attach-time tenant config (#4255)

This PR adds support for supplying the tenant config upon /attach.

Before this change, when relocating a tenant using `/detach` and
`/attach`, the tenant config after `/attach` would be the default config
from `pageserver.toml`.
That is undesirable for settings such as the PITR-interval: if the
tenant's config on the source was `30 days` and the default config on
the attach-side is `7 days`, then the first GC run would eradicate 23
days worth of PITR capability.

The API change is backwards-compatible: if the body is empty, we
continue to use the default config.
We'll remove that capability as soon as the cloud.git code is updated to
use attach-time tenant config
(https://github.com/neondatabase/neon/issues/4282 keeps track of this).

unblocks https://github.com/neondatabase/cloud/issues/5092 
fixes https://github.com/neondatabase/neon/issues/1555
part of https://github.com/neondatabase/neon/issues/886 (Tenant
Relocation)

Implementation
==============

The preliminary PRs for this work were (most-recent to least-recent)

* https://github.com/neondatabase/neon/pull/4279
* https://github.com/neondatabase/neon/pull/4267
* https://github.com/neondatabase/neon/pull/4252
* https://github.com/neondatabase/neon/pull/4235

test_runner/fixtures/pageserver/http.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import json
 import time
 from collections import defaultdict
 from dataclasses import dataclass
@@ -109,6 +110,10 @@ class PageserverHttpClient(requests.Session):
         if auth_token is not None:
             self.headers["Authorization"] = f"Bearer {auth_token}"
 
+    @property
+    def base_url(self) -> str:
+        return f"http://localhost:{self.port}"
+
     def verbose_error(self, res: requests.Response):
         try:
             res.raise_for_status()
@@ -168,8 +173,22 @@ class PageserverHttpClient(requests.Session):
         assert isinstance(new_tenant_id, str)
         return TenantId(new_tenant_id)
 
-    def tenant_attach(self, tenant_id: TenantId):
-        res = self.post(f"http://localhost:{self.port}/v1/tenant/{tenant_id}/attach")
+    def tenant_attach(
+        self, tenant_id: TenantId, config: None | Dict[str, Any] = None, config_null: bool = False
+    ):
+        if config_null:
+            assert config is None
+            body = "null"
+        else:
+            # null-config is prohibited by the API
+            if config is None:
+                config = {}
+            body = json.dumps({"config": config})
+        res = self.post(
+            f"http://localhost:{self.port}/v1/tenant/{tenant_id}/attach",
+            data=body,
+            headers={"Content-Type": "application/json"},
+        )
         self.verbose_error(res)
 
     def tenant_detach(self, tenant_id: TenantId, detach_ignored=False):

