iam - Get, set, or change bucket and/or object IAM permissions.
Synopsis
gsutil iam set [-afRr] [-e <etag>] file url ...
gsutil iam get url
gsutil iam ch [-fRr] binding ... url
where each binding is of the form:
[-d] ("user"|"serviceAccount"|"domain"|"group"):id:role[,...]
[-d] ("allUsers"|"allAuthenticatedUsers"):role[,...]
-d ("user"|"serviceAccount"|"domain"|"group"):id
-d ("allUsers"|"allAuthenticatedUsers")
Note: The "iam ch" command does not support changing IAM policies with
bindings that contain conditions. As such, "iam ch" cannot be used to add
conditions to a policy or to change the policy of a resource that already
contains conditions. See additional details below.
Note: The "gsutil iam" command disallows using project convenience groups
(projectOwner, projectEditor, projectViewer) as the first segment of a binding
because these groups go against the principle of least privilege.
Description
The iam command has three sub-commands:
Get
The iam get
command gets the IAM policy for a bucket or object, which you
can save and edit for use with the iam set
command.
For example:
gsutil iam get gs://example > bucket_iam.txt
gsutil iam get gs://example/important.txt > object_iam.txt
The IAM policy returned by iam get
includes the etag of the IAM policy and
will be used in the precondition check for iam set
, unless the etag is
overridden by setting the iam set -e
option.
Set
The iam set
command sets the IAM policy for one or more buckets and / or
objects. It overwrites the current IAM policy that exists on a bucket (or
object) with the policy specified in the input file. The iam set
command
takes as input a file with an IAM policy in the format of the output
generated by iam get
.
The iam ch
command can be used to edit an existing policy. It works
correctly in the presence of concurrent updates. You may also do this
manually by using the -e flag and overriding the etag returned in iam get
.
Specifying -e with an empty string (i.e. gsutil iam set -e '' ...
) will
instruct gsutil to skip the precondition check when setting the IAM policy.
If you wish to set an IAM policy on a large number of objects, you may want to use the gsutil -m option for concurrent processing. The following command will apply iam.txt to all objects in the "cats" bucket.
gsutil -m iam set -r iam.txt gs://cats
Note that only object-level IAM applications are parallelized; you do not gain any additional performance when applying an IAM policy to a large number of buckets with the -m flag.
Set Options
The set
sub-command has the following options
-R, -r | Performs iam set recursively to all objects under the
specified bucket. |
-a | Performs iam set request on all object versions. |
-e <etag> | Performs the precondition check on each object with the specified etag before setting the policy. |
-f | Default gsutil error handling is fail-fast. This flag changes the request to fail-silent mode. This is implicitly set when invoking the gsutil -m option. |
Ch
The iam ch
command incrementally updates IAM policies. You may specify
multiple access grants and removals in a single command invocation, which
will be batched and applied as a whole to each url via an IAM patch.
The patch will be constructed by applying each access grant or removal in the
order in which they appear in the command line arguments. Each access change
specifies a member and the role that will be either granted or revoked.
The gsutil -m option may be set to handle object-level operations more efficiently.
Note: The iam ch
command may NOT be used to change the IAM policy of a
resource that contains conditions in its policy bindings. Attempts to do so
will result in an error. To change the IAM policy of such a resource, you can
perform a read-modify-write operation by using gsutil iam get
to save the
policy to a file, editing the file, and using gsutil iam set
to set the
updated policy.
Ch Examples
Examples for the ch
sub-command:
To grant a single role to a single member for some targets:
gsutil iam ch user:john.doe@example.com:objectCreator gs://ex-bucket
To make a bucket's objects publicly readable:
gsutil iam ch allUsers:objectViewer gs://ex-bucket
To grant multiple bindings to a bucket:
gsutil iam ch user:john.doe@example.com:objectCreator \
domain:www.my-domain.org:objectViewer gs://ex-bucket
To specify more than one role for a particular member:
gsutil iam ch user:john.doe@example.com:objectCreator,objectViewer \
gs://ex-bucket
To specify a custom role for a particular member:
gsutil iam ch user:john.doe@example.com:roles/customRoleName gs://ex-bucket
To apply a grant and simultaneously remove a binding to a bucket:
gsutil iam ch -d group:readers@example.com:legacyBucketReader \
group:viewers@example.com:objectViewer gs://ex-bucket
To remove a user from all roles on a bucket:
gsutil iam ch -d user:john.doe@example.com gs://ex-bucket
Ch Options
The ch
sub-command has the following options
-R, -r | Performs iam ch recursively to all objects under the
specified bucket. |
-f | Default gsutil error handling is fail-fast. This flag changes the request to fail-silent mode. This is implicitly set when invoking the gsutil -m option. |