Vernice errore "FetchError no backend connection"

Varnishlog:

    0 CLI          - Rd ping
    0 CLI          - Wr 200 19 PONG 1340829925 1.0
   12 SessionOpen  c 79.124.74.11 3063 :80
   12 SessionClose c EOF
   12 StatSess     c 79.124.74.11 3063 0 1 0 0 0 0 0 0
    0 CLI          - Rd ping
    0 CLI          - Wr 200 19 PONG 1340829928 1.0
    0 CLI          - Rd ping
    0 CLI          - Wr 200 19 PONG 1340829931 1.0
   12 SessionOpen  c 108.62.115.226 46211 :80
   12 ReqStart     c 108.62.115.226 46211 467185881
   12 RxRequest    c GET
   12 RxURL        c /
   12 RxProtocol   c HTTP/1.0
   12 RxHeader     c User-Agent: Pingdom.com_bot_version_1.4_(http://www.pingdom.com/)
   12 RxHeader     c Host: www.mysite.com
   12 VCL_call     c recv lookup
   12 VCL_call     c hash
   12 Hash         c /
   12 Hash         c www.mysite.com
   12 VCL_return   c hash
   12 VCL_call     c miss fetch
   12 FetchError   c no backend connection
   12 VCL_call     c error deliver
   12 VCL_call     c deliver deliver
   12 TxProtocol   c HTTP/1.1
   12 TxStatus     c 503
   12 TxResponse   c Service Unavailable
   12 TxHeader     c Server: Varnish
   12 TxHeader     c Content-Type: text/html; charset=utf-8
   12 TxHeader     c Retry-After: 5
   12 TxHeader     c Content-Length: 418
   12 TxHeader     c Accept-Ranges: bytes
   12 TxHeader     c Date: Wed, 27 Jun 2012 20:45:31 GMT
   12 TxHeader     c X-Varnish: 467185881
   12 TxHeader     c Age: 1
   12 TxHeader     c Via: 1.1 varnish
   12 TxHeader     c Connection: close
   12 Length       c 418
   12 ReqEnd       c 467185881 1340829931.192433119 1340829931.891024113 0.000051022 0.698516846 0.000074035
   12 SessionClose c error
   12 StatSess     c 108.62.115.226 46211 1 1 1 0 0 0 256 418
    0 CLI          - Rd ping
    0 CLI          - Wr 200 19 PONG 1340829934 1.0
    0 CLI          - Rd ping
    0 CLI          - Wr 200 19 PONG 1340829937 1.0

netstat -tlnp
 Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:8080            0.0.0.0:*               LISTEN      3086/nginx      
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      1915/varnishd   
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1279/sshd       
tcp        0      0 127.0.0.2:25            0.0.0.0:*               LISTEN      3195/sendmail: MTA:
tcp        0      0 127.0.0.2:6082          0.0.0.0:*               LISTEN      1914/varnishd   
tcp        0      0 127.0.0.2:9000          0.0.0.0:*               LISTEN      1317/php-fpm.conf)
tcp        0      0 127.0.0.2:3306          0.0.0.0:*               LISTEN      1192/mysqld     
tcp        0      0 127.0.0.2:587           0.0.0.0:*               LISTEN      3195/sendmail: MTA:
tcp        0      0 127.0.0.2:11211         0.0.0.0:*               LISTEN      3072/memcached  
tcp6       0      0 :::8080                 :::*                    LISTEN      3086/nginx      
tcp6       0      0 :::80                   :::*                    LISTEN      1915/varnishd   
tcp6       0      0 :::22                   :::*                    LISTEN      1279/sshd  

/ Etc / nginx / site-enabled / default

server {
    listen   8080; ## listen for ipv4; this line is default and implied
    listen   [::]:8080 default ipv6only=on; ## listen for ipv6

    root /usr/share/nginx/www;
    index index.html index.htm index.php;

    # Make site accessible from http://localhost/
    server_name localhost;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to index.html
        try_files $uri $uri/ /index.html;
    }

    location /doc {
        root /usr/share;
        autoindex on;
        allow 127.0.0.2;
        deny all;
    }

    location /images {
        root /usr/share;
        autoindex off;
    }

    #error_page 404 /404.html;

    # redirect server error pages to the static page /50x.html
    #
    #error_page 500 502 503 504 /50x.html;
    #location = /50x.html {
    #   root /usr/share/nginx/www;
    #}

    # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    #
    #location ~ \.php$ {
    #   proxy_pass http://127.0.0.1;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    location ~ \.php$ {
        fastcgi_pass 127.0.0.2:9000;
        fastcgi_index index.php;
        include fastcgi_params;
    }

