Caution
Grafana Alloy is the new name for our distribution of the OTel collector. Grafana Agent has been deprecated and is in Long-Term Support (LTS) through October 31, 2025. Grafana Agent will reach an End-of-Life (EOL) on November 1, 2025. Read more about why we recommend migrating to Grafana Alloy.
Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.
otelcol.exporter.loadbalancing
BETA: This is a beta component. Beta components are subject to breaking changes, and may be replaced with equivalent functionality that cover the same use case.
otelcol.exporter.loadbalancing
accepts logs and traces from other otelcol
components
and writes them over the network using the OpenTelemetry Protocol (OTLP) protocol.
NOTE:
otelcol.exporter.loadbalancing
is a wrapper over the upstream OpenTelemetry Collectorloadbalancing
exporter. Bug reports or feature requests will be redirected to the upstream repository, if necessary.
Multiple otelcol.exporter.loadbalancing
components can be specified by giving them
different labels.
The decision which backend to use depends on the trace ID or the service name. The backend load doesn’t influence the choice. Even though this load-balancer won’t do round-robin balancing of the batches, the load distribution should be very similar among backends, with a standard deviation under 5% at the current configuration.
otelcol.exporter.loadbalancing
is especially useful for backends configured with tail-based samplers
which choose a backend based on the view of the full trace.
When a list of backends is updated, some of the signals will be rerouted to different backends. Around R/N of the “routes” will be rerouted differently, where:
- A “route” is either a trace ID or a service name mapped to a certain backend.
- “R” is the total number of routes.
- “N” is the total number of backends.
This should be stable enough for most cases, and the larger the number of backends, the less disruption it should cause.
Usage
otelcol.exporter.loadbalancing "LABEL" {
resolver {
...
}
protocol {
otlp {
client {}
}
}
}
Arguments
otelcol.exporter.loadbalancing
supports the following arguments:
Name | Type | Description | Default | Required |
---|---|---|---|---|
routing_key | string | Routing strategy for load balancing. | "traceID" | no |
The routing_key
attribute determines how to route signals across endpoints. Its value could be one of the following:
"service"
: spans with the sameservice.name
will be exported to the same backend. This is useful when using processors like the span metrics, so all spans for each service are sent to consistent Agent instances for metric collection. Otherwise, metrics for the same services would be sent to different Agents, making aggregations inaccurate."traceID"
: spans belonging to the same traceID will be exported to the same backend.
Blocks
The following blocks are supported inside the definition of
otelcol.exporter.loadbalancing
:
Hierarchy | Block | Description | Required |
---|---|---|---|
resolver | resolver | Configures discovering the endpoints to export to. | yes |
resolver > static | static | Static list of endpoints to export to. | no |
resolver > dns | dns | DNS-sourced list of endpoints to export to. | no |
resolver > kubernetes | kubernetes | Kubernetes-sourced list of endpoints to export to. | no |
protocol | protocol | Protocol settings. Only OTLP is supported at the moment. | no |
protocol > otlp | otlp | Configures an OTLP exporter. | no |
protocol > otlp > client | client | Configures the exporter gRPC client. | no |
protocol > otlp > client > tls | tls | Configures TLS for the gRPC client. | no |
protocol > otlp > client > keepalive | keepalive | Configures keepalive settings for the gRPC client. | no |
protocol > otlp > queue | queue | Configures batching of data before sending. | no |
protocol > otlp > retry | retry | Configures retry mechanism for failed requests. | no |
debug_metrics | debug_metrics | Configures the metrics that this component generates to monitor its state. | no |
The >
symbol indicates deeper levels of nesting. For example, resolver > static
refers to a static
block defined inside a resolver
block.
resolver block
The resolver
block configures how to retrieve the endpoint to which this exporter will send data.
Inside the resolver
block, either the dns block or the static block
should be specified. If both dns
and static
are specified, dns
takes precedence.
static block
The static
block configures a list of endpoints which this exporter will send data to.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
hostnames | list(string) | List of endpoints to export to. | yes |
dns block
The dns
block periodically resolves an IP address via the DNS hostname
attribute. This IP address
and the port specified via the port
attribute will then be used by the gRPC exporter
as the endpoint to which to export data to.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
hostname | string | DNS hostname to resolve. | yes | |
interval | duration | Resolver interval. | "5s" | no |
timeout | duration | Resolver timeout. | "1s" | no |
port | string | Port to be used with the IP addresses resolved from the DNS hostname. | "4317" | no |
kubernetes block
You can use the kubernetes
block to load balance across the pods of a Kubernetes service. The Agent will be notified
by the Kubernetes API whenever a new pod is added or removed from the service.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
service | string | Kubernetes service to resolve. | yes | |
ports | list(number) | Ports to use with the IP addresses resolved from service . | [4317] | no |
If no namespace is specified inside service
, an attempt will be made to infer the namespace for this Agent.
