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SysDB Development Discontinued

SysDB was started as a personal side-project and, to be honest, a personal playground. At the moment, I have no personal use-case for it any more and, hence, I’m discontinuing active development indefinetly. If you are interested in taking over or discussing options, please reach out to Sebastian tokkee Harl. I’ll watch the Github repository on a best-effort basis.

2016-02-25: Version 0.8.0

This release focuses on a generic and much more powerful store (query) interface and modular store implementations via plugins. The in-memory store has been moved into a plugin on top of that. Various fixes and improvements, mostly related to iterators, have been applied to the parser and query language.

  • build system:

    • Fix VPATH (out of tree) builds.

    • Fixed a build issue (configure failure) when using RRDtool 1.5.

    • Enable silent build rules by default (if supported).

    • Fix build issues with GCC 5.

  • parser:

    • Add a new, standalone parser module based on a generic (public) AST (abstract syntax tree). This replaces the (internal) parser of the frontend module.

    • Improved error reporting for syntactic and semantic errors by propagating error messages in the parser and analyzer.

  • core / store:

    • Fully support array access and comparison (all element types).

    • Service/metric parent host names are now available via the "hostname" attribute (populated automatically).

    • Rebase the store query interface on top of the new parser: store implementations prepare actual queries from an AST, thus, allowing multiple implementations of store readers.

    • Querying the store (through the new interface) will emit data to an arbitrary writer implementation allowing for more flexible post- processing.

    • Fixed a memory leak in the TIMESERIES implementation.

    • data: Added support for boolean values; this is a backward incompatible change which breaks the network encoding.

    • Include nano-second fraction of datatime values (if any) in the string format (including JSON query results).

    • Add new callback type for store-readers (query plugins) based on the new generic query interface.

    • memstore: Refactor the in-memory store implementation into a separate data-type. It implements the writer and query/reader APIs.

    • The main, in-memory store is no longer enabled by default (see store::memory plugin). Instead, all updates go through the plugin API and are distributed to all registered writers.

    • Handle hostname canonicalization in the generic plugin module instead of requiring each writer plugin to do so.

    • Do not canonicalize hostnames when fetching time-series.

    • Determine an object’s backends and update interval in the generic plugin module and pass it on to writer plugins which are expected to merge it with existing entries.

    • Let the JSON formatter implement the writer API to make it more flexible and uncouple it from the memstore module; let it support arbitrary top-level objects (besides hosts).

    • FETCH (in the core) now supports all object types and child objects as well as fetching the base object without children / siblings.

  • frontend:

    • Added the SERVER_VERSION command; this allows clients to check for supported servers.

    • Fixed a memory leak in failed FETCH commands.

    • Switch to the new, pluggable query interface: use registered plugins to write to or query the SysDB store.

    • Move protocol-specific (query) logic out of the core and into the frontend (based on the new query API).

    • A generic TIMESERIES implementation based on the query API replaces the in-core implementation.

  • query language:

    • Check types of comparison operands and arithmetic expression and treat mismatches as errors; previously those comparisons would fail silently.

    • Added the NOT IN operator.

    • Support iterators (ANY/ALL) of arbitrary array expressions.

    • Change child-object iterator syntax to ANY/ALL <type>.name, that is, require the field name and add support for accessing arbitrary fields.

    • Added new field "value" for attribute values.

    • Added new field "timeseries" (boolean) for metrics indicating whether a time-series store is known to SysDB.

    • Support attribute and backend iterators in FILTER expressions.

    • Enforce that TIMESERIES end times are greater than start times.

    • Added unary IS TRUE / IS FALSE operators.

    • Iterator expressions may now reference a chain of sibling objects as long as only one such reference is an iterator. For example, LOOKUP services MATCHING ANY host.backend =~ 'foo'.

  • testing:

    • Use check "loop" tests; this will run all test-cases even if there are failures.

    • Create separate binaries for each test; this allows to run more in parallel.