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #   deny all;
    #}
}

/etc/nginx/sites-enabled/www.mysite.com.vhost

server {
       listen 8080;
       server_name www.mysite.com mysite.com.net;
       root /var/www/www.mysite.com/web;
       if ($http_host != "www.mysite.com") {
                 rewrite ^ http://www.mysite.com$request_uri permanent;
       }
       index index.php index.html;
       location = /favicon.ico {
                log_not_found off;
                access_log off;
       }
       location = /robots.txt {
                allow all;
                log_not_found off;
                access_log off;
       }
       # Deny all attempts to access hidden files such as .htaccess, .htpasswd, .DS_Store (Mac).
       location ~ /\. {
                deny all;
                access_log off;
                log_not_found off;
       }
       location / {
                try_files $uri $uri/ /index.php?$args;
       }
       # Add trailing slash to */wp-admin requests.
       rewrite /wp-admin$ $scheme://$host$uri/ permanent;
       location ~*  \.(jpg|jpeg|png|gif|css|js|ico)$ {
                expires max;
                log_not_found off;
       }
       location ~ \.php$ {
                try_files $uri =404;
                include /etc/nginx/fastcgi_params;
                fastcgi_pass 127.0.0.2:9000;
                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
       }

include /var/www/www.mysite.com/web/nginx.conf;
       location ~ /nginx.conf {
                deny all;
                access_log off;
                log_not_found off;
       }

}

/etc/varnish/default.vcl

# This is a basic VCL configuration file for varnish.  See the vcl(7)
# man page for details on VCL syntax and semantics.
# 
# Default backend definition.  Set this to point to your content
# server.
# 
backend default {
    .host = "127.0.0.2";
    .port = "8080";
    # .connect_timeout = 600s;
    #.first_byte_timeout = 600s;
    # .between_bytes_timeout = 600s;
    # .max_connections = 800;

Nota: decommentare le ultime quattro opzioni su default.vcl non ha fatto alcuna differenza.

cat / etc / default / varnish

# Configuration file for varnish
#
# /etc/init.d/varnish expects the variables $DAEMON_OPTS, $NFILES and $MEMLOCK
# to be set from this shell script fragment.
#

# Should we start varnishd at boot?  Set to "yes" to enable.
START=yes

# Maximum number of open files (for ulimit -n)
NFILES=131072

# Maximum locked memory size (for ulimit -l)
# Used for locking the shared memory log in memory.  If you increase log size,
# you need to increase this number as well
MEMLOCK=82000

# Default varnish instance name is the local nodename.  Can be overridden with
# the -n switch, to have more instances on a single server.
INSTANCE=$(uname -n)

# This file contains 4 alternatives, please use only one.

## Alternative 1, Minimal configuration, no VCL
#
# Listen on port 6081, administration on localhost:6082, and forward to
# content server on localhost:8080.  Use a 1GB fixed-size cache file.
#
# DAEMON_OPTS="-a :6081 \
#              -T localhost:6082 \
#        -b localhost:8080 \
#        -u varnish -g varnish \
#            -S /etc/varnish/secret \
#        -s file,/var/lib/varnish/$INSTANCE/varnish_storage.bin,1G"


## Alternative 2, Configuration with VCL
#
# Listen on port 6081, administration on localhost:6082, and forward to
# one content server selected by the vcl file, based on the request.  Use a 1GB
# fixed-size cache file.
#
DAEMON_OPTS="-a :80 \
             -T 127.0.0.2:6082 \
             -f /etc/varnish/default.vcl \
             -S /etc/varnish/secret \
             -s file,/var/lib/varnish/$INSTANCE/varnish_storage.bin,1G"

Se hai bisogno di altre informazioni fammi sapere. Non ho idea di quale sia il problema.

l'intestazione del ricciolo mi dà questo:

curl -v -I -H "Testing: Test header so you see this works" http://www.mysite.com:8080
* About to connect() to www.mysite.com port 8080 (#0)
*   Trying 176.31.158.78... connected
* Connected to www.mysite.com (176.31.158.78) port 8080 (#0)
> HEAD / HTTP/1.1
> User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8r zlib/1.2.5
> Host: www.mysite.com:8080
> Accept: */*
> Testing: Test header so you see this works
> 
< HTTP/1.1 301 Moved Permanently
HTTP/1.1 301 Moved Permanently
< Server: nginx/1.0.5
Server: nginx/1.0.5
< Date: Thu, 28 Jun 2012 11:01:23 GMT
Date: Thu, 28 Jun 2012 11:01:23 GMT
< Content-Type: text/html
Content-Type: text/html
< Content-Length: 184
Content-Length: 184
< Connection: keep-alive
Connection: keep-alive
< Location: http://www.mysite.com/
Location: http://www.mysite.com/

< 
* Connection #0 to host www.mysite.com left intact
* Closing connection #0

Ho avuto un problema simile quando provavo a provare la vernice locale con diversi backend. L'utilizzo ha 127.0.0.1:8080funzionato bene, ma cambiando la porta per 8081darmi un 503, anche se quel backend ha funzionato perfettamente per me al di fuori di Varnish.

