diff --git a/metropolis/proto/api/BUILD.bazel b/metropolis/proto/api/BUILD.bazel
new file mode 100644
index 0000000..ec40562
--- /dev/null
+++ b/metropolis/proto/api/BUILD.bazel
@@ -0,0 +1,27 @@
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+
+proto_library(
+    name = "api_proto",
+    srcs = [
+        "debug.proto",
+        "enrolment.proto",
+    ],
+    visibility = ["//visibility:public"],
+)
+
+go_proto_library(
+    name = "api_go_proto",
+    compilers = ["@io_bazel_rules_go//proto:go_grpc"],
+    importpath = "git.monogon.dev/source/nexantic.git/metropolis/proto/api",
+    proto = ":api_proto",
+    visibility = ["//visibility:public"],
+)
+
+go_library(
+    name = "go_default_library",
+    embed = [":api_go_proto"],
+    importpath = "git.monogon.dev/source/nexantic.git/metropolis/proto/api",
+    visibility = ["//visibility:public"],
+)
diff --git a/metropolis/proto/api/debug.proto b/metropolis/proto/api/debug.proto
new file mode 100644
index 0000000..2483360
--- /dev/null
+++ b/metropolis/proto/api/debug.proto
@@ -0,0 +1,164 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+package smalltown.core.proto.api;
+option go_package = "git.monogon.dev/source/nexantic.git/metropolis/proto/api";
+
+import "metropolis/proto/api/enrolment.proto";
+
+// NodeDebugService exposes debug and testing endpoints that allow introspection into a running Smalltown instance.
+// It is not authenticated and will be disabled in production. It is currently consumed by metropolis/cli/dbg and
+// by tests.
+service NodeDebugService {
+    // GetDebugKubeconfig issues kubeconfigs with arbitrary identities and groups for debugging
+    rpc GetDebugKubeconfig(GetDebugKubeconfigRequest) returns (GetDebugKubeconfigResponse);
+
+    // GetLogs Returns historical and/or streaming logs for a given DN with given filters from the system global
+    // LogTree.
+    //
+    // For more information about this API, see //metropolis/node/core/logtree. But, in summary:
+    //   - All logging is performed to a DN (distinguished name), which is a dot-delimited string like foo.bar.baz.
+    //   - Log entries can be either raw (coming from unstructured logging from an external service, like a running
+    //     process) or leveled (emitted by Smalltown code with a source line, timestamp, and severity).
+    //   - The DNs form a tree of logging nodes - and when requesting logs, a given subtree of DNs can be requested,
+    //     instead of just a given DN.
+    //   - All supervised processes live at `root.<supervisor DN>`. For more example paths, see the console logs of
+    //     a running Smalltown instance, or request all logs (at DN "").
+    //
+    // TODO(q3k): move method and its related messages to the non-debug node endpoint once we have one.
+    rpc GetLogs(GetLogsRequest) returns (stream GetLogsResponse);
+
+    // GetGoldenTicket requests a 'golden ticket' which can be used to enroll any node into the cluster.
+    // This bypasses integrity checks.
+    rpc GetGoldenTicket(GetGoldenTicketRequest) returns (GetGoldenTicketResponse);
+}
+
+
+message GetDebugKubeconfigRequest {
+    string id = 1; // Kubernetes identity (user)
+    repeated string groups = 2; // Kubernetes groups
+}
+
+message GetDebugKubeconfigResponse {
+    string debug_kubeconfig = 1;
+}
+
+// Severity level corresponding to //metropolis/node/core/logtree.Severity.
+enum LeveledLogSeverity {
+    INVALID = 0;
+    INFO = 1;
+    WARNING = 2;
+    ERROR = 3;
+    FATAL = 4;
+}
+
+// Filter set when requesting logs for a given DN. This message is equivalent to the following GADT enum:
+// data LogFilter = WithChildren
+//                | OnlyRaw
+//                | OnlyLeveled
+//                | LeveledWithMinimumSeverity(Severity)
+//
+// Multiple LogFilters can be chained/combined when requesting logs, as long as they do not conflict.
+message LogFilter {
+    // Entries will be returned not only for the given DN, but all child DNs as well. For instance, if the
+    // requested DN is foo, entries logged to foo, foo.bar and foo.bar.baz will all be returned.
+    message WithChildren {
+    }
+    // Only raw logging entries will be returned. Conflicts with OnlyLeveled filters.
+    message OnlyRaw {
+    }
+    // Only leveled logging entries will be returned. Conflicts with OnlyRaw filters.
+    message OnlyLeveled {
+    }
+    // If leveled logs are returned, all entries at severity lower than `minimum` will be discarded.
