Simple base container for rancher sidekicks whose responsibility is to write configuration files for other services. Includes janeczku/go-rancher-gen for templated configuration based on rancher metadata and awscli + scripts for mounting EBS volumes and pulling files from S3.
Add your rancher-gen configuration file as /etc/rancher-conf/config.toml. You can do this by creating a new image with this base and copying your configuration in, or mounting your configuration in at runtime.
Run this container with the following environment variables set, and on startup it will find a free device and create/attach your volume. Newly created volumes will be formatted with the xfs filesystem. If the specified volume is already attached to a different instance, it will be forcibly detached and attached to this instance.
The general use-case that this feature is designed for is the ability to specify an EBS volume that 'follows' a service container across hosts. In it's current form, it's really only intended to be used with a service of
scale: 1(because all instances will attempt to take control of the volume named$EBS_VOLUME_NAMEand this will not end well if they are on different hosts or aren't supposed to share data). In the future I may consider an implementation that can handle scaling services by including the service index in the volume name.
| Environment Variable | Default | Role |
|---|---|---|
EBS_VOLUME_NAME |
- |
Look for an EBS volume with this name in the current AZ. If it doesn't exist, create it. Then attaches this volume to an available device if not already attached. If not set, no volume will be mounted. |
EBS_VOLUME_DIR |
/ebs/${EBS_VOLUME_NAME} |
Where to mount the volume. |
EBS_VOLUME_SIZE |
- |
If the named volume doesn't exist, it will be created with this size, otherwise this is ignored. Must be in <size>G format (e.g. 50G). |
EBS_VOLUME_USER_ID |
- |
The user id to permission the ebs volume for. |
EBS_VOLUME_FS |
xfs |
Formats the volume with the given filesystem. |
EBS_VOLUME_TYPE |
gp2 |
If the named volume doesn't exist, it will be created with this type, otherwise ignored. |
EBS_VOLUME_IOPS |
- |
If specified and the named volume doesn't exist, it will be provisioned with the specified IOPS. Otherwise ignored. |
Run this container with the following environment variables set, and on startup it will download the contents of the specified s3 folder to the local drive.
| Environment Variable | Default | Role |
|---|---|---|
S3_BUCKET |
- |
Specifies the S3 bucket to download. If not set, no S3 bucket will be downloaded. |
S3_PREFIX |
- |
Specifies a subfolder within the S3 bucket to download. If specified, nothing in $S3_BUCKET outside of this prefix will be downloaded. This will be ignored unless $S3_BUCKET is specified. |
S3_MOUNT_DIR |
/s3/${S3_BUCKET}/${S3_PREFIX} |
Where to locally store the S3 files. |
It's sometimes useful to override the entrypoint of your service with a simple wrapper around the original, especially if you need to wait for a config file to be written or a volume to mount before allowing it to start. This can generally be accomplished by copying such a script into a volume shared with your service container, and setting the entrypoint for your service to use that script. Technically, you can use any directory for this because it's completely specified in the docker-compose file for your specific stack. But for the sake of consistency, /opt/rancher/bin/ is preconfigured in this image as a volume for this purpose. It is generally assumed that anything placed in this directory is intended to be shared from a sidekick and run from within the primary service container.
- Independent volumes for services with scale > 1
- Restore EBS from snapshot in
EBS_SNAPSHOT_ID - Resize EBS by updating
EBS_VOLUME_SIZE - Migrate volume from a different AZ
- Add EBS snapshotting scripts