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Sending data to a GCS bucket

Connecting to a GCS bucket

Section titled “Connecting to a GCS bucket”

To send data to a GCS bucket, you need to execute connect send gcs with following mandatory parameter:

  • --bucket then the GCS bucket name

Depending on the type of authentication you need to either use --auth-json for key based authentication or use the service account assigned to the instance (if the server is running on GCP).

To use JSON key for the authentication you need to provide:

  • --auth-json then the path to the file containing the auth JSON

To authenticate with Application Default Credentials (ADC) you need to set GOOGLE_APPLICATION_CREDENTIALS environment variable that points to the key file.

Terminal window
export GOOGLE_APPLICATION_CREDENTIALS="/path/to/key-file.json"

Then you can omit providing the key file as it will be obtained from the environment variable.

For user credentials, ADC can be set by running Following

Terminal window
$ gcloud auth application-default login

Once authenticated you can connect without specifying the JSON key.

Sending single file to a GCS bucket

Section titled “Sending single file to a GCS bucket”

To send a single file to a GCS bucket you should use

  • --file followed by the file name to be sent

Following command will send file1.zip file to a GCS bucket my-gcs-bucket using JSON key for the authentication.

Terminal window
$ connect send gcs --file file1.zip --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 13:50:14 INFO Sending files to gcs://my-gcs-bucket/
2025/06/03 13:50:14 INFO Files to send: count=1
[file1.zip] 10.00 MiB / 10.00 MiB done

Sending multiple files to a GCS bucket

Section titled “Sending multiple files to a GCS bucket”

If you’d like to send multiple files to a GCS bucket you need to specify either file mask or file regular expression for the files.

  • --file-mask a file mask
  • --file-regex regular expression

This will cause all files that match a certain mask or pattern to be sent. You can also provide an optional source folder that contain the files to be sent:

  • -s, --src-folder

If you don’t provide the source folder files will be sent from the current folder.

Following command will send all .zip files from /data folder to a GCS bucket my-gcs-bucket using JSON key for the authentication.

Terminal window
$ connect send gcs --file-mask "*.zip" -s /data --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 13:59:22 INFO Sending files to gcs://my-gcs-bucket/
2025/06/03 13:59:22 INFO Files to send: count=3
[file3.zip] 10.00 MiB / 10.00 MiB done
[file2.zip] 10.00 MiB / 10.00 MiB done
[file1.zip] 10.00 MiB / 10.00 MiB done

You can also provide an optional destination folder on GCS bucket:

  • -d, --dst-folder

If you don’t provide the destination folder files will be sent to the “home folder” of the GCS bucket (top-level of the GCS bucket).

In below example all .zip files from /data folder will be sent to remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication.

Terminal window
$ connect send gcs --file-regex ".+\.zip" -s /data -d remote --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 14:03:59 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:03:59 INFO Files to send: count=3
[file3.zip] 10.00 MiB / 10.00 MiB done
[file2.zip] 10.00 MiB / 10.00 MiB done
[file1.zip] 10.00 MiB / 10.00 MiB done

Sending files in batch mode to a GCS bucket

Section titled “Sending files in batch mode to a GCS bucket”

When using the application in batch or non-interactive mode, such as in a script or scheduler, you should disable the progress bar by using

  • --batch to send files in batch mode

Following command will send all .zip files from the /data folder to the remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication.

Terminal window
$ connect send gcs --file-mask "*.zip" -s /data -d remote --batch --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 14:05:37 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:05:37 INFO Files to send: count=3
2025/06/03 14:05:37 INFO Transferring file=/data/file3.zip targetFolder=remote
2025/06/03 14:05:39 INFO File transferred successfully bytesTransferred=10485760 duration=1s706ms transferRate=5.86MB/s file=/data/file3.zip targetFolder=remote
2025/06/03 14:05:39 INFO Transferring file=/data/file2.zip targetFolder=remote
2025/06/03 14:05:41 INFO File transferred successfully bytesTransferred=10485760 duration=1s713ms transferRate=5.84MB/s file=/data/file2.zip targetFolder=remote
2025/06/03 14:05:41 INFO Transferring file=/data/file1.zip targetFolder=remote
2025/06/03 14:05:43 INFO File transferred successfully bytesTransferred=10485760 duration=1s886ms transferRate=5.30MB/s file=/data/file1.zip targetFolder=remote

