Merge pull request #15 from allenai/lazy-docker

initialize Docker client lazily

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+- Docker Client is initialized lazily so that some functionality of `Beaker` client can be used on systems without Docker.
+
 ## [v0.2.3](https://github.com/allenai/beaker-py/releases/tag/v0.2.3) - 2021-12-09
 
 ### Fixed

beaker/client.py

@@ -28,7 +28,7 @@ class Beaker:
     def __init__(self, config: Config):
         self.config = config
         self.base_url = f"{self.config.agent_address}/api/{self.API_VERSION}"
-        self.docker = docker.from_env()
+        self._docker: Optional[docker.DockerClient] = None
 
     @property
     def user(self) -> str:
@@ -44,6 +44,13 @@ def from_env(cls, **overrides) -> "Beaker":
         """
         return cls(Config.from_env(**overrides))
 
+    @property
+    def docker(self) -> docker.DockerClient:
+        if self._docker is None:
+            self._docker = docker.from_env()
+        assert self._docker is not None
+        return self._docker
+
     @contextmanager
     def _session_with_backoff(self) -> requests.Session:
         session = requests.Session()