Add readme for AntiEtcd

- Add support for HTTPS client certificates
- Make requests wait for quorum by default
- Extract vitastor_persist_filter from main code
- Do not use Promise.allSettled
- Throw 501 in etctree on unsupported features

ANTIETCD.md

@@ -0,0 +1,439 @@
+# AntiEtcd
+
+Simplistic miniature etcd replacement based on [TinyRaft](https://git.yourcmc.ru/vitalif/tinyraft/)
+
+- Embeddable
+- REST API only, gRPC is shit and will never be supported
+- [TinyRaft](https://git.yourcmc.ru/vitalif/tinyraft/)-based leader election
+- Websocket-based cluster communication
+- Supports a limited subset of etcd REST APIs
+- Optional persistence
+
+(c) Vitaliy Filippov, 2024
+
+License: Mozilla Public License 2.0 or [VNPL-1.1](https://git.yourcmc.ru/vitalif/vitastor/src/branch/master/VNPL-1.1.txt)
+
+## CLI Usage
+
+```
+npm install antietcd
+
+node_modules/.bin/antietcd \
+    [--cert ssl.crt] [--key ssl.key] [--port 12379] \
+    [--data data.gz] [--persist_interval 500] \
+    [--node_id node1 --cluster_key abcdef --cluster node1=http://localhost:12379,node2=http://localhost:12380,node3=http://localhost:12381]
+    [other options]
+```
+
+Antietcd doesn't background itself, so use systemd or start-stop-daemon to run it as a background service.
+
+## Options
+
+### HTTP
+
+<dl>
+
+<dt>--port 2379</dt>
+<dd>Listen port</dd>
+
+<dt>--cert \<cert\></dt>
+<dd>Use TLS with this certificate file (PEM format)</dd>
+
+<dt>--key \<key\></dt>
+<dd>Use TLS with this key file (PEM format)</dd>
+
+<dt>--ca \<ca\></dt>
+<dd>Use trusted root certificates from this file.
+Specify \<ca\> = \<cert\> if your certificate is self-signed.</dd>
+
+<dt>--client_cert_auth 1</dt>
+<dd>Require TLS client certificates signed by <ca> or by default CA to connect.</dd>
+
+<dt>--ws_keepalive_interval 30000</dt>
+<dd>Client websocket ping (keepalive) interval in milliseconds</dd>
+
+</dl>
+
+### Persistence
+
+<dl>
+
+<dt>--data \<filename\></dt>
+<dd>Store persistent data in \<filename\></dd>
+
+<dt>--persist_interval \<milliseconds\></dt>
+<dd>Persist data on disk after this interval, not immediately after change</dd>
+
+<dt>--persist_filter ./filter.js</dt>
+<dd>Use persistence filter from ./filter.js (or a module). <br />
+Persistence filter is a function(cfg) returning function(key, value) ran
+for every change and returning a new value or undefined to skip persistence.</dd>
+
+</dl>
+
+### Clustering
+
+<dl>
+
+<dt>--node_id \<id></dt>
+<dd>ID of this cluster node</dd>
+
+<dt>--cluster \<id1\>=\<url1\>,\<id2\>=\<url2\>,...</dt>
+<dd>All other cluster nodes</dd>
+
+<dt>--cluster_key \<key\></dt>
+<dd>Shared cluster key for identification</dd>
+
+<dt>--election_timeout 5000</dt>
+<dd>Raft election timeout</dd>
+
+<dt>--heartbeat_timeout 1000</dt>
+<dd>Raft leader heartbeat timeout</dd>
+
+<dt>--wait_quorum_timeout 30000</dt>
+<dd>Timeout for requests to wait for quorum to come up</dd>
+
+<dt>--leader_priority \<number\></dt>
+<dd>Raft leader priority for this node (optional)</dd>
+
+<dt>--stale_read 1</dt>
+<dd>Allow to serve reads from followers. Specify 0 to disallow</dd>
+
+<dt>--reconnect_interval 1000</dt>
+<dd>Unavailable peer connection retry interval</dd>
+
+<dt>--dump_timeout 5000</dt>
+<dd>Timeout for dump command in milliseconds</dd>
+
+<dt>--load_timeout 5000</dt>
+<dd>Timeout for load command in milliseconds</dd>
+
+<dt>--forward_timeout 1000</dt>
+<dd>Timeout for forwarding requests from follower to leader in milliseconds</dd>
