Questions
Find answers to frequently asked development questions. For information about Better Stack products, explore our docs.
Elasticsearch: No Handler for Type [Keyword] Declared on Field [Hostname]
The error No Handler for Type [Keyword] Declared on Field [Hostname] in Elasticsearch usually indicates that there's an issue with the mapping type for the field Hostname. This error often occurs w...
Filebeat: Check if a String Starts With Number Using Regular Expression
To check if a string starts with a number using Filebeat and regular expressions, you can use the processors configuration in Filebeat. Specifically, you’ll use the grok processor to match patterns...
Kibana Logstash Elasticsearch | Unindexed Fields Cannot Be Searched
The error "Unindexed fields cannot be searched" in Kibana typically occurs when you try to search or filter on fields that are not indexed in Elasticsearch. This happens because Elasticsearch, by default, only indexes certain fields for search and aggregation operations. Fields that are not indexed cannot be used for querying or filtering, which is why you encounter this error.
Logstash Optional Fields in Logfile
When processing logs with Logstash, some fields in the log files might be optional, meaning they may or may not be present in every log entry. To handle optional fields in Logstash, especially when using Grok filters, you can design your Grok patterns and configuration to be flexible enough to accommodate these cases.
Error: Index_not_found_exception
The index_not_found_exception error in Elasticsearch occurs when a request is made to an index that does not exist. This error typically happens when you're trying to query, delete, or index documents into an Elasticsearch index that hasn’t been created yet or was accidentally deleted.
What Is the Format of Logstash Config File
The Logstash configuration file (.conf) is structured to define how Logstash processes and transforms data. It consists of three main sections: input, filter, and output. Each section is responsible for a different stage of the data pipeline.
Kibana Returns "Connection Failed"
The "Connection Failed" error in Kibana typically indicates an issue with Kibana's ability to connect to Elasticsearch. This can happen due to several reasons, ranging from Elasticsearch being down, incorrect configurations in Kibana, or networking issues.
Change Default Mapping of String to "Not Analyzed" in Elasticsearch
To change the default mapping of string fields to "not analyzed" in Elasticsearch, especially in Elasticsearch 5.x and earlier (when string was a field type), you would typically modify the mappings of your indices. In Elasticsearch 6.x and later, string fields were replaced by text (for analyzed content) and keyword (for not-analyzed content). Thus, the approach would differ slightly depending on the Elasticsearch version you're using.
How to Log Js Errors From a Client Into Kibana?
To log JavaScript errors from a client (e.g., a web application) into Kibana, you'll need to set up a process that captures these errors on the client side, sends them to a logging service, and then indexes them into Elasticsearch, which Kibana can then visualize.
Which Serilog Sink to Use for Sending to Logstash?
When sending logs from Serilog to Logstash, you'll generally want to use a sink that can format the logs in a way that Logstash can process efficiently. For this purpose, the Serilog.Sinks.Network package is commonly used, specifically the Tcp or Udp sinks, depending on your needs.
Sync Postgresql Data With Elasticsearch
Syncing PostgreSQL data with Elasticsearch involves setting up a system that regularly updates Elasticsearch with changes from a PostgreSQL database. This can be achieved through several methods, including using data synchronization tools, writing custom scripts, or employing dedicated ETL (Extract, Transform, Load) tools.
Removing Old Indices in Elasticsearch
Removing old indices in Elasticsearch is important for managing disk space and maintaining optimal performance. Here are several methods to delete old indices in Elasticsearch:
How to Add a Numeric Filter on Kibana Dashboard?
Adding a numeric filter to a Kibana dashboard allows you to filter data based on numerical values, such as range limits or specific numeric criteria. Here's how you can add and use numeric filters effectively in Kibana:
What Are the Main Differences Between Graylog2 and Kibana
Graylog and Kibana are both popular tools used for log management and data analysis in combination with centralized log collection systems like Elasticsearch. However, they differ significantly in their features, use cases, and focus. Below is a comparison of the main differences between Graylog2 (often referred to simply as Graylog) and Kibana:
How to Handle Non-matching Logstash Grok Filters
In Logstash, handling non-matching Grok filters is essential to ensure that data processing continues even if a Grok pattern fails to match. By default, if a Grok pattern doesn't match, Logstash ad...
Using Log4j With Logstash
Integrating Log4j with Logstash Log4j and Logstash together enable centralized logging for Java applications, helping with real-time log analysis, troubleshooting, and monitoring. Here's a concise ...
How to Integrate Elasticsearch With Mysql?
Integrating Elasticsearch with MySQL allows you to index and search data from a relational database in Elasticsearch, enabling powerful full-text search capabilities and analytical queries. There are several ways to integrate Elasticsearch with MySQL, depending on your use case, including syncing data between MySQL and Elasticsearch or querying both systems.
How to Do "Where Not Exists" Type Filtering in Kibana/elk?
In Kibana and Elasticsearch, you can perform a "WHERE NOT EXISTS" type of filtering (i.e., finding documents where a field does not exist) by using a must_not clause in an Elasticsearch query or applying the appropriate filter in Kibana's interface.
Export to Csv/excel From Kibana
Exporting data from Kibana to CSV or Excel can be done in a few different ways, depending on what data you want to export, such as raw search results, aggregation results, or table data. Below are the common methods to achieve this:
How to Retrieve Unique Count of a Field Using Kibana + Elastic Search
To retrieve the unique count of a field using Kibana and Elasticsearch, you can use the "Cardinality Aggregation" in Kibana's interface. This allows you to calculate the unique values of a specifie...
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