@classmethod<EOL><INDENT>def from_env(cls, reactor=None, env=os.environ):<DEDENT>
address = env.get('<STR_LIT>', '<STR_LIT>')<EOL>token = env.get('<STR_LIT>', '<STR_LIT>')<EOL>ca_cert = env.get('<STR_LIT>')<EOL>tls_server_name = env.get('<STR_LIT>')<EOL>client_cert = env.get('<STR_LIT>')<EOL>client_key = env.get('<STR_LIT>')<EOL>cf = ClientPolicyForHTTPS.from_pem_files(<EOL>caKey=ca_cert, privateKey=client_key, certKey=client_cert,<EOL>tls_server_name=tls_server_name<EOL>)<EOL>client, reactor = default_client(reactor, contextFactory=cf)<EOL>return cls(address, token, client=client, reactor=reactor)<EOL>
Create a Vault client with configuration from the environment. Supports
a limited number of the available config options:
https://www.vaultproject.io/docs/commands/index.html#environment-variables
https://github.com/hashicorp/vault/blob/v0.11.3/api/client.go#L28-L40

Supported:
- ``VAULT_ADDR``
- ``VAULT_CACERT``
- ``VAULT_CLIENT_CERT``
- ``VAULT_CLIENT_KEY``
- ``VAULT_TLS_SERVER_NAME``
- ``VAULT_TOKEN``

Not currently supported:
- ``VAULT_CAPATH``
- ``VAULT_CLIENT_TIMEOUT``
- ``VAULT_MAX_RETRIES``
- ``VAULT_MFA``
- ``VAULT_RATE_LIMIT``
- ``VAULT_SKIP_VERIFY``
- ``VAULT_WRAP_TTL``