Truncate generated container names to the Kubernetes 63-character limit

cli/polyaxon/_containers/names.py

@@ -22,6 +22,20 @@
 INIT_PREFIX = "init"
 SIDECAR_PREFIX = "sidecar"
 
+# Container names are Kubernetes DNS labels, capped at 63 characters.
+MAX_CONTAINER_NAME_LENGTH = 63
+
+
+def _trim(value: str, max_length: int) -> str:
+    """Cut a name component down to `max_length` characters.
+
+    A DNS label must start and end with an alphanumeric character, so any
+    dashes exposed by the cut are stripped as well.
+    """
+    if max_length <= 0:
+        return ""
+    return value[:max_length].strip("-")
+
 
 def generate_container_name(
     prefix: str, suffix: Optional[str] = None, unique: bool = True
@@ -33,12 +47,18 @@ def generate_container_name(
     if suffix:
         suffix = suffix.replace("_", "-")
         if unique:
-            suffix = "{}-{}".format(suffix, unique_value)
+            # Reserve room for the prefix, the two joining dashes and the
+            # unique value so that the generated name always stays within the
+            # Kubernetes limit, and trim the caller-supplied part only.
+            budget = MAX_CONTAINER_NAME_LENGTH - len(prefix) - len(unique_value) - 2
+            suffix = "{}-{}".format(_trim(suffix, budget), unique_value)
+        else:
+            suffix = _trim(suffix, MAX_CONTAINER_NAME_LENGTH - len(prefix) - 1)
     else:
         suffix = unique_value
-    return "{}-{}".format(prefix, suffix)
+    return sanitize_container_name("{}-{}".format(prefix, suffix))
 
 
 def sanitize_container_name(name: str) -> str:
-    name = name.replace("_", "-")
-    return name.lower()
+    name = name.replace("_", "-").lower()
+    return _trim(name, MAX_CONTAINER_NAME_LENGTH)

cli/tests/test_containers/test_names.py

@@ -0,0 +1,67 @@
+import pytest
+
+from polyaxon._containers.names import (
+    INIT_ARTIFACTS_CONTAINER_PREFIX,
+    INIT_GIT_CONTAINER_PREFIX,
+    MAX_CONTAINER_NAME_LENGTH,
+    generate_container_name,
+    sanitize_container_name,
+)
+from polyaxon._utils.test_utils import BaseTestCase
+
+LONG_CONNECTION_NAME = "very-long-artifacts-store-connection-name-for-the-team"
+
+
+@pytest.mark.converter_mark
+class TestContainerNames(BaseTestCase):
+    def test_generate_container_name_short_suffix_is_untouched(self):
+        name = generate_container_name(
+            INIT_ARTIFACTS_CONTAINER_PREFIX, "s3-store", False
+        )
+        assert name == "polyaxon-init-artifacts-s3-store"
+
+    def test_generate_container_name_replaces_underscores(self):
+        name = generate_container_name(
+            INIT_ARTIFACTS_CONTAINER_PREFIX, "my_store", False
+        )
+        assert name == "polyaxon-init-artifacts-my-store"
+
+    def test_generate_container_name_respects_k8s_limit(self):
+        for prefix in (
+            INIT_ARTIFACTS_CONTAINER_PREFIX,
+            INIT_GIT_CONTAINER_PREFIX,
+        ):
+            for unique in (True, False):
+                name = generate_container_name(prefix, LONG_CONNECTION_NAME, unique)
+                assert len(name) <= MAX_CONTAINER_NAME_LENGTH
+                assert name.startswith(prefix)
+
+    def test_generate_container_name_keeps_unique_value_when_truncating(self):
+        names = {
+            generate_container_name(
+                INIT_ARTIFACTS_CONTAINER_PREFIX, LONG_CONNECTION_NAME
+            )
+            for _ in range(100)
+        }
+        # Truncation must not collapse distinct runs onto the same name.
+        assert len(names) == 100
+
+    def test_generate_container_name_is_a_valid_dns_label(self):
+        name = generate_container_name(
+            INIT_ARTIFACTS_CONTAINER_PREFIX, LONG_CONNECTION_NAME
+        )
+        assert not name.startswith("-")
+        assert not name.endswith("-")
+        assert name == name.lower()
+
+    def test_sanitize_container_name_truncates(self):
+        name = sanitize_container_name(
+            "polyaxon-init-artifacts-" + LONG_CONNECTION_NAME
+        )
+        assert len(name) <= MAX_CONTAINER_NAME_LENGTH
+        assert not name.endswith("-")
+
+    def test_sanitize_container_name_leaves_valid_names_alone(self):
+        assert sanitize_container_name("polyaxon_init_Artifacts") == (
+            "polyaxon-init-artifacts"
+        )