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Invoking an existing lambda will trigger an error on 'start_server!' #18
Description
The suggested configuration here:
Line 42 in 77e05e3
... will cause an Errno::EADDRINUSE error to be raised if a lambda is invoked manually, because the LambdaPunch server will have already been started. A call to aws lambda invoke for example yields the following error and stack trace:
Address already in use - bind(2) for "127.0.0.1" port 9030
/usr/local/lib/ruby/2.7.0/drb/drb.rb:883:in 'initialize':
Address already in use - bind(2) for "127.0.0.1" port 9030 (Errno::EADDRINUSE)
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:883:in 'open'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:883:in 'open_server'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:766:in 'block in open_server'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:764:in 'each'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:764:in 'open_server'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:1466:in 'initialize'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:1772:in 'new'
from /usr/local/lib/ruby/2.7.0/drb/drb.rb:1772:in 'start_service'
from /app/vendor/bundle/ruby/2.7.0/gems/lambda_punch-1.0.3/lib/lambda_punch/server.rb:22:in 'initialize'
from /usr/local/lib/ruby/2.7.0/singleton.rb:125:in 'new'
from /usr/local/lib/ruby/2.7.0/singleton.rb:125:in 'block in instance'
from /usr/local/lib/ruby/2.7.0/singleton.rb:123:in 'synchronize'
from /usr/local/lib/ruby/2.7.0/singleton.rb:123:in 'instance'
from /app/vendor/bundle/ruby/2.7.0/gems/lambda_punch-1.0.3/lib/lambda_punch/server.rb:15:in 'start!'
from /app/vendor/bundle/ruby/2.7.0/gems/lambda_punch-1.0.3/lib/lambda_punch.rb:36:in 'start_server!'
from /app/config/environments/production.rb:141:in 'block (2 levels) in <main>'
I was able to work around this doing something like the following:
config.to_prepare do
LambdaPunch.start_server!
rescue Errno::EADDRINUSE => e
Rails.logger.info("LambdaPunch is already running! (#{e.class})")
endIs there a better way to do this, or is there something that LambdaPunch can support natively to check to see if a server is already running, e.g. an alive? predicate similar to what's in DRb?
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brcarp commentedon Jun 9, 2023
💭 Another idea i had was to investigate
ARGVand maybe skip thestart_server!call if Rails was executed withrunner?Unfortunately
RunnerCommanddoesARGV.replace(command_argv)which basically removesrunnerfromARGV. 😞brcarp commentedon Jun 9, 2023
Ooh, what if I add
if Rails.const_defined?(:Server)? That might be sufficient to distinguishrails serverfromrails runner.metaskills commentedon Jun 12, 2023
Oh, I see the problem. Invoking is not the issue, technically there is no double init process for Lambda. What is happening is that when you are invoking, you are starting another Rails process off on the same function. Never anticipated that. I think ideally you could talk to the existing process. Not only would the that mean the "runner" action(s) and even "tasks" would be faster... but it would mean you can rely on LambdaPunch just working inside those tasks without coordination. How do you feel about the following.
We make a small change to Lamby's cmd handler (https://github.com/rails-lambda/lamby/blob/master/lib/lamby/handler.rb#L84-L103) to have one more... the last thing we will ever need... a basic method executor interface.
{ "lamby": { "cmd": { "method": "SomeConstant.method", "args": ["..."] } } }So the idea here would be that anything would work here. We can use this vs the runner. Builders can add syntactic sugar to this. For example, want to call a migration? There are top level methods to do that. We could even build a virtual REPL on this if the interface detected an array of commands. Thoughts? See where I am headed?
brcarp commentedon Jun 12, 2023
For the record, this does NOT work. These Rails lambdas are not running "rails server", which I might have realized if I thought about it for two seconds.
metaskills commentedon Jun 14, 2023
@brcarp Would you like to make a PR to LambdaPunch that does the
Errno::EADDRINUSEin the gem? That sounds like the best way forward?metaskills commentedon Jun 9, 2024
Added this in v1.1.4.