If this fails, the default
namespace will be used.
Each of the ports listed in ports
will be used with each of the IPs resolved from service
.
The “get”, “list”, and “watch” roles must be granted in Kubernetes for the resolver to work.
protocol block
The protocol
block configures protocol-related settings for exporting.
At the moment only the OTLP protocol is supported.
otlp block
The otlp
block configures OTLP-related settings for exporting.
client block
The client
block configures the gRPC client used by the component.
The endpoints used by the client block are the ones from the resolver
block
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
compression | string | Compression mechanism to use for requests. | "gzip" | no |
read_buffer_size | string | Size of the read buffer the gRPC client to use for reading server responses. | no | |
write_buffer_size | string | Size of the write buffer the gRPC client to use for writing requests. | "512KiB" | no |
wait_for_ready | boolean | Waits for gRPC connection to be in the READY state before sending data. | false | no |
headers | map(string) | Additional headers to send with the request. | {} | no |
balancer_name | string | Which gRPC client-side load balancer to use for requests. | pick_first | no |
authority | string | Overrides the default :authority header in gRPC requests from the gRPC client. | no | |
auth | capsule(otelcol.Handler) | Handler from an otelcol.auth component to use for authenticating requests. | no |
By default, requests are compressed with gzip.
The compression
argument controls which compression mechanism to use. Supported strings are:
"gzip"
"zlib"
"deflate"
"snappy"
"zstd"
If compression
is set to "none"
or an empty string ""
, no compression is used.
The supported values for balancer_name
are listed in the gRPC documentation on Load balancing:
pick_first
: Tries to connect to the first address, uses it for all RPCs if it connects, or tries the next address if it fails (and keeps doing that until one connection is successful). Because of this, all the RPCs will be sent to the same backend.round_robin
: Connects to all the addresses it sees and sends an RPC to each backend one at a time in order. For example, the first RPC is sent to backend-1, the second RPC is sent to backend-2, and the third RPC is sent to backend-1.
The :authority
header in gRPC specifies the host to which the request is being sent.
It’s similar to the Host
header in HTTP requests.
By default, the value for :authority
is derived from the endpoint URL used for the gRPC call.
Overriding :authority
could be useful when routing traffic using a proxy like Envoy, which makes routing decisions based on the value of the :authority
header.
You can configure an HTTP proxy with the following environment variables:
HTTPS_PROXY
NO_PROXY
The HTTPS_PROXY
environment variable specifies a URL to use for proxying
requests. Connections to the proxy are established via the HTTP CONNECT
method.
The NO_PROXY
environment variable is an optional list of comma-separated
hostnames for which the HTTPS proxy should not be used. Each hostname can be
provided as an IP address (1.2.3.4
), an IP address in CIDR notation
(1.2.3.4/8
), a domain name (example.com
), or *
. A domain name matches
that domain and all subdomains. A domain name with a leading “.”
(.example.com
) matches subdomains only. NO_PROXY
is only read when
HTTPS_PROXY
is set.
Because otelcol.exporter.loadbalancing
uses gRPC, the configured proxy server must be
able to handle and proxy HTTP/2 traffic.
tls block
The tls
block configures TLS settings used for the connection to the gRPC
server.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
ca_file | string | Path to the CA file. | no | |
ca_pem | string | CA PEM-encoded text to validate the server with. | no | |
cert_file | string | Path to the TLS certificate. | no | |
cert_pem | string | Certificate PEM-encoded text for client authentication. | no | |
insecure_skip_verify | boolean | Ignores insecure server TLS certificates. | no | |
insecure | boolean | Disables TLS when connecting to the configured server. | no | |
key_file | string | Path to the TLS certificate key. | no | |
key_pem | secret | Key PEM-encoded text for client authentication. | no | |
max_version | string | Maximum acceptable TLS version for connections. | "TLS 1.3" | no |
min_version | string | Minimum acceptable TLS version for connections. | "TLS 1.2" | no |
reload_interval | duration | The duration after which the certificate is reloaded. | "0s" | no |
server_name | string | Verifies the hostname of server certificates when set. | no |
If the server doesn’t support TLS, you must set the insecure
argument to true
.
To disable tls
for connections to the server, set the insecure
argument to true
.
If reload_interval
is set to "0s"
, the certificate never reloaded.
