object-api/v1/section_object-api-tempurl.xml
Andreas Jaeger c8728fdd98 Fix swift invocation
swift -m adds X-Account-Meta to each parameter, fix the invocation.

Change-Id: I7989829cd22f040c54b2878ab9c5d17a823eacd9
Closes-Bug: #1325780
2014-07-13 11:04:50 +02:00

220 lines
11 KiB
XML

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE section [
<!-- Useful for describing APIs -->
<!ENTITY GET '<command xmlns="http://docbook.org/ns/docbook">GET</command>'>
<!ENTITY HEAD '<command xmlns="http://docbook.org/ns/docbook">HEAD</command>'>
<!ENTITY PUT '<command xmlns="http://docbook.org/ns/docbook">PUT</command>'>
<!ENTITY POST '<command xmlns="http://docbook.org/ns/docbook">POST</command>'>
<!ENTITY DELETE '<command xmlns="http://docbook.org/ns/docbook">DELETE</command>'>
]>
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:m="http://www.w3.org/1998/Math/MathML"
xmlns:html="http://www.w3.org/1999/xhtml"
xmlns:db="http://docbook.org/ns/docbook" version="5.0"
xml:id="tempurl">
<?dbhtml stop-chunking?>
<title>Temporary URL middleware</title>
<para>To discover whether your Object Storage system supports
this feature, see <xref linkend="discoverability"
/>. Alternatively, check with your service provider.</para><para>A temporary URL gives users temporary access to objects. For
example, a website might want to provide a link to download a
large object in Object Storage, but the Object Storage account
has no public access. The website can generate a URL that
provides time-limited &GET; access to the object. When the web
browser user clicks on the link, the browser downloads the
object directly from Object Storage, eliminating the need for
the website to act as a proxy for the request.</para>
<para>Ask your cloud administrator to enable the temporary URL
feature. For information, see <link
xlink:href="http://docs.openstack.org/havana/config-reference/content/object-storage-tempurl.html"
>Temporary URL</link> in the <citetitle>OpenStack
Configuration Reference</citetitle>.</para>
<note>
<para>To use &POST; requests to upload objects to specific
Object Storage locations, use form &POST; instead of
temporary URL middleware. See <xref linkend="form-post"
/>.</para>
</note>
<section xml:id="temp-url-format">
<title>Temporary URL format</title>
<para>A temporary URL is comprised of the URL for an object
with added query parameters:</para>
<example xml:id="tempurl-example">
<title>Temporary URL format</title>
<programlistingco>
<areaspec>
<area xml:id="tempurl.txt.object_url"
units="linecolumn" coords="1 66"/>
<area xml:id="tempurl.txt.temp_url_sig"
units="linecolumn" coords="2 56"/>
<area xml:id="tempurl.txt.temp_url_expires"
units="linecolumn" coords="3 31"/>
<area xml:id="tempurl.txt.filename"
units="linecolumn" coords="4 28"/>
</areaspec>
<programlisting language="bash"><xi:include href="samples/tempurl.txt" parse="text"/></programlisting>
</programlistingco>
</example>
<para>The example shows
these elements:</para>
<calloutlist>
<callout arearefs="tempurl.txt.object_url">
<para><emphasis role="bold">Object
URL</emphasis></para>
<para>Required. The full path URL to the
object.</para>
</callout>
<callout arearefs="tempurl.txt.temp_url_sig">
<para><emphasis role="bold"
>temp_url_sig</emphasis></para>
<para>Required. An HMAC-SHA1 cryptographic signature
that defines the allowed HTTP method, expiration
date, full path to the object, and the secret key
for the temporary URL.</para>
<para>For more information about secret keys, see
<xref linkend="account-secret-keys-temp-url"
/>.</para>
<para>For more information about signatures, see <xref
linkend="signature-temp-url"/>.</para>
</callout>
<callout arearefs="tempurl.txt.temp_url_expires">
<para><emphasis role="bold"
>temp_url_expires</emphasis></para>
<para>Required. An expiration date as a UNIX Epoch
timestamp, which is an integer value. For example,
<literal>1390852007</literal> represents
<literal>Mon, 27 Jan 2014 19:46:47
GMT</literal>.</para>
<para>For more information, see <link
xlink:href="http://www.epochconverter.com/"
>Epoch &amp; Unix Timestamp Conversion
Tools</link>.</para>
</callout>
<callout arearefs="tempurl.txt.temp_url_expires">
<para><emphasis role="bold">filename</emphasis></para>
<para>Optional. Overrides the default file name.
Object Storage generates a default file name for
&GET; temporary URLs that is based on the object
name. Object Storage returns this value in the
<literal>Content-Disposition</literal>
