antietcd
v1.1.1
Published
Simplistic etcd replacement based on TinyRaft
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vitalifReadme
AntiEtcd
Simplistic miniature etcd replacement based on TinyRaft
- Embeddable
- REST API only, gRPC is shit and will never be supported
- TinyRaft-based leader election
- Websocket-based cluster communication
- Supports a limited subset of etcd REST APIs
- With optional persistence
Contents
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.
CLI Client
node_modules/.bin/anticli [OPTIONS] put <key> [<value>]
node_modules/.bin/anticli [OPTIONS] get <key> [-p|--prefix] [-v|--print-value-only] [-k|--keys-only] [--no-temp]
node_modules/.bin/anticli [OPTIONS] del <key> [-p|--prefix]
node_modules/.bin/anticli [OPTIONS] load [--with-lease] < dump.jsonFor put, if <value> is not specified, it will be read from STDIN.
Options:
Options
HTTP
Persistence
Clustering
Embedded Usage
const AntiEtcd = require('antietcd');
// Configuration may contain all the same options like in CLI, without "--"
// Except that persist_filter should be a callback (key, value) => newValue
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
}
}
// Watch API:
const watch_id = await srv.create_watch(params, (message) => console.log(message));
await srv.cancel_watch(watch_id);
// Stop server
srv.stop();About 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:
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:
type 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:
type TxnResponse = {
header: { revision: number },
succeeded: boolean,
responses: (
{ response_put: PutResponse }
| { response_range: RangeResponse }
| { response_delete_range: DeleteRangeResponse }
)[],
}/v3/kv/put
Request:
type PutRequest = {
key: string,
value: string,
lease?: string,
}Other parameters are not supported: prev_kv, ignore_value, ignore_lease.
Response:
type PutResponse = {
header: { revision: number },
}/v3/kv/range
Request:
type 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:
type RangeResponse = {
header: { revision: number },
kvs: { key: string }[] | {
key: string,
value: string,
lease?: string,
mod_revision: number,
}[],
}/v3/kv/deleterange
Request:
type DeleteRangeRequest = {
key: string,
range_end?: string,
}Other parameters are not supported: prev_kv.
Response:
type DeleteRangeResponse = {
header: { revision: number },
// number of deleted keys
deleted: number,
}/v3/lease/grant
Request:
type LeaseGrantRequest = {
ID?: string,
TTL: number,
}Response:
type LeaseGrantResponse = {
header: { revision: number },
ID: string,
TTL: number,
}/v3/lease/keepalive
Request:
type LeaseKeepaliveRequest = {
ID: string,
}Response:
type LeaseKeepaliveResponse = {
result: {
header: { revision: number },
ID: string,
TTL: number,
}
}/v3/lease/revoke or /v3/kv/lease/revoke
Request:
type LeaseRevokeRequest = {
ID: string,
}Response:
type LeaseRevokeResponse = {
header: { revision: number },
}/v3/maintenance/status
Request:
{}
Response:
type MaintenanceStatusResponse = {
header: {
member_id?: string,
revision: number,
compact_revision: number,
raft_term?: number,
},
version: string,
cluster?: { [string]: string },
leader?: string,
followers?: string[],
raftTerm?: string,
raftState?: 'leader'|'follower'|'candidate',
// dbSize actually reports process memory usage
dbSize: 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 = {
result: {
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
Author and License
Author: Vitaliy Filippov, 2024
License: Mozilla Public License 2.0 or Vitastor Network Public License 1.1