The thanos query command (also known as "Querier") implements the Prometheus HTTP v1 API to query data in a Thanos cluster via PromQL.
In short, it gathers the data needed to evaluate the query from underlying StoreAPIs, evaluates the query and returns the result.
Querier is fully stateless and horizontally scalable.
Example command to run Querier:
thanos query \
--http-address "0.0.0.0:9090" \
--endpoint "<store-api>:<grpc-port>" \
--endpoint "<store-api2>:<grpc-port>"Thanos Querier essentially allows to aggregate and optionally deduplicate multiple metrics backends under single Prometheus Query endpoint.
Since for Querier "a backend" is anything that implements gRPC StoreAPI we can aggregate data from any number of the different storages like:
- Prometheus (see Sidecar)
- Object Storage (see Store Gateway)
- Global alerting/recording rules evaluations (see Ruler)
- Metrics received from Prometheus remote write streams (see Receiver)
- Another Querier (you can stack Queriers on top of each other)
- Non-Prometheus systems!
- e.g OpenTSDB
Thanks to that, you can run queries (manually, from Grafana or via Alerting rule) that aggregate metrics from mix of those sources.
Some examples:
-
sum(cpu_used{cluster=~"cluster-(eu1|eu2|eu3|us1|us2|us3)", job="service1"})that will give you sum of CPU used inside all listed clusters for serviceservice1. This will work even if those clusters runs multiple Prometheus servers each. Querier will know which data sources to query. -
In single cluster you shard Prometheus functionally or have different Prometheus instances for different tenants. You can spin up Querier to have access to both within single Query evaluation.
Prometheus is stateful and does not allow replicating its database. This means that increasing high availability by running multiple Prometheus replicas is not very easy to use. Simple load balancing will not work as for example after some crash, replica might be up but querying such replica will result in small gap during the period it was down. You have a second replica that maybe was up, but it could be down in other moment (e.g rolling restart), so load balancing on top of those is not working well.
Thanos Querier instead pulls the data from both replicas, and deduplicate those signals, filling the gaps if any, transparently to the Querier consumer.
Overall QueryAPI exposed by Thanos is guaranteed to be compatible with Prometheus 2.x. API. The above diagram shows what Querier does for each Prometheus query request.
See here on how to connect Querier with desired StoreAPIs.
The query layer can deduplicate series that were collected from high-availability pairs of data sources such as Prometheus. A fixed single or multiple replica labels must be chosen for the entire cluster and can then be passed to query nodes on startup.
Two or more series that are only distinguished by the given replica label, will be merged into a single time series. This also hides gaps in collection of a single data source.
- Prometheus + sidecar "A":
cluster=1,env=2,replica=A - Prometheus + sidecar "B":
cluster=1,env=2,replica=B - Prometheus + sidecar "A" in different cluster:
cluster=2,env=2,replica=A
If we configure Querier like this:
thanos query \
--http-address "0.0.0.0:9090" \
--query.replica-label "replica" \
--endpoint "<store-api>:<grpc-port>" \
--endpoint "<store-api2>:<grpc-port>" \
And we query for metric up{job="prometheus",env="2"} with this option we will get 2 results:
up{job="prometheus",env="2",cluster="1"} 1up{job="prometheus",env="2",cluster="2"} 1
WITHOUT this replica flag (deduplication turned off), we will get 3 results:
up{job="prometheus",env="2",cluster="1",replica="A"} 1up{job="prometheus",env="2",cluster="1",replica="B"} 1up{job="prometheus",env="2",cluster="2",replica="A"} 1
- Prometheus + sidecar "A":
cluster=1,env=2,replica=A,replicaX=A - Prometheus + sidecar "B":
cluster=1,env=2,replica=B,replicaX=B - Prometheus + sidecar "A" in different cluster:
cluster=2,env=2,replica=A,replicaX=A
thanos query \
--http-address "0.0.0.0:9090" \
--query.replica-label "replica" \
--query.replica-label "replicaX" \
--endpoint "<store-api>:<grpc-port>" \
--endpoint "<store-api2>:<grpc-port>" \
This logic can also be controlled via parameter on QueryAPI. More details below.
By default, Thanos querier comes with standard Prometheus PromQL engine. However, when --query.promql-engine=thanos is specified, Thanos will use experimental Thanos PromQL engine which is a drop-in, efficient implementation of PromQL engine with query planner and optimizers.
To learn more, see the introduction talk from the PromConEU 2022.
This feature is still experimental given active development. All queries should be supported due to bulit-in fallback to old PromQL if something is not yet implemented.
