CocConfig

{
    "languageserver": {
      "golang": {
        "command": "gopls",
        "rootPatterns": ["go.mod", ".vim/", ".git/", ".hg/"],
        "filetypes": ["go"],
        "initializationOptions": {
          "usePlaceholders": true
        }
    },
        "ccls": {
      "command": "ccls",
      "filetypes": [
        "c",
        "cpp",
        "cuda",
        "objc",
        "objcpp"
      ],
      "rootPatterns": [
        ".ccls-root",
        "compile_commands.json",
        ".git/",
        ".ccls"
      ],
      "initializationOptions": {
        "cache": {
          "directory": "/tmp/ccls"
        },
        "client": {
          "snippetSupport": true
        },
        "highlight": {
          "lsRanges": true
        }
      }
    },

    "sql": {
      "command": "sql-language-server",
      "args" : ["up", "--method", "stdio"],
      "filetypes": ["sql", "mysql"]
     },
     "graphql": {
      "command": "graphql-lsp",
      "args": ["server", "-m", "stream"],
      // customize filetypes to your needs
      "filetypes": ["typescript", "typescriptreact", "graphql"]
    },
    "python": {
      "command": "python",
      "args": [
        "-mpyls",
        "-vv",
        "--log-file",
        "/tmp/lsp_python.log"
      ],
      "trace.server": "verbose",
      "filetypes": [
         "python"
      ],
      "settings": {
        "pyls": {
          "enable": true,
          "trace": {
            "server": "verbose"
          },
          "commandPath": "",
          "configurationSources": [
            "pycodestyle"
          ],
          "plugins": {
            "jedi_completion": {
              "enabled": true
            },
            "jedi_hover": {
              "enabled": true
            },
            "jedi_references": {
              "enabled": true
            },
            "jedi_signature_help": {
              "enabled": true
            },
            "jedi_symbols": {
             "enabled": true,
              "all_scopes": true
            },
            "mccabe": {
              "enabled": true,
              "threshold": 15
            },
            "preload": {
              "enabled": true
            },
            "pycodestyle": {
              "enabled": true
            },
            "pydocstyle": {
              "enabled": false,
              "match": "(?!test_).*\\.py",
              "matchDir": "[^\\.].*"
            },
            "pyflakes": {
              "enabled": true
            },
            "rope_completion": {
              "enabled": true
            },
            "yapf": {
              "enabled": true
            }
          }
        }
      }
    },
    "dockerfile": {
      "command": "docker-langserver",
      "filetypes": ["dockerfile"],
      "args": ["--stdio"]
    },
    "bash": {
      "command": "bash-language-server",
      "args": ["start"],
      "filetypes": ["sh"],
      "ignoredRootPaths": ["~"]
    },
    "cmake": {
      "command": "cmake-language-server",
      "filetypes": ["cmake"],
      "rootPatterns": [
        "build/"
      ],
      "initializationOptions": {
        "buildDirectory": "build"
      }
    }
  }
}

https://github.com/neoclide/coc.nvim/wiki/Language-servers

neoclide/coc.nvim#2088 (comment)