The following pairs of arguments are mutually exclusive and can’t both be set simultaneously:
ca_pem
andca_file
cert_pem
andcert_file
key_pem
andkey_file
keepalive block
The keepalive
block configures keepalive settings for gRPC client
connections.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
ping_wait | duration | How often to ping the server after no activity. | no | |
ping_response_timeout | duration | Time to wait before closing inactive connections if the server does not respond to a ping. | no | |
ping_without_stream | boolean | Send pings even if there is no active stream request. | no |
queue block
The queue
block configures an in-memory buffer of batches before data is sent
to the gRPC server.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
enabled | boolean | Enables an in-memory buffer before sending data to the client. | true | no |
num_consumers | number | Number of readers to send batches written to the queue in parallel. | 10 | no |
queue_size | number | Maximum number of unwritten batches allowed in the queue at the same time. | 5000 | no |
When enabled
is true
, data is first written to an in-memory buffer before sending it to the configured server.
Batches sent to the component’s input
exported field are added to the buffer as long as the number of unsent batches doesn’t exceed the configured queue_size
.
queue_size
determines how long an endpoint outage is tolerated.
Assuming 100 requests/second, the default queue size 5000
provides about 50 seconds of outage tolerance.
To calculate the correct value for queue_size
, multiply the average number of outgoing requests per second by the time in seconds that outages are tolerated.
The num_consumers
argument controls how many readers read from the buffer and send data in parallel.
Larger values of num_consumers
allow data to be sent more quickly at the expense of increased network traffic.
retry block
The retry
block configures how failed requests to the gRPC server are
retried.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
enabled | boolean | Enables retrying failed requests. | true | no |
initial_interval | duration | Initial time to wait before retrying a failed request. | "5s" | no |
max_elapsed_time | duration | Maximum time to wait before discarding a failed batch. | "5m" | no |
max_interval | duration | Maximum time to wait between retries. | "30s" | no |
multiplier | number | Factor to grow wait time before retrying. | 1.5 | no |
randomization_factor | number | Factor to randomize wait time before retrying. | 0.5 | no |
When enabled
is true
, failed batches are retried after a given interval.
The initial_interval
argument specifies how long to wait before the first retry attempt.
If requests continue to fail, the time to wait before retrying increases by the factor specified by the multiplier
argument, which must be greater than 1.0
.
The max_interval
argument specifies the upper bound of how long to wait between retries.
The randomization_factor
argument is useful for adding jitter between retrying agents.
If randomization_factor
is greater than 0
, the wait time before retries is multiplied by a random factor in the range [ I - randomization_factor * I, I + randomization_factor * I]
, where I
is the current interval.
If a batch hasn’t been sent successfully, it is discarded after the time specified by max_elapsed_time
elapses.
If max_elapsed_time
is set to "0s"
, failed requests are retried forever until they succeed.
debug_metrics block
The debug_metrics
block configures the metrics that this component generates to monitor its state.
The following arguments are supported:
Name | Type | Description | Default | Required |
---|---|---|---|---|
disable_high_cardinality_metrics | boolean | Whether to disable certain high cardinality metrics. | false | no |
disable_high_cardinality_metrics
is the Grafana Agent equivalent to the telemetry.disableHighCardinalityMetrics
feature gate in the OpenTelemetry Collector.
It removes attributes that could cause high cardinality metrics.
For example, attributes with IP addresses and port numbers in metrics about HTTP and gRPC connections are removed.
Exported fields
The following fields are exported and can be referenced by other components:
Name | Type | Description |
---|---|---|
input | otelcol.Consumer | A value that other components can use to send telemetry data to. |
input
accepts otelcol.Consumer
OTLP-formatted data for telemetry signals of these types:
- logs
- traces
Component health
otelcol.exporter.loadbalancing
is only reported as unhealthy if given an invalid
configuration.
Debug information
otelcol.exporter.loadbalancing
does not expose any component-specific debug
information.
Example
This example accepts OTLP logs and traces over gRPC. It then sends them in a load-balanced way to “localhost:55690” or “localhost:55700”.
otelcol.receiver.otlp "default" {
grpc {}
output {
traces = [otelcol.exporter.loadbalancing.default.input]
logs = [otelcol.exporter.loadbalancing.default.input]
}
}
otelcol.exporter.loadbalancing "default" {
resolver {
static {
hostnames = ["localhost:55690", "localhost:55700"]
}
}
protocol {
otlp {
client {}
}
}
}
Compatible components
otelcol.exporter.loadbalancing
has exports that can be consumed by the following components:
- Components that consume OpenTelemetry
otelcol.Consumer
Note
Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.