Selector¶
In GOST, the selection of nodes in a node group is done through node selector. The selector is responsible for selecting zero or one nodes in a node group using the node selection strategy. Selector can be applied to forwarding chains, hops, and forwarders. Node selectors are used in GOST for load balancing.
strategy(string, default=round)-
Node selection strategy:
round- round robinrand- randomfifo- top-downhash- Based on a specific hash value (client IP or destination address)
maxFails(int, default=1)- The maximum number of failed connections for a specified node, When the number of failed connections with a node exceeds this set value, the node will be marked as a dead node, dead node will not be selected to use.
failTimeout(duration, default=10s)- Specify the dead node's timeout period. When a node is marked as a dead node, it will not be selected within this set time interval. After this set time interval, it will participate in node selection again.
Forwarding Chain¶
Selector can be set on each hop level of chain. The default selector uses the round strategy for node selection.
services:
- name: service-0
addr: ":8080"
handler:
type: http
chain: chain-0
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
selector:
strategy: rand
maxFails: 3
failTimeout: 60s
nodes:
- name: node-0
addr: 192.168.1.1:1080
connector:
type: socks5
dialer:
type: tcp
- name: node-1
addr: 192.168.1.2:1080
connector:
type: socks5
dialer:
type: tcp
Forwarder¶
Forwarder is used for port forwarding, it consists of a node group and a node selector. When forwarding is performed, zero or one node is selected from the node group for the forwarding destination address through the selector. The forwarder is now similar to a single-hop forwarding chain.
Chain Group¶
services:
- name: service-0
addr: ":8080"
handler:
type: http
chainGroup:
chains:
- chain-0
- chain-1
selector:
strategy: round
maxFails: 1
failTimeout: 10s
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8081
connector:
type: http
dialer:
type: tcp
- name: chain-1
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8082
connector:
type: http
dialer:
type: tcp
Backup Node and Chain¶
By marking one or more nodes or chains as backup, all backup nodes or chains will only participate in selection when all non-backup nodes or chains are marked as failed.
Backup Nodes¶
services:
- name: service-0
addr: :8080
handler:
type: http
chain: chain-0
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
selector:
strategy: round
maxFails: 1
failTimeout: 10s
nodes:
- name: node-0
addr: :8081
metadata:
maxFails: 3
failTimeout: 30s
connector:
type: http
dialer:
type: tcp
- name: node-1
addr: :8082
connector:
type: http
dialer:
type: tcp
- name: node-2
addr: :8083
metadata:
backup: true
connector:
type: http
dialer:
type: tcp
- name: node-3
addr: :8084
metadata:
backup: true
connector:
type: http
dialer:
type: tcp
Mark nodes as backup via the metadata.backup option.
Under normal circumstances, only two non-backup nodes node-0 and node-1 participate in node selection. When both node-0 and node-1 are marked as failed, node-2 and node-3 will participate in node selection. When any one of node-0 and node-1 is recovered, node-2 and node-3 exit node selection.
Node-level Failure State Control
Pay attention to the node-0 node here, through the metadata.maxFails and metadata.failTimeout options, you can control the failure status of this node separately, and the corresponding parameters in the selector are used by default.
Backup Chains¶
services:
- name: service-0
addr: :8080
handler:
type: http
chainGroup:
chains:
- chain-0
- chain-1
- chain-2
- chain-3
selector:
strategy: round
maxFails: 1
failTimeout: 10s
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8081
connector:
type: http
dialer:
type: tcp
- name: chain-1
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8082
connector:
type: http
dialer:
type: tcp
- name: chain-2
metadata:
backup: true
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8083
connector:
type: http
dialer:
type: tcp
- name: chain-3
metadata:
backup: true
hops:
- name: hop-0
nodes:
- name: node-0
addr: :8084
connector:
type: http
dialer:
type: tcp
Similar to backup nodes, chains chain-2 and chain-3 are marked as backup via the metadata.backup option.
Weighted Random Selection Strategy¶
The selector supports setting weights for nodes and chains based on the random selection strategy. The default weight is 1.
services:
- name: service-0
addr: :8080
handler:
type: auto
chain: chain-0
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
selector:
strategy: rand
maxFails: 1
failTimeout: 10s
nodes:
- name: node-0
addr: :8081
metadata:
weight: 20
connector:
type: http
dialer:
type: tcp
- name: node-1
addr: :8082
metadata:
weight: 10
connector:
type: http
dialer:
type: tcp
Set weights on nodes (or chains) via the metadata.weight option. The weight ratio of node-0 to node-1 is 2:1, so node-0 is twice as likely to be selected as node-1.
Hash Strategy¶
Hash strategy is based on the Hash value of a specific data to select. The current Hash type supports the client IP and the request target host address, and the client IP is used by default.
Target Address Hash Value¶
Each service can set the hash type individually.
services:
- name: service-0
addr: ":8080"
handler:
type: http
chain: chain-0
metadata:
hash: host
listener:
type: tcp
chains:
- name: chain-0
hops:
- name: hop-0
selector:
strategy: hash
maxFails: 1
failTimeout: 10s
nodes:
- name: node-0
addr: 192.168.1.1:1080
connector:
type: socks5
dialer:
type: tcp
- name: node-1
addr: 192.168.1.2:1080
connector:
type: socks5
dialer:
type: tcp
Specify the hash type as host with the hash option.