fix: ensure deploy does not write data

conda_forge_tick/deploy.py

@@ -14,6 +14,7 @@
 from .lazy_json_backends import (
     CF_TICK_GRAPH_DATA_HASHMAPS,
     get_lazy_json_backends,
+    lazy_json_override_backends,
 )
 from .os_utils import clean_disk_space
 from .settings import settings
@@ -304,11 +305,11 @@ def deploy(
         return
 
     # make sure the graph can load, if not it will error
-    gx = load_existing_graph()
-    # TODO: be more selective about which json to check
-    for node, attrs in gx.nodes.items():
-        with attrs["payload"]:
-            pass
+    with lazy_json_override_backends(["file-read-only"], use_file_cache=False):
+        gx = load_existing_graph()
+        for node, attrs in gx.nodes.items():
+            with attrs["payload"]:
+                pass
 
     with fold_log_lines("cleaning up disk space for deploy"):
         clean_disk_space()

conda_forge_tick/lazy_json_backends.py

@@ -200,6 +200,26 @@ def hget(self, name: str, key: str) -> str:
         return data_str
 
 
+class ReadOnlyFileLazyJsonBackend(FileLazyJsonBackend):
+    _write_warned = False
+
+    @classmethod
+    def _ignore_write(cls) -> None:
+        if cls._write_warned:
+            return
+        logger.info("Note: Write operations to the read-only file backend are ignored.")
+        cls._write_warned = True
+
+    def hset(self, name: str, key: str, value: str) -> None:
+        self._ignore_write()
+
+    def hmset(self, name: str, mapping: Mapping[str, str]) -> None:
+        self._ignore_write()
+
+    def hdel(self, name: str, keys: Iterable[str]) -> None:
+        self._ignore_write()
+
+
 class GithubLazyJsonBackend(LazyJsonBackend):
     """
     Read-only backend that makes live requests to https://raw.githubusercontent.com
@@ -709,6 +729,7 @@ def hget(self, name, key):
 
 LAZY_JSON_BACKENDS: dict[str, type[LazyJsonBackend]] = {
     "file": FileLazyJsonBackend,
+    "file-read-only": ReadOnlyFileLazyJsonBackend,
     "mongodb": MongoDBLazyJsonBackend,
     "github": GithubLazyJsonBackend,
     "github_api": GithubAPILazyJsonBackend,

tests/test_lazy_json_backends.py

@@ -1047,3 +1047,106 @@ def test_lazy_json_backends_contexts_double_write():
             # now the file exists at the end of the context block
             assert os.path.exists(lzj.sharded_path)
             assert lzj.data == {"hi": "world"}
+
+
+def test_lazy_json_file_read_only_backend(tmpdir):
+    with pushd(tmpdir):
+        old_backend = conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_BACKENDS
+        old_cache = (
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_USE_FILE_CACHE
+        )
+        try:
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_BACKENDS = (
+                "file-read-only",
+            )
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_PRIMARY_BACKEND = (
+                "file-read-only"
+            )
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_USE_FILE_CACHE = (
+                False
+            )
+
+            f = "hi.json"
+            sharded_path = get_sharded_path(f)
+            assert not os.path.exists(f)
+            lj = LazyJson(f)
+
+            assert not os.path.exists(sharded_path)
+            assert not os.path.exists(lj.file_name)
+
+            with pytest.raises(AssertionError):
+                lj.update({"hi": "globe"})
+            assert not os.path.exists(sharded_path)
+            assert not os.path.exists(lj.file_name)
+
+            p = pickle.dumps(lj)
+            lj2 = pickle.loads(p)
+            assert not getattr(lj2, "_data", None)
+            assert not os.path.exists(sharded_path)
+            assert not os.path.exists(lj.file_name)
+
+            with lj as attrs:
+                attrs["hi"] = "world"
+            assert lj == {}
+            assert not os.path.exists(sharded_path)
+            assert not os.path.exists(lj.file_name)
+
+            with open(sharded_path, "w") as ff:
+                assert ff.write(dumps({"hi": "world"}))
+            lj = LazyJson(f)
+            assert lj == {"hi": "world"}
+
+            with lj as attrs:
+                attrs.update({"hi": "globe"})
+                attrs.setdefault("lst", []).append("universe")
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+
+            with lj as attrs:
+                attrs.setdefault("lst", []).append("universe")
+                with lj as attrs_again:
+                    attrs_again.setdefault("lst", []).append("universe")
+                    attrs.setdefault("lst", []).append("universe")
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+
+            with lj as attrs:
+                with lj as attrs_again:
+                    attrs_again.setdefault("lst2", []).append("universe")
+                    attrs.setdefault("lst2", []).append("universe")
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+
+            with lj as attrs:
+                del attrs["hi"]
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+
+            with lj as attrs:
+                attrs.pop("hi")
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+
+            assert len(lj) == 1
+            assert {k for k in lj} == {"hi"}
+
+            with lj as attrs:
+                attrs.clear()
+            assert lj == {"hi": "world"}
+            with open(sharded_path) as ff:
+                assert ff.read() == dumps({"hi": "world"})
+        finally:
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_BACKENDS = (
+                old_backend
+            )
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_PRIMARY_BACKEND = (
+                old_backend[0]
+            )
+            conda_forge_tick.lazy_json_backends.CF_TICK_GRAPH_DATA_USE_FILE_CACHE = (
+                old_cache
+            )