jrasell/levant repository overview

⁠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

• The Levant binary can be downloaded from the GitHub releases page⁠ using curl -L https://github.com/jrasell/levant/releases/download/0.2.3/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 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.