The thanos sidecar command runs a component that gets deployed along with a Prometheus instance. This allows sidecar to optionally upload metrics to object storage and allow Queriers to query Prometheus data with common, efficient StoreAPI.
In details:
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It implements Thanos' Store API on top of Prometheus' remote-read API. This allows Queriers to treat Prometheus servers as yet another source of time series data without directly talking to its APIs.
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Optionally, the sidecar uploads TSDB blocks to an object storage bucket as Prometheus produces them every 2 hours. This allows Prometheus servers to be run with relatively low retention while their historic data is made durable and queryable via object storage.
NOTE: This still does NOT mean that Prometheus can be fully stateless, because if it crashes and restarts you will lose ~2 hours of metrics, so persistent disk for Prometheus is highly recommended. The closest to stateless you can get is using remote write (which Thanos supports, see Receiver. Remote write has other risks and consequences, and still if crashed you lose in positive case seconds of metrics data, so persistent disk is recommended in all cases.
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Optionally Thanos sidecar is able to watch Prometheus rules and configuration, decompress and substitute environment variables if needed and ping Prometheus to reload them. Read more about this in here
Prometheus servers connected to the Thanos cluster via the sidecar are subject to a few limitations and recommendations for safe operations:
- The recommended Prometheus version is 2.2.1 or greater (including newest releases). This is due to Prometheus instability in previous versions as well as lack of
flagsendpoint. - (!) The Prometheus
external_labelssection of the Prometheus configuration file has unique labels in the overall Thanos system. Those external labels will be used by the sidecar and then Thanos in many places. See external labels docs. - The
--web.enable-admin-apiflag is enabled to support sidecar to get metadata from Prometheus like external labels. - The
--web.enable-lifecycleflag is enabled if you want to use sidecar reloading features (--reload.*flags).
If you choose to use the sidecar to also upload data to object storage:
- Must specify object storage (
--objstore.*flags) - It only uploads uncompacted Prometheus blocks. For compacted blocks, see Upload compacted blocks.
- The
--storage.tsdb.min-block-durationand--storage.tsdb.max-block-durationmust be set to equal values to disable local compaction in order to use Thanos sidecar upload, otherwise leave local compaction on if sidecar just exposes StoreAPI and your retention is normal. The default of2his recommended. Mentioned parameters set to equal values disable the internal Prometheus compaction, which is needed to avoid the corruption of uploaded data when Thanos compactor does its job, this is critical for data consistency and should not be ignored if you plan to use Thanos compactor. Even though you set mentioned parameters equal, you might observe Prometheus internal metricprometheus_tsdb_compactions_totalbeing incremented, don't be confused by that: Prometheus writes initial head block to filesystem via its internal compaction mechanism, but if you have followed recommendations - data won't be modified by Prometheus before the sidecar uploads it. Thanos sidecar will also check sanity of the flags set to Prometheus on the startup and log errors or warning if they have been configured improperly (#838). - The retention of Prometheus is recommended to not be lower than three times of the min block duration, so 6 hours. This achieves resilience in the face of connectivity issues to the object storage since all local data will remain available within the Thanos cluster. If connectivity gets restored the backlog of blocks gets uploaded to the object storage.
Thanos can watch changes in Prometheus configuration and refresh Prometheus configuration if --web.enable-lifecycle enabled.
You can configure watching for changes in directory via --reloader.rule-dir=DIR_NAME flag.
Thanos sidecar can watch --reloader.config-file=CONFIG_FILE configuration file, replace environment variables found in there in $(VARIABLE) format, and produce generated config in --reloader.config-envsubst-file=OUT_CONFIG_FILE file.
prometheus \
--storage.tsdb.max-block-duration=2h \
--storage.tsdb.min-block-duration=2h \
--web.enable-lifecyclethanos sidecar \
--tsdb.path "/path/to/prometheus/data/dir" \
--prometheus.url "http://localhost:9090" \
--objstore.config-file "bucket.yml"The example content of bucket.yml:
type: GCS
config:
bucket: ""
service_account: ""If you want to migrate from a pure Prometheus setup to Thanos and have to keep the historical data, you can use the flag --shipper.upload-compacted. This will also upload blocks that were compacted by Prometheus. Values greater than 1 in the compaction.level field of a Prometheus block’s meta.json file indicate level of compaction.
To use this, the Prometheus compaction needs to be disabled. This can be done by setting the following flags for Prometheus:
--storage.tsdb.min-block-duration=2h--storage.tsdb.max-block-duration=2h
usage: thanos sidecar [<flags>]
Sidecar for Prometheus server.
Flags:
--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-grace-period=2m Time to wait after an interrupt received for
GRPC Server.
--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
--hash-func= Specify which hash function to use when
calculating the hashes of produced files. If no
function has been specified, it does not
happen. This permits avoiding downloading some
files twice albeit at some performance cost.
Possible values are: "", "SHA256".
-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.
--min-time=0000-01-01T00:00:00Z
Start of time range limit to serve. Thanos
sidecar will serve only metrics, which happened
later than this value. Option can be a constant
time in RFC3339 format or time duration
relative to current time, such as -1d or 2h45m.
Valid duration units are ms, s, m, h, d, w, y.
--objstore.config=<content>
Alternative to 'objstore.config-file' flag
(mutually exclusive). Content of YAML file that
contains object store configuration. See format
details:
https://thanos.io/tip/thanos/storage.md/#configuration
--objstore.config-file=<file-path>
Path to YAML file that contains object store
configuration. See format details:
https://thanos.io/tip/thanos/storage.md/#configuration
--prometheus.http-client=<content>
Alternative to 'prometheus.http-client-file'
flag (mutually exclusive). Content of YAML file
or string with http client configs. see Format
details : ...
--prometheus.http-client-file=<file-path>
Path to YAML file or string with http client
configs. see Format details : ...
--prometheus.ready_timeout=10m
Maximum time to wait for the Prometheus
instance to start up
--prometheus.url=http://localhost:9090
URL at which to reach Prometheus's API. For
better performance use local network.
--reloader.config-envsubst-file=""
Output file for environment variable
substituted config file.
--reloader.config-file="" Config file watched by the reloader.
--reloader.retry-interval=5s
Controls how often reloader retries config
reload in case of error.
--reloader.rule-dir=RELOADER.RULE-DIR ...
Rule directories for the reloader to refresh
(repeated field).
--reloader.watch-interval=3m
Controls how often reloader re-reads config and
rules.
--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://gist.github.com/yashrsharma44/02f5765c5710dd09ce5d14e854f22825
--request.logging-config-file=<file-path>
Path to YAML file with request logging
configuration. See format details:
https://gist.github.com/yashrsharma44/02f5765c5710dd09ce5d14e854f22825
--shipper.upload-compacted
If true shipper will try to upload compacted
blocks as well. Useful for migration purposes.
Works only if compaction is disabled on
Prometheus. Do it once and then disable the
flag when done.
--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
--tsdb.path="./data" Data directory of TSDB.
--version Show application version.