Particles

Particles is a very simple CDN service written in Go. With Particles you can handle multiple domains by defining them in the configuration file. It also supports certificates so that you can load the keys and certs of HTTPS website you wish to use the CDN for.

Once started, depending on the configuration, Particles will expose:

• API endpoint: used for administrative tasks
• HTTP endpoint: CDN for HTTP websites
• HTTPS endpoint: CDN for HTTPS websites

For more details look at the configuration section to find out more about how to configure Particles.

Caching

There are currently two caching solutions:

• memory: stores data into a map kept in memory
• memcached: uses memcached as a backend

API

An API is exposed on a separte port in order to purge entries from the cache. To purge a cache entry:

curl http://localhost:7546/purge -d '{"resource": "http://www.example.com:80/wp-content/uploads/2017/03/banner.jpg"}'

Metrics

Metrics are exposed via Prometheus, using the /metrics endpoint of the API server:

curl http://localhost:7546/metrics

Configuration

The configuration is composed of four sections: api, cache, http, https. For the api and cache section the configuration is straightforward and specifically to the cache varies depending on which backend is used. The http and https endpoints are optional and in case backends aren't defined at all for either of them, that particular server won't be started. For HTTPS backends keys and certs are required in order to load the certificates for the domains.

api:
  address: 0.0.0.0
  port : 7546
cache:
  type: "memory"
  options:
    memory_limit: 10240
    ttl: 86400
    patterns: "test/css"
http:
  port: 80
  backends:
    - name: "example"
      domain: "www.example.com"
      ip: "12.34.56.78"
      port: 8080
      ifmodified_validation: 450
https:
  port: 443
  backends:
    - name: "secure-example"
      domain: "www.secure-example.com"
      ip: "34.56.78.90"
      port: 8443

Configuration parameters

Parameter	Description	Default	Required
api.address	The listening address of the API	0.0.0.0	no
api.port	The port the API listens on	7546	no
api.cert	The certificate to use for the API endpoints	""	no
api.key	The key for the certificate to use for the API endpoints	""	no
cache.type	The type of cache to use	"memory"	no
cache.options	Dynamic map varying based on the cache type	{memory_limit": "10240", "ttl": "86400"}	no
http.address	The listening address to receive HTTP traffic	"0.0.0.0"	no
http.port	The port to receive HTTP traffic	80	no
http.backends	List of backends handled on the HTTP port	[]	no
https.address	The listening address to receive HTTPS traffic	"0.0.0.0"	no
https.port	The port to receive HTTPS traffic	443	no
https.backends	List of backends handled on the HTTPS port	[]	no

Cache options configuration

Memory

Parameter	Description	Default	Required
memory_limit	The memory size allocatable	1073741824	no
patterns	The content-types to cache expressed as regexp	`"^(image	audio
force_purge	Delete random items if memory can't be freed up	true	no

Memcached

Parameter	Description	Default	Required
endpoints	Comma separated list of memcached endpoints	"127.0.0.1:11211"	no
patterns	The content-types to cache expressed as regexp	`"^(image	audio

Backend configuration

Parameter	Description	Default	Required
name	The name of the backend	-	yes
domain	The domain for the backend	-	yes
ip	The IP of the original source for this backend	-	yes
port	The port of the original source for this backend	80 if defined in the HTTP section or 443 if in the HTTPS	no
ifmodified_validation	The amount of seconds to wait before issuing an If-Not-Modified request	300	no

Note that for each backend you can optionally specify an IP. This will cause the HTTP client to override the DNS results and point to that specific IP address. The same configuration is valid for the port: backends listening on different ports than the one used by Particles are supported, just override the port by defining a new one for each backend you wish to override. Again, IP and port for backends are absolutely optional and Particles would use by default the same port defined for the HTTP or HTTPS Particles endpoints.