Bow

Bow detects updated image tags from a Docker registry of images defined in a GitOps deployment repository containing Kubernetes Deployments/StatefulSets or Helm templates.

Since it is forked from Keel.sh, it supports many of its features as well.

Getting started

Bow needs to have write access to the deployment repository to update it when Bow detects new images. You can either set REPO_USERNAME and REPO_PASSWORD environment variables (ideally from a Kubernetes Secret) or mount the files id_rsa and known_hosts into /root/.ssh/.

• create secret to use for git auth
  kubectl -n bow create secret generic ssh-key-secret --from-file=/home/alwin/.ssh/id_rsa --from-file=/home/alwin/.ssh/known_hosts
• check and adapt deployment/deployment-norbac.yaml
  • specifically set REPO_ environment variables
• apply yaml kubectl apply -f deployment/deployment-norbac.yaml
• check logs

Good to know

• the private key needs to be mounted in /root/.ssh/id_rsa
• a valid known_hosts in /root/.ssh is needed
• for username, password auth, the environment variables REPO_USERNAME and REPO_PASSWORD can be populated from a secret
• to access private docker registries, a full dockercfg can be passed in DOCKER_REGISTRY_CFG
• REPO_USERNAME and _PASSWORD or a private key and known_hosts need to be provided in any case, otherwise bow cannot push anyway
• provide path to Helm chart home as you would for helm template from the git repos home with REPO_CHART_PATH
• use REPO_BRANCH to update different and watch branch different to master
• you have to use annotations like bow/pollSchedule instead of keel.sh/pollSchedule

Development

• make sure to download dependencies with dep ensure
• manually build cmd/bow/main.go
• or build using Docker docker-compose build
• run generated binary or Docker image docker-compose up -d
• to test kubernetes, push new image to registry and change path in deployment/deployment-norbac.yaml

Features confirmed working (in some limited way)

• webhook triggers
• approvals
• chat notifications
• Docker registry secret from env
• running from binary, in Docker container and k8s cluster
• web frontend (set BASIC_AUTH_USER and BASIC_AUTH_PASSWORD to enable)
• git authentication with username/password or private key
• polling enabled by default (different to Keel)

Roadmap

• test semver support
• bug fixes - tell me about bugs

Limitations

• image name including tag needs to appear somewhere - don't move only the tag to values.yml
• everything is considered a Helm chart - if you have plain Kubernetes yamls, please create the folder structure of a Helm chart and put your files in the templates folder
• if the same image is referenced twice with different rules, the replacement process might not work as intended