prometheus

Commit Graph

Author	SHA1	Message	Date
Julius Volz	61d26e8445	Add optional sample replication to OpenTSDB. Prometheus needs long-term storage. Since we don't have enough resources to build our own timeseries storage from scratch ontop of Riak, Cassandra or a similar distributed datastore at the moment, we're planning on using OpenTSDB as long-term storage for Prometheus. It's data model is roughly compatible with that of Prometheus, with some caveats. As a first step, this adds write-only replication from Prometheus to OpenTSDB, with the following things worth noting: 1) I tried to keep the integration lightweight, meaning that anything related to OpenTSDB is isolated to its own package and only main knows about it (essentially it tees all samples to both the existing storage and TSDB). It's not touching the existing TieredStorage at all to avoid more complexity in that area. This might change in the future, especially if we decide to implement a read path for OpenTSDB through Prometheus as well. 2) Backpressure while sending to OpenTSDB is handled by simply dropping samples on the floor when the in-memory queue of samples destined for OpenTSDB runs full. Prometheus also only attempts to send samples once, rather than implementing a complex retry algorithm. Thus, replication to OpenTSDB is best-effort for now. If needed, this may be extended in the future. 3) Samples are sent in batches of limited size to OpenTSDB. The optimal batch size, timeout parameters, etc. may need to be adjusted in the future. 4) OpenTSDB has different rules for legal characters in tag (label) values. While Prometheus allows any characters in label values, OpenTSDB limits them to a to z, A to Z, 0 to 9, -, _, . and /. Currently any illegal characters in Prometheus label values are simply replaced by an underscore. Especially when integrating OpenTSDB with the read path in Prometheus, we'll need to reconsider this: either we'll need to introduce the same limitations for Prometheus labels or escape/encode illegal characters in OpenTSDB in such a way that they are fully decodable again when reading through Prometheus, so that corresponding timeseries in both systems match in their labelsets. Change-Id: I8394c9c55dbac3946a0fa497f566d5e6e2d600b5	13 years ago

Author

SHA1

Message

Date

Julius Volz

61d26e8445

Add optional sample replication to OpenTSDB.

Prometheus needs long-term storage. Since we don't have enough resources
to build our own timeseries storage from scratch ontop of Riak,
Cassandra or a similar distributed datastore at the moment, we're
planning on using OpenTSDB as long-term storage for Prometheus. It's
data model is roughly compatible with that of Prometheus, with some
caveats.

As a first step, this adds write-only replication from Prometheus to
OpenTSDB, with the following things worth noting:

1)
I tried to keep the integration lightweight, meaning that anything
related to OpenTSDB is isolated to its own package and only main knows
about it (essentially it tees all samples to both the existing storage
and TSDB). It's not touching the existing TieredStorage at all to avoid
more complexity in that area. This might change in the future,
especially if we decide to implement a read path for OpenTSDB through
Prometheus as well.

2)
Backpressure while sending to OpenTSDB is handled by simply dropping
samples on the floor when the in-memory queue of samples destined for
OpenTSDB runs full.  Prometheus also only attempts to send samples once,
rather than implementing a complex retry algorithm. Thus, replication to
OpenTSDB is best-effort for now.  If needed, this may be extended in the
future.

3)
Samples are sent in batches of limited size to OpenTSDB. The optimal
batch size, timeout parameters, etc. may need to be adjusted in the
future.

4)
OpenTSDB has different rules for legal characters in tag (label) values.
While Prometheus allows any characters in label values, OpenTSDB limits
them to a to z, A to Z, 0 to 9, -, _, . and /. Currently any illegal
characters in Prometheus label values are simply replaced by an
underscore. Especially when integrating OpenTSDB with the read path in
Prometheus, we'll need to reconsider this: either we'll need to
introduce the same limitations for Prometheus labels or escape/encode
illegal characters in OpenTSDB in such a way that they are fully
decodable again when reading through Prometheus, so that corresponding
timeseries in both systems match in their labelsets.

Change-Id: I8394c9c55dbac3946a0fa497f566d5e6e2d600b5

13 years ago

1 Commits (c35db9f080e534bc1be69e7cf28acbdcf8a79f5b)