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The run command

The run command runs Alloy in the foreground until an interrupt is received.

Usage

shell 
alloy run [<FLAG> ...] <PATH_NAME>

Replace the following:

  • <FLAG>: One or more flags that define the input and output of the command.
  • <PATH_NAME>: Required. The Alloy configuration file/directory path.

If the <PATH_NAME> argument isn’t provided, or if the configuration path can’t be loaded or contains errors during the initial load, the run command immediately exits and shows an error message.

If you give the <PATH_NAME> argument a directory path, Alloy finds *.alloy files (ignoring nested directories) and loads them as a single configuration source. However, component names must be unique across all Alloy configuration files, and configuration blocks must not be repeated.

Alloy continues to run if subsequent reloads of the configuration file fail, potentially marking components as unhealthy depending on the nature of the failure. When this happens, Alloy continues functioning in the last valid state.

run launches an HTTP server that exposes metrics about itself and its components. The HTTP server is also exposes a UI at / for debugging running components.

The following flags are supported:

  • --server.http.enable-pprof: Enable /debug/pprof profiling endpoints. (default true).
  • --server.http.memory-addr: Address to listen for in-memory HTTP traffic on (default alloy.internal:12345).
  • --server.http.listen-addr: Address to listen for HTTP traffic on (default 127.0.0.1:12345).
  • --server.http.ui-path-prefix: Base path where the UI is exposed (default /).
  • --storage.path: Base directory where components can store data (default data-alloy/).
  • --disable-reporting: Disable data collection (default false).
  • --disable-support-bundle: Disable support bundle endpoint (default false).
  • --cluster.enabled: Start Alloy in clustered mode (default false).
  • --cluster.node-name: The name to use for this node (defaults to the environment’s hostname).
  • --cluster.join-addresses: Comma-separated list of addresses to join the cluster at (default ""). Mutually exclusive with --cluster.discover-peers.
  • --cluster.discover-peers: List of key-value tuples for discovering peers (default ""). Mutually exclusive with --cluster.join-addresses.
  • --cluster.rejoin-interval: How often to rejoin the list of peers (default "60s").
  • --cluster.advertise-address: Address to advertise to other cluster nodes (default "").
  • --cluster.advertise-interfaces: List of interfaces used to infer an address to advertise. Set to all to use all available network interfaces on the system. (default "eth0,en0").
  • --cluster.max-join-peers: Number of peers to join from the discovered set (default 5).
  • --cluster.name: Name to prevent nodes without this identifier from joining the cluster (default "").
  • --cluster.enable-tls: Specifies whether TLS should be used for communication between peers (default false).
  • --cluster.tls-ca-path: Path to the CA certificate file used for peer communication over TLS.
  • --cluster.tls-cert-path: Path to the certificate file used for peer communication over TLS.
  • --cluster.tls-key-path: Path to the key file used for peer communication over TLS.
  • --cluster.tls-server-name: Server name used for peer communication over TLS.
  • --config.format: The format of the source file. Supported formats: alloy, otelcol, prometheus, promtail, static (default "alloy").
  • --config.bypass-conversion-errors: Enable bypassing errors when converting (default false).
  • --config.extra-args: Extra arguments from the original format used by the converter.
  • --stability.level: The minimum permitted stability level of functionality to run. Supported values: experimental, public-preview, generally-available (default "generally-available").
  • --feature.community-components.enabled: Enable community components (default false).

Update the configuration file

The configuration file can be reloaded from disk by either:

  • Sending an HTTP POST request to the /-/reload endpoint.
  • Sending a SIGHUP signal to the Alloy process.

When this happens, the component controller synchronizes the set of running components with the latest set of components specified in the configuration file. Components that are no longer defined in the configuration file after reloading are shut down, and components that have been added to the configuration file since the previous reload are created.

All components managed by the component controller are reevaluated after reloading.

Permitted stability levels

By default, Alloy only allows you to use functionality that is marked Generally available.

To use Experimental or Public preview functionality, set the --stability.level flag to the level you want to use:

  • --stability.level=experimental: Use functionality marked as Experimental and above.
  • --stability.level=public-preview: Use functionality marked as Public preview and above.
  • --stability.level=generally-available: Use functionality marked as Generally available.

Caution

Setting --stability.level to experimental or public-preview may enable Experimental or Public preview behavior for items otherwise marked Generally available, such as:

  • The component controller
  • Components in the main configuration or in imported modules
  • Configuration blocks in the main configuration

Refer to Release life cycle for Grafana Labs for the definition of each stability level.