    • Make it possible to run unit and integration tests separately; see README.


  • store::memory: Added a store-writer/store-reader plugin providing an in-memory store replacing the previous, always-enabled store. It is based on the memstore module.

2015-02-21: Version 0.7.0

This release introduces various features related to running SysDB as an agent. Objects may now also be submitted by arbitrary applications using the network protocol. Two new plugins are available to collect local facter fact values and to mirror all store operations to another instance. Various fixes and improvements have been applied to the client program (sysdb).

  • build system:

    • Added support for C++.

  • sysdb:

    • Fixed terminal resets on exit.

    • Don’t exit if the server closed the connection; instead reconnect automatically on the next user input.

    • Fixed string parsing: previously, quoted strings were not handled at all and might have been terminated by an embedded semicolon.

    • Also store failed commands in the history to enable history editing in such cases.

    • Improved program output: don’t mix log messages with prompts after sending a command; print log messages to the standard error channel.

    • Fixed lookup of the .sysdb_history file for cases where the SysDB user does not match the current operating system user.

  • sysdbd:

    • SSL options can be specified inside a <Listen> block.

    • Unload all plugins on exit to ensure a clean shutdown.

  • client:

    • Simplified RPC handling by providing a helper function.

    • Added support for TCP connections using SSL/TLS and supporting, both, IPv4 and IPv6. Remote peer verification is required for any such connection.

    • New command line flags -K, -C, and -A to specify the SSL private key, client certificate, and CA certificates file names.

  • core:

    • Fully support arrays of all types.

    • Fixed (implemented) reloading of time-series fetcher plugins.

    • Added new callback type for "store-writers", making that part of the store pluggable (queries are not supported).

  • store:

    • Added support for querying an object’s siblings.

    • Send all stored objects to store-writer plugins in addition to storing them in the in-memory store.

  • frontend:

    • Fixed parsing of time values.

    • Add support for storing hosts, services, metrics, and attributes using the new STORE command.

    • Fixed handling of subsequent requests on the same connection by avoiding unnecessary pauses of up to one second, thus, greatly speeding up request handling.

    • Added support for TCP connections supporting, both, IPv4 and IPv6. SSL/TLS is enforced for any such connection.

    • Added support for and require actual client authentication: UNIX socket connections require peer authentication. TCP connections require client SSL certificate authentication.

  • query language:

    • Added support for expressions accessing an object’s siblings by using the <object_type>.<sibling_type> syntax.

  • JSON format:

    • Fixed handling of special characters which are now being escaped.

    • Include a flag indicating whether time-series data are available for a metric.

  • utils:

    • os: This utility module provides some Operating System related helper functions: access user information (current user, homedir), manage directories (create, delete, resolve), I/O helpers (select, read, write), networking helpers (DNS resolution).

    • proto: Added support for marshaling and unmarshaling messages encoding a datum of any type, hosts, services, metrics, and attributes.

    • ssl: This new module provides convenience functions for SSL/TLS servers, clients, and sessions using OpenSSL.


  • facter: Added a plugin collecting local facter fact values using libcfacter (C++).


  • store::network: Added a store-writer plugin sending all data to another SysDB instance using the client library and low-level STORE commands.


  • syslog: The log-level is now configurable using the "LogLevel" option.

2014-12-22: Preview of the web-interface

Early in December, a preview of the web-based SysDB user-interface has been pushed to GitHub. It provides a graphical client application for browsing and querying the system database.

  • Browse all hosts, services, and metrics and display details about them.

  • Query hosts, services, and metrics using a simple query language:

    • Specify the object-type by name as first word in the query.

    • Query by name simply by specifying an (optionally quoted) string which is treated as a regex.

    • Query by attribute using the <name>:<value> syntax.

  • Display graphs for all metrics supporting it. The time-range is configurable in the user-interface.

