Commit 21a59b23 authored by Job van der Voort's avatar Job van der Voort
Browse files

Merge branch 'add_lfs_doc' into 'master'

Documentation for Git LFS

Doc explaining how to use Git LFS, how to use Git LFS with GitLab, known issues and troubleshooting tips.

See merge request !1813
# Git LFS
Managing large files such as audio, video and graphics files has always been one of the shortcomings of Git.
The general recommendation is to not have Git repositories larger than 1GB to preserve performance.
GitLab already supports [managing large files with git annex](http://doc.gitlab.com/ee/workflow/git_annex.html) (EE only), however in certain
environments it is not always convenient to use different commands to differentiate between the large files and regular ones.
Git LFS makes this simpler for the end user by removing the requirement to learn new commands.
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## How it works
Git LFS client talks with the GitLab server over HTTPS. It uses HTTP Basic Authentication to authorize client requests.
Once the request is authorized, Git LFS client receives instructions from where to fetch or where to push the large file.
## Requirements
* Git LFS is supported in GitLab starting with version 8.2
* Git LFS client version 0.6.0 and up
## GitLab and Git LFS
### Configuration
Git LFS objects can be large in size. By default, they are stored on the server GitLab is installed on.
There are two configuration options to help GitLab server administrators:
* Enabling/disabling Git LFS support
* Changing the location of LFS object storage
#### Omnibus packages
In `/etc/gitlab/gitlab.rb`:
```ruby
gitlab_rails['lfs_enabled'] = false
gitlab_rails['lfs_storage_path'] = "/mnt/storage/lfs-objects"
```
#### Installations from source
In `config/gitlab.yml`:
```yaml
lfs:
enabled: false
storage_path: /mnt/storage/lfs-objects
```
## Known limitations
* Git LFS v1 original API is not supported since it was deprecated early in LFS development, starting with Git LFS version 0.6.0
* When SSH is set as a remote, Git LFS objects still go through HTTPS
* Any Git LFS request will ask for HTTPS credentials to be provided so good Git credentials store is recommended
* Currently, storing GitLab Git LFS objects on a non-local storage (like S3 buckets) is not supported
* Git LFS always assumes HTTPS so if you have GitLab server on HTTP you will have to add the url to Git config manually (see #troubleshooting-tips)
## Using Git LFS
Lets take a look at the workflow when you need to check large files into your Git repository with Git LFS:
For example, if you want to upload a very large file and check it into your Git repository:
```bash
git clone git@gitlab.example.com:group/project.git
git lfs init # initialize the Git LFS project project
git lfs track "*.iso" # select the file extensions that you want to treat as large files
```
Once a certain file extension is marked for tracking as a LFS object you can use Git as usual without having to redo the command to track a file with the same extension:
```bash
cp ~/tmp/debian.iso ./ # copy a large file into the current directory
git add . # add the large file to the project
git commit -am "Added Debian iso" # commit the file meta data
git push origin master # sync the git repo and large file to the GitLab server
```
Downloading a single large file is also very simple:
```bash
git clone git@gitlab.example.com:group/project.git
git lfs fetch debian.iso # download the large file
```
## Troubleshooting
### error: Repository or object not found
There are a couple of reasons why this error can occur:
* Wrong version of LFS client used:
Check the version of Git LFS on the client machine with `git lfs version`. Only version 0.6.0 and newer are supported.
* Project is using deprecated LFS API
Check the Git config of the project for traces of deprecated API with `git lfs -l`. If `batch = false` is set in the config, remove the line and try using Git LFS client newer than 0.6.0.
### Invalid status for <url> : 501
When attempting to push a LFS object to a GitLab server that doesn't have Git LFS support enabled, server will return status `error 501`. Check with your GitLab administrator why Git LFS is not enabled on the server. See [Configuration section](#configuration) for instructions on how to enable LFS support.
### getsockopt: connection refused
If you push a LFS object to a project and you receive an error similar to: `Post <URL>/info/lfs/objects/batch: dial tcp IP: getsockopt: connection refused`,
the LFS client is trying to reach GitLab through HTTPS. However, your GitLab instance is being served on HTTP.
This behaviour is caused by Git LFS using HTTPS connections by default when a `lfsurl` is not set in the Git config.
To prevent this from happening, set the lfs url in project Git config:
```bash
git config --add lfs.url "http://gitlab.example.com/group/project.git/info/lfs/objects/batch"
```
### Credentials are always required when pushing an object
Given that Git LFS uses HTTP Basic Authentication to authenticate the user pushing the LFS object on every push for every object, user HTTPS credentials are required.
By default, Git has support for remembering the credentials for each repository you use. This is described in [Git credentials man pages](https://git-scm.com/docs/gitcredentials).
For example, you can tell Git to remember the password for a period of time in which you expect to push the objects:
```bash
git config --global credential.helper 'cache --timeout=3600'
```
This will remember the credentials for an hour after which Git operations will require re-authentication.
If you are using OS X you can use `osxkeychain` to store and encrypt your credentials. For Windows, `wincred` is available.
More details about various methods of storing the user credentials can be found on [Git Credential Storage documentation](https://git-scm.com/book/en/v2/Git-Tools-Credential-Storage)
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