Sending files from scheduler to a GCS bucket

Section titled “Sending files from scheduler to a GCS bucket”

When running the application from a scheduler, it’s recommended to ensure only one instance operates on a specific folder. It’s possible to configure the application to create a flag file at startup and delete it upon completion. If another instance tries to start while one is already running, it will detect the flag file and exit. This approach ensures that only one instance of the application runs at any given time. To do that use

  • --flag path to the flag file

Following command will send all .zip files from the /data folder to the remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication and /tmp/flag1 as a flag file. Mind that we are using batch mode as it’s required for the application to run correctly from script or scheduler.

Terminal window
$ connect send gcs --flag /tmp/flag1 --batch --file-mask "*.zip" -s /data -d remote --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 14:07:00 INFO Using flag file: /tmp/flag1
2025/06/03 14:07:00 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:07:00 INFO Files to send: count=3
2025/06/03 14:07:00 INFO Transferring file=/data/file3.zip targetFolder=remote
2025/06/03 14:07:02 INFO File transferred successfully bytesTransferred=10485760 duration=2s326ms transferRate=4.30MB/s file=/data/file3.zip targetFolder=remote
2025/06/03 14:07:02 INFO Transferring file=/data/file2.zip targetFolder=remote
2025/06/03 14:07:04 INFO File transferred successfully bytesTransferred=10485760 duration=1s717ms transferRate=5.82MB/s file=/data/file2.zip targetFolder=remote
2025/06/03 14:07:04 INFO Transferring file=/data/file1.zip targetFolder=remote
2025/06/03 14:07:06 INFO File transferred successfully bytesTransferred=10485760 duration=1s735ms transferRate=5.76MB/s file=/data/file1.zip targetFolder=remote
2025/06/03 14:07:06 INFO Removing flag file: /tmp/flag1

Sending files in parallel to a GCS bucket

Section titled “Sending files in parallel to a GCS bucket”

To speed up file delivery you can send files simultaneously. Application will then send files using multiple sessions. To specify number of concurrent GCS sessions use:

  • --parallel number of GCS sessions

Following command will send all .zip files from the /data folder to the remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication and 3 parallel sessions.

Terminal window
$ connect send gcs --file-mask "*.zip" -s /data -d remote --batch --parallel 3 --bucket my-gcs-bucket --auth-json /path/to/key-file.json
2025/06/03 14:08:40 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:08:40 INFO Files to send: count=3
2025/06/03 14:08:40 INFO Transferring file=/data/file1.zip targetFolder=remote
2025/06/03 14:08:40 INFO Transferring file=/data/file2.zip targetFolder=remote
2025/06/03 14:08:40 INFO Transferring file=/data/file3.zip targetFolder=remote
2025/06/03 14:08:41 INFO File transferred successfully bytesTransferred=10485760 duration=1s701ms transferRate=5.88MB/s file=/data/file1.zip targetFolder=remote
2025/06/03 14:08:41 INFO File transferred successfully bytesTransferred=10485760 duration=1s731ms transferRate=5.78MB/s file=/data/file2.zip targetFolder=remote
2025/06/03 14:08:41 INFO File transferred successfully bytesTransferred=10485760 duration=1s785ms transferRate=5.60MB/s file=/data/file3.zip targetFolder=remote

Sending files in sequence to a GCS bucket

Section titled “Sending files in sequence to a GCS bucket”

If you don’t specify the --parallel option then files will be sent using single session in the same order as they showed up on the filesystem (oldest files first).

Action after file is delivered to a GCS bucket

Section titled “Action after file is delivered to a GCS bucket”

After file is successfully delivered to remote location it’s possible to remove it from source or move it to a different folder at the source system.

  • --delete delete a file after it’s delivered
  • --move-folder target folder to move the file after it’s delivered

Following command will send all .zip files from the /data folder to the remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication and 3 parallel sessions and then move the files to /archive at the source system.