/images/sysdb_graph.png /images/sysdb_host.png /images/sysdb_metrics.png

2014-11-17: Version 0.6.0

This release focuses on a clearer query language. The underlying architecture has been refactored to allow for more powerful and generic expressions.

  • core:

    • Added support for arrays. Elements may be of any other supported data-type but only integers, decimals, and strings are fully supported.

  • store:

    • Refactored matchers: all matchers now operate on one or two expressions or other matchers, replacing the old and less flexible conditional matchers.

    • Attribute values may now be used anywhere in an expression.

    • On data-type mismatch when comparing attribute values, the values will be cast to string (previously only done for regex matches).

    • Added support for querying an object’s backends (array of strings).

    • Added support for iterating child objects and array values.

    • All matchers now return false if any operand is NULL (except for IS NULL).

    • All operations now return NULL if any operand is NULL.

    • Fixed behavior of not-operators (!=, !~) and let them not match if any of the operands is NULL.

    • Add support for looking up all object types (hosts, services, metrics).

    • Refactored the JSON formatter to be more flexible and powerful.

    • Record parent objects for each stored object.

  • frontend:

    • Added a separate parser mode for expressions.

    • Added a new queryable field name to be used in place of the rather magical keyword host when looking up hosts.

    • Improved error reporting in the parser and the (newly introduced) analyzer.

    • Apply filters to hosts in the FETCH command.

  • query language:

    • All operators may now be used in all places if the involved data-types support the respective operation. For example, regular expressions may be used to match any value. Non-string values are cast to strings for that purpose. IS NULL / IS NOT NULL may be applied to arbitrary expressions.

    • Introduced the IN operator to check if a value or an array of values is included in an array.

    • Added support for arrays: [<elem1>,<elem2>,…]

    • Added support for string and array concatenation using the || operator.

    • Attribute names have to be strings instead of identifiers now.

    • Access object fields using <field> rather than .<field>.

    • Let the LOOKUP and FETCH commands support services and metrics.

    • Introduced FETCH service|metric <host>.<name for fetching services and metrics.

    • Added support for ANY and ALL operators which apply a matcher to each value emitted by an iterator (a host’s services and metrics or arrays). MATCHING ANY service|metric|attribute <cmp> <expr> replaces MATCHING service|metric|attribute <cmp> <value> expressions.

2014-10-06: Version 0.5.0

This release focuses on simplifications and more flexibility in the frontend and the query language. Most of those changes are not backward-compatible but easy client implementations.

  • sysdb:

    • Include priority when printing log messages.

    • Fixed handling of empty queries.

  • store:

    • When serializing the entire store (LIST command), return an array of host objects (rather than wrapping it into another object).

    • Fixed JSON format of time-series data.

    • Fixed error checks of invalid compare expressions and reject them.

    • Fixed lookups by back-end name.

    • Added support for comparing attributes with different types by comparing their string values.

  • frontend:

    • Clarified details about asynchronous messages and authentication options and made client implementation more robust.

    • Introduced a new message type encoding the JSON serialized response of a query and its data type.

    • Include the priority in log messages.

    • Include object types in FETCH, LIST, and LOOKUP messages.

    • Added support for including services and metrics in LIST responses and skip hosts without the respective children.

  • query language:

    • Added support for services and metrics to LIST command.

    • Changed syntax for attribute lookup to attributes[<name>].

    • Changed syntax for accessing queryable fields to .<field>.

  • utils:

    • strbuf: Improved memory management.

2014-09-21: Go bindings for SysDB

A few days ago, the first version of Go bindings for SysDB have been pushed to The project provides a set of packages for the Go programming language (golang) which implement a SysDB client and helper functions for handling the front-end protocol.

Install the package into your GOPATH using the go get command:

go get

The documentation is included with the source code in a way compatible with the godoc tool and the latest version can be viewed online.

At the moment, the following packages are available:

  • client: A SysDB client implementation.

  • proto: Helper functions for using the SysDB front-end protocol. That’s the protocol used for communication between a client and a SysDB server instance.

