ccp

ccp copies files across different file services

Usage

Copy

ccp http://example.com /tmp/file
ccp /tmp/file s3://bucket/file
ccp s3://bucket/file gs://bucket/file
ccp s3://bucket/file s3://bucket/file2

List

ccp -ls s3://bucket/
ccp -ls s3://bucket/dir

Test

The test flag will cause ccp to verify that it can read and write to the locations without copying data. The first example will check read access only, whereas the second also creates an empty file2. This is useful when you need to verify bucket permissions in advance before copying large files, however, it will create empty files.

ccp -test s3://bucket/file -
ccp -test s3://bucket/file s3://bucket/file2

You can also use ccp -ls to check access controls, however some schemes will allow accounts to list a file and then deny read access to that file.

Feature Matrix

SCHEME	SRC	DST	COMMENT
s3	x	x	amazon s3
gs	x	x	google cloud storage
http/https	x
file	x	x	local file
	x	x	alias for file

Configuration

gs/s3 are configured through the common environment variables used by the respective sdks

UNIX-like Usage Example

A more in-depth example is necessary to see how ccp can integrate with your existing UNIX tools.

# Step 1:
# Create four test files in /tmp/ccp

ccp http://example.com /tmp/ccp/file1
ccp http://example.com /tmp/ccp/file2
ccp http://example.com /tmp/ccp/file3
echo hello | ccp - /tmp/ccp/file4

# Step 2:
# Use ccp -ls to list these files
# This will generate a tab seperated list of $size, $file
ccp -ls /tmp/ccp

	1256	/tmp/ccp/file1
	1256	/tmp/ccp/file2
	1256	/tmp/ccp/file3
	6	/tmp/ccp/file4

# Step 3:
# To see what ccp is going to do, run it -dry
# The output can be piped to the shell to execute the copy
# Or you can just remove the -dry flag.
#
ccp -l -dry /tmp/ccp /tmp/ccp.bak/

	ccp "/tmp/ccp/file1" "/tmp/ccp.bak/file1" # 1256
	ccp "/tmp/ccp/file2" "/tmp/ccp.bak/file2" # 1256
	ccp "/tmp/ccp/file3" "/tmp/ccp.bak/file3" # 1256
	ccp "/tmp/ccp/file4" "/tmp/ccp.bak/file4" # 6

# Step 4:
# Earlier you ran a command to consume stdin and write
# that to file4. CCP can, in addition to reading file contents,
# read a newline-seperated list of files from stdin with the "ccp -l" flag

ccp -ls /tmp/ccp | ccp -l -dry - /tmp/ccp.bak/

	ccp "/tmp/ccp/file1" "/tmp/ccp.bak/file1" # 1256
	ccp "/tmp/ccp/file2" "/tmp/ccp.bak/file2" # 1256
	ccp "/tmp/ccp/file3" "/tmp/ccp.bak/file3" # 1256
	ccp "/tmp/ccp/file4" "/tmp/ccp.bak/file4" # 6

# Step 5:
# The above output is identical to "ccp -l -dry /tmp/ccp /tmp/ccp.bak/"
# However, it is more powerful.


# Filter out the undesirable "file4" from the copy
ccp -ls /tmp/ccp | egrep -v file4 | ccp -l -dry - /tmp/ccp.bak/

	ccp "/tmp/ccp/file1" "/tmp/ccp.bak/file1" # 1256
	ccp "/tmp/ccp/file2" "/tmp/ccp.bak/file2" # 1256
	ccp "/tmp/ccp/file3" "/tmp/ccp.bak/file3" # 1256

# Filter files larger than 10 bytes
ccp -ls /tmp/ccp | awk '{ if ($1 <= 10) print }'  | ccp -l -dry - /tmp/ccp.bak/

	ccp "/tmp/ccp/file4" "/tmp/ccp.bak/file4" # 6

# All of these tricks can be used with gs and s3 buckets as well
# to copy files across different cloud providers.

Notes

GS to S3 compatibility mode

The gs protocol supports an s3 compatibility mode wherein an s3 client can speak to a gs bucket using the s3 protocol. This usage mode is not well-documented, and involves generating aws-compatible hmac keys (aka $AWS_ACCESS_KEY_ID, $AWS_SECRET_ACCESS_KEY). This usage mode is not supported and in my experience does not work reliably. To fix this, use GOOGLE_APPLICATION_CREDENTIALS or some other credentials auto-detected by the google SDK.

Cross-Account Copying

Currently, it is not possible to copy files across accounts using the same scheme. For example, two s3 buckets managed by different accounts. This is not possible to resolve without introducing a config file that properly initializes credentials based on the source or destination path.

Cross-Scheme Directory Structures

Schemes like s3 (and possibly gs) do not have a concept of directories. Hence, it is possible to create s3://bucket/file.mp4 and s3://bucket/file.mp4/file.txt. The ccp program always operates on a directory structure, so ccp -ls s3://bucket/file.mp4 on such a layout will produce a list of outputs including both files. The best solution is to use a sane directory-based layout to migitage potentially undefined behavior when copying these resources to a local filesystem.

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