Nginx Cache Purge

An alternative way to do proxy_cache_purge or fastcgi_cache_purge for Nginx.

Usage

Installation / Uninstallation

cargo install nginx-cache-purge

# cargo uninstall nginx-cache-purge

From GitHub (Linux x86_64),

curl -fL "$(curl -fsS https://api.github.com/repos/magiclen/nginx-cache-purge/releases/latest | sed -r -n 's/.*"browser_download_url": *"(.*\/nginx-cache-purge_'$(uname -m)')".*/\1/p')" -O && sudo mv nginx-cache-purge_$(uname -m) /usr/local/bin/nginx-cache-purge && sudo chmod +x /usr/local/bin/nginx-cache-purge

# sudo rm /usr/local/bin/nginx-cache-purge

CLI Help

EXAMPLES:
nginx-cache-purge p /path/to/cache 1:2 http/blog/             # Purge the cache with the key "http/blog/" in the "cache zone" whose "path" is /path/to/cache, "levels" is 1:2
nginx-cache-purge p /path/to/cache 1:1:1 'http/blog*'         # Purge the caches with the key which has "http/blog" as its prefix in the "cache zone" whose "path" is /path/to/cache, "levels" is 1:1:1
nginx-cache-purge p /path/to/cache 2:1 '*/help*'              # Purge the caches with the key which contains the substring "/help" in the "cache zone" whose "path" is /path/to/cache, "levels" is 2:1
nginx-cache-purge p /path/to/cache 1 '*'                      # Purge all caches in the "cache zone" whose "path" is /path/to/cache, "levels" is 1
nginx-cache-purge p /path/to/cache 2 '*' -e 'http/static/*'   # Purge all caches except for those whose key starts with "http/static/" in the "cache zone" whose "path" is /path/to/cache, "levels" is 2
nginx-cache-purge s                                           # Start a server which listens on "/tmp/nginx-cache-purge.sock" to handle purge requests
nginx-cache-purge s /run/nginx-cache-purge.sock               # Start a server which listens on "/run/nginx-cache-purge.sock" to handle purge requests

Usage: nginx-cache-purge <COMMAND>

Commands:
  purge  Purge the cache immediately [aliases: p]
  start  Start a server to handle purge requests [aliases: s]
  help   Print this message or the help of the given subcommand(s)

Options:
  -h, --help     Print help
  -V, --version  Print version

If the purge command successfully removes any cache, it returns the exit status 0. If no cache needs to be removed, it returns the exit status 44.

Nginx + Nginx Cache Purge

Start the Service of Nginx Cache Purge (systemd for example)

Assume we have already put the executable file nginx-cache-purge in /usr/local/bin/.

/etc/systemd/system/nginx-cache-purge.service

[Unit]
Description=Nginx Cache Purge
After=network.target

[Service]
# same as the user/group of the nginx process
User=www-data
Group=www-data

ExecStart=/usr/local/bin/nginx-cache-purge start
Restart=always
RestartSec=3s

[Install]
WantedBy=multi-user.target

Run the following commands,

sudo systemctl daemon-reload
sudo systemctl start nginx-cache-purge
sudo systemctl status nginx-cache-purge

sudo systemctl enable nginx-cache-purge

Edit Nginx' Configuration File

Assume we want to put the cache in /tmp/cache.

http {
    ...

    map $request_method $is_purge {
        default   0;
        PURGE     1;
    }

    proxy_cache_path /tmp/cache levels=1:2 keys_zone=my_cache:10m;
    proxy_cache_key $scheme$request_uri;

    server {
        ...

        location / {
            if ($is_purge) {
                set $my_cache_key $scheme$request_uri;
                proxy_pass http://unix:/tmp/nginx-cache-purge.sock;
                rewrite ^ /?cache_path=/tmp/cache&levels=1:2&key=$my_cache_key break;
                # all purge
                #rewrite ^ /?remove_first=/&cache_path=/tmp/cache&levels=1:2&key=* break;
            }

            proxy_cache my_cache;
            proxy_pass upstream;
            include proxy_params;
        }
    }
}

Remember to add your access authentication mechanisms to prevent strangers from purging your cache. And note that the cache key should not contain $proxy_host because it will be empty when the request is in proxy_pass http://unix:....

After finishing the settings:

Request PURGE /path/to/abc to purge the cache from GET /path/to/abc.
Request PURGE /path/to/* to purge all caches from GET /path/to/**/*.
Request PURGE /path/to/*/foo/*/bar to purge caches from GET /path/to/**/foo/**/bar.

If the service successfully removes any cache, it will respond the HTTP status code 200. If no cache needs to be removed, it will respond the HTTP status code 202.

Other fields that can be set to the query of the / endpoint URL:

remove_first: Allow the exclusion of the prefix from the request path of the key. The format should be like ?remove_first=/purge.
exclude_keys (can be more than one): Exclude those keys from the purging process. It also supports the use of wildcards. The format should be like ?exclude_keys=http/static/*&exclude_keys=http/1. The remove_first field does not affect exclude_keys fields.

No Service

If we want to use nginx-cache-purge CLI with lua-nginx-module, instead of running the service in the background.

We can choose to disable the default features to obtain a much smaller executable binary.

cargo install nginx-cache-purge --no-default-features

Deployment example

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  template:
    spec:
      containers:
        - name: nginx
          image: nginx:1.25.5
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 80
              name: http
          volumeMounts:
            - name: nginx-cache-purge
              mountPath: /tmp
        - name: nginx-cache-purge
          image: netaskd/nginx-cache-purge:v0.4.4
          imagePullPolicy: IfNotPresent
          volumeMounts:
            - name: nginx-cache-purge
              mountPath: /tmp
      volumes:
        - name: nginx-cache-purge
          emptyDir: {}

License

MIT