  • sysdb: Core constants and types used by SysDB packages.

2014-09-01: Version 0.4.0

This release features support for metrics and transparent access to a backend’s time-series data. Some backward-incompatible changes were applied to some query commands for more consistency.

  • build system:

    • Added checks for format strings and arguments.

    • Changed configure option for collectd::unixsock to --enable-collectd-unixsock.

  • core:

    • Added support for “metric” objects which may be assigned to a host.

    • Introduced support for handling time-series data: added new data structures describing time-series data and a new type of plugins called “time-series fetchers” which are used to access time-series information.

  • store:

    • Fixed a memory leak.

    • Apply (very) simple optimizations to lookup expressions.

    • Added support for metrics and their “data-stores” (describing how to access the actual data references by a metric).

    • Added support for querying time-series data through the newly introduced “time-series fetcher” plugins.

  • frontend:

    • Fixed a bug that might have caused reading too much data from the connection buffer in certain situations.

  • query language:

    • The ‘MATCHING’ clause is now optional in ‘LOOKUP’ queries.

    • The ‘LIST’ and ‘FETCH’ commands support ‘FILTER’ clauses as well.

    • ‘LIST’ / ‘FETCH’ were changed to ‘LIST hosts’ / ‘FETCH host’.

    • Added the ‘TIMESERIES’ command to query arbitrary time-series which fetches time-series data from a backend’s data-store for a given period of time.

    • Added support for date/time values.

    • Added support for single quotes in string values: two adjacent single quotes may be used to specify a single quote.

  • documentation:

    • Documented the frontend protocol in frontend/proto.h.

    • Documented changes to the query language and new / updated plugins.

    • Documented all supported data types.


  • collectd::unixsock:

    • The plugin now uses metrics in place of services.

    • New config options ‘TimeseriesBackend’ and ‘TimeseriesBaseURL’ to specify access to time-series, currently limited to ‘rrdtool’ and ‘rrdcached’ access.


  • timeseries::rrdtool:

    • New plugin adding support to fetch time-series from local RRD files.

    • Supports flushing of values in RRDCacheD.

2014-08-01: Version 0.3.0

This release includes major enhancements and new features in the SysDB store which is the core of the database. Most notably, complex expressions are now supported when looking up information and filters may be used to preselect the information to be returned. Some backward-incompatible changes were introduced in the query language to avoid potentially confusing semantics.

  • sysdb: Fixed non-interactive mode when using libedit.

  • core:

    • Fixed weird behavior when collector callbacks were registered without any plugin context information (as it would, e.g., happen when using LoadPlugin instead of LoadBackend in sysdbd).

  • store:

    • Introduced service attributes — similar to host attributes but assigned to a service object.

    • Don’t log “value too old” messages if an updated object uses the same timestamp as the old object.

    • Switched from linked-lists to AVL trees for storing all object types to reduce lookup times from O(n) to O(log n).

    • Added infrastructure for handling and evaluating arithmetic expressions and filters (see also the changes to the query language below).

    • Export various fields describing base attributes of all stored object types: last_update, age, interval, and backend. These fields may be used when querying the store.

  • frontend: Include new service attributes in JSON output.

  • query language:

    • Added support for ‘IS NULL’ attribute checks matching on non-existent attributes.

    • Changed ‘LOOKUP … WHERE’ queries to ‘LOOKUP … MATCHING’ to avoid confusion with SQL semantics.

    • Switched from ‘<obj>.name’ to ‘<obj>’ in MATCHING clauses, thus, no longer shadowing attributes called “name”.

    • Added support for arithmetic expressions in places that used simple data values before. Arithmetic expressions support addition, subtraction, multiplication, division, modulo, and concatenation operations. The expressions may be based on constant values or queryable fields of the stored objects (specified as ‘:last_update’, ‘:age’, ‘:interval’, and ‘:backend’).

