How to set lager.error_logger_hwm in RabbitMQ by rabbitmqctl command

Question

This How to set error_logger_hwm in the new RabbitMQ .conf configuration file format? not suitable for my situation which running rabbitmq(RabbitMQ 3.7.10 on Erlang 20.2.2 -- Ubuntu 16.04) by docker container.

I could add advanced.config in the host's directory, and update config.json for generating /var/lib/rabbitmq/config/generated/rabbitmq.config automatically after restart it.

root@*-pc:/etc/kolla/rabbitmq# cat advanced.config 
[
    {lager, [
        {error_logger_hwm, 4000}
    ]}
].

root@*-pc:/etc/kolla/rabbitmq# cat config.json 
{
    "command": "/usr/sbin/rabbitmq-server",
    "config_files": [
        {
            "source": "/var/lib/kolla/config_files/advanced.config",
            "dest": "/etc/rabbitmq/advanced.config",
            "owner": "rabbitmq",
            "perm": "0600"
        },
        {
            "source": "/var/lib/kolla/config_files/rabbitmq.conf",
            "dest": "/etc/rabbitmq/rabbitmq.conf",
            "owner": "rabbitmq",
            "perm": "0600"
        },
        ......

root@*-pc:/etc/kolla/rabbitmq# docker restart  rabbitmq 
rabbitmq
root@*-pc:/etc/kolla/rabbitmq# docker exec rabbitmq rabbitmqctl eval 'application:get_env(lager, error_logger_hwm).'
{ok,4000}

Question:

• Is there any command to set the environment parameter such as 'application:get_env(lager, error_logger_hwm).' for get the environment parameter. Also can't find any clue at rabbitmq configuration.

# docker exec rabbitmq rabbitmqctl eval '[lager:set_loghwm(error_logger_hwm, 4000)]'
Error (argument validation): "syntax error before: "
Arguments given:
    eval [lager:set_loghwm(error_logger_hwm, 4000)]

Usage:
rabbitmqctl [-n <node>] [-l] [-q] eval <expr>

It also seems doesn't raise the limit, I don't know what's that meaning. Reference from RabbitMQ lager_error_logger_h dropped messages.

# docker exec rabbitmq rabbitmqctl eval 'application:get_env(lager, error_logger_hwm).'
{ok,50}

# docker exec rabbitmq rabbitmqctl eval '[lager:set_loghwm(H, 4000) || H <- gen_event:which_handlers(lager_event)].'
[{last_loghwm,50},ok]

# docker exec rabbitmq rabbitmqctl eval 'application:get_env(lager, error_logger_hwm).'
{ok,50}

# docker exec rabbitmq rabbitmqctl eval '[lager:set_loghwm(H, 4000) || H <- gen_event:which_handlers(lager_event)].'
[{last_loghwm,4000},ok]

# docker exec rabbitmq rabbitmqctl eval 'application:get_env(lager, error_logger_hwm).'
{ok,50}

Answer 1

You can try

docker exec rabbitmq rabbitmqctl eval 'application:set_env(lager,error_logger_hwm,4000).' 

Maybe it works. https://www.erlang.org/doc/man/application.html#set_env-2

lager:set_loghwm(error_logger_hwm, 4000)]

The above code does not work because lager application doesn't start and lager's function can't be called. https://hexdocs.pm/lager/lager.html#set_loghwm-2