I try to start Inets httpd server and have some documents in the document_root, but I can not start up the server. How can I start it?
This is the config I start it with:
>{ok, Pid} = inets:start(httpd, [{port, 8070}, {server_name, "myhttpd"},
>{server_root, "/Users/jonas/code"},
>{document_root, "/Users/jonas/code/mydocs"},
>{bind_address, "localhost"}]).
** exception error: no match of right hand side value {error, inets_not_started}
You should first call inets:start/0.
Related
I am stuck in a bit of a fix trying to run gen_server on another node. So I have a common gen_server class which looks like this
start(FileName) ->
start_link(node(), FileName).
start_link(ThisNode, FileName) ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [ThisNode, FileName], []).
init([ThisNode, FileName]) ->
process_flag(trap_exit, true),
{ok, Terms} = file:consult(FileName),
{A1, B1, C1} = lists:nth(1,Terms),
place_objects(A1, B1, C1).
Now I want to start multiple nodes that will run the same gen_server and somehow communicate with each other, and use a another node to orchestrate that. (All these nodes are started on my local terminal).
So I start a new node in one terminal using erl -sname bar where I intend to run the gen_server, and compile the gen_server module on this node. Then I start another node called 'sup' which I intend to use as a coordinator for all the other nodes. If I run the command my_gen_server:start("config_bar.txt"). on bar, it successfully returns but when I run the command rpc:call('bar#My-MacBook-Pro', my_gen_server, start, ["config_bar.txt"]). on sup, it successfully returns from the init method (I checked this by putting in the logs) but immediately after that, I get this error:
{ok,<9098.166.0>}
(sup#My-MacBook-Pro)2> =ERROR REPORT==== 21-Feb-2022::11:12:30.443051 ===
** Generic server my_gen_server terminating
** Last message in was {'EXIT',<9098.165.0>,
{#Ref<0.3564861827.2990800899.137513>,return,
{ok,<9098.166.0>}}}
** When Server state == {10,10,#Ref<9098.1313723616.3973185546.82660>,
'bar#My-MacBook-Pro'}
** Reason for termination ==
** {#Ref<0.3564861827.2990800899.137513>,return,{ok,<9098.166.0>}}
=CRASH REPORT==== 21-Feb-2022::11:12:30.443074 ===
crasher:
initial call: my_gen_server:init/1
pid: <9098.166.0>
registered_name: my_gen_server
exception exit: {#Ref<0.3564861827.2990800899.137513>,return,
{ok,<9098.166.0>}}
in function gen_server:decode_msg/9 (gen_server.erl, line 481)
ancestors: [<9098.165.0>]
message_queue_len: 0
messages: []
links: []
dictionary: []
trap_exit: true
status: running
heap_size: 1598
stack_size: 29
reductions: 3483
neighbours:
I can't seem to figure out what causes the error and if there's anything I need to add to my gen_server code to fix it. Would really appreciate some help on this one!
The gen_server in the remote node is linked to an ephemeral process created for the rpc call.
As this ephemeral process exits with a term that's different from normal (the actual result of the rpc call), the exit signal propagates to the gen_server, killing it.
You can use gen_server:start instead of gen_server:start_link or, if you want the gen_server to be part of the supervission tree, instruct its supervisor to spawn it:
rpc:call('bar#My-MacBook-Pro', my_gen_sup, start_child, ["config_bar.txt"]).
I faced with a problem and hope that someone can help me.
I try to start net_kernel by :
net_kernel:start([test,shortnames]).
But I faced with this error :
{error,
{{shutdown,
{failed_to_start_child,net_kernel,{'EXIT',nodistribution}}},
{child,undefined,net_sup_dynamic,
{erl_distribution,start_link,[[test,shortnames]]},
permanent,1000,supervisor,
[erl_distribution]}}}
=INFO REPORT==== 23-Apr-2017::21:07:43 ===
Protocol: "inet_tcp": register/listen error: econnrefused
Amazing tip is that when trying to start net_kernel by:
erl -sname test
net_kernel will start successfully
and another amazing tip is that after start net_kernel at least one time after OS boot and exit erl shell , the first way to start net_kernel will work successfully :|
( net_kernel:start([...]) )
after some search I found that CouchBase and RabbitMQ-Server and Ejabberd and some other apps that uses erlang , reported this error ( nodistribution error )
You have no epmd running, that'll be what the econnrefused is about. When you start net_kernel it wants to register a name with epmd so the node is findable.
Make sure there is an epmd process running at the time you start net_kernel and I bet the problem goes away.
Regarding erl -sname test working, I expect that starts epmd for you?
I have a yaws runmod defined in yaws.conf as:
runmod = sg_app
the module contains an exported function:
start()->
io:format("~p start~n", [ sg_sup:start_link() ]).
When I start yaws I see a call to the runmod:
=INFO REPORT==== 29-Oct-2015::16:46:51 === sync call sg_app:start
{ok,<0.61.0>} start
But the supervisor is nonexistent:
1> whereis(sg_sup).
undefined
If I call the runmod:start manually, the supervisor hangs around.
2> sg_app:start().
{ok,<0.73.0>} start
ok
3> whereis(sg_sup).
<0.73.0>
What have I done wrong?
