don't require pyessv-archive to run whole package

Makefile

@@ -18,15 +18,15 @@ STAC_HOST ?= http://localhost:8880/stac
 # CATALOG = https://daccs.cs.toronto.edu/twitcher/ows/proxy/thredds/catalog/datasets/CMIP6/CMIP/NUIST/catalog.html
 CATALOG = https://daccs.cs.toronto.edu/twitcher/ows/proxy/thredds/catalog/datasets/CMIP6/CMIP/MIROC/catalog.html
 
-PYESSV_ARCHIVE_DIR ?= ~/.esdoc/pyessv-archive
+PYESSV_ARCHIVE_HOME ?= ~/.esdoc/pyessv-archive
 PYESSV_ARCHIVE_REF ?= https://github.com/ES-DOC/pyessv-archive
 
 ## -- Testing targets -------------------------------------------------------------------------------------------- ##
 
 setup-pyessv-archive:
-	@echo "Updating pyessv archive [$(shell realpath $(PYESSV_ARCHIVE_DIR))]..."
-	@[ -d $(PYESSV_ARCHIVE_DIR) ] || git clone "$(PYESSV_ARCHIVE_REF)" $(PYESSV_ARCHIVE_DIR)
-	@cd $(PYESSV_ARCHIVE_DIR) && git pull
+	@echo "Updating pyessv archive [$(shell realpath $(PYESSV_ARCHIVE_HOME))]..."
+	@[ -d $(PYESSV_ARCHIVE_HOME) ] || git clone "$(PYESSV_ARCHIVE_REF)" $(PYESSV_ARCHIVE_HOME)
+	@cd $(PYESSV_ARCHIVE_HOME) && git pull
 
 test-cmip6:
 	python $(IMP_DIR)/CMIP6_UofT/add_CMIP6.py $(STAC_HOST) $(CATALOG)

README.md

@@ -49,18 +49,49 @@ You should then be able to call the STAC populator CLI with following commands:
 
 ```shell
 # obtain the installed version of the STAC populator
-stac-popultaor --version
+stac-populator --version
 
 # obtain general help about available commands
-stac-popultaor --help
+stac-populator --help
 
 # obtain general help about available STAC populator implementations
-stac-popultaor run --help
+stac-populator run --help
 
 # obtain help specifically for the execution of a STAC populator implementation
-stac-popultaor run [implementation] --help
+stac-populator run [implementation] --help
 ```
 
+### CMIP6 extension: extra requirements
+
+The CMIP6 stac-populator extension requires that the [pyessv-archive](https://github.com/ES-DOC/pyessv-archive) data 
+files be installed. To install this package to the default location in your home directory at `~/.esdoc/pyessv-archive`:
+
+```shell
+git clone https://github.com/ES-DOC/pyessv-archive ~/.esdoc/pyessv-archive
+# OR
+make setup-pyessv-archive
+```
+
+You can also choose to install them to a location on disk other than the default:
+
+```shell
+git clone https://github.com/ES-DOC/pyessv-archive /some/other/place
+# OR
+PYESSV_ARCHIVE_HOME=/some/other/place make setup-pyessv-archive
+```
+
+*Note*: <br>
+If you have installed the [pyessv-archive](https://github.com/ES-DOC/pyessv-archive) data files to a non-default
+location, you need to specify that location with the `PYESSV_ARCHIVE_HOME` environment variable. For example,
+if you've installed the pyessv-archive files to `/some/other/place` then run the following before executing 
+any of the example commands above:
+
+```shell
+export PYESSV_ARCHIVE_HOME=/some/other/place
+```
+
+### Docker
+
 You can also employ the pre-built Docker, which can be called as follows,
 where `[command]` corresponds to any of the above example operations.
 

STACpopulator/cli.py

@@ -4,6 +4,7 @@
 import logging
 import os
 import sys
+import warnings
 from datetime import datetime
 from http import cookiejar
 from typing import Callable, Optional
@@ -13,6 +14,7 @@
 from requests.sessions import Session
 
 from STACpopulator import __version__
+from STACpopulator.exceptions import STACPopulatorError
 from STACpopulator.logging import setup_logging
 
 POPULATORS = {}
@@ -151,7 +153,11 @@ def make_run_command_parser(parent) -> argparse.ArgumentParser:
         populator_name, pop_mod_file = populator_py_mod.rsplit(".", 1)
         populator_root = f"STACpopulator.{populators_impl}.{populator_name}"
         pop_mod_file_loc = f"{populator_root}.{pop_mod_file}"
-        populator_module = importlib.import_module(pop_mod_file_loc, populator_root)
+        try:
+            populator_module = importlib.import_module(pop_mod_file_loc, populator_root)
+        except STACPopulatorError as e:
+            warnings.warn(f"Could not load extension {populator_name} because of error {e}")
+            continue
         parser_maker: Callable[[], argparse.ArgumentParser] = getattr(populator_module, "make_parser", None)
         populator_runner = getattr(populator_module, "runner", None)  # optional, call main directly if not available
         populator_caller = getattr(populator_module, "main", None)

STACpopulator/exceptions.py

@@ -0,0 +1,5 @@
+class STACPopulatorError(Exception):
+    pass
+
+class ExtensionLoadError(STACPopulatorError):
+    pass

STACpopulator/extensions/cmip6.py

@@ -15,7 +15,6 @@
     get_args,
 )
 
-import pyessv
 import pystac
 from pydantic import (
     AnyHttpUrl,
@@ -34,6 +33,7 @@
     SummariesExtension,
 )
 
+from STACpopulator.exceptions import ExtensionLoadError
 from STACpopulator.models import AnyGeometry
 from STACpopulator.stac_utils import (
     ServiceType,
@@ -42,6 +42,11 @@
     ncattrs_to_geometry,
 )
 
+try:
+    import pyessv
+except OSError as e:
+    raise ExtensionLoadError(str(e)) from e
+
 T = TypeVar("T", pystac.Collection, pystac.Item, pystac.Asset, item_assets.AssetDefinition)
 
 SchemaName = Literal["cmip6"]