Preventing duplication of files in a storage device

1. A non-transitory computer-readable medium comprising instructions for a kernel of an operating system, the kernel being executable by a processor for causing the processor to:

determine a checksum of a file in a software package by:

retrieving a manifest file from a remote computing device, the manifest file including checksums of files in the software package; and

extracting the checksum of the file from the manifest file;

determine that the file is absent from a storage device by issuing a command for accessing the file based on the checksum; and

in response to determining that the file is absent from the storage device, download a copy of the file from the remote computing device to the storage device over a network.

2. The non-transitory computer-readable medium of claim 1 , wherein the kernel is further executable by the processor for causing the processor to:

determine another checksum of another file of the software package;

determine that the other file exists in the storage device by issuing another command for accessing the other file based on the other checksum; and

in response to determining that the other file exists in the storage device, store a memory link in a second memory location of the storage device, wherein the memory link references a first memory location in which the other file is stored in the storage device.

3. The non-transitory computer-readable medium of claim 2 , wherein the kernel is further executable by the processor for causing the processor to, in response to determining that the other file exists in the storage device:

prevent a copy of the other file from being downloaded over the network from the remote computing device to the storage device.

4. The non-transitory computer-readable medium of claim 1 , wherein the kernel is further executable by the processor for causing the processor to:

prior to issuing the command, modify an attribute of the file such that the file is immutable.

5. The non-transitory computer-readable medium of claim 1 , wherein the command is configured to request a file descriptor of the file, and wherein the kernel is further executable by the processor for causing the processor to:

determine that the file is absent from the storage device based on the command returning an error value rather than the file descriptor.

6. The non-transitory computer-readable medium of claim 1 , wherein the command is an fs-verity command.

7. The non-transitory computer-readable medium of claim 1 , wherein the software package is a container image that includes one or more layers of files.

8. A system comprising:

a processor; and

a memory including instructions for a kernel of an operating system, the kernel being executable by the processor for causing the processor to:

determine a checksum of a file in a software package;

determine that the file is absent from a storage device by:

issuing a command for accessing the file based on the checksum, wherein the command is configured to request a file descriptor of the file; and

receiving an error value rather than the file descriptor in return from issuing the command; and

in response to determining that the file is absent from the storage device, download a copy of the file from a remote computing device to the storage device over a network.

9. The system of claim 8 , wherein the kernel is further executable by the processor for causing the processor to:

determine another checksum of another file of the software package;

determine that the other file exists in the storage device by issuing another command for accessing the other file based on the other checksum; and

in response to determining that the other file exists in the storage device, store a memory link in a second memory location of the storage device, wherein the memory link references a first memory location in which the other file is stored in the storage device.

10. The system of claim 9 , wherein the kernel is further executable by the processor for causing the processor to, in response to determining that the other file exists in the storage device:

prevent a copy of the other file from being downloaded over the network from the remote computing device to the storage device.

11. The system of claim 8 , wherein the kernel is further executable by the processor for causing the processor to:

prior to issuing the command, modify an attribute of the file such that the file is immutable.

12. The system of claim 8 , wherein the kernel is further executable by the processor for causing the processor to determine the checksum of the file by:

retrieving a manifest file from the remote computing device, the manifest file including checksums of files in the software package; and

extracting the checksum of the file from the manifest file.

13. The system of claim 8 , wherein the command is an fs-verity command.

14. The system of claim 8 , wherein the software package is a container image that includes one or more layers of files.

15. A method comprising:

determining, by a kernel executing on a processor, a checksum of a file in a software package by:

retrieving a manifest file from a remote computing device, the manifest file including checksums of files in the software package; and

extracting the checksum of the file from the manifest file;

determining, by the kernel, that the file is absent from a storage device by issuing a command for accessing the file based on the checksum; and

in response to determining that the file is absent from the storage device, downloading, by the kernel, a copy of the file from the remote computing device to the storage device over a network.

16. The method of claim 15 , further comprising:

determining, by the kernel, another checksum of another file of the software package;

determining, by the kernel, that the other file exists in the storage device by issuing another command for accessing the other file based on the other checksum; and

in response to determining that the other file exists in the storage device, storing a memory link in a second memory location of the storage device, wherein the memory link references a first memory location in which the other file is stored in the storage device.

17. The method of claim 16 , further comprising:

preventing, by the kernel, a copy of the other file from being downloaded from the remote computing device to the storage device.

18. The method of claim 15 , further comprising:

prior to issuing the command, modifying, by the kernel, an attribute of the file such that the file is immutable.