For new engine bugs/issues, please use https://github.com/thanos-community/promql-engine GitHub issues.
As mentioned, Query API exposed by Thanos is guaranteed to be compatible with Prometheus 2.x. API. However for additional Thanos features on top of Prometheus, Thanos adds:
- partial response behaviour
- several additional parameters listed below
- custom response fields.
Let's walk through all of those extensions:
QueryAPI and StoreAPI has additional behaviour controlled via query parameter called PartialResponseStrategy.
This parameter controls tradeoff between accuracy and availability.
Partial response is a potentially missed result within query against QueryAPI or StoreAPI. This can happen if one of StoreAPIs is returning error or timeout whereas couple of others returns success. It does not mean you are missing data, you might lucky enough that you actually get the correct data as the broken StoreAPI did not have anything for your query.
If partial response happen QueryAPI returns human readable warnings explained here.
Now it supports two strategies:
- "warn"
- "abort" (default)
NOTE: Having a warning does not necessarily mean partial response (e.g no store matched query warning).
Querier also allows to configure different timeouts:
--query.timeout--store.response-timeout
If you prefer availability over accuracy you can set tighter timeout to underlying StoreAPI than overall query timeout. If partial response strategy is NOT abort, this will "ignore" slower StoreAPIs producing just warning with 200 status code response.
| HTTP URL/FORM parameter | Type | Default | Example |
|---|---|---|---|
replicaLabels |
[]string |
query.replica-label flag (default: empty). |
replicaLabels=replicaA&replicaLabels=replicaB |
This overwrites the query.replica-label cli flag to allow dynamic replica labels at query time.
| HTTP URL/FORM parameter | Type | Default | Example |
|---|---|---|---|
dedup |
Boolean |
True, but effect depends on query.replica configuration flag. |
1, t, T, TRUE, true, True for "True" |
This controls if query results should be deduplicated using the replica labels.
| HTTP URL/FORM parameter | Type | Default | Example |
|---|---|---|---|
max_source_resolution |
Float64/time.Duration/model.Duration |
step / 5 or 0 if query.auto-downsampling is false (default: False) |
5m |
Max source resolution is max resolution in seconds we want to use for data we query for.
Available options:
auto- Select downsample resolution automatically based on the query.0- Only use raw data.5m- Use max 5m downsampling.1h- Use max 1h downsampling.
| HTTP URL/FORM parameter | Type | Default | Example |
|---|---|---|---|
partial_response |
Boolean |
query.partial-response flag (default: True) |
1, t, T, TRUE, true, True for "True" |
If true, then all storeAPIs that will be unavailable (and thus return no data) will not cause query to fail, but instead return warning.
Any additional field does not break compatibility, however there is no guarantee that Grafana or any other client will understand those.
Currently Thanos UI exposed by Thanos understands
type queryData struct {
ResultType promql.ValueType `json:"resultType"`
Result promql.Value `json:"result"`
// Additional Thanos Response field.
Warnings []error `json:"warnings,omitempty"`
}Additional field is Warnings that contains every error that occurred that is assumed non critical. partial_response option controls if storeAPI unavailability is considered critical.
Thanos Querier has the ability to perform concurrent select request per query. It dissects given PromQL statement and executes selectors concurrently against the discovered StoreAPIs. The maximum number of concurrent requests are being made per query is controlled by query.max-concurrent-select flag. Keep in mind that the maximum number of concurrent queries that are handled by querier is controlled by query.max-concurrent. Please consider implications of combined value while tuning the querier.
It's possible to provide a set of matchers to the Querier api to select specific stores to be used during the query using the storeMatch[] parameter. It is useful when debugging a slow/broken store. It uses the same format as the matcher of Prometheus' federate api. Note that at the moment the querier only supports the __address__ which contain the address of the store as it is shown on the /stores endpoint of the UI.
Example:
- targets:
- prometheus-foo.thanos-sidecar:10901
- prometheus-bar.thanos-sidecar:10901
http://localhost:10901/api/v1/query?query=up&dedup=true&partial_response=true&storeMatch[]={__address__=~"prometheus-foo.*"}
Will only return metrics from prometheus-foo.thanos-sidecar:10901
It is possible to expose thanos-query UI and optionally API on a sub-path. The sub-path can be defined either statically or dynamically via an HTTP header. Static path prefix definition follows the pattern used in Prometheus, where web.route-prefix option defines HTTP request path prefix (endpoints prefix) and web.external-prefix prefixes the URLs in HTML code and the HTTP redirect responses.