+
+<dt>--replication_timeout 1000</dt>
+<dd>Timeout for replicating requests from leader to follower in milliseconds</dd>
+
+<dt>--compact_revisions 1000</dt>
+<dd>Number of previous revisions to keep deletion information in memory</dd>
+
+<dt>--compact_timeout 1000</dt>
+<dd>Timeout for compaction requests from leader to follower in milliseconds</dd>
+
+</dl>
+
+## Embedded Usage
+
+```js
+const AntiEtcd = require('antietcd');
+
+const srv = new AntiEtcd({ ...configuration });
+
+// Start server
+srv.start();
+
+// Make a local API call in generic style:
+let res = await srv.api('kv_txn'|'kv_range'|'kv_put'|'kv_deleterange'|'lease_grant'|'lease_revoke'|'lease_keepalive', { ...params });
+
+// Or function-style:
+res = await srv.txn(params);
+res = await srv.range(params);
+res = await srv.put(params);
+res = await srv.deleterange(params);
+res = await srv.lease_grant(params);
+res = await srv.lease_revoke(params);
+res = await srv.lease_keepalive(params);
+
+// Error handling:
+try
+{
+    res = await srv.txn(params);
+}
+catch (e)
+{
+    if (e instanceof AntiEtcd.RequestError)
+    {
+        // e.code is HTTP code
+        // e.message is error message
+    }
+}
+
+// Stop server
+srv.stop();
+```
+
+## Persistence
+
+Persistence is very simple: full database is dumped into JSON, gzipped and saved as file.
+
+By default, it is written and fsynced on disk on every change, but it can be configured
+to dump DB on disk at fixed intervals, for example, at most every 500 ms - of course,
+at expense of slightly reduced crash resiliency (example: `--persist_interval 500`).
+
+You can also specify a filter to exclude some data from persistence by using the option
+`--persist_filter ./filter.js`. Persistence filter code example:
+
+```js
+function example_filter(cfg)
+{
+    // <cfg> contains all command-line options
+    const prefix = cfg.exclude_keys;
+    if (!prefix)
+    {
+        return null;
+    }
+    return (key, value) =>
+    {
+        if (key.substr(0, prefix.length) == prefix)
+        {
+            // Skip all keys with prefix from persistence
+            return undefined;
+        }
+        if (key === '/statistics')
+        {
+            // Return <unneeded_key> from inside value
+            const decoded = JSON.parse(value);
+            return JSON.stringify({ ...decoded, unneeded_key: undefined });
+        }
+        return value;
+    };
+}
+
+module.exports = example_filter;
+```
+
+## Supported etcd APIs
+
+NOTE: `key`, `value` and `range_end` are always encoded in base64, like in original etcd.
+
+Range requests are only supported across "directories" separated by `/`.
+
+It means that in range requests `key` must always end with `/` and `range_end` must always
+end with `0`, and that such request will return a whole subtree of keys.
+
+### /v3/kv/txn
+
+Request:
+
+```
+interface TxnRequest {
+  compare?: (
+    { key: string, target: "MOD", mod_revision: number, result?: "LESS" }
+    | { key: string, target: "CREATE", create_revision: number, result?: "LESS" }
+    | { key: string, target: "VERSION", version: number, result?: "LESS" }
+    | { key: string, target: "LEASE", lease: string, result?: "LESS" }
+    | { key: string, target: "VALUE", value: string }
+  )[],
+  success?: (
+    { request_put: PutRequest }
+    | { request_range: RangeRequest }
+    | { request_delete_range: DeleteRangeRequest }
+  )[],
+  failure?: (
+    { request_put: PutRequest }
