceful RESTful api for file uploading like POST|PUT /files/{filename} is encouraged but not mandatory. In whatever way you like, the filename should be passed into this Lua module as a parameter as mentioned in Get Started.

Request Header: Content-Length

Required. Implies the size of request body, e.g.

  • Content-Length: 4 : body size 4 bytes.

Request Header: Content-Range

Required if this is a chunk, not a complete file. Implies the info of this chunk while uploading. It is a standard HTTP Header designed for download, but here we use it for upload. The format is like Content-Range: bytes {from}-{to}/{total}, e.g.

  • Content-Range: bytes 0-3/20 : file size 20 bytes, chunk size 4 bytes, that is [0, 3].
  • Content-Range: bytes 5-9/20 : file size 20 bytes, chunk size 5 bytes, that is [5, 9].
  • Content-Range: bytes 0-19/20 : the chunk is a complete file.

Be careful to set the value of {from}. If the file does not exist on server, {from} can only be 0. If the file exists and let's say the size is n, the value of {from} can only be n in POST mode; while in PUT mode, any 0 <= {from} <= n is valid. See Request Method.

Note: If you are uploading an empty file (by setting Content-Length: 0), the header Content-Range will be ignored.

Request Header: X-Checksum-*

Required if corresponding checksum is turned on while uploading the last chunk. Calculated by client, used for server to check the file integrity. The following kind of checksum is supported:

  • X-Checksum-CRC32 : hex string with fixed length 8, e.g. abcdef12.
  • X-Checksum-MD5 : hex string with fixed length 32, e.g. 0123456789abcdef0123456789abcdef.
  • X-Checksum-SHA1 : hex string with fixed length 40, e.g. 0123456789abcdef0123456789abcdef01234567.

Request Body

The bytes of this file chunk.

Upload Response

Response Status Code

  • 201 Created : success
  • 400 Bad Request : general client error
  • 405 Method Not Allowed : http method not allowed
  • 409 Conflict : checksum conflict
  • 411 Length Required : header Content-Length missing or illegal
  • 416 Range Not Satisfiable : header Content-Range missing or illegal
  • 500 Internal Server Error : general server error

Response Header: Content-Range

Implies the info of file the server already got. See also Request Header: Content-Range. E.g. assuming the total size of file is 20 bytes, and the server already got 9 bytes, this header should be Content-Range: bytes 0-8/20.

Response Header: X-Checksum-*

Implies the checksum calculated by server. See also Request Header: X-Checksum-*. This is only present while uploading the last chunk of file and the checksum is turned on, and especially useful while checksums conflict.

Response Body

Contains error message if something is wrong.

Example Conversation

Let's upload a file which has 20 bytes content:

This world is great.

We split it into 3 chunks:

Chunk 1

> POST /files/abc.testfile
> Content-Range: bytes 0-6/20
> Content-Length: 7
>
> This wo

< 201 Created
< Content-Range: bytes 0-6/20

Chunk 2

> POST /files/abc.testfile
> Content-Range: bytes 7-14/20
> Content-Length: 8
>
> rld is g

< 201 Created
< Content-Range: bytes 0-14/20

Chunk 3

> POST /files/abc.testfile
> Content-Range: bytes 15-19/20
> Content-Length: 5
> X-Checksum-MD5: 8339ed7abf090b1e370edbd93a1f5432
>
> reat.

< 201 Created
< Content-Range: bytes 0-19/20
< X-Checksum-MD5: 8339ed7abf090b1e370edbd93a1f5432