How can I move data directly from one Google Cloud Storage project to another?

How can I move data directly from one Google Cloud Storage project to another? I understand how to upload and how to download, but I want to transfer directly between projects.

To copy any single object from one GCS location to another, you can use the copy command. This can be done from either of our public APIs, or by using the command-line client, gsutil.

With gsutil, the cp command could be used like this:

gsutil cp gs://bucket1/obj gs://bucket2/obj2

Edit:
Since I wrote this, the Google Cloud Transfer Service has become available, which is good for copying whole buckets between GCS projects, or for copying whole buckets from S3 into GCS. You can find out more here.

Open The Web console Storage > Tranfer to create a new transfer.

Select the source bucket you want to copy from. Just like cratervale menitoned just above here, bucket identifiers are globally unique (this is key to the solution). So once you get to the destination part of the transfer form, you can write/paste the target bucket right in it's text input. Even if that bucket is from another project. It will show you a green icon once the target has been verified being an existing bucket. You can continue the form again to finalise your setup.

Once you started the transfer from the form, you can follow it's progress by hitting the refresh button on top of the console.

This is [one of] the quickest ways to do it:

gsutil -m rsync -r gs://bucket-source/dir gs://bucket-destination/dir

Please note that /dir refers to a directory [or sub-directories e.g. /dir1/dir2] under the main bucket. It does not refer to a file name. If you try to transfer individual files, you will get an error.

See more configuration options in the official docs.

However, there are a few things you should setup properly to prevent issues. Here's a setup list:

1. Create a service account for your source bucket [from the source project, Google Cloud Console -> IAM -> Service Account]. Use Storage Admin as Role. Make sure you create a JSON key and download this to a safe place on your computer. Take note of the path to this file [e.g. path/to/source-service-account.json] as you will need it later.
2. Create a service account for your destination bucket [same process as above, but make sure to switch to the destination project]. You may download JSON key if you need to use it later, but this is optional.
3. Add the service account of the source bucket [created in 1. above] to the destination bucket [From the destination project, Google Cloud Console -> Storage -> Browser, then click on the main bucket, then click on the Permissions tab, then click on the "Add Members" button. Add the email address of the source bucket service account in the text box provided, then give Storage Admin permissions]
4. If you're using gcloud cli [command line tools], are logged in to the source project, you can run the gsutil command now. However, if you're not properly authenticated, you might get access permission errors. You can authenticate using the service account file [the one you created and downloaded in 1. above] by running the following command gcloud auth activate-service-account --key-file=/path/to/source-service-account.json. Once you do this, you will be logged in to GCP using the service account. You may now run the gsutil command to transfer your files.
5. When you're done, check your login status using gcloud auth list. And, you can switch accounts using gcloud config set account 'ACCOUNT'

Cheers.

If you want to use the console follow @Martin van Dam's answer.

If you want to use the shell :

Step 1. Open google cloud shell

Step 2. Run gcloud init & follow the process to connect to the cloud project that bucket1 belongs to.

Step 3. run gsutil cp -r gs://[bucket1]/* gs://[bucket2]

You are done!

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*Now there's a catch! If both bucket belongs to the same project these steps will work flawlessly. But in case both buckets don't belong to the same project or the same google cloud account. It won't work. You need to fix the permissions.

If they belong to the same GCP account :

Go to Storage > Browser > Select bucket > Options > Edit bucket permissions > add member > insert the service account email id for the project that the bucket2 belongs to > set role to Storage.Storage Admin > Save. Then run gstuil cp command.

If they belong to the separate GCP accounts :

Go to Storage > Browser > Select bucket > Options > Edit bucket permissions > add member > insert the gmail id which the project that the bucket2 belongs to > set role to Storage.Storage Admin > Save. Then run gstuil cp command.

Bucket names in GCS are unique across all of your projects. For example, Project1 and Project2 cannot both have buckets named 'images', although they can each have folders inside those buckets named 'images'.

This can seem misleading because gsutil may ask you to select a project to work with. For the copy command, this selection can be disregarded.

gsutil cp gs://bucket1/obj gs://bucket2/obj

will allow you to copy an object in Project1/bucket1 to Project2/bucket2

If you have a key or a service account that gives you access to both projects, it is super simple and works at light speed to use gsutils.

This is what I did from my local mac and synced terabytes of data in minutes (yes, minutes and not hours)

gsutil -m rsync -r gs://my/source/project/bucket/files/ gs://my/target/project/bucket/directory/

The key here is to use -m flag.

Check official docs at https://cloud.google.com/storage/docs/gsutil/commands/rsync for more details.

Using Google Cloud Shell

Go to the first project which has the bucket you wanted to copy
gcloud config set project [PROJECT1 ID]

Made a directory you can mount that bucket to
mkdir test

Mount the bucket to the directory
gcsfuse [BUCKET1] test

Switch to the second project, which had the bucket you wanted to populate
gcloud config set project [PROJECT2 ID]

Copy the contents of the new folder to the second bucket
gsutil cp -r /home/user/test gs://[BUCKET2]

As per the docs Moving Buckets.

You can simply use gsutil.

gsutil cp -r gs://[SOURCE_BUCKET]/* gs://[DESTINATION_BUCKET]

note: _if using zsh. Make sure you wrap your source bucket in single quotes. Because zsh will attempt to expand the wildcard before gsutil sees it. See here.

You can find the link for gsutil in your storage browser Overview tab.