Additionally, Thanos supports dynamic prefix configuration, which is not yet implemented by Prometheus. Dynamic prefixing simplifies setup when thanos query is exposed on a sub-path behind a reverse proxy, for example, via a Kubernetes ingress controller Traefik or nginx. If PathPrefixStrip: /some-path option or traefik.frontend.rule.type: PathPrefixStrip Kubernetes Ingress annotation is set, then Traefik writes the stripped prefix into X-Forwarded-Prefix header. Then, thanos query --web.prefix-header=X-Forwarded-Prefix will serve correct HTTP redirects and links prefixed by the stripped path.
--store.sd-files flag provides a path to a JSON or YAML formatted file, which contains a list of targets in Prometheus target format.
Example file SD file in YAML:
- targets:
- prometheus-0.thanos-sidecar:10901
- prometheus-1.thanos-sidecar:10901
- thanos-store:10901
- thanos-short-store:10901
- thanos-rule:10901
- targets:
- prometheus-0.thanos-sidecar.infra:10901
- prometheus-1.thanos-sidecar.infra:10901
- thanos-store.infra:10901
--query.active-query-path is an option which allows the user to specify a directory which will contain a queries.active file to track active queries. To enable this feature, the user has to specify a directory other than "", since that is skipped being the default.
Tenant information is captured in relevant Thanos exported metrics in the Querier, Query Frontend and Store. In order make use of this functionality requests to the Query/Query Frontend component should include the tenant-id in the appropriate HTTP request header as configured with --query.tenant-header. The tenant information is passed through components (including Query Frontend), down to the Thanos Store, enabling per-tenant metrics in these components also. If no tenant header is set to requests to the query component, the default tenant as defined by --query.tenant-default-id will be used.
Enforcement of tenancy can be enabled using --query.enforce-tenancy. If enabled, queries will only fetch series containing a specific matcher, while evaluating PromQL expressions. The matcher label name is --query.tenant-label-name and the matcher value matches the tenant, as sent to the querier in the HTTP header configured with --query-tenant-header. This functionality requires that metrics are injected with a tenant label when ingested into Thanos. This can be done for example by enabling tenancy in the Thanos Receive component.
In case of nested Thanos Query components, it's important to note that tenancy enforcement will only occur in the querier which the initial request is sent to, the layered queriers will not perform any enforcement.
Further, note that there are no authentication mechanisms in Thanos, so anyone can set an arbitrary tenant in the HTTP header. It is recommended to use a proxy in front of the querier in case an authentication mechanism is needed. The Query UI also includes an option to set an arbitrary tenant, and should therefore not be exposed to end-users if users should not be able to see each others data.
The distributed execution mode can be enabled using --query.mode=distributed. When this mode is enabled, the Querier will break down each query into independent fragments and delegate them to components which implement the Query API.
This mode is particularly useful in architectures where multiple independent Queriers are deployed in separate environments (different regions or different Kubernetes clusters) and are federated through a separate central Querier. A Querier running in the distributed mode will only talk to Queriers, or other components which implement the Query API. Endpoints which only act as Stores (e.g. Store Gateways or Rulers), and are directly connected to a distributed Querier, will not be included in the execution of a distributed query. This constraint should help with keeping the distributed query execution simple and efficient, but could be removed in the future if there are good use cases for it.
For further details on the design and use cases of this feature, see the official design document.
usage: thanos query [<flags>]
Query node exposing PromQL enabled Query API with data retrieved from multiple
store nodes.
Flags:
--alert.query-url=ALERT.QUERY-URL
The external Thanos Query URL that would be set
in all alerts 'Source' field.
--endpoint=<endpoint> ... Addresses of statically configured Thanos
API servers (repeatable). The scheme may be
prefixed with 'dns+' or 'dnssrv+' to detect
Thanos API servers through respective DNS
lookups.
--endpoint-group=<endpoint-group> ...
Experimental: DNS name of statically configured
Thanos API server groups (repeatable). Targets
resolved from the DNS name will be queried in
a round-robin, instead of a fanout manner.
This flag should be used when connecting a
Thanos Query to HA groups of Thanos components.
--endpoint-group-strict=<endpoint-group-strict> ...
Experimental: DNS name of statically configured
Thanos API server groups (repeatable) that are
always used, even if the health check fails.
--endpoint-strict=<staticendpoint> ...
Addresses of only statically configured Thanos
API servers that are always used, even if
the health check fails. Useful if you have a
caching layer on top.
--grpc-address="0.0.0.0:10901"
Listen ip:port address for gRPC endpoints
(StoreAPI). Make sure this address is routable
from other components.
