Nathan's answer helped get me started. I've included two solutions that are currently working for me.
The first solution uses plain Python. The second uses boto.
I tried to get boto working first, but kept getting errors. So I went back to the Amazon ruby documentation and got S3 to accept files using python without boto. (Browser Uploads to S3 using HTML POST)
After understanding what was going on, I was able to fix my errors and use boto, which is a simpler solution.
I'm including solution 1 because it shows explicitly how to setup the policy document and signature using python.
My goal was to create the html upload page as a dynamic page, along with the "success" page the user sees after a successful upload. Solution 1 shows the dynamic creation of the form upload page, while solution 2 shows the creation of both the upload form page and the success page.
Solution 1:
import base64
import hmac, hashlib
###### EDIT ONLY THE FOLLOWING ITEMS ######
DEBUG = 1
AWS_SECRET_KEY = "MySecretKey"
AWS_ACCESS_KEY = "MyAccessKey"
HTML_NAME = "S3PostForm.html"
EXPIRE_DATE = "2015-01-01T00:00:00Z" # Jan 1, 2015 gmt
FILE_TO_UPLOAD = "${filename}"
BUCKET = "media.mysite.com"
KEY = ""
ACL = "public-read" # or "private"
SUCCESS = "http://media.mysite.com/success.html"
CONTENT_TYPE = ""
CONTENT_LENGTH = 1024**3 # One gigabyte
HTTP_OR_HTTPS = "http" # Or "https" for better security
PAGE_TITLE = "My Html Upload to S3 Form"
ACTION = "%s://%s.s3.amazonaws.com/" % (HTTP_OR_HTTPS, BUCKET)
###### DON'T EDIT FROM HERE ON DOWN ######
policy_document_data = {
"expire": EXPIRE_DATE,
"bucket_name": BUCKET,
"key_name": KEY,
"acl_name": ACL,
"success_redirect": SUCCESS,
"content_name": CONTENT_TYPE,
"content_length": CONTENT_LENGTH,
}
policy_document = """
{"expiration": "%(expire)s",
"conditions": [
{"bucket": "%(bucket_name)s"},
["starts-with", "$key", "%(key_name)s"],
{"acl": "%(acl_name)s"},
{"success_action_redirect": "%(success_redirect)s"},
["starts-with", "$Content-Type", "%(content_name)s"],
["content-length-range", 0, %(content_length)d]
]
}
""" % policy_document_data
policy = base64.b64encode(policy_document)
signature = base64.b64encode(hmac.new(AWS_SECRET_KEY, policy, hashlib.sha1).digest())
html_page_data = {
"page_title": PAGE_TITLE,
"action_name": ACTION,
"filename": FILE_TO_UPLOAD,
"access_name": AWS_ACCESS_KEY,
"acl_name": ACL,
"redirect_name": SUCCESS,
"policy_name": policy,
"sig_name": signature,
"content_name": CONTENT_TYPE,
}
html_page = """
<html>
<head>
<title>%(page_title)s</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<form action="%(action_name)s" method="post" enctype="multipart/form-data">
<input type="hidden" name="key" value="%(filename)s">
<input type="hidden" name="AWSAccessKeyId" value="%(access_name)s">
<input type="hidden" name="acl" value="%(acl_name)s">
<input type="hidden" name="success_action_redirect" value="%(redirect_name)s">
<input type="hidden" name="policy" value="%(policy_name)s">
<input type="hidden" name="signature" value="%(sig_name)s">
<input type="hidden" name="Content-Type" value="%(content_name)s">
<!-- Include any additional input fields here -->
Browse to locate the file to upload:<br \> <br \>
<input name="file" type="file"><br> <br \>
<input type="submit" value="Upload File to S3">
</form>
</body>
</html>
""" % html_page_data
with open(HTML_NAME, "wb") as f:
f.write(html_page)
###### Dump output if testing ######
if DEBUG:
