How to judge whether `manager-api` has been started successfully

[showniu]

Please answer these questions before submitting your issue.

• Why do you submit this issue?
• Question or discussion
• Bug
• Requirements
• Feature or performance improvement
• Other

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Question

• What do you want to know?

Has the manager-api started successfully? No output. Is manager-api listening on the port or starting a process?

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Bug

• Which version of Apache APISIX Dashboard, OS and Broswer?
  apisix 1.5
  Centos7

• What happened?
  If possible, provide a way to reproduce the error.

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Requirement or improvement

• Please describe your requirements or improvement suggestions.

[gxthrj]

Usually our logs are printed on stdout. The situation you encounter is generally a startup failure, usually because of port conflicts. the default port of manager-api is 8080.
Here is a new PR #409 about the log output after startup failure.