--grpc-client-server-name=""
Server name to verify the hostname on
the returned gRPC certificates. See
https://tools.ietf.org/html/rfc4366#section-3.1
--grpc-client-tls-ca="" TLS CA Certificates to use to verify gRPC
servers
--grpc-client-tls-cert="" TLS Certificates to use to identify this client
to the server
--grpc-client-tls-key="" TLS Key for the client's certificate
--grpc-client-tls-secure Use TLS when talking to the gRPC server
--grpc-client-tls-skip-verify
Disable TLS certificate verification i.e self
signed, signed by fake CA
--grpc-compression=none Compression algorithm to use for gRPC requests
to other clients. Must be one of: snappy, none
--grpc-grace-period=2m Time to wait after an interrupt received for
GRPC Server.
--grpc-server-max-connection-age=60m
The grpc server max connection age. This
controls how often to re-establish connections
and redo TLS handshakes.
--grpc-server-tls-cert="" TLS Certificate for gRPC server, leave blank to
disable TLS
--grpc-server-tls-client-ca=""
TLS CA to verify clients against. If no
client CA is specified, there is no client
verification on server side. (tls.NoClientCert)
--grpc-server-tls-key="" TLS Key for the gRPC server, leave blank to
disable TLS
-h, --help Show context-sensitive help (also try
--help-long and --help-man).
--http-address="0.0.0.0:10902"
Listen host:port for HTTP endpoints.
--http-grace-period=2m Time to wait after an interrupt received for
HTTP Server.
--http.config="" [EXPERIMENTAL] Path to the configuration file
that can enable TLS or authentication for all
HTTP endpoints.
--log.format=logfmt Log format to use. Possible options: logfmt or
json.
--log.level=info Log filtering level.
--query.active-query-path=""
Directory to log currently active queries in
the queries.active file.
--query.auto-downsampling Enable automatic adjustment (step / 5) to what
source of data should be used in store gateways
if no max_source_resolution param is specified.
--query.conn-metric.label=external_labels... ...
Optional selection of query connection metric
labels to be collected from endpoint set
--query.default-evaluation-interval=1m
Set default evaluation interval for sub
queries.
--query.default-step=1s Set default step for range queries. Default
step is only used when step is not set in UI.
In such cases, Thanos UI will use default
step to calculate resolution (resolution
= max(rangeSeconds / 250, defaultStep)).
This will not work from Grafana, but Grafana
has __step variable which can be used.
--query.default-tenant-id="default-tenant"
Default tenant ID to use if tenant header is
not present
--query.enable-x-functions
Whether to enable extended rate functions
(xrate, xincrease and xdelta). Only has effect
when used with Thanos engine.
--query.enforce-tenancy Enforce tenancy on Query APIs. Responses
are returned only if the label value of the
configured tenant-label-name and the value of
the tenant header matches.
--query.lookback-delta=QUERY.LOOKBACK-DELTA
The maximum lookback duration for retrieving
metrics during expression evaluations.
PromQL always evaluates the query for the
certain timestamp (query range timestamps are
deduced by step). Since scrape intervals might
be different, PromQL looks back for given
amount of time to get latest sample. If it
exceeds the maximum lookback delta it assumes
series is stale and returns none (a gap).
This is why lookback delta should be set to at
least 2 times of the slowest scrape interval.
If unset it will use the promql default of 5m.
--query.max-concurrent=20 Maximum number of queries processed
concurrently by query node.
--query.max-concurrent-select=4
Maximum number of select requests made
concurrently per a query.
--query.metadata.default-time-range=0s
The default metadata time range duration for
retrieving labels through Labels and Series API
when the range parameters are not specified.
The zero value means range covers the time
since the beginning.
--query.mode=local PromQL query mode. One of: local, distributed.
--query.partial-response Enable partial response for queries if
no partial_response param is specified.
--no-query.partial-response for disabling.
--query.promql-engine=prometheus
Default PromQL engine to use.
--query.replica-label=QUERY.REPLICA-LABEL ...
Labels to treat as a replica indicator along
which data is deduplicated. Still you will
be able to query without deduplication using
'dedup=false' parameter. Data includes time
series, recording rules, and alerting rules.
--query.telemetry.request-duration-seconds-quantiles=0.1... ...
The quantiles for exporting metrics about the
request duration quantiles.
--query.telemetry.request-samples-quantiles=100... ...
The quantiles for exporting metrics about the
samples count quantiles.
--query.telemetry.request-series-seconds-quantiles=10... ...
The quantiles for exporting metrics about the
series count quantiles.
