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Documentation Grafana Alloy Reference Command-line interface Environment variables

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
• HTTPS_PROXY
• NO_PROXY
• PPROF_MUTEX_PROFILING_PERCENT
• PPROF_BLOCK_PROFILING_RATE
• GOMEMLIMIT
• AUTOMEMLIMIT
• AUTOMEMLIMIT_EXPERIMENT
• GOGC
• GOMAXPROCS
• GOTRACEBACK

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.

HTTP_PROXY, HTTPS_PROXY, NO_PROXY

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

You can use the HTTPS_PROXY environment variable to define the proxy server for HTTPS requests in the same manner as HTTP_PROXY.

The NO_PROXY environment variable is used to define any hosts that should be excluded from proxying. NO_PROXY should contain a comma delimited list of any of the following options.

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 using the automemlimit module, or you can explicitly set the GOMEMLIMIT environment variable before you run Alloy. You can also change the 90% ratio by setting the AUTOMEMLIMIT environment variable to a float value between 0 and 1.0. No changes occur if the limit can’t be determined and you didn’t explicitly define a GOMEMLIMIT value. The AUTOMEMLIMIT_EXPERIMENT variable can be set to system to use the automemlimit module’s System provider, which sets GOMEMLIMIT based on the same ratio applied to the total system memory. As cgroup is a Linux specific concept, this is the only way to use the automemlimit module to automatically set GOMEMLIMIT on non-Linux OSes.

GOGC

The GOGC environment variable controls the mechanism that triggers Go’s garbage collection. It represents the garbage collection target percentage. A collection is triggered when the ratio of freshly allocated data to live data remaining after the previous collection reaches this percentage. If you don’t provide this variable, GOGC defaults to 100. You can set GOGC=off to disable garbage collection.

Configuring this value in conjunction with GOMEMLIMIT can help in situations where Alloy is consuming too much memory. Go provides a very in-depth guide to understanding GOGC and GOMEMLIMIT.

GOMAXPROCS

The GOMAXPROCS environment variable defines the limit of OS threads that can simultaneously execute user-level Go code. This limit doesn’t affect the number of threads that can be blocked in system calls on behalf of Go code and those threads aren’t counted against GOMAXPROCS.

GOTRACEBACK

The GOTRACEBACK environment variable defines the behavior of the Go panic output. The standard panic output behavior is usually sufficient to debug and resolve an issue. If required, you can use this setting to collect additional information from the runtime. The following values are supported.