The CLI emqx_ctl fails:
```
./bin/emqx_ctl status
Node not initialized?
Generated config file vm.*.args is not found for command 'ctl'
in config dir: /Users/liuxy/code/emqx50/_build/emqx/rel/emqx/-emqx_data_dir /Users/liuxy/code/emqx50/_build/emqx/rel/emqx/data --/configs
In case the file has been deleted while the node is running,
set environment variable 'EMQX_NODE__NAME' to continue
```
The main slow-down is the overheads of booting up beam with the
'start_clean' boot file (which loads all modules).
Prior to this change, beam is started multiple times in order to
resolve configuration values.
After this change:
* For boot commands such as 'start', 'console' and
'foreground', it starts beam twice:
- 1st is to check platform compatibility
- 2nd is to resolve all configs required for boot in a batch
* For non-boot commands, such as 'ctl' and 'ping', it does not
require to start beam for config resolution at all
Adds a check to `bin/emqx` to see if the OTP version being used has
support for `mnesia_hook`, which is required by Mria for using the
RLOG backend. If OTP is not compatible and the user tries to use
RLOG, a warning is printed during startup and the configuration falls
back to using the Mnesia backend.
some of the find_ functions are generated from the old rebar template
which will never be used since we:
1. always release erts
2. always generate sys.config
3. always generate vm.args
for remsh prefixed nodes, ekka pick a random port to listen on
instead of following the conventional port mapping rule:
ekka listens on 4370 for emqx or emqx0 and 4371 for emqx1 and so on
With the previous arguments, a fresh hidden node with the same name as
the expected running one was being started and commands were being run
there. This caused commands like `ekka_cluster:info()` to report
seemingly weird results.
OTP release handler only works with .tar.gz
as a result, we had to unpack .zip and re-pack .tar.gz
just to make OTP happy.
Now since we will be building .tar.gz packages
there is no need for this re-pack step anymore
* refine usage print
* deleted restart command, as it only works for daemon mode.
e.g. if EMQ X is started in 'foreground' mode the 'restart'
command will make it start in daemon mode
* some commands such as ertspath does not requre RPC