+    | { request_range: RangeRequest }
+    | { request_delete_range: DeleteRangeRequest }
+  )[],
+  serializable?: boolean,
+}
+```
+
+`serializable` allows to serve read-only requests from follower even if `stale_read` is not enabled.
+
+Response:
+
+```
+interface TxnResponse {
+  header: { revision: number },
+  succeeded: boolean,
+  responses: (
+    { response_put: PutResponse }
+    | { response_range: RangeResponse }
+    | { response_delete_range: DeleteRangeResponse }
+  )[],
+}
+```
+
+### /v3/kv/put
+
+Request:
+
+```
+interface PutRequest {
+  key: string,
+  value: string,
+  lease?: string,
+}
+```
+
+Other parameters are not supported: prev_kv, ignore_value, ignore_lease.
+
+Response:
+
+```
+interface PutResponse {
+  header: { revision: number },
+}
+```
+
+### /v3/kv/range
+
+Request:
+
+```
+interface RangeRequest {
+  key: string,
+  range_end?: string,
+  keys_only?: boolean,
+  serializable?: boolean,
+}
+```
+
+`serializable` allows to serve read-only requests from follower even if `stale_read` is not enabled.
+
+Other parameters are not supported: revision, limit, sort_order, sort_target,
+count_only, min_mod_revision, max_mod_revision, min_create_revision, max_create_revision.
+
+Response:
+
+```
+interface RangeResponse {
+  header: { revision: number },
+  kvs: { key: string }[] | {
+    key: string,
+    value: string,
+    lease?: string,
+    mod_revision: number,
+  }[],
+}
+```
+
+### /v3/kv/deleterange
+
+Request:
+
+```
+interface DeleteRangeRequest {
+  key: string,
+  range_end?: string,
+}
+```
+
+Other parameters are not supported: prev_kv.
+
+Response:
+
+```
+interface DeleteRangeResponse {
+  header: { revision: number },
+  // number of deleted keys
+  deleted: number,
+}
+```
+
+### /v3/lease/grant
+
+Request:
+
+```
+interface LeaseGrantRequest {
+  ID?: string,
+  TTL: number,
+}
+```
+
+Response:
+
+```
+interface LeaseGrantResponse {
+  header: { revision: number },
+  ID: string,
+  TTL: number,
+}
+```
+
+### /v3/lease/keepalive
+
+Request:
+
+```
+interface LeaseKeepaliveRequest {
+  ID: string,
+}
+```
+
+Response:
+
+```
+interface LeaseKeepaliveResponse {
+  header: { revision: number },
+  ID: string,
+  TTL: number,
+}
+```
+
+### /v3/lease/revoke or /v3/kv/lease/revoke
+
+Request:
+
+```
+interface LeaseRevokeRequest {
+  ID: string,
+}
+```
+
+Response:
+
+```
+interface LeaseRevokeResponse {
+  header: { revision: number },
+}
+```
+
+### Websocket-based watch APIs
+
+Client-to-server message format:
+
+```
+type ClientMessage =
+  { create_request: {
+    key: string,
+    range_end?: string,
+    start_revision?: number,
+    watch_id?: string,
+  } }
+  | { cancel_request: {
+    watch_id: string,
+  } }
+  | { progress_request: {} }
+```
+
+Server-to-client message format:
+
+```
+type ServerMessage = {
+  header: { revision: number },
+  watch_id: string,
+  created?: boolean,
+  canceled?: boolean,
+  compact_revision?: number,
+  events?: {
+    type: 'PUT'|'DELETE',
+    kv: {
+      key: string,
+      value: string,
+      lease?: string,
+      mod_revision: number,
+    },
+  }[],
+} | { error: 'bad-json' } | { error: 'empty-message' }
+```
+
+### HTTP Error Codes
+
+- 400 for invalid requests
+- 404 for unsupported API / URL not found
+- 405 for non-POST request method
+- 501 for unsupported API feature - non-directory range queries and so on
+- 502 for server is stopping
+- 503 for quorum-related errors - quorum not available and so on

