# `juju enable-ha` ## Summary Ensure that sufficient controllers exist to provide redundancy. ## Usage `juju enable-ha [options] ` ### Options | Flag | Default | Usage | |----------------------------|-----------|------------------------------------------------------------| | `-B`, `--no-browser-login` | false | Do not use web browser for authentication | | `-c`, `--controller` | | Controller to operate in | | `--constraints` | [] | Additional machine constraints | | `--format` | simple | Specify output format (json|simple|yaml) | | `-n` | 0 | Number of controllers to make available | | `-o`, `--output` | | Specify an output file | | `--to` | | The machine(s) to become controllers, bypasses constraints | ## Examples Ensure that the controller is still in highly available mode. If there is only 1 controller running, this will ensure there are 3 running. If you have previously requested more than 3, then that number will be ensured. ```none juju enable-ha ``` Ensure that 5 controllers are available: ```none juju enable-ha -n 5 ``` Ensure that 7 controllers are available, with newly created controller machines having at least 8GB RAM. ```none juju enable-ha -n 7 --constraints mem=8G ``` Ensure that 7 controllers are available, with machines `server1` and `server2` used first, and if necessary, newly created controller machines having at least 8GB RAM. ```none juju enable-ha -n 7 --to server1,server2 --constraints mem=8G ``` ## Details To ensure availability of deployed applications, the Juju infrastructure must itself be highly available. The `enable-ha` command will ensure that the specified number of controller machines are used to make up the controller. An odd number of controllers is required.