Google Cloud Storage

Bucket and Object Naming Guidelines

You must follow bucket and object naming guidelines when you use the Google Cloud Storage API. Requests that use malformed or disallowed names will often fail.

Contents

  1. Bucket Name Requirements
  2. Object Name Requirements
  3. Bucket Name Verification

Bucket Name Requirements

Bucket names reside in a single Google Cloud Storage namespace. As a consequence, every bucket name must be unique across the entire Google Cloud Storage namespace. If you try to create a bucket with a bucket name that is already taken, Google Cloud Storage responds with an error message.

As a best practice, bucket names must conform to standard DNS naming conventions. This is because a bucket name can appear in a DNS record as part of a CNAME redirect. In addition to meeting DNS naming requirements, Google Cloud Storage imposes other requirements on bucket naming as well. At a minimum, your bucket names must meet the following requirements:

  • Bucket names must contain only lowercase letters, numbers, dashes (-), underscores (_), and dots (.). Names containing dots require verification.
  • Bucket names must start and end with a number or letter.
  • Bucket names must contain 3 to 63 characters. Names containing dots can contain up to 222 characters, but each dot-separated component can be no longer than 63 characters.
  • Bucket names cannot be represented as an IP address in dotted-decimal notation (for example, 192.168.5.4).
  • Bucket names cannot begin with the "goog" prefix.

Also, for DNS compliance and future compatibility, you should not use underscores (_) or have a period adjacent to another period or dash. For example, ".." or "-." or ".-" are not valid in DNS names.

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Object Name Requirements

Object names can contain any sequence of valid Unicode characters, of length 1-1024 bytes when UTF-8 encoded, and must not contain Carriage Return or Line Feed characters.

For more information about Carriage Return and Line Feed characters, see Newline.

We strongly recommend that you abide by the following object naming conventions:

  • Avoid using control characters that are illegal in XML 1.0 in your object names (#x7F–#x84 and #x86–#x9F). These characters will cause XML listing issues when you try to list your objects.
  • Avoid using "#" in your object names. gsutil interprets object names ending with #<numeric string> as version identifiers, so including "#" in object names can make it difficult or impossible to perform various operations on such objects using gsutil (see Object Versioning and Concurrency Control).
  • Avoid using "[", "]", "*", or "?" in your object names. gsutil interprets these characters as wildcards, so including any of these characters in object names can make it difficult or impossible to perform various wildcard operations using gsutil (see Wildcard Names).

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Bucket Name Verification

Google Cloud Storage requires that bucket names with the following characteristics undergo domain ownership verification:

  • Contains dots
  • Are syntactically valid DNS names (for example, bucket..example.com is not valid because it contains two dots in a row)
  • Ends with a currently-recognized top-level domain, such as .com

Bucket names containing these attributes are considered domain names, and require domain ownership verification before they can be created.

If your project needs to have a domain-named bucket, you need to have one team member both verify the domain and create the bucket. This is because Google Cloud Storage checks for domain ownership against the user who creates the bucket, so the user who creates the bucket must also be verified as an owner or manager of the domain.

To verify as the owner or manager of a domain, use the Google Webmaster Tools verification process. The Webmaster Tools verification process provides three methods for verifying an owner or manager of a domain:

  • Adding a special Meta tag to a site's homepage.
  • Uploading a special HTML file to a site.
  • Adding a DNS TXT record to a domain's DNS configuration.

Meta tag verification and HTML file verification are easier to perform and are probably adequate for most situations. DNS TXT record verification is a domain-based verification method that is useful in situations where a site wants to tightly control who can create domain-named buckets. Once a site creates a DNS TXT record to verify ownership of a domain, it takes precedence over meta tag and HTML file verification. For example, you might have two IT staff members who are responsible for managing your site, called "example.com." If they complete the DNS TXT record verification, only they would be able to create buckets called "example.com", "reports.example.com", "downloads.example.com", and other domain-named buckets.

Authorizing Robot Accounts
Once you have performed domain verification, you can authorize a robot account to create buckets under that domain. Go to the Google Webmaster site at the following URL https://www.google.com/webmasters/verification/details?hl=en&domain=<your-domain.com>. If you click the button Add an owner at the end of the page, you can add the email address for your robot.
Site-based Verification

If you have administrative control over the HTML files that make up a site, you can use one of the site-based verification methods to verify that you control or own a site. When you do this, Google Cloud Storage lets you create buckets representing the verified site and any subsites—provided nobody has used the DNS TXT record method to verify domain ownership of a parent of the site.

As an example, assume that nobody has used the DNS TXT record method to verify ownership of the following domains: abc.def.example.com, def.example.com, and example.com. In this case, Google Cloud Storage lets you create a bucket named abc.def.example.com if you verify that you own or control any of the following sites:

  • http://abc.def.example.com
  • http://def.example.com
  • http://example.com
Domain-based Verification

If you have administrative control over a domain's DNS configuration, you can use the DNS TXT record verification method to verify that you own or control a domain. When you use the domain-based verification method to verify that you own or control a domain, Google Cloud Storage lets you create buckets that represent any subdomain under the verified domain. Furthermore, Google Cloud Storage prevents anybody else from creating buckets under that domain unless you add their name to the list of verified domain owners or they have verified their domain ownership by using the DNS TXT record verification method.

For example, if you use the DNS TXT record verification method to verify your ownership of the domain example.com, Google Cloud Storage will let you create bucket names that represent any subdomain under the example.com domain, such as abc.def.example.com, example.com, or abc.example.com.

Using the DNS TXT record method to verify domain ownership supersedes verification by site-based verification methods. For example, if you use the Meta tag method or HTML file method to verify domain ownership of http://example.com, but someone else uses the DNS TXT record method to verify ownership of the example.com domain, Google Cloud Storage will not allow you to create a bucket named example.com. To create the bucket example.com, the domain owner who used the DNS TXT method to verify domain ownership must add you to the list of verified domain owners for example.com.

The DNS TXT record verification method is particularly useful if you manage a domain for a large organization that has numerous subdomains because it lets you control who can create buckets representing those domain names.

Note: If you use the DNS TXT record verification method to verify ownership of a domain, you cannot create a CNAME record for that domain. RFC 1034 disallows inclusion of any other resource records if there is a CNAME resource record present. If you want to create a CNAME resource record for a domain, you must use the Meta tag verification method or the HTML file verification method.

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