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consul_kv

Summary#

For users that are using nginx-upsync-module and Consul KV as a service discovery, like the Weibo Mobile Team, this may be needed.

Thanks to @fatman-x guy, who developed this module, called consul_kv, and its worker process data flow is below:

Configuration for discovery client#

Configuration for Consul KV#

Add following configuration in conf/config.yaml :

discovery:
consul_kv:
servers:
- "http://127.0.0.1:8500"
- "http://127.0.0.1:8600"
prefix: "upstreams"
skip_keys: # if you need to skip special keys
- "upstreams/unused_api/"
timeout:
connect: 1000 # default 2000 ms
read: 1000 # default 2000 ms
wait: 60 # default 60 sec
weight: 1 # default 1
fetch_interval: 5 # default 3 sec, only take effect for keepalive: false way
keepalive: true # default true, use the long pull way to query consul servers
default_server: # you can define default server when missing hit
host: "127.0.0.1"
port: 20999
metadata:
fail_timeout: 1 # default 1 ms
weight: 1 # default 1
max_fails: 1 # default 1
dump: # if you need, when registered nodes updated can dump into file
path: "logs/consul_kv.dump"
expire: 2592000 # unit sec, here is 30 day

And you can config it in short by default value:

discovery:
consul_kv:
servers:
- "http://127.0.0.1:8500"

The keepalive has two optional values:

  • true, default and recommend value, use the long pull way to query consul servers
  • false, not recommend, it would use the short pull way to query consul servers, then you can set the fetch_interval for fetch interval

Dump Data#

When we need reload apisix online, as the consul_kv module maybe loads data from CONSUL slower than load routes from ETCD, and would get the log at the moment before load successfully from consul:

 http_access_phase(): failed to set upstream: no valid upstream node

So, we import the dump function for consul_kv module. When reload, would load the dump file before from consul; when the registered nodes in consul been updated, would dump the upstream nodes into file automatically.

The dump has three optional values now:

  • path, the dump file save path
    • support relative path, eg: logs/consul_kv.dump
    • support absolute path, eg: /tmp/consul_kv.bin
    • make sure the dump file's parent path exist
    • make sure the apisix has the dump file's read-write access permission,eg: chown www:root conf/upstream.d/
  • load_on_init, default value is true
    • if true, just try to load the data from the dump file before loading data from consul when starting, does not care the dump file exists or not
    • if false, ignore loading data from the dump file
    • Whether true or false, we don't need to prepare a dump file for apisix at anytime
  • expire, unit sec, avoiding load expired dump data when load
    • default 0, it is unexpired forever
    • recommend 2592000, which is 30 days(equals 3600 * 24 * 30)

Register Http API Services#

Service register Key&Value template:

Key:    {Prefix}/{Service_Name}/{IP}:{Port}
Value: {"weight": <Num>, "max_fails": <Num>, "fail_timeout": <Num>}

The register consul key use upstreams as prefix by default. The http api service name called webpages for example, and you can also use webpages/oneteam/hello as service name. The api instance of node's ip and port make up new key: <IP>:<Port>.

Now, register nodes into consul:

curl \
-X PUT \
-d ' {"weight": 1, "max_fails": 2, "fail_timeout": 1}' \
http://127.0.0.1:8500/v1/kv/upstreams/webpages/172.19.5.12:8000

curl \
-X PUT \
-d ' {"weight": 1, "max_fails": 2, "fail_timeout": 1}' \
http://127.0.0.1:8500/v1/kv/upstreams/webpages/172.19.5.13:8000

In some case, same keys exist in different consul servers. To avoid confusion, use the full consul key url path as service name in practice.

Upstream setting#

Here is an example of routing a request with a URL of "/*" to a service which named "http://127.0.0.1:8500/v1/kv/upstreams/webpages/" and use consul_kv discovery client in the registry :

$ curl http://127.0.0.1:9180/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -i -d '
{
"uri": "/*",
"upstream": {
"service_name": "http://127.0.0.1:8500/v1/kv/upstreams/webpages/",
"type": "roundrobin",
"discovery_type": "consul_kv"
}
}'

The format response as below:

{
"node": {
"value": {
"priority": 0,
"update_time": 1612755230,
"upstream": {
"discovery_type": "consul_kv",
"service_name": "http://127.0.0.1:8500/v1/kv/upstreams/webpages/",
"hash_on": "vars",
"type": "roundrobin",
"pass_host": "pass"
},
"id": "1",
"uri": "/*",
"create_time": 1612755230,
"status": 1
},
"key": "/apisix/routes/1"
}
}

You could find more usage in the apisix/t/discovery/consul_kv.t file.

Debugging API#

It also offers control api for debugging.

Memory Dump API#

GET /v1/discovery/consul_kv/dump

For example:

# curl http://127.0.0.1:9090/v1/discovery/consul_kv/dump | jq
{
"config": {
"fetch_interval": 3,
"timeout": {
"wait": 60,
"connect": 6000,
"read": 6000
},
"prefix": "upstreams",
"weight": 1,
"servers": [
"http://172.19.5.30:8500",
"http://172.19.5.31:8500"
],
"keepalive": true,
"default_service": {
"host": "172.19.5.11",
"port": 8899,
"metadata": {
"fail_timeout": 1,
"weight": 1,
"max_fails": 1
}
},
"skip_keys": [
"upstreams/myapi/gateway/apisix/"
]
},
"services": {
"http://172.19.5.31:8500/v1/kv/upstreams/webpages/": [
{
"host": "127.0.0.1",
"port": 30513,
"weight": 1
},
{
"host": "127.0.0.1",
"port": 30514,
"weight": 1
}
],
"http://172.19.5.30:8500/v1/kv/upstreams/1614480/grpc/": [
{
"host": "172.19.5.51",
"port": 50051,
"weight": 1
}
],
"http://172.19.5.30:8500/v1/kv/upstreams/webpages/": [
{
"host": "127.0.0.1",
"port": 30511,
"weight": 1
},
{
"host": "127.0.0.1",
"port": 30512,
"weight": 1
}
]
}
}

Show Dump File API#

It offers another control api for dump file view now. Maybe would add more api for debugging in future.

GET /v1/discovery/consul_kv/show_dump_file

For example:

curl http://127.0.0.1:9090/v1/discovery/consul_kv/show_dump_file | jq
{
"services": {
"http://172.19.5.31:8500/v1/kv/upstreams/1614480/webpages/": [
{
"host": "172.19.5.12",
"port": 8000,
"weight": 120
},
{
"host": "172.19.5.13",
"port": 8000,
"weight": 120
}
]
},
"expire": 0,
"last_update": 1615877468
}