anticluster.js

@@ -5,6 +5,10 @@ const { runCallbacks, RequestError } = require('./common.js');
 
 const LEADER_MISMATCH = 'raft leader/term mismatch';
 
+const LEADER_ONLY = 1;
+const NO_WAIT_QUORUM = 2;
+const READ_FROM_FOLLOWER = 4;
+
 class AntiCluster
 {
     constructor(antietcd)
@@ -48,7 +52,7 @@ class AntiCluster
         if (node_id != this.cfg.node_id && this.cfg.cluster[node_id] &&
             (!this.cluster_connections[node_id] || !this.antietcd.clients[this.cluster_connections[node_id]]))
         {
-            const socket = new ws.WebSocket(this.cfg.cluster[node_id].replace(/^http/, 'ws'));
+            const socket = new ws.WebSocket(this.cfg.cluster[node_id].replace(/^http/, 'ws'), this.antietcd.tls);
             const client_id = this.antietcd._startWebsocket(socket, () => setTimeout(() => this.connectToNode(node_id), this.cfg.reconnect_interval||1000));
             this.cluster_connections[node_id] = client_id;
             socket.on('open', () =>
@@ -337,25 +341,33 @@ class AntiCluster
         {
             return null;
         }
-        if (leaderonly && this.raft.state != TinyRaft.LEADER)
+        if (leaderonly == LEADER_ONLY && this.raft.state != TinyRaft.LEADER)
         {
             throw new RequestError(503, 'Not leader');
         }
-        if (this.raft.state == TinyRaft.CANDIDATE)
+        if (leaderonly == NO_WAIT_QUORUM && this.raft.state == TinyRaft.CANDIDATE)
         {
             throw new RequestError(503, 'Quorum not available');
         }
-        else if (this.raft.state == TinyRaft.FOLLOWER &&
+        if (!this.synced)
-            (!this.cfg.stale_read || this._isWrite(path, data)))
+        {
+            // Wait for quorum / initial sync with timeout
+            await new Promise((ok, no) =>
+            {
+                this.wait_sync.push(ok);
+                setTimeout(() =>
+                {
+                    this.wait_sync = this.wait_sync.filter(cb => cb != ok);
+                    no(new RequestError(503, 'Quorum not available'));
+                }, this.cfg.wait_quorum_timeout||30000);
+            });
+        }
+        if (this.raft.state == TinyRaft.FOLLOWER &&
+            (this._isWrite(path, data) || !this.cfg.stale_read && !(leaderonly & READ_FROM_FOLLOWER)))
         {
             // Forward to leader
             return await this._forwardToLeader(path, data);
         }
-        else if (!this.synced)
-        {
-            // Wait for initial sync for read-only requests
-            await new Promise(ok => this.wait_sync.push(ok));
-        }
         return null;
     }
 
@@ -503,4 +515,8 @@ class AntiCluster
     }
 }
 
+AntiCluster.LEADER_ONLY = LEADER_ONLY;
+AntiCluster.NO_WAIT_QUORUM = NO_WAIT_QUORUM;
+AntiCluster.READ_FROM_FOLLOWER = READ_FROM_FOLLOWER;
+
 module.exports = AntiCluster;

antietcd-app.js

@@ -1,17 +1,16 @@
 #!/usr/bin/env node
 
 const AntiEtcd = require('./antietcd.js');
-const vitastor_persist_filter = require('./vitastor_persist_filter.js');
 
 const help_text = `Miniature etcd replacement based on TinyRaft
 (c) Vitaliy Filippov, 2024
-License: Mozilla Public License 2.0
+License: Mozilla Public License 2.0 or Vitastor Network Public License 1.1
 
 Usage:
 
 ${process.argv[0]} ${process.argv[1]}
     [--cert ssl.crt] [--key ssl.key] [--port 12379]
-    [--data data.gz] [--vitastor-persist-filter /vitastor] [--no-persist-filter] [--persist_interval 500]
+    [--data data.gz] [--persist-filter ./filter.js] [--persist_interval 500]
     [--node_id node1 --cluster_key abcdef --cluster node1=http://localhost:12379,node2=http://localhost:12380,node3=http://localhost:12381]
     [other options]
 
@@ -27,23 +26,28 @@ HTTP:
 
 --port 2379
     Listen port
---cert <filename>
+--cert <cert>
     Use TLS with this certificate file (PEM format)
---key <filename>
+--key <key>
     Use TLS with this key file (PEM format)
+--ca <ca>
+    Use trusted root certificates from this file.
+    Specify <ca> = <cert> if your certificate is self-signed.
+--client_cert_auth 1
+    Require TLS client certificates signed by <ca> or by default CA to connect.
 --ws_keepalive_interval 30000
     Client websocket ping (keepalive) interval in milliseconds
 
 Persistence:
 
 --data <filename>
-    Use <filename> to store persistent data
+    Store persistent data in <filename>
 --persist_interval <milliseconds>
-    Persist data on disk after this interval, not immediately
+    Persist data on disk after this interval, not immediately after change
---no_persist_filter
+--persist_filter ./filter.js
-    Store all data
+    Use persistence filter from ./filter.js (or a module).
---vitastor_persist_filter <prefix>
+    Persistence filter is a function(cfg) returning function(key, value) ran
-    Store only data required for Vitastor with prefix <prefix> on disk
+    for every change and returning a new value or undefined to skip persistence.
 