Your runmod's start/0 function is starting the supervisor with start_link/0, which means it's getting linked to the parent process. When that process dies, it takes your runmod process down with it, due to the link. The runmod feature isn't designed for starting a supervision tree.
You might instead consider using a yapp, which allows your code to run as a regular Erlang application in the same Erlang node as Yaws and be registered to have Yaws dispatch requests into it.
Another option is to launch your application using a separately spawned, infinite process:
start()->
spawn(fun () ->
application:start(my_app, permanent),
receive after infinity -> ok end
end).
I am having trouble starting the cowboy application it is giving me following error. For some reason the ranch is not starting, although I have added code to start the ranch in my application.
I see a new git repo cowlib being pulled. but still having trouble.
1> application:start(satomi).
{error,
{bad_return,
{{satomi_app,start,[normal,[]]},
{'EXIT',
{noproc,
{gen_server,call,
[ranch_sup,
{start_child,
{{ranch_listener_sup,http},
{ranch_listener_sup,start_link,
[http,100,ranch_tcp,
[{port,9090}],
cowboy_protocol,
[{...}]]},
permanent,5000,supervisor,
[ranch_listener_sup]}},
infinity]}}}}}}
=INFO REPORT==== 12-Sep-2013::11:42:46 ===
application: satomi
exited: {bad_return,
{{satomi_app,start,[normal,[]]},
{'EXIT',
{noproc,
{gen_server,call,
[ranch_sup,
{start_child,
{{ranch_listener_sup,http},
{ranch_listener_sup,start_link,
[http,100,ranch_tcp,
[{port,9090}],
cowboy_protocol,
[{env,
[{dispatch,
[{'_',[],[{[],[],toppage_handler,[]}]}]}]}]]},
permanent,5000,supervisor,
[ranch_listener_sup]}},
infinity]}}}}}
type: temporary
Following is my app.src
>cat satomi.app.src
{application, satomi,
[
{description, ""},
{vsn, "1"},
{registered, []},
{applications, [
kernel,
stdlib,
cowboy
]},
{mod, { satomi_app, []}},
{env, []}
]}.
>cat satomi.erl
-module(satomi).
-export([start/0]).
start()->
ok = application:start(crypto),
ok = application:start(sasl),
ok = application:start(ranch),
ok = application:start(cowlib),
ok = application:start(cowboy),
ok = application:start(satomi).
I am trying to figure out what's going wrong here
Can anyone point me to the working sample of cowboy that I can use as a template. I am using rebar to compile the code. I don't think that should make any difference.
I am using following command to start the application
erl -pa ./ebin ./deps/*/ebin
When calling application:start(satomi) from the shell it doesn't automatically start the applications it depends on, those need to be started manually.
The satomi:start/0 function you have does exactly this, so the solution is to call satomi:start() from the shell.
The reason is that application:start(satomi) will actually not call satomi:start(), it is a convenience method for starting the application and its dependencies when the application is not part of an Erlang release.
UPDATE: Since Erlang R16B02, there is also application:ensure_all_started. It starts all the dependencies automatically.
When starting gen_server's from a supervisor (which itself is started by a application) I have the problem that when the start_link of the gen_server doesn't return {ok, ...} but {error, Reason} the only error message I see is:
=INFO REPORT==== 20-Jan-2011::13:14:43 ===
application: foo
exited: {shutdown,{foo_app,start,[normal,[]]}}
type: temporary
The Reason that for terminating is not shown/logged.
Is there a way to see/log these error returns to the supervisor?
The childspec I'm using is e.g.:
{ok, {{one_for_one, 3, 10}, ...
{usb_mux_1,
{usb_mux, start_link,
[Some_Params]},
permanent,
10000,
worker,
[usb_mux]}, ...
Edit: Clarification
I know about error_logger and using it already. The question is not how to get something logged but how to get supervisor to log the reason for it terminating, e.g. log who terminated with an error return and what did it return.
And just to get this also out of the way, yes I start erlang with sasl on:
-boot start_sasl
Just discovered the answer myself:
The supervisor is really logging the error exit as crash report.
The problem is the shell doesn't show these crash reports. Just to confuse me it shows info/warning and error reports but no progess reports and crash reports from the supervisor.
If I look in the on disk log there is a detailed crash report there:
10> rb:show(4).
CRASH REPORT <0.53.0> 2011-01-20 17:33:52
===============================================================================
Crashing process
initial_call {usb_mux,init,['Argument__1']}
pid <0.53.0>
registered_name []
error_info
{exit,{undef,[{usb_port,get_gw_hw_spec,[<0.59.0>]},
...
The reason the SASL events were not shown on the screen was a ommission in the -config file, which looked like this:
[{sasl, [
{sasl_error_logger, false}, %% no SASL error logger installed
{error_logger_mf_dir,"./log"},
{error_logger_mf_maxbytes,10485760}, % 10 MB
{error_logger_mf_maxfiles, 10}
]}].
Meaning there was a multi-file erroro logger installen (all the error_logger_mf_* entries) but no on screen logger for SASL events.
Changing the entry like this fixed it:
{sasl_error_logger, tty}, %% SASL reports to tty
From the sasl manpage:
sasl_report_tty_h:
Formats and writes supervisor reports, crash reports and progress reports to stdio .