Hi!

As this is an event with low probabilities, I think the dump function can
be implemented in a separate script, when the network is partitioned,
running
this script (maybe in one of the pod/vm of etcd instances) and getting this
config.yaml,
uploading/mount it to the machine/pod of APISIX. APISIX only needs to
support load
the static configuration when communicating to etcd failed.

Chao Zhang
https://github.com/tokers

On April 14, 2021 at 17:46:04, 聂永 ([email protected]) wrote:

Hi,

We need the `etcd` cluster for storing gateway's config, but we are afraid
of it being inaccessible when we reload or deploy gateway distance as
network issues.

## Dump etcd

So, we need the apisix to dump the etcd's stored data into
`conf/apisix.yaml ` file, when it is running every 5 minutes.

And, if the already existed apisix distance need to restart in some
unexpected case, or we need do deploy a large number of distance online in
a short time, if the distance queries data from `etcd` unsuccessfully when
starting, we need to load the dumped `conf/apisix.yaml` file into memory
once.

Firstly, we need to import the `dump` for `etcd` config:

```yaml
etcd:
host:
- "http://172.19.5.10:23792";
prefix: "/apisix"
dump:
interval: 300 # unit seconds
load_on_failure: true # if true, then try to load data from dumped
conf/apisix.yaml file when querying etcd failure first
```

And, when initializing, it will start a timer for dumping in cycles:

```lua
local dump_conf = etcd_conf.dump
local dump_interval = dump_conf.interval or 300

if dump_interval > 0 and 0 == ngx.worker.id() then
ngx_timer_every(dump_interval, dump_etcd)
end
```

If it queries `etcd` failure first time, then will try to load data from
`conf/apisix.yaml` file once,(with its work flow pic
https://user-images.githubusercontent.com/548385/114687020-e8dc7b80-9d45-11eb-94ea-1f28465e0580.png),
and its code snippet below:

```lua
local ok, err = sync_data(self)
if err then
if i == 1 and self.fail_load_yaml and not failure_map[self.key] then
failure_map[self.key] = 1
try_load_data_from_yaml(self)
end

......
```

## More usage

If we use [`Stand-alone mode`](
https://github.com/apache/apisix/blob/master/docs/en/latest/stand-alone.md)
below:

```yaml
config_center: yaml
```

We can also use it to update `conf/apisix.yaml` file periodically.

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