Environment variables

You can use environment variables to control the run-time behavior of Grafana Alloy.

The following environment variables are supported:

GODEBUG
HTTP_PROXY
PPROF_MUTEX_PROFILING_PERCENT
PPROF_BLOCK_PROFILING_RATE
GOMEMLIMIT

Refer to the Go runtime documentation for more information about Go runtime environment variables.

GODEBUG

You can use the GODEBUG environment variable to control the debugging variables within the Go runtime. The following arguments are supported.

Argument	Description	Default
`x509usefallbackroots`	Enforce a fallback on the X.509 trusted root certificates. Set to `1` to enable.	`0`
`netdns`	Force a resolver. Set to `go` for a pure Go resolver. Set to `cgo` or `win32` for a native resolver.
`netdns`	Show resolver debugging information. Set to `1` for basic information. Set to `2` for verbose.

HTTP_PROXY

You can use the HTTP_PROXY environment variable to define the hostname or IP address of the proxy server. For example, you can set the proxy to http://proxy.example.com.

PPROF_MUTEX_PROFILING_PERCENT

You can use the PPROF_MUTEX_PROFILING_PERCENT environment variable to define the percentage of mutex profiles to retrieve from the pprof mutex endpoint. If you set this variable to 5, then 5 percent of the mutexes are sampled. The default value is 0.01.

PPROF_BLOCK_PROFILING_RATE

You can use the PPROF_BLOCK_PROFILING_RATE environment variable to define the rate that mutexes are tracked. You can use the following values with this environment variable. The default value is 10000.

0: Nothing is tracked.
1: All mutexes are tracked.
A value greater than 1: The number of nanoseconds to track mutexes.

GOMEMLIMIT

Usually, the Go runtime will release memory back to the operating system when requested. In some environments, this may cause issues such as Out Of Memory (OOM) errors. You can use the GOMEMLIMIT environment variable to set a soft memory cap and limit the maximum memory Alloy can use. You can set GOMEMLIMIT to a numeric value in bytes with an optional unit suffix. The supported unit suffixes are B, KiB, MiB, GiB, and TiB. Don’t treat the GOMEMLIMIT environment variable as a hard memory limit. Alloy processes can use more memory if that memory is required. A rough number is to set GOMEMLIMIT to is 90% of the maximum memory required. For example, if you want to keep memory usage below 10GiB, use GOMEMLIMIT=9GiB.

Automatically set GOMEMLIMIT

The GOMEMLIMIT environment variable is either automatically set to 90% of an available cgroup value, or you can explicitly set the GOMEMLIMIT environment variable before you run Alloy. No changes will occur if the limit cannot be determined and you did not explicitly define a GOMEMLIMIT value.