Nginx -- static file serving confusion with root alias

Question

I need to serve my app through my app server at 8080  and my static files from a directory without touching the app server  The nginx config I have is something like this           app server on port 8080       nginx listens on port 8123     server               listen          8123              access log      off               location  static                          root  var www app static                       alias  var www app static                       autoindex off                              location                         proxy pass              http   127 0 0 1 8080                      proxy set header        Host              host                      proxy set header        X-Real-IP         remote addr                      proxy set header        X-Forwarded-For   proxy add x forwarded for                        Now  with this config  everything is working fine  Note that the root directive is commented out   If I activate root and deactivate the alias -- it stops working  However  when I remove the trailing  static  from the root it starts working again   Can someone explain what s going on  Also please explain clearly and verbosely what are the differences between root and alias  and their purposes

User · Answer

alias is used to replace the location part path  LPP  in the request path  while the root is used to be prepended to the request path   They are two ways to map the request path to the final file path   alias could only be used in location block  and it will override the outside root   alias and root cannot be used in location block together

User · Answer

server       server name xyz com      root  home ubuntu project folder        client max body size 10M      access log   var log nginx project access log      error log   var log nginx project error log       location  static           index index html             location  media           alias  home ubuntu project media             Server block to live the static page on nginx

User · Answer

as say as  treecoder      In case of the root directive  full path is appended to the root including the location part  whereas in case of the alias directive  only the portion of the path NOT including the location part is appended to the alias    A picture is worth a thousand words  for root     for alias

User · Answer

I have found answers to my confusions   There is a very important difference between the root and the alias directives  This difference exists in the way the path specified in the root or the alias is processed   In case of the root directive  full path is appended to the root including the location part  whereas in case of the alias directive  only the portion of the path NOT including the location part is appended to the alias   To illustrate   Let s say we have the config  location  static        root  var www app static       autoindex off      In this case the final path that Nginx will derive will be   var www app static static   This is going to return 404 since there is no static  within static   This is because the location part is appended to the path specified in the root  Hence  with root  the correct way is  location  static        root  var www app       autoindex off      On the other hand  with alias  the location part gets dropped  So for the config  location  static        alias  var www app static       autoindex off                                                                          pay attention to this trailing slash   the final path will correctly be formed as   var www app static   The case of trailing slash for alias directive  There is no definitive guideline about whether a trailing slash is mandatory per Nginx documentation  but a common observation by people here and elsewhere seems to indicate that it is   A few more places have discussed this  not conclusively though   https   serverfault com questions 376162 how-can-i-create-a-location-in-nginx-that-works-with-and-without-a-trailing-slas  https   serverfault com questions 375602 why-is-my-nginx-alias-not-working

User · Answer

In your case  you can use root directive  because  uri part of the location directive is the same with last root directive part      Nginx documentation advices it as well    When location matches the last part of the directive   s value   location  images        alias  data w3 images           it is better to use the root directive instead   location  images        root  data w3       and root directive will append  uri to the path

User · Answer

In other words on keeping this brief  in case of root  location argument specified is part of filesystem s path and URI   On the other hand     for alias directive argument of  location statement is part of URI only  So  alias is a different name that maps certain URI to certain path in the filesystem  whereas root appends location argument to the root path given as argument to root directive

User · Answer

Just a quick addendum to  good computer s very helpful answer  I wanted to replace to root of the URL with a folder  but only if it matched a subfolder containing static files  which I wanted to retain as part of the path    For example if file requested is in  app js or  app css  look in  app location public  that folder     I got this to work using a regex    location     app   images  stylesheets  javascripts              alias  home user sites app public  1       access log off       expires max

[nginx] Nginx -- static file serving confusion with root & alias

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