Docker Compose for a full-stack lancache.

This docker-compose is meant as an example for running our lancache stack, It will run out of the box with minimal changes to the .env file for your local IP address and disk settings.

Once (and only once) you have a working system run sudo ./enable_autostart.sh to allow the containers to run at system startup

Settings

You MUST set at least LANCACHE_IP and DNS_BIND_IP. It is highly recommended that you change CACHE_ROOT to a folder of your choosing, and set CACHE_DISK_SIZE to a value that suits your storage capacity.

USE_GENERIC_CACHE

This controls IP assignment within the DNS service - it assumes that every service is reachable by default on every IP given in LANCACHE_IP. See the lancache-dns project for documentation on customising the behaviour of the DNS service.

LANCACHE_IP

This provides one or more IP addresses to the DNS service to advertise the cached services. If your cache host has exactly one IP address (e.g. 192.168.0.10), specify that here. If your cache host has more IP addresses, you can list all of them, separated by spaces (e.g. 192.168.0.10 192.168.0.11 192.168.0.12) - DNS entries will be configured for all services and all IPs by default.

Note: unless your cache host is at 10.0.39.1, you will want to change this value.

DNS_BIND_IP

This sets the IP address that the DNS service will listen on. If your cache host has exactly one IP address (eg. 192.168.0.10), specify that here. If your cache host has multiple IPs, specify exactly one and use that. This compose stack does not support the DNS service listening on multiple IPs by default.

Note: unless your cache host is at 10.0.39.1, you will want to change this value.

There are a few ways to make your local network aware of the cache server.

1. Advertise the IP given in DNS_BIND_IP via DHCP to your network as a nameserver. In this scenario, all clients configured to use the nameservers from DNS will use the lancache-dns service. This allows the lancache-dns service to provide clients with the appropriate local IPs for cached services, and all other requests will be passed to UPSTREAM_DNS.
2. Use the configuration generators available from UKLANs' cache-domains project to create configuration data to load into your network's existing DNS infrastructure

METRIC_BIND_IP

This sets the IP address that the metric services will listen on. If your cache host has exactly one IP address (eg. 192.168.0.10), specify that here. If your cache host has multiple IPs, specify exactly one and use that.

This may be used to segregate the cache and dns ip endpoints from the metrics endpoints.

For prometheus to scrape the metrics, you will need to add the following to your prometheus.yml file:

Please note, that Prometheus is not included in this docker-compose stack.

scrape_configs:
  - job_name: 'lancache'
    static_configs:
      - targets: ['<METRIC_BIND_IP>:<METRIC_PORT>']

• <METRIC_BIND_IP> is the IP address you set in the METRIC_BIND_IP environment variable
• <METRIC_PORT> is the port of the metric services. Please see below for the ports used by the metric services.

Service	Port
Bind (DNS)	9119
Monolithic	9113

Prometheus example

The following is a full example of a prometheus.yml file that will scrape the metrics from the lancache services.

scrape_configs:
  - job_name: 'lancache-dns'
    static_configs:
      - targets: ['192.168.0.10:9119']
  - job_name: 'lancache-monolithic'
    static_configs:
      - targets: ['192.168.0.10:9113']

UPSTREAM_DNS

This allows you to choose one or more IP addresses for upstream DNS resolution if a name is not matched by the lancache-dns service (e.g. non-cached services, local hostname resolution).

Whichever resolver you choose depends on your network's requirements - if you don't need to provide internal DNS names, you can point UPSTREAM_DNS directly to an external resolver (the default is Google's DNS at 8.8.8.8).

If you run internal services on your network, you can set UPSTREAM_DNS to be your internal DNS resolver(s), semicolon separated (e.g. 192.168.0.1; 192.168.0.2).

Example external resolvers

• Google DNS:
  • 8.8.8.8
  • 8.8.4.4
• Cloudflare
  • 1.1.1.1
• OpenDNS
  • 208.67.222.222
  • 208.67.220.220

CACHE_ROOT

This will be used as the base directory for storing cached data (as CACHE_ROOT/cache) and logs (as CACHE_ROOT/logs).

The CACHE_ROOT should either be on a separate partition, or ideally on separate storage devices entirely, from your system root.

Note: this setting defaults to ./lancache. Unless your cache storage lives here, you probably want to change this value.

CACHE_DISK_SIZE

This setting will constrain the upper limit of space used by cached data. You generally want to leave a small gap (10-20GB at least) between the size listed here and the available storage space used for the cached data, just in case.

The cache server will automatically delete cached data when the total stored amount approaches this limit, in a least-recently-used fashion (oldest data, least accessed deleted first).

Note: that this must be given in either:

• gigabytes, with g suffix (e.g. the default value, 1000g)
• megabytes, with m suffix (e.g. 900000m)

CACHE_INDEX_SIZE

Change this to allow sufficient index memory for the nginx cache manager (default 500m) We recommend 250m of index memory per 1TB of CACHE_DISK_SIZE

Note: this setting does not limit the amount of memory that the Linux host will use for page caches, only what the cache server will use itself - see the Docker documentation on limiting memory consumption for a container if you wish to constrain the total memory consumption of the cache server, but generally you want as much memory as possible on your cache server to be used to store hot data.

CACHE_MAX_AGE

This setting allows you to control the maximum duration cached data will be kept for. The default should be fine for most use cases - the CACHE_DISK_SIZE setting will generally be used before this for aging out data.

Note: this must be given as a number of days in age before expiry, with a d suffix (e.g. the default value, 3650d).

TZ

This setting allows you to set the timezone that is used by the docker containers. Most notably changing the timestamps of the logs. Useful for debugging without having to think sometimes multiple hours in the future/past.

For a list of all timezones see https://en.wikipedia.org/wiki/List_of_tz_database_time_zones.

More information

The LanCache docker-stack is generated automatically from the data over at UKLans. All services that are listed in the UKLans repository are available and supported inside this docker-compose.

For an FAQ see https://lancache.net/docs/faq/