Clustering

The --cluster.enabled command-line argument starts Alloy in clustering mode. The rest of the --cluster.* command-line flags can be used to configure how nodes discover and connect to one another.

Each cluster member’s name must be unique within the cluster. Nodes which try to join with a conflicting name are rejected and fall back to bootstrapping a new cluster of their own.

Peers communicate over HTTP/2 on the built-in HTTP server. Each node must be configured to accept connections on --server.http.listen-addr and the address defined or inferred in --cluster.advertise-address.

If the --cluster.advertise-address flag isn’t explicitly set, Alloy tries to infer a suitable one from --cluster.advertise-interfaces. If --cluster.advertise-interfaces isn’t explicitly set, Alloy infers one from the eth0 and en0 local network interfaces. Alloy will fail to start if it can’t determine the advertised address. Since Windows doesn’t use the interface names eth0 or en0, Windows users must explicitly pass at least one valid network interface for --cluster.advertise-interfaces or a value for --cluster.advertise-address.

The comma-separated list of addresses provided in --cluster.join-addresses can either be IP addresses or DNS names to lookup (supports SRV and A/AAAA records). In both cases, the port number can be specified with a :<port> suffix. If ports aren’t provided, default of the port used for the HTTP listener is used. If you don’t provide the port number explicitly, you must ensure that all instances use the same port for the HTTP listener.

The --cluster.enable-tls flag can be set to enable TLS for peer-to-peer communications. Additional arguments are required to configure the TLS client, including the CA certificate, the TLS certificate, the key, and the server name.

The --cluster.discover-peers command-line flag expects a list of tuples in the form of provider=XXX key=val key=val .... Clustering uses the go-discover package to discover peers and fetch their IP addresses, based on the chosen provider and the filtering key-values it supports. Clustering supports the default set of providers available in go-discover and registers the k8s provider on top.

If either the key or the value in a tuple pair contains a space, a backslash, or double quotes, then it must be quoted with double quotes. Within this quoted string, the backslash can be used to escape double quotes or the backslash itself.

The --cluster.rejoin-interval flag defines how often each node should rediscover peers based on the contents of the --cluster.join-addresses and --cluster.discover-peers flags and try to rejoin them. This operation is useful for addressing split-brain issues if the initial bootstrap is unsuccessful and for making clustering easier to manage in dynamic environments. To disable this behavior, set the --cluster.rejoin-interval flag to "0s".

Discovering peers using the --cluster.join-addresses and --cluster.discover-peers flags only happens on startup. After that, cluster nodes depend on gossiping messages with each other to converge on the cluster’s state.

The first node that’s used to bootstrap a new cluster (also known as the “seed node”) can either omit the flags that specify peers to join or can try to connect to itself.

To join or rejoin a cluster, Alloy tries to connect to a certain number of peers limited by the --cluster.max-join-peers flag. This flag can be useful for clusters of significant sizes because connecting to a high number of peers can be an expensive operation. To disable this behavior, set the --cluster.max-join-peers flag to 0. If the value of --cluster.max-join-peers is higher than the number of peers discovered, Alloy connects to all of them.

The --cluster.name flag can be used to prevent clusters from accidentally merging. When --cluster.name is provided, nodes only join peers who share the same cluster name value. By default, the cluster name is empty, and any node that doesn’t set the flag can join. Attempting to join a cluster with a wrong --cluster.name results in a “failed to join memberlist” error.

Clustering states

Clustered Alloys are in one of three states:

  • Viewer: Alloy has a read-only view of the cluster and isn’t participating in workload distribution.
  • Participant: Alloy is participating in workload distribution for components that have clustering enabled.
  • Terminating: Alloy is shutting down and no longer assigning new work to itself.

Each Alloy initially joins the cluster in the viewer state and then transitions to the participant state after the process startup completes. Each Alloy then transitions to the terminating state when shutting down.

The current state of a clustered Alloy is shown on the clustering page in the UI.

Configuration conversion

Public preview: This is a public preview component. Public preview components are subject to breaking changes, and may be replaced with equivalent functionality that cover the same use case. The stability.level flag must be set to public-preview or below to use the component.

When you use the --config.format command-line argument with a value other than alloy, Alloy converts the configuration file from the source format to Alloy and immediately starts running with the new configuration. This conversion uses the converter API described in the alloy convert docs.

If you include the --config.bypass-conversion-errors command-line argument, Alloy ignores errors from the converter. Use this argument with caution because the resulting conversion may not be equivalent to the original configuration.

Include --config.extra-args to pass additional command line flags from the original format to the converter. Refer to alloy convert for more details on how extra-args work.