levant

Levant

Levant is an open source templating and deployment tool for HashiCorp Nomad jobs that provides realtime feedback and detailed failure messages upon deployment issues.

Features

• Realtime Feedback: Using watchers, Levant provides realtime feedback on Nomad job deployments allowing for greater insight and knowledge about application deployments.

• Advanced Job Status Checking: Particulary for system and batch jobs, Levant will ensure the job, evaluations and allocations all reach the desired state providing feedback at every stage.

• Dynamic Job Group Counts: If the Nomad job is currently running on the cluster, Levant will dynamically update the rendered template with the relevant job group counts before deployment.

• Failure Inspection: Upon a deployment failure, Levant will inspect each allocation and log information about each event, providing useful information for debugging without the need for querying the cluster retrospectively.

• Canary Auto Promotion: In environments with advanced automation and alerting, automatic promotion of canary deployments may be desirable after a certain time threshold. Levant allows the user to specify a canary-auto-promote time period, which if reached with a healthy set of canaries, will automatically promote the deployment.

• Multiple Variable File Formats: Currently Levant supports .json, .tf, .yaml, and .yml file extensions for the declaration of template variables.

• Auto Revert Checking: In the event that a job deployment does not pass its healthy threshold and the job has auto-revert enabled; Levant will track the resulting rollback deployment so you can see the exact outcome of the deployment process.

Download & Install

• Levant can be installed via go toolkit using go get github.com/jrasell/levant && go install github.com/jrasell/levant

• The Levant binary can be downloaded from the GitHub releases page using curl -L https://github.com/jrasell/levant/releases/download/0.2.8/linux-amd64-levant -o levant

• A docker image can be found on Docker Hub, the latest version can be downloaded using docker pull jrasell/levant.

• Levant can be built from source by firstly cloning the repository git clone git://github.com/jrasell/levant.git. Once cloned the binary can be built using the make command or invoking the build.sh script located in the scripts directory.

• There is a Levant Ansible role available to help installation on machines. Thanks to @stevenscg for this.

Templating

Levant includes functionality to perform template variables substituion as well as trigger built-in template function to add timestamps or retrive information from Consul. For full details please check out the templates documentation page.

Commands

Levant supports a number of command line arguments which provide control over the Levant binary. For detail about each commands and its supported flags, please head over to the commands documentation page.

Clients

Levant utilises the Nomad and Consul offical clients and configuration can be done via a number of environment variables. For detail about these please read through the clients documentation page.

Contributing

Contributions to Levant are very welcome! Please refer to our contribution guide for details about hacking on Levant.