Subject: Re: bug#49431: [PATCH maintenance.git] nginx: berlin: Redirect old video URLs for each language.

From: "pelzflorian (Florian Pelz)" <[email-masked]>
Date: Fri, 9 Jul 2021 09:15:04 +0200

Thank you two for your opinion, Luis and Ludo.

On Thu, Jul 08, 2021 at 03:53:16PM +0200, Ludovic Courtès wrote:
> Shouldn’t we also redirect
> 
>   /$lang/videos/everyday-use-of-gnu-guix,-part-one/ -> /$lang/videos/2020/everyday-use-of-gnu-guix-part-one/
> 
> since the left-hand side here was the right-hand side of the previous
> redirects?

Each valid $lang was handled further down, but my patch was confusing,
especially when somebody wants to add more redirections.  Find
attached a revised patch with per-language redirection in only one
place, namely new procedure
`guix.gnu.org-redirects-for-each-language'.

Do I need to add a copyright header?  I hereby license/declare my
patch CC0 <https://creativecommons.org/publicdomain/zero/1.0/>.

In the previous patch I had missed some cases without /LANG like

/videos/everyday-use-of-gnu-guix,-part-one/index.html -> /$lang/videos/2020/everyday-use-of-gnu-guix-part-one/

Redirecting was unnecessary for

/videos/everyday-use-of-gnu-guix,-part-one/ -> /$lang/videos/2020/everyday-use-of-gnu-guix-part-one/

which already gets taken care of by

/videos/everyday-use-of-gnu-guix,-part-one -> /$lang/videos/2020/everyday-use-of-gnu-guix-part-one/

thanks to nginx location normalization.

Shall I push and then wait until someone guix system reconfigures
berlin?

Regards,
Florian
>From f07c22a4a8a26a203f3bf27f619d023d4c668cf3 Mon Sep 17 00:00:00 2001
From: Florian Pelz <[email-masked]>
Date: Fri, 9 Jul 2021 07:11:00 +0200
Subject: [PATCH] nginx: berlin: Redirect old video URLs for each language.

* hydra/nginx/berlin.scm (languages-to-accept): New list.  Move here
the languages list from ...
(%extra-content) ... here.  Use languages from 'languages-to-accept'.
(guix.gnu.org-redirects-for-each-language): New procedure.  Add
new video redirections.
(guix.gnu.org-redirect-locations): New list.  Move here the
old redirections.
(guix.gnu.org-other-locations): New list.  Move here the other nginx
locations from ...
(guix.gnu.org-locations): ... here.  Reimplement in terms of the above.
---
 hydra/nginx/berlin.scm | 91 +++++++++++++++++++++++++++++++++---------
 1 file changed, 72 insertions(+), 19 deletions(-)

diff --git a/hydra/nginx/berlin.scm b/hydra/nginx/berlin.scm
index 443294e..912024d 100644
--- a/hydra/nginx/berlin.scm
+++ b/hydra/nginx/berlin.scm
@@ -188,7 +188,7 @@ PUBLISH-URL."
             (body
              (list "root /var/www/guix;"))))))
 
