http_headers: Substitute Nginx version based on OS.

success-http-headers-bionic.txt and success-http-headers-focal.txt
differ only in the nginx version so this substitution will allow
us to have single file for both of them. Also this change helps
to avoid CI failure if Nginx version is updated in the OS.

.circleci/config.yml

@@ -299,8 +299,7 @@ jobs:
           # Must be relative path from root
           paths:
             - zulip-server-test.tar.gz
-            - success-http-headers-bionic.txt
-            - success-http-headers-focal.txt
+            - success-http-headers.template.txt
             - production-install
             - production-verify
             - production-upgrade-pg

tools/ci/production-build

@@ -32,8 +32,7 @@ fi
 # .circleci/config.yml
 mv /tmp/tmp.*/zulip-server-test.tar.gz /tmp/
 cp -a \
-   tools/ci/success-http-headers-bionic.txt \
-   tools/ci/success-http-headers-focal.txt \
+   tools/ci/success-http-headers.template.txt \
    tools/ci/production-install \
    tools/ci/production-verify \
    tools/ci/production-upgrade-pg \

tools/ci/production-verify

@@ -5,11 +5,6 @@
 set -e
 set -x
 
-if [ -f /etc/os-release ]; then
-    os_info="$(. /etc/os-release; printf '%s\n' "$VERSION_CODENAME")"
-    { read -r os_version_codename || true; } <<< "$os_info"
-fi
-
 cat >>/etc/zulip/settings.py <<EOF
 # CircleCI override settings above
 AUTHENTICATION_BACKENDS = ( 'zproject.backends.EmailAuthBackend', )
@@ -43,13 +38,15 @@ echo; echo "Now testing that the newly installed server's homepage loads"; echo
 wget https://localhost -O /tmp/index.html --no-check-certificate -S 2> /tmp/wget-output || true # || true so we see errors.log if this 500s
 grep -vi '\(Vary\|Content-Language\|expires\|issued by\|modified\|saved\|[.][.][.]\|Date\|[-][-]\)' /tmp/wget-output > /tmp/http-headers-processed
 
+nginx_version="$(nginx -v 2>&1 | awk '{print $3, $4}')"
+
 # Simplify the diff by getting replacing 4-5 digit length numbers with <Length>.
 sed -i 's|Length: [0-9]\+\( [(][0-9]\+[.][0-9]K[)]\)\?|Length: <Length>|' /tmp/http-headers-processed
-sed -i 's|Length: [0-9]\+\( [(][0-9]\+[.][0-9]K[)]\)\?|Length: <Length>|' /tmp/success-http-headers-"$os_version_codename".txt
-if ! diff -ur /tmp/http-headers-processed /tmp/success-http-headers-"$os_version_codename".txt; then
+sed -i -e 's|Length: [0-9]\+\( [(][0-9]\+[.][0-9]K[)]\)\?|Length: <Length>|' -e "s|{nginx_version_string}|$nginx_version|g"  /tmp/success-http-headers.template.txt
+if ! diff -ur /tmp/http-headers-processed /tmp/success-http-headers.template.txt; then
     set +x
     echo
-    echo "FAILURE: The HTTP Headers returned from loading the homepage on the server do not match the contents of tools/ci/success-http-headers.txt.  Typically, this means that the server threw a 500 when trying to load the homepage."
+    echo "FAILURE: The HTTP Headers returned from loading the homepage on the server do not match the contents of tools/ci/success-http-headers.template.txt.  Typically, this means that the server threw a 500 when trying to load the homepage."
     echo "Displaying the contents of the server's error log:"
     echo
     cat /var/log/zulip/errors.log

tools/ci/success-http-headers-focal.txt

@@ -1,28 +0,0 @@
-  Self-signed certificate encountered.
-    WARNING: certificate common name ‘127.0.0.1’ doesn't match requested host name ‘localhost’.
-  HTTP/1.1 302 Found
-  Server: nginx/1.18.0 (Ubuntu)
-  Content-Type: text/html; charset=utf-8
-  Content-Length: 0
-  Connection: keep-alive
-  Location: /login/
-  Strict-Transport-Security: max-age=15768000
-  X-Frame-Options: DENY
-  X-Content-Type-Options: nosniff
-  X-XSS-Protection: 1; mode=block
-Location: /login/ [following]
-Reusing existing connection to localhost:443.
-  HTTP/1.1 200 OK
-  Server: nginx/1.18.0 (Ubuntu)
-  Content-Type: text/html; charset=utf-8
-  Content-Length: 6361
-  Connection: keep-alive
-  Strict-Transport-Security: max-age=15768000
-  X-Frame-Options: DENY
-  X-Content-Type-Options: nosniff
-  X-XSS-Protection: 1; mode=block
-Length: 6361 (6.2K) [text/html]
-Saving to: ‘/tmp/index.html’
-
-
-

tools/ci/success-http-headers.template.txt

@@ -1,7 +1,7 @@
   Self-signed certificate encountered.
     WARNING: certificate common name ‘127.0.0.1’ doesn't match requested host name ‘localhost’.
   HTTP/1.1 302 Found
-  Server: nginx/1.14.0 (Ubuntu)
+  Server: {nginx_version_string}
   Content-Type: text/html; charset=utf-8
   Content-Length: 0
   Connection: keep-alive
@@ -13,7 +13,7 @@
 Location: /login/ [following]
 Reusing existing connection to localhost:443.
   HTTP/1.1 200 OK
-  Server: nginx/1.14.0 (Ubuntu)
+  Server: {nginx_version_string}
   Content-Type: text/html; charset=utf-8
   Content-Length: 6361
   Connection: keep-alive

tools/linter_lib/custom_check.py

@@ -65,7 +65,7 @@ whitespace_rules: List["Rule"] = [
      },
     {'pattern': '\t',
      'strip': '\n',
-     'exclude': {'tools/ci/success-http-headers-bionic.txt', 'tools/ci/success-http-headers-focal.txt'},
+     'exclude': {'tools/ci/success-http-headers.template.txt'},
      'description': 'Fix tab-based whitespace'},
 ]
 comma_whitespace_rule: List["Rule"] = [