Terminal window
$ connect send gcs --file-mask "*.zip" -s /data -d remote --batch --parallel 3 --bucket my-gcs-bucket --move-folder /archive --auth-json /path/to/key-file.json
2025/06/03 14:09:35 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:09:35 INFO Files to send: count=3
2025/06/03 14:09:35 INFO Transferring file=/data/file2.zip targetFolder=remote
2025/06/03 14:09:35 INFO Transferring file=/data/file3.zip targetFolder=remote
2025/06/03 14:09:35 INFO Transferring file=/data/file1.zip targetFolder=remote
2025/06/03 14:09:37 INFO File moved to folder folder=/archive file=/data/file1.zip
2025/06/03 14:09:37 INFO File transferred successfully bytesTransferred=10485760 duration=1s770ms transferRate=5.65MB/s file=/data/file1.zip targetFolder=remote
2025/06/03 14:09:37 INFO File moved to folder folder=/archive file=/data/file2.zip
2025/06/03 14:09:37 INFO File transferred successfully bytesTransferred=10485760 duration=1s805ms transferRate=5.54MB/s file=/data/file2.zip targetFolder=remote
2025/06/03 14:09:37 INFO File moved to folder folder=/archive file=/data/file3.zip
2025/06/03 14:09:37 INFO File transferred successfully bytesTransferred=10485760 duration=2s19ms transferRate=4.95MB/s file=/data/file3.zip targetFolder=remote

Following command will send all .zip files from the /data folder to the remote folder of GCS bucket my-gcs-bucket using JSON key for the authentication and 3 parallel sessions and then removes the files from source.

Terminal window
$ connect send gcs --file-mask "*.zip" -s /data -d remote --batch --parallel 3 --bucket my-gcs-bucket --delete --auth-json /path/to/key-file.json
2025/06/03 14:22:19 INFO Sending files to gcs://my-gcs-bucket/remote
2025/06/03 14:22:19 INFO Files to send: count=3
2025/06/03 14:22:19 INFO Transferring file=/data/file1.zip targetFolder=remote
2025/06/03 14:22:19 INFO Transferring file=/data/file2.zip targetFolder=remote
2025/06/03 14:22:19 INFO Transferring file=/data/file3.zip targetFolder=remote
2025/06/03 14:22:21 INFO File deleted file=/data/file1.zip
2025/06/03 14:22:21 INFO File transferred successfully bytesTransferred=10485760 duration=1s744ms transferRate=5.73MB/s file=/data/file1.zip targetFolder=remote
2025/06/03 14:22:21 INFO File deleted file=/data/file3.zip
2025/06/03 14:22:21 INFO File transferred successfully bytesTransferred=10485760 duration=1s824ms transferRate=5.48MB/s file=/data/file3.zip targetFolder=remote
2025/06/03 14:22:22 INFO File deleted file=/data/file2.zip
2025/06/03 14:22:22 INFO File transferred successfully bytesTransferred=10485760 duration=2s315ms transferRate=4.32MB/s file=/data/file2.zip targetFolder=remote

All GCS Send Options

Section titled “All GCS Send Options”
Terminal window
Usage:
  connect send gcs [command] [flags]


Flags:
      --auth-json string   GCS authentication json file
      --bucket string      GCS bucket


Global Flags:
      --batch                     No progress bars
      --delete                    Delete files after successful send
  -d, --dst-folder string         Folder where files should be sent
      --file string               File name to be sent
      --file-mask string          File mask to filter files for sending
      --file-regex string         File regex to filter files for sending
      --flag string               Flag file name
      --from-mail string          From mail used to send notifications (only in batch mode)
      --godebug                   Turns on debug mode
      --help                      Prints help for the command
      --log-format string         Log output format: text|json (default "text")
      --mail-format string        Mail format [text|html] (only in batch mode) (default "plain")
      --move-folder string        Folder to move files after successful send
      --no-color                  Do not use colors in logs
      --parallel uint             Number of sessions used to send files (default 1)
      --quiet                     Makes no output
  -s, --src-folder string         Folder containing files to be sent (default "./")
      --to-mail-failure strings   Email list to send failure notification (only in batch mode)
      --to-mail-success strings   Email list to send success notification (only in batch mode)

Errors

Section titled “Errors”

Please check here for information on the possible errors.