prevent ethpm import issues without ipfshttpclient

ethpm/_utils/backend.py

@@ -10,9 +10,6 @@
 from eth_utils import (
     to_tuple,
 )
-from ipfshttpclient.exceptions import (
-    ConnectionError,
-)
 
 from ethpm.backends.base import (
     BaseURIBackend,
@@ -30,6 +27,12 @@
     RegistryURIBackend,
 )
 
+try:
+    from ipfshttpclient.exceptions import ConnectionError as IpfsConnectionError
+except ImportError:
+    pass
+
+
 logger = logging.getLogger("ethpm.utils.backend")
 
 ALL_URI_BACKENDS = [
@@ -41,6 +44,19 @@
 ]
 
 
+def _handle_optional_ipfs_backend_exception(e: Exception) -> None:
+    try:
+        # if optional `ipfshttpclient` module is present, catch and debug if
+        # IpfsConnectionError, else raise original exception.
+        if isinstance(e, IpfsConnectionError):
+            logger.debug("No local IPFS node available on port 5001.", exc_info=True)
+        else:
+            raise e
+    except NameError:
+        # if optional `ipfshttpclient` module is not present, raise original exception
+        raise e
+
+
 @to_tuple
 def get_translatable_backends_for_uri(
     uri: URI,
@@ -50,8 +66,8 @@ def get_translatable_backends_for_uri(
         try:
             if backend().can_translate_uri(uri):  # type: ignore
                 yield backend
-        except ConnectionError:
-            logger.debug("No local IPFS node available on port 5001.", exc_info=True)
+        except Exception as e:
+            _handle_optional_ipfs_backend_exception(e)
 
 
 @to_tuple
@@ -71,7 +87,5 @@ def get_resolvable_backends_for_uri(
                 try:
                     if backend_class().can_resolve_uri(uri):  # type: ignore
                         yield backend_class
-                except ConnectionError:
-                    logger.debug(
-                        "No local IPFS node available on port 5001.", exc_info=True
-                    )
+                except Exception as e:
+                    _handle_optional_ipfs_backend_exception(e)

ethpm/_utils/ipfs.py

@@ -9,9 +9,6 @@
     parse,
 )
 
-from base58 import (
-    b58encode,
-)
 from eth_utils import (
     to_text,
 )
@@ -24,6 +21,15 @@
     PBNode,
 )
 
+try:
+    # `ipfshttpclient` backend is optional. This is only imported if the "web3[ipfs]"
+    # install extra is installed
+    from base58 import (
+        b58encode,
+    )
+except ImportError:
+    pass
+
 
 def dummy_ipfs_pin(path: Path) -> Dict[str, str]:
     """

ethpm/backends/ipfs.py

@@ -15,7 +15,6 @@
     import_string,
     to_bytes,
 )
-import ipfshttpclient
 
 from ethpm import (
     get_ethpm_spec_dir,
@@ -39,6 +38,13 @@
     EthPMValidationError,
 )
 
+try:
+    # `ipfshttpclient` backend is optional. This is only imported if the "web3[ipfs]"
+    # install extra is installed
+    import ipfshttpclient
+except ImportError:
+    pass
+
 
 class BaseIPFSBackend(BaseURIBackend):
     """

newsfragments/2775.bugfix.rst

@@ -0,0 +1 @@
+Fix ``ethpm`` import issues after making ``ipfshttpclient`` optional.