test_runner/regress/test_attach_tenant_config.py

@@ -0,0 +1,200 @@
+from dataclasses import dataclass
+from typing import Generator, Optional
+
+import pytest
+from fixtures.neon_fixtures import (
+    LocalFsStorage,
+    NeonEnv,
+    NeonEnvBuilder,
+    RemoteStorageKind,
+)
+from fixtures.pageserver.http import PageserverApiException, TenantConfig
+from fixtures.types import TenantId
+from fixtures.utils import wait_until
+
+
+@pytest.fixture
+def positive_env(neon_env_builder: NeonEnvBuilder) -> NeonEnv:
+    neon_env_builder.enable_remote_storage(
+        remote_storage_kind=RemoteStorageKind.LOCAL_FS,
+        test_name="test_attach_tenant_config",
+    )
+    env = neon_env_builder.init_start()
+    assert isinstance(env.remote_storage, LocalFsStorage)
+    return env
+
+
+@dataclass
+class NegativeTests:
+    neon_env: NeonEnv
+    tenant_id: TenantId
+    config_pre_detach: TenantConfig
+
+
+@pytest.fixture
+def negative_env(neon_env_builder: NeonEnvBuilder) -> Generator[NegativeTests, None, None]:
+    neon_env_builder.enable_remote_storage(
+        remote_storage_kind=RemoteStorageKind.LOCAL_FS,
+        test_name="test_attach_tenant_config",
+    )
+    env = neon_env_builder.init_start()
+    assert isinstance(env.remote_storage, LocalFsStorage)
+
+    ps_http = env.pageserver.http_client()
+    (tenant_id, _) = env.neon_cli.create_tenant()
+    assert ps_http.tenant_config(tenant_id).tenant_specific_overrides == {}
+    config_pre_detach = ps_http.tenant_config(tenant_id)
+    assert tenant_id in [TenantId(t["id"]) for t in ps_http.tenant_list()]
+    ps_http.tenant_detach(tenant_id)
+    assert tenant_id not in [TenantId(t["id"]) for t in ps_http.tenant_list()]
+
+    yield NegativeTests(env, tenant_id, config_pre_detach)
+
+    assert tenant_id not in [
+        TenantId(t["id"]) for t in ps_http.tenant_list()
+    ], "tenant should not be attached after negative test"
+
+    env.pageserver.allowed_errors.append(".*Error processing HTTP request: Bad request")
+
+    def log_contains_bad_request():
+        env.pageserver.log_contains(".*Error processing HTTP request: Bad request")
+
+    wait_until(50, 0.1, log_contains_bad_request)
+
+
+def test_null_body(negative_env: NegativeTests):
+    """
+    If we send `null` in the body, the request should be rejected with status 400.
+    """
+    env = negative_env.neon_env
+    tenant_id = negative_env.tenant_id
+    ps_http = env.pageserver.http_client()
+
+    res = ps_http.post(
+        f"{ps_http.base_url}/v1/tenant/{tenant_id}/attach",
+        data=b"null",
+        headers={"Content-Type": "application/json"},
+    )
+    assert res.status_code == 400
+
+
+def test_null_config(negative_env: NegativeTests):
+    """
+    If the `config` field is `null`, the request should be rejected with status 400.
+    """
+
+    env = negative_env.neon_env
+    tenant_id = negative_env.tenant_id
+    ps_http = env.pageserver.http_client()
+
+    res = ps_http.post(
+        f"{ps_http.base_url}/v1/tenant/{tenant_id}/attach",
+        data=b'{"config": null}',
+        headers={"Content-Type": "application/json"},
+    )
+    assert res.status_code == 400
+
+
+def test_config_with_unknown_keys_is_bad_request(negative_env: NegativeTests):
+    """
+    If we send a config with unknown keys, the request should be rejected with status 400.
+    """
+
+    env = negative_env.neon_env
+    tenant_id = negative_env.tenant_id
+    ps_http = env.pageserver.http_client()
+
+    config_with_unknown_keys = {
+        "compaction_period": "1h",
+        "this_key_does_not_exist": "some value",
+    }
+
+    with pytest.raises(PageserverApiException) as e:
+        ps_http.tenant_attach(tenant_id, config=config_with_unknown_keys)
+    assert e.type == PageserverApiException
+    assert e.value.status_code == 400
+
+
+@pytest.mark.parametrize("content_type", [None, "application/json"])
+def test_empty_body(positive_env: NeonEnv, content_type: Optional[str]):
+    """
+    For backwards-compatiblity: if we send an empty body,
+    the request should be accepted and the config should be the default config.
+    """
+    env = positive_env
+    ps_http = env.pageserver.http_client()
+    (tenant_id, _) = env.neon_cli.create_tenant()
+    assert ps_http.tenant_config(tenant_id).tenant_specific_overrides == {}
+    config_pre_detach = ps_http.tenant_config(tenant_id)
+    assert tenant_id in [TenantId(t["id"]) for t in ps_http.tenant_list()]
+    ps_http.tenant_detach(tenant_id)
+    assert tenant_id not in [TenantId(t["id"]) for t in ps_http.tenant_list()]
+
+    ps_http.post(
+        f"{ps_http.base_url}/v1/tenant/{tenant_id}/attach",
+        data=b"",
+        headers=None if content_type else {"Content-Type": "application/json"},
+    ).raise_for_status()
+
+    assert ps_http.tenant_config(tenant_id).tenant_specific_overrides == {}
+    assert ps_http.tenant_config(tenant_id).effective_config == config_pre_detach.effective_config
+
+
+def test_fully_custom_config(positive_env: NeonEnv):
+    """
+    If we send a valid config in the body, the request should be accepted and the config should be applied.
+    """
+    env = positive_env
+
+    fully_custom_config = {
+        "compaction_period": "1h",
+        "compaction_threshold": 13,
+        "compaction_target_size": 1048576,
+        "checkpoint_distance": 10000,
+        "checkpoint_timeout": "13m",
+        "eviction_policy": {
+            "kind": "LayerAccessThreshold",
+            "period": "20s",
+            "threshold": "23h",
+        },
+        "evictions_low_residence_duration_metric_threshold": "2days",
+        "gc_horizon": 23 * (1024 * 1024),
+        "gc_period": "2h 13m",
+        "image_creation_threshold": 7,
+        "pitr_interval": "1m",
+        "lagging_wal_timeout": "23m",
+        "max_lsn_wal_lag": 230000,
+        "min_resident_size_override": 23,
+        "trace_read_requests": True,
+        "walreceiver_connect_timeout": "13m",
+    }
+
+    ps_http = env.pageserver.http_client()
+
+    initial_tenant_config = ps_http.tenant_config(env.initial_tenant)
+    assert initial_tenant_config.tenant_specific_overrides == {}
+    assert set(initial_tenant_config.effective_config.keys()) == set(
+        fully_custom_config.keys()
+    ), "ensure we cover all config options"
+
+    (tenant_id, _) = env.neon_cli.create_tenant()
+    ps_http.set_tenant_config(tenant_id, fully_custom_config)
+    our_tenant_config = ps_http.tenant_config(tenant_id)
+    assert our_tenant_config.tenant_specific_overrides == fully_custom_config
+    assert set(our_tenant_config.effective_config.keys()) == set(
+        fully_custom_config.keys()
+    ), "ensure we cover all config options"
+    assert {
+        k: initial_tenant_config.effective_config[k] != our_tenant_config.effective_config[k]
+        for k in fully_custom_config.keys()
+    } == {
+        k: True for k in fully_custom_config.keys()
+    }, "ensure our custom config has different values than the default config for all config options, so we know we overrode everything"
+
+    ps_http.tenant_detach(tenant_id)
+    ps_http.tenant_attach(tenant_id, config=fully_custom_config)
+
+    assert ps_http.tenant_config(tenant_id).tenant_specific_overrides == fully_custom_config
+    assert set(ps_http.tenant_config(tenant_id).effective_config.keys()) == set(
+        fully_custom_config.keys()
+    ), "ensure we cover all config options"