Il problema è stato causato da SELinux che non consentiva la connessione. L'ho scoperto mettendo a tacere il registro di controllo e provocando il 503 di Varnish:

$ sudo tail -f /var/log/audit/audit.log type=AVC msg=audit(1539253067.438:1379): avc: denied { name_connect } for pid=10154 comm="varnishd" dest=8081 scontext=system_u:system_r:varnishd_t:s0 tcontext=system_u:object_r:transproxy_port_t:s0 tclass=tcp_socket

Per vedere le porte consentite da SELinux da Varnish puoi usare questo comando:

$ sudo semanage port -l | grep http_cache_port_t http_cache_port_t tcp 8080, 8118, 8123, 10001-10010

Per risolvere il problema è possibile utilizzare un'altra porta, ad esempio 8118oppure chiedere a SELinux di consentire le connessioni 8081da Varnish.

Il comando per aggiungere la porta è: il -aflag è aggiungere la porta:

semanage port -a -t http_cache_port_t -p tcp 8081

Se ricevi un messaggio che ti informa che la porta è già definita, devi modificare anziché aggiungere la porta:

ValueError: Port tcp/8081 already defined

Il comando scambia il -aflag per -m- 'modifica':

semanage port -m -t http_cache_port_t -p tcp 8081

Dovresti provare ad accedere con l'utente varnish e testare la connessione nel backend Nginx (127.0.0.2:8080) con arricciatura o wget per assicurarti che funzioni come previsto.

Come ha detto cyberx86 nei commenti, può essere un problema SELinux (o qualsiasi altro modulo di sicurezza come apparmor, grsec, ecc.) Che non consente la connessione tra i servizi e dovresti anche controllare i log di controllo per assicurarti che non stia accadendo nel tuo server .

Se il tuo back-end non funziona correttamente (errori nell'esecuzione di Nginx) avrai questo tipo di problemi, prova ad accedere direttamente al back-end e controlla i log per assicurarti che tutto funzioni come previsto (Pax te lo ha detto anche nei commenti) .

Varnish sta ricevendo i dati in anticipo e dovrebbe ascoltare la porta 80. I dati da Varnish sono proxy di Nginx che ascolta la porta 8080.

Config Nginx

server {
    listen 800;
    server_name www.example.com
}

Varnish Config - sudo nano / etc / default / varnish

DAEMON_OPTS="-a :80 \               #note on port 80 here
         -T localhost:6082 \
         -f /etc/varnish/default.vcl \
         -S /etc/varnish/secret \
         -s malloc,256m"

Quindi ecco la configurazione del proxy Varnish sulla porta 8080 (Nginx) - sudo nano /etc/varnish/default.vcl

backend default {
.host = "127.0.0.1";
.port = "8080";
}

Ho avuto lo stesso errore in una configurazione di più siti e il problema era il reindirizzamento dei domini da non www a www . Ecco come l'ho configurato (parti rilevanti).

Nel tuo .vcl, dentrosub vcl_recv

vcl 4.0;

sub vcl_recv {
    #THIS IS THE IMPORTANT POINT
    #redirect non www to www domains ip no subdomain defined
    if (req.http.host ~ "^([-0-9a-zA-Z]+)\.([a-zA-Z]+)$") {
       return (synth (750, ""));
    }

    # Normalize the header, remove the port
    set req.http.host = regsub(req.http.host, ":[0-9]+", "");

    #OFTEN SHIPS WITH THIS OTHER ONE, COMMENT IT OTHERWISE IT WILL FAIL
    #set req.http.Host = regsub(req.http.Host, "^www\.", "");

    # For the sake of example, a couple of custom backends, 
    # note www is specified in the req.http.host
    if (req.http.host ~ "foo.example.tld") {
         set req.backend_hint = example;
    }
     elseif (req.http.host ~ "www.other.com") {
         set req.backend_hint = other;
    }

Quindi sub vcl_synth, aggiungi questo:

sub vcl_synth {
    if (resp.status == 750) {
        #redirect non www to www
        set resp.status = 301;
        set resp.http.Location = "http://www." + req.http.host + req.url;
        return(deliver);
    }

In questo modo il reindirizzamento verrà gestito da Varnish prima di richiedere backend , evitando loop o nessuna connessione backend ...

Infine, nel vhost del tuo sito, non è più necessario avere due blocchi server, puoi commentare o rimuovere quello non www

#server {
#        listen 1.2.3.4:8080;
#        server_name example.tld;
#        return 301 http://www.example.tld;
#}

server {
        listen 1.2.3.4:8080;
        server_name www.example.tld;