-(define guix.gnu.org-locations
+(define guix.gnu.org-redirect-locations
   (list
    ;; Short URL for the installation script
    (redirect "/install.sh" "https://git.savannah.gnu.org/cgit/guix.git/plain/etc/guix-install.sh")
@@ -688,15 +688,71 @@ PUBLISH-URL."
    (redirect "/screenshots/virtual-machine" "/$lang/screenshots/virtual-machine/")
    (redirect "/screenshots/xfce" "/$lang/screenshots/xfce/")
    (redirect "/security" "/$lang/security/")
-   (redirect "/videos" "/$lang/videos/")
-   (redirect "/videos/asking-for-help" "/$lang/videos/asking-for-help/")
-   (redirect "/videos/everyday-use-of-gnu-guix,-part-one" "/$lang/videos/everyday-use-of-gnu-guix,-part-one/")
-   (redirect "/videos/everyday-use-of-gnu-guix,-part-two" "/$lang/videos/everyday-use-of-gnu-guix,-part-two/")
-   (redirect "/videos/installation-from-script" "/$lang/videos/installation-from-script/")
-   (redirect "/videos/packaging,-part-one" "/$lang/videos/packaging,-part-one/")
-   (redirect "/videos/packaging,-part-two" "/$lang/videos/packaging,-part-two/")
-   (redirect "/videos/packaging,-part-three" "/$lang/videos/packaging,-part-three/")
-
+   (redirect "/videos" "/$lang/videos/")))
+
+(define languages-to-accept
+  ;; List of languages for redirection; see 'accept-languages' further
+  ;; below.
+  '(("en")
+    ("de")
+    ("eo")
+    ("es")
+    ("fr")
+    ("ko")
+    ("ru")
+    ("sk")
+    ("zh-CN" "zh" "zh-Hans" "zh-Hans-CN")))
+
+(define (guix.gnu.org-redirects-for-each-language)
+  ;; These old URL request paths existed in many forms; without /LANG
+  ;; in front and with /LANG in front for each language.  Redirect
+  ;; each of them.
+  (define redirections
+    (list
+     (cons "/videos/everyday-use-of-gnu-guix,-part-one" "/videos/2020/everyday-use-of-gnu-guix-part-one/")
+     (cons "/videos/everyday-use-of-gnu-guix,-part-two" "/videos/2020/everyday-use-of-gnu-guix-part-two/")
+     (cons "/videos/system-graphical-installer" "/videos/2020/system-graphical-installer/")
+     (cons "/videos/asking-for-help" "/videos/2020/asking-for-help/")
+     (cons "/videos/installation-from-script" "/videos/2020/installation-from-script/")
+     (cons "/videos/packaging,-part-one" "/videos/2020/packaging-part-one/")
+     (cons "/videos/packaging,-part-two" "/videos/2020/packaging-part-two/")
+     (cons "/videos/packaging,-part-three" "/videos/2020/packaging-part-three/")))
+
+  (define (redirect-directory old new)
+    ;; Match nginx' behavior that request URLs with suffix "", "/"
+    ;; "/index.html" lead to the same file.  The suffix "/" is not taken
+    ;; care of here because it already gets normalized by nginx location
+    ;; handling.  The URLs in 'guix.gnu.org-redirect-locations' do not
+    ;; need this treatment, because they get an /index.html suffix
+    ;; through rewriting.
+    (let ((old-with-slashes-trimmed (string-trim-right old #\/)))
+      (list
+       (redirect old-with-slashes-trimmed new)
+       (redirect (string-append old-with-slashes-trimmed "/index.html") new))))
+
+  (define (guix.gnu.org-redirect-locations-for-lang lang)
+    (define (redirect-lang old new)
+      (redirect-directory (string-append "/" lang old)
+                          (string-append "/" lang new)))
+    (append-map redirect-lang (map car redirections) (map cdr redirections)))
+
+  (append
+   ;; Now all needed redirections are:
+   ;;
+   ;; 1) those without /LANG/ in front get redirected to /$lang/
+   (append-map redirect-directory
+               (map car redirections) ;old URLs without /LANG
+               ;; new URLs with /$lang prepended:
+               (map (compose (lambda (new-without-lang)
+                               (string-append "/$lang" new-without-lang))
+                             cdr)
+                    redirections))
+   ;; 2) those with /LANG/ in front get redirected to the same /LANG/
+   (append-map guix.gnu.org-redirect-locations-for-lang
+               (map car languages-to-accept))))
+
+(define guix.gnu.org-other-locations
+  (list
    (nginx-location-configuration
     (uri "/guix-videos")
     (body (list "alias /srv/videos;")))
@@ -754,6 +810,11 @@ PUBLISH-URL."
     (uri "/.well-known")
     (body (list "root /var/www;")))))
 
+(define guix.gnu.org-locations
+  (append guix.gnu.org-redirect-locations
+          (guix.gnu.org-redirects-for-each-language)
+          guix.gnu.org-other-locations))
+
 (define %publish-url "http://localhost:3000")
 
 (define %berlin-servers
@@ -1033,15 +1094,7 @@ synonymous IETF language tags that should be mapped to the same $lang."
    "default_type  application/octet-stream;"
    "sendfile        on;"
 
-   (accept-languages '(("en")
-                       ("de")
-                       ("eo")
-                       ("es")
-                       ("fr")
-                       ("ko")
-                       ("ru")
-                       ("sk")
-                       ("zh-CN" "zh" "zh-Hans" "zh-Hans-CN")))
+   (accept-languages languages-to-accept)
 
    ;; Maximum chunk size to send.  Partly this is a workaround for
    ;; <http://bugs.gnu.org/19939>, but also the nginx docs mention that
-- 
2.32.0