dotfiles/nvim/after/lsp/yamlls.lua

-- YAML LSP specific settings with a number of custom tags specifically for use with AWS CloudFormation templates

return {
    cmd = function (dispatchers, _)
        return vim.lsp.rpc.start({'yaml-language-server', '--stdio'}, dispatchers)
    end,
    filetypes = { 'yaml', 'yaml.docker-compose', 'yaml.gitlab', 'yaml.helm-values' },
    root_markers = { '.git' },
    settings = {
        redhat = { telemetry = { enabled = false } },
        yaml = {
            customTags = {
                '!fn',
                '!And',
                '!If',
                '!Not',
                '!Equals',
                '!Or',
                '!FindInMap sequence',
                '!Base64',
                '!Cidr',
                '!Ref',
                '!Ref Scalar',
                '!Sub',
                '!GetAtt',
                '!GetAZs',
                '!ImportValue',
                '!Select',
                '!Split',
                '!Join sequence'
            },
            format = { enable = true, singleQuote = true },
            hover = true,
            schemaStore = { enable = true },
            validate = true,
        }
    },
    on_init = function(client)
        -- From nvim-lspconfig's yamlls.lua
        --- https://github.com/neovim/nvim-lspconfig/pull/4016
        --- Since formatting is disabled by default if you check `client:supports_method('textDocument/formatting')`
        --- during `LspAttach` it will return `false`. This hack sets the capability to `true` to facilitate
        --- autocmd's which check this capability
        client.server_capabilities.documentFormattingProvider = true
    end,
}