    • Added ‘FILTER’ support to ‘LOOKUP’ queries. Filters are conditional expressions which may optionally be used to limit the query and the result to object (of any type) matching the filter condition.

    • Added support to specify date and time values.

  • utils:

    • avltree: Added an AVL tree (self-balancing binary tree) implementation.

  • documentation: Added documentation for the new query language features.

  • testing: Run all unit tests through valgrind by default (if available).


  • collectd::unixsock:

    • Added support for spaces in identifiers.

    • Store plugin identifier (host, plugin, plugin_instance, type, type_instance) as service attributes.

2014-07-02: Version 0.2.0

This is another development snapshot of SysDB. The main focus of this release is on stabilizing existing features and extending the query infrastructure to support all attribute types and further operators.

  • build system: Fixed linking of sysdbd to include all necessary object files. This bug caused some plugins to be un-loadable.

  • sysdbd: Fixed shutdown process in case of errors.

  • sysdb: Fixed a bug causing some server replies to be ignored when exiting from the client.

  • core:

    • Always log to the standard output stream if no user-provided logging callbacks had been specified. Previously this was disabled after enabling logging to clients in the frontend.

    • Simplified plugin naming information and determine configuration callback names automatically to ensure better consistency.

  • store:

    • Simplified internal data management.

    • Store the list of backends along with each stored object which provide the respective object.

  • frontend:

    • Simplified and improved the internal architecture matching / looking up objects.

    • Fixed parser to correctly reject invalid object types.

    • Automatically create the base directory of a listening UNIX socket.

  • query language: Added support for numeric constants and added operators for less and greater than or equal attribute comparison.

  • documentation: Added missing files to the distribution tarball.


  • syslog: Don’t log debug messages to syslog.

2014-06-01: Version 0.1.0

This is the initial release of SysDB. It provides the following core features:

  • sysdb: A terminal-based, interactive client program. Supports line-editing and history based on libreadline or libedit and uses an asynchronous, event-driven architecture to handle user input and server replies simultaneously.

  • sysdbd: The database backend service configurable through a configuration file. The daemon supports online reconfiguration.

  • core: Flexible, multi-threaded core architecture providing a configurable plugin infrastructure for querying external data-sources and extending core functionality. The following plugin types are supported:

    • data collection

    • hostname canonicalization

    • logging

  • store: Central, in-memory object store managing host and service objects and their attributes. Host names may be canonicalized through respective plugins. Each object is automatically attributed with last update and interval information using nano-seconds resolution. Attributes may have various types (integer, decimal, string, date-time, binary).

  • frontend: The frontend handling client connections uses a multi-threaded, asynchronous, event-driven architecture capable of handling multiple listen addresses.

  • query language: The store may be queried using the ‘LIST’, ‘LOOKUP’, and ‘FETCH’ commands returning JSON formatted objects.

  • utils: A rich set of abstract data-types and utility functions for internal use:

    • generic channels for asynchronous, multi-threaded I/O

    • DBI wrapper to ease common database access operations

    • thread-aware error handling and reporting

    • doubly linked-lists

    • dynamic sized memory buffers supporting formatted strings and binary

    • data

    • UNIX socket client implementation

  • documentation: Full documentation for the tools, all plugins, and the query language provided as manpages and HTML pages.

  • testing: Unit and integration tests exist for most parts except plugins covering 77% of all functions. Valgrind and Clang’s address sanitzer are used to detect memory leaks and programming errors.

The following plugins are shipped with this version of SysDB:


  • collectd::unixsock: Query collectd through its ‘unixsock’ interface

  • mk-livestatus: Query arbitrary (monitoring) systems using the Check_MK Livestatus interface.

  • puppet::store-configs: Query Puppet through its “stored configuration” database.


  • cname::dns: Canonicalize hostnames by querying DNS information.

  • syslog: Send log messages to the system log service.

Latest Releases:

» 0.8.0 — 2016-02-25
» 0.7.0 — 2015-02-21
» 0.6.0 — 2014-11-17

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