+    message LeveledWithMinimumSeverity {
+        LeveledLogSeverity minimum = 1;
+    }
+    oneof filter {
+        WithChildren with_children = 1;
+        OnlyRaw only_raw = 3;
+        OnlyLeveled only_leveled = 4;
+        LeveledWithMinimumSeverity leveled_with_minimum_severity = 5;
+    }
+}
+
+message GetLogsRequest {
+    // DN from which to request logs. All supervised runnables live at `root.`, the init code lives at `init.`.
+    string dn = 1;
+    // Filters to apply to returned data.
+    repeated LogFilter filters = 2;
+
+    enum BacklogMode {
+        BACKLOG_INVALID = 0;
+        // No historic data will be returned.
+        BACKLOG_DISABLE = 1;
+        // All available historic data will be returned.
+        BACKLOG_ALL = 2;
+        // At most backlog_count entries will be returned, if available.
+        BACKLOG_COUNT = 3;
+    }
+    BacklogMode backlog_mode = 3;
+    int64 backlog_count = 4;
+
+    enum StreamMode {
+        STREAM_INVALID = 0;
+        // No streaming entries, gRPC stream will be closed as soon as all backlog data is served.
+        STREAM_DISABLE = 1;
+        // Entries will be streamed as early as available right after all backlog data is served.
+        STREAM_UNBUFFERED = 2;
+    }
+    StreamMode stream_mode = 5;
+}
+
+message GetLogsResponse {
+    // Entries from the requested historical entries (via WithBackLog). They will all be served before the first
+    // stream_entries are served (if any).
+    repeated LogEntry backlog_entries = 1;
+    // Entries streamed as they arrive. Currently no server-side buffering is enabled, instead every line is served
+    // as early as it arrives. However, this might change in the future, so this behaviour cannot be depended
+    // upon.
+    repeated LogEntry stream_entries = 2;
+}
+
+message LogEntry {
+    message Leveled {
+        repeated string lines = 1;
+        int64 timestamp = 2;
+        LeveledLogSeverity severity = 3;
+        string location = 4;
+    }
+    message Raw {
+        string data = 1;
+        int64 original_length = 2;
+    }
+
+    string dn = 1;
+    oneof kind {
+        Leveled leveled = 2;
+        Raw raw = 3;
+    }
+}
+
+message GetGoldenTicketRequest {
+    // IP address at which the new node will run.
+    string external_ip = 1;
+}
+
+message GetGoldenTicketResponse {
+    // Ticket to use in the new node's EnrolmentConfig.
+    GoldenTicket ticket = 1;
+}
diff --git a/metropolis/proto/api/enrolment.proto b/metropolis/proto/api/enrolment.proto
new file mode 100644
index 0000000..c07e4ea
--- /dev/null
+++ b/metropolis/proto/api/enrolment.proto
@@ -0,0 +1,63 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+package smalltown.core.proto.api;
+option go_package = "git.monogon.dev/source/nexantic.git/metropolis/proto/api";
+
+// EnrolmentConfig is the single boot configuration file contained in the Smalltown ESP. It configures
+// the way the node will start up (what cluster it will join/enroll into/create).
+message EnrolmentConfig {
+    // Debug/temporary cluster enrolment method. If set, the node will attempt to enroll into the
+    // cluster that this ticket was generated for. Otherwise, a new cluster will be created.
+    GoldenTicket golden_ticket = 1;
+
+    // Filled in by node after it is enrolled
+    string node_id = 2;
+}
+
+// GoldenTicket is a ticket that allows any node to enroll into a cluster, bypassing any integrity
+// checks.
+//
+// Currently, enrolling into a cluster does not use a TPM-based workflow, and instead
+// bases on a simplified workflow of joining consensus by being started with a
+// TLS client certificate. This is a short-circuit fix to allow multi-node
+// clusters for testing before we design the final cluster node lifecycle system.
+message GoldenTicket {
+    // Etcd peer CA certificate.
+    bytes etcd_ca_cert = 1;
+    // Etcd peer client certificate.
+    bytes etcd_client_cert = 2;
+    // Etcd peer client key.
+    bytes etcd_client_key = 3;
+    // Initial etcd peer CRL.
+    bytes etcd_crl = 4;
+
+    message EtcdPeer {
+        string name = 1;
+        string address = 2;
+    }
+    // All other current etcd peers in the cluster.
+    repeated EtcdPeer peers = 5;
+    // The peer that this node should start running.
+    EtcdPeer this = 6;
+
+    // Node configuration. Currently unused (in the future, this will be used to run a node
+    // management service separate from etcd clustering).
+    string node_id = 7;
+    bytes node_cert = 8;
+    bytes node_key = 9;
+}