Before this change, if a license in `emqx.conf` was of type
`key`/`file` and then changed to the opposite type, such change would
be saved to `{cluster,local}-overrides.conf`. When the node restarts
after that, the configs are merged naively and becomes invalid, as it
contains both the `key` and `file` keys, and crashes.
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.
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
Surprisingly enough, by doing small cirurgical changes in the existing
EMQX control scripts, we are able to get it running with Elixir and
with existing functionalities (`console`, `remote_console`, `start`,
`stop`, `ctl`, `foreground`, `eval`).
Ivan Dyachkov