if 1: # Set true if not using the LEO editor
class G:
def es(self, data):print(data)
g = G()
items = [
"",
"",
"policy_document: %s" % policy_document,
"ploicy: %s" % policy,
"signature: %s" % signature,
"",
"",
]
for item in items:
g.es(item)
Solution 2:
from boto.s3 import connection
###### EDIT ONLY THE FOLLOWING ITEMS ######
DEBUG = 1
AWS_SECRET_KEY = "MySecretKey"
AWS_ACCESS_KEY = "MyAccessKey"
HTML_NAME = "S3PostForm.html"
SUCCESS_NAME = "success.html"
EXPIRES = 60*60*24*356 # seconds = 1 year
BUCKET = "media.mysite.com"
KEY = "${filename}" # will match file entered by user
ACL = "public-read" # or "private"
SUCCESS = "http://media.mysite.com/success.html"
CONTENT_TYPE = "" # seems to work this way
CONTENT_LENGTH = 1024**3 # One gigabyte
HTTP_OR_HTTPS = "http" # Or https for better security
PAGE_TITLE = "My Html Upload to S3 Form"
###### DON'T EDIT FROM HERE ON DOWN ######
conn = connection.S3Connection(AWS_ACCESS_KEY,AWS_SECRET_KEY)
args = conn.build_post_form_args(
BUCKET,
KEY,
expires_in=EXPIRES,
acl=ACL,
success_action_redirect=SUCCESS,
max_content_length=CONTENT_LENGTH,
http_method=HTTP_OR_HTTPS,
fields=None,
conditions=None,
storage_class='STANDARD',
server_side_encryption=None,
)
form_fields = ""
line = ' <input type="hidden" name="%s" value="%s" >\n'
for item in args['fields']:
new_line = line % (item["name"], item["value"])
form_fields += new_line
html_page_data = {
"page_title": PAGE_TITLE,
"action": args["action"],
"input_fields": form_fields,
}
html_page = """
<html>
<head>
<title>%(page_title)s</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<form action="%(action)s" method="post" enctype="multipart/form-data" >
%(input_fields)s
<!-- Include any additional input fields here -->
Browse to locate the file to upload:<br \> <br \>
<input name="file" type="file"><br> <br \>
<input type="submit" value="Upload File to S3">
</form>
</body>
</html>
""" % html_page_data
with open(HTML_NAME, "wb") as f:
f.write(html_page)
success_page = """
<html>
<head>
<title>S3 POST Success Page</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script src="jquery.js"></script>
<script src="purl.js"></script>
<!--
Amazon S3 passes three data items in the url of this page if
the upload was successful:
bucket = bucket name
key = file name upload to the bucket
etag = hash of file
The following script parses these values and puts them in
the page to be displayed.
-->
<script type="text/javascript">
var pname,url,val,params=["bucket","key","etag"];
$(document).ready(function()
{
url = $.url();
for (param in params)
{
pname = params[param];
val = url.param(pname);
if(typeof val != 'undefined')
document.getElementById(pname).value = val;
}
});
</script>
</head>
<body>
<div style="margin:0 auto;text-align:center;">
<p>Congratulations!</p>
<p>You have successfully uploaded the file.</p>
<form action="#" method="get"
>Location:
<br />
<input type="text" name="bucket" id="bucket" />
<br />File Name:
<br />
<input type="text" name="key" id="key" />
<br />Hash:
<br />
<input type="text" name="etag" id="etag" />
</form>
</div>
</body>
</html>
"""
with open(SUCCESS_NAME, "wb") as f:
f.write(success_page)
###### Dump output if testing ######
if DEBUG:
if 1: # Set true if not using the LEO editor
class G:
def es(self, data):print(data)
g = G()
g.es("conn = %s" % conn)
for key in args.keys():
if key is not "fields":
g.es("%s: %s" % (key, args[key]))
continue
for item in args['fields']:
g.es(item)