 Clustering:
 
@@ -57,10 +61,12 @@ Clustering:
     Raft election timeout
 --heartbeat_timeout 1000
     Raft leader heartbeat timeout
+--wait_quorum_timeout 30000
+    Timeout for requests to wait for quorum to come up
 --leader_priority <number>
     Raft leader priority for this node (optional)
---stale_read 0|1
+--stale_read 1
-    Allow to serve reads from followers
+    Allow to serve reads from followers. Specify 0 to disallow
 --reconnect_interval 1000
     Unavailable peer connection retry interval
 --dump_timeout 5000
@@ -79,9 +85,7 @@ Clustering:
 
 function parse()
 {
-    const options = {
+    const options = { stale_read: 1 };
-        persist_filter: vitastor_persist_filter('/vitastor'),
-    };
     for (let i = 2; i < process.argv.length; i++)
     {
         const arg = process.argv[i].toLowerCase().replace(/^--(.+)$/, (m, m1) => '--'+m1.replace(/-/g, '_'));
@@ -90,19 +94,16 @@ function parse()
             console.error(help_text.trim());
             process.exit();
         }
-        else if (arg == '--no_persist_filter')
+        else if (arg.substr(0, 2) == '--')
-        {
-            options['persist_filter'] = null;
-        }
-        else if (arg == '--vitastor_persist_filter')
-        {
-            options['persist_filter'] = vitastor_persist_filter(process.argv[++i]||'');
-        }
-        else if (arg.substr(0, 2) == '--' && arg != '--persist_filter')
         {
             options[arg.substr(2)] = process.argv[++i];
         }
     }
+    options['stale_read'] = options['stale_read'] === '1' || options['stale_read'] === 'yes' || options['stale_read'] === 'true';
+    if (options['persist_filter'])
+    {
+        options['persist_filter'] = require(options['persist_filter'])(options);
+    }
     return options;
 }
 

antietcd.js

@@ -49,7 +49,18 @@ class AntiEtcd extends EventEmitter
         }
         if (this.cfg.cert)
         {
-            this.tls = { key: await fsp.readFile(this.cfg.key), cert: await fsp.readFile(this.cfg.cert) };
+            this.tls = {
+                key: await fsp.readFile(this.cfg.key),
+                cert: await fsp.readFile(this.cfg.cert),
+            };
+            if (this.cfg.ca)
+            {
+                this.tls.ca = await fsp.readFile(this.cfg.ca);
+            }
+            if (this.cfg.client_cert_auth)
+            {
+                this.tls.requestCert = true;
+            }
             this.server = https.createServer(this.tls, (req, res) => this._handleRequest(req, res));
         }
         else
@@ -93,18 +104,25 @@ class AntiEtcd extends EventEmitter
         {
             res.push(this.persistence.persistChange(msg));
         }
-        if (res.length)
+        if (res.length == 1)
         {
-            res = await Promise.allSettled(res);
+            await res[0];
-            const errors = res.filter(r => r.status == 'rejected');
+        }
-            if (errors.length)
+        else if (res.length > 0)
+        {
+            let done = 0;
+            await new Promise((allOk, allNo) =>
             {
-                for (const e of errors)
+                res.map(promise => promise.then(res =>
                 {
-                    console.error(e.reason);
+                    if ((++done) == res.length)
-                }
+                        allOk();
-                throw errors[0].reason;
+                }).catch(e =>
-            }
+                {
+                    console.error(e);
+                    allNo(e);
+                }));
+            });
         }
     }
 
