git-sync is a simple command that pulls a git repository into a local directory. It is a perfect "sidecar" container in Kubernetes - it can periodically pull files down from a repository so that an application can consume them.

git-sync can pull one time, or on a regular interval. It can pull from the HEAD of a branch, from a git tag, or from a specific git hash. It will only re-pull if the target of the run has changed in the upstream repository. When it re-pulls, it updates the destination directory atomically. In order to do this, it uses a git worktree in a subdirectory of the --root and flips a symlink.

git-sync can pull over HTTP(S) (with authentication or not) or SSH.

git-sync can also be configured to make a webhook call upon successful git repo synchronization. The call is made after the symlink is updated.

We use docker buildx to build images.

# build the container
make container REGISTRY=registry VERSION=tag

# build the container behind a proxy
make container REGISTRY=registry VERSION=tag \
    HTTP_PROXY=http://<proxy_address>:<proxy_port> \
    HTTPS_PROXY=https://<proxy_address>:<proxy_port>

# build the container for an OS/arch other than the current (e.g. you are on
# MacOS and want to run on Linux)
make container REGISTRY=registry VERSION=tag \
    GOOS=linux GOARCH=amd64

# make a directory (owned by you) for the volume
export DIR="/tmp/git-data"
mkdir -p $DIR

# run the container (as your own UID)
docker run -d \
    -v $DIR:/tmp/git \
    -u$(id -u):$(id -g) \
    registry/git-sync:tag \
        --repo=https://github.com/kubernetes/git-sync \
        --branch=master \
        --wait=30

# run an nginx container to serve the content
docker run -d \
    -p 8080:80 \
    -v $DIR:/usr/share/nginx/html \
    nginx

Webhooks are executed asynchronously from the main git-sync process. If a webhook-url is configured, when a change occurs to the local git checkout a call is sent using the method defined in webhook-method (default to POST). git-sync will continually attempt this webhook call until it succeeds (based on webhook-success-status). If unsuccessful, git-sync will wait webhook-backoff (default 3s) before re-attempting the webhook call.

Usage

A webhook is configured using a set of CLI flags. At its most basic only webhook-url needs to be set.

docker run -d \
    -v $DIR:/tmp/git \
    registry/git-sync:tag \
        --repo=https://github.com/kubernetes/git-sync \
        --branch=master \
        --wait=30 \
        --webhook-url="http://localhost:9090/-/reload"