caddy-loki-logger

Push logs from your Caddy web server directly to a Loki instance.

Usage

Building

To use this module with Caddy, you'll need to create a custom build with xcaddy.

xcaddy build --with github.com/trea/caddy-loki-logger

Via Docker

You can build this module (and others) into Caddy with xcaddy using Docker. The following example uses a multi-phase build to build the Caddy binary with xcaddy, and then copies your newly built binary over the original binary in the core Caddy image.

FROM caddy:2.6.4-builder AS builder

RUN xcaddy --with github.com/trea/caddy-loki-logger

FROM caddy:2.6.4

COPY --from=builder /usr/bin/caddy /usr/bin/caddy

Caddyfile Configuration Examples

Accepted Caddyfile Syntax

(
    log default {
        output loki <loki_endpoint> {
            label {
                <label_name> <label_value>
                ...
            }
        }
    }
)

loki_endpoint can be any valid HTTP/HTTPS URI, including using basic authentication. It may also contain variables including environment variables like {env.LOKI_ENDPOINT}.

label is not required. It may contain as many label-value pairs as desired. label_value may contain variables including environment variables.

The output does not have to be a block:

output loki <loki_endpoint>

Examples

{
    log default {
        output loki {$LOKI_SERVER}
    }
}

Sends log output to a Loki server whose address is set as LOKI_SERVER in the environment Caddy is running in.

{
    log default {
        output loki https://myuser:password@loki.example.com {
            label {
                REGION iad
            }
        }
    }
}

Sends log messages to a Loki instance running at loki.example.com using basic authentication and with the REGION=iad label.