@@ -263,6 +281,14 @@ class AntiEtcd extends EventEmitter
         {
             data.leaderonly = true;
         }
+        if (requestUrl.searchParams.get('serializable'))
+        {
+            data.serializable = true;
+        }
+        if (requestUrl.searchParams.get('nowaitquorum'))
+        {
+            data.nowaitquorum = true;
+        }
         try
         {
             if (requestUrl.pathname.substr(0, 4) == '/v3/')
@@ -306,7 +332,13 @@ class AntiEtcd extends EventEmitter
         }
         if (path !== 'dump' && this.cluster)
         {
-            const res = await this.cluster.checkRaftState(path, data.leaderonly, data);
+            const res = await this.cluster.checkRaftState(
+                path,
+                (data.leaderonly ? AntiCluster.LEADER_ONLY : 0) |
+                (data.serializable ? AntiCluster.READ_FROM_FOLLOWER : 0) |
+                (data.nowaitquorum ? AntiCluster.NO_WAIT_QUORUM : 0),
+                data
+            );
             if (res)
             {
                 return res;

etctree.js

@@ -1,5 +1,6 @@
 const crypto = require('crypto');
 const stableStringify = require('./stable-stringify.js');
+const { RequestError } = require('./common.js');
 
 /*type TreeNode = {
     value?: any,
@@ -85,9 +86,14 @@ class EtcTree
             check_value = cur && cur.lease;
             ref_value = chk.lease;
         }
+        else if (chk.target === 'VALUE')
+        {
+            check_value = cur && cur.value;
+            ref_value = chk.value;
+        }
         else
         {
-            throw new Error('Unsupported comparison target: '+chk.target);
+            throw new RequestError(501, 'Unsupported comparison target: '+chk.target);
         }
         if (chk.result === 'LESS')
         {
@@ -95,7 +101,7 @@ class EtcTree
         }
         else if (chk.result)
         {
-            throw new Error('Unsupported comparison result: '+chk.result);
+            throw new RequestError(501, 'Unsupported comparison result: '+chk.result);
         }
         return check_value == ref_value;
     }
@@ -113,7 +119,7 @@ class EtcTree
         if (end != null && (key[key.length-1] != '/' || end[end.length-1] != '0' ||
             end.substr(0, end.length-1) !== key.substr(0, key.length-1)))
         {
-            throw new Error('Non-directory range queries are unsupported');
+            throw new RequestError(501, 'Non-directory range queries are unsupported');
         }
         const parts = this._key_parts(key);
         return { parts, all: end != null };
@@ -380,7 +386,7 @@ class EtcTree
         const id = req.ID;
         if (!this.leases[id])
         {
-            throw new Error('unknown lease');
+            throw new RequestError(400, 'unknown lease');
         }
         const lease = this.leases[id];
         if (lease.timer_id)
@@ -430,7 +436,7 @@ class EtcTree
     {
         if (!this.leases[id])
         {
-            throw new Error('unknown lease');
+            throw new RequestError(400, 'unknown lease');
         }
         for (const key in this.leases[id].keys)
         {
@@ -446,7 +452,7 @@ class EtcTree
         {
             if (no_throw)
                 return null;
-            throw new Error('unknown lease');
+            throw new RequestError(400, 'unknown lease');
         }
         this.mod_revision++;
         this._sync_revoke_lease(req.ID, notifications, this.mod_revision);
@@ -540,7 +546,7 @@ class EtcTree
         let watch_id = req.watch_id;
         if (watch_id instanceof Object)
         {
-            throw new Error('invalid watch_id');
+            throw new RequestError(400, 'invalid watch_id');
         }
         if (!watch_id)
         {
@@ -735,7 +741,7 @@ class EtcTree
             {
                 if (!this.leases[request_put.lease])
                 {
-                    throw new Error('unknown lease: '+request_put.lease);
+                    throw new RequestError(400, 'unknown lease: '+request_put.lease);
                 }
                 cur.lease = request_put.lease;
                 this.leases[request_put.lease].keys[key] = true;

vitastor_persist_filter.js

@@ -1,5 +1,6 @@
-function vitastor_persist_filter(prefix)
+function vitastor_persist_filter(cfg)
 {
+    const prefix = cfg.vitastor_prefix || '/vitastor';
     return (key, value) =>
     {
         if (key.substr(0, prefix.length+'/osd/stats/'.length) == prefix+'/osd/stats/')