--query.tenant-certificate-field=
Use TLS client's certificate field to determine
tenant for write requests. Must be one of
organization, organizationalUnit or commonName.
This setting will cause the query.tenant-header
flag value to be ignored.
--query.tenant-header="THANOS-TENANT"
HTTP header to determine tenant.
--query.tenant-label-name="tenant_id"
Label name to use when enforcing tenancy (if
--query.enforce-tenancy is enabled).
--query.timeout=2m Maximum time to process query by query node.
--request.logging-config=<content>
Alternative to 'request.logging-config-file'
flag (mutually exclusive). Content
of YAML file with request logging
configuration. See format details:
https://thanos.io/tip/thanos/logging.md/#configuration
--request.logging-config-file=<file-path>
Path to YAML file with request logging
configuration. See format details:
https://thanos.io/tip/thanos/logging.md/#configuration
--selector-label=<name>="<value>" ...
Query selector labels that will be exposed in
info endpoint (repeated).
--store=<store> ... Deprecation Warning - This flag is deprecated
and replaced with `endpoint`. Addresses of
statically configured store API servers
(repeatable). The scheme may be prefixed with
'dns+' or 'dnssrv+' to detect store API servers
through respective DNS lookups.
--store-strict=<staticstore> ...
Deprecation Warning - This flag is deprecated
and replaced with `endpoint-strict`. Addresses
of only statically configured store API servers
that are always used, even if the health check
fails. Useful if you have a caching layer on
top.
--store.limits.request-samples=0
The maximum samples allowed for a single
Series request, The Series call fails if
this limit is exceeded. 0 means no limit.
NOTE: For efficiency the limit is internally
implemented as 'chunks limit' considering each
chunk contains a maximum of 120 samples.
--store.limits.request-series=0
The maximum series allowed for a single Series
request. The Series call fails if this limit is
exceeded. 0 means no limit.
--store.response-timeout=0ms
If a Store doesn't send any data in this
specified duration then a Store will be ignored
and partial data will be returned if it's
enabled. 0 disables timeout.
--store.sd-dns-interval=30s
Interval between DNS resolutions.
--store.sd-files=<path> ...
Path to files that contain addresses of store
API servers. The path can be a glob pattern
(repeatable).
--store.sd-interval=5m Refresh interval to re-read file SD files.
It is used as a resync fallback.
--store.unhealthy-timeout=5m
Timeout before an unhealthy store is cleaned
from the store UI page.
--tracing.config=<content>
Alternative to 'tracing.config-file' flag
(mutually exclusive). Content of YAML file
with tracing configuration. See format details:
https://thanos.io/tip/thanos/tracing.md/#configuration
--tracing.config-file=<file-path>
Path to YAML file with tracing
configuration. See format details:
https://thanos.io/tip/thanos/tracing.md/#configuration
--version Show application version.
--web.disable-cors Whether to disable CORS headers to be set by
Thanos. By default Thanos sets CORS headers to
be allowed by all.
--web.external-prefix="" Static prefix for all HTML links and
redirect URLs in the UI query web interface.
Actual endpoints are still served on / or the
web.route-prefix. This allows thanos UI to be
served behind a reverse proxy that strips a URL
sub-path.
--web.prefix-header="" Name of HTTP request header used for dynamic
prefixing of UI links and redirects.
This option is ignored if web.external-prefix
argument is set. Security risk: enable
this option only if a reverse proxy in
front of thanos is resetting the header.
The --web.prefix-header=X-Forwarded-Prefix
option can be useful, for example, if Thanos
UI is served via Traefik reverse proxy with
PathPrefixStrip option enabled, which sends the
stripped prefix value in X-Forwarded-Prefix
header. This allows thanos UI to be served on a
sub-path.
--web.route-prefix="" Prefix for API and UI endpoints. This allows
thanos UI to be served on a sub-path.
Defaults to the value of --web.external-prefix.
This option is analogous to --web.route-prefix
of Prometheus.
Thanos Query also exports metrics about its own performance. You can find a list with these metrics below.
Disclaimer: this list is incomplete. The remaining metrics will be added over time.
| Name | Type | Labels | Description |
|---|---|---|---|
| grpc_client_handled_total | Counter | grpc_code, grpc_method, grpc_service, grpc_type | Number of gRPC client requests handled by this query instance (including errors) |
| grpc_server_handled_total | Counter | grpc_code, grpc_method, grpc_service, grpc_type | Number of gRPC server requests handled by this query instance (including errors) |
| thanos_store_api_query_duration_seconds | Histogram | samples_le, series_le | Duration of the Thanos Store API select phase for a query according to the amount of samples and series selected. |