response header. Browsers can interpret this file
name value as a file attachment to be
saved.</para>
</callout>
</calloutlist>
</section>
<section xml:id="account-secret-keys-temp-url">
<title>Account secret keys</title>
<para>Object Storage supports up to two secret keys. You set
secret keys at the account level.</para>
<para>To set these keys, set one or both of the following
request headers to arbitrary values:</para>
<itemizedlist>
<listitem>
<para><literal>X-Account-Meta-Temp-URL-Key</literal></para>
</listitem>
<listitem>
<para><literal>X-Account-Meta-Temp-URL-Key-2</literal></para>
</listitem>
</itemizedlist>
<para>The arbitrary values serve as the secret keys.</para>
<para>Object Storage checks signatures against both keys, if
present, to enable key rotation without invalidating
existing temporary URLs.</para>
<para>For example, use the <command>swift post</command>
command to set the secret key to
<replaceable>MYKEY</replaceable>:</para>
<screen><prompt>$</prompt> <userinput>swift post -m "Temp-URL-Key:<replaceable>MYKEY</replaceable>"</userinput></screen>
<note>
<para>Changing these headers invalidates any previously
generated temporary URLs within 60 seconds, which is
the memcache time for the key.</para>
</note>
</section>
<section xml:id="signature-temp-url">
<title>HMAC-SHA1 signature for temporary URLs</title>
<para>Temporary URL middleware uses an HMAC-SHA1 cryptographic
signature. This signature includes
these elements:</para>
<itemizedlist>
<listitem>
<para>The allowed method. Typically, &GET; or
&PUT;.</para>
</listitem>
<listitem>
<para>Expiry time. In <xref
linkend="signature-example-temporary-urls"/>,
the expiry time is set to <literal>86400</literal>
seconds (or 1 day) into the future.</para>
</listitem>
<listitem>
<para>The path. Starting with <literal>/v1/</literal>
onwards and including a container name and object.
In <xref
linkend="signature-example-temporary-urls"/>,
the path is
<literal>/v1/my_account/container/object</literal>.
Do not URL-encode the path at this stage.</para>
</listitem>
<listitem>
<para>The secret key. Set as the
<literal>X-Account-Meta-Temp-URL-Key</literal>
header value.</para>
</listitem>
</itemizedlist>
<para>This sample Python code shows how to compute a signature
for use with temporary URLs:</para>
<example xml:id="signature-example-temporary-urls">
<title>HMAC-SHA1 signature for temporary URLs</title>
<programlisting language="python">import hmac
from hashlib import sha1
from time import time
method = 'GET'
duration_in_seconds = 60*60*24
expires = int(time() + duration_in_seconds)
path = '/v1/my_account/container/object'
key = '<replaceable>MYKEY</replaceable>'
hmac_body = '%s\n%s\n%s' % (method, expires, path)
signature = hmac.new(key, hmac_body, sha1).hexdigest()</programlisting>
</example>
<para>Do not URL-encode the path when you generate the
HMAC-SHA1 signature. However, when you make the actual
HTTP request, you should properly URL-encode the
URL.</para>
<para>The <replaceable>MYKEY</replaceable> value is the value
you set in the
<literal>X-Account-Meta-Temp-URL-Key</literal> request
header on the account.</para>
<para>For more information, see <link
xlink:href="http://www.ietf.org/rfc/rfc2104.txt">RFC
2104: HMAC: Keyed-Hashing for Message
Authentication</link>.</para>
</section>
<section xml:id="swift-temp-url-script">
<title>swift-temp-url script</title>
<para>Object Storage provides the
<command>swift-temp-url</command> script that
auto-generates the <parameter>temp_url_sig</parameter> and
<parameter>temp_url_expires</parameter> query
parameters. For example, you might run this
command:</para>
<screen><prompt>$</prompt> <userinput>bin/swift-temp-url GET 3600 /v1/my_account/container/object <replaceable>MYKEY</replaceable></userinput></screen>
<para>This command returns the path:</para>
<screen><computeroutput>/v1/my_account/container/object
?temp_url_sig=5c4cc8886f36a9d0919d708ade98bf0cc71c9e91
&amp;temp_url_expires=1374497657</computeroutput></screen>
<para>To create the temporary URL, prefix this path with the
Object Storage storage host name. For example, prefix the
path with
<literal>https://swift-cluster.example.com</literal>,
as follows:</para>
<screen><computeroutput>https://swift-cluster.example.com/v1/my_account/container/object
?temp_url_sig=5c4cc8886f36a9d0919d708ade98bf0cc71c9e91
&amp;temp_url_expires=1374497657</computeroutput></screen>
</section>
</section>