https://github.com/magnusbaeck/logstash-filter-verifier
https://github.com/magnusbaeck/logstash-filter-verifier
hacktoberfest logstash testing-tools
Last synced: about 1 year ago
JSON representation
- Host: GitHub
- URL: https://github.com/magnusbaeck/logstash-filter-verifier
- Owner: magnusbaeck
- License: apache-2.0
- Created: 2015-11-21T20:25:32.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2025-03-13T00:29:47.000Z (over 1 year ago)
- Last Synced: 2025-04-09T21:12:46.918Z (about 1 year ago)
- Topics: hacktoberfest, logstash, testing-tools
- Language: Go
- Homepage:
- Size: 704 KB
- Stars: 197
- Watchers: 6
- Forks: 27
- Open Issues: 42
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
# Logstash Filter Verifier
[](https://goreportcard.com/report/github.com/magnusbaeck/logstash-filter-verifier)
[](https://raw.githubusercontent.com/magnusbaeck/logstash-filter-verifier/master/LICENSE)
* [Introduction](#introduction)
* [Installing](#installing)
* [Standalone and Daemon mode (since Version 2.0)](#standalone-and-daemon-mode-since-version-20)
* [Examples](#examples)
* [Syslog messages](#syslog-messages)
* [Beats messages](#beats-messages)
* [JSON messages](#json-messages)
* [Version 2.0 (Daemon mode only)](#version-20-daemon-mode-only)
* [Test case file reference](#test-case-file-reference)
* [Standalone mode / Logstash Filter Verifier before version 2.0](#standalone-mode--logstash-filter-verifier-before-version-20)
* [Daemon mode](#daemon-mode)
* [Plugin mock](#plugin-mock)
* [Migrating to the current test case file format](#migrating-to-the-current-test-case-file-format)
* [Notes](#notes)
* [The \-\-sockets flag](#the---sockets-flag)
* [The \-\-logstash\-arg flag](#the---logstash-arg-flag)
* [Logstash compatibility](#logstash-compatibility)
* [Standalone mode](#standalone-mode)
* [Daemon mode](#daemon-mode)
* [Windows compatibility](#windows-compatibility)
* [Plugin ID (Daemon mode)](#plugin-id-daemon-mode)
* [Logstash Plugins](#logstash-plugins)
* [@metadata field](#metadata-field)
* [Development](#development)
* [Dependencies](#dependencies)
* [Run Integration Tests](#run-integration-tests)
* [Known limitations and future work](#known-limitations-and-future-work)
* [License](#license)
## Introduction
The [Logstash](https://www.elastic.co/products/logstash) program for
collecting and processing logs from is popular and commonly used to
process e.g. syslog messages and HTTP logs.
Apart from ingesting log events and sending them to one or more
destinations it can transform the events in various ways, including
extracting discrete fields from flat blocks of text, joining multiple
physical lines into singular logical events, parsing JSON and XML, and
deleting unwanted events. It uses its own domain-specific
configuration language to describe both inputs, outputs, and the
filters that should be applied to events.
Writing the filter configurations necessary to parse events isn't
difficult for someone with basic programming skills, but verifying
that the filters do what you expect can be tedious; especially when
you tweak existing filters and want to make sure that all kinds of
logs will continue to be processed as before. If you get something
wrong you might have millions of incorrectly parsed events before you
realize your mistake.
This is where Logstash Filter Verifier comes in. It lets you define
test case files containing lines of input together with the expected
output from Logstash. Pass one of more such test case files to
Logstash Filter Verifier together with all of your Logstash filter
configuration files and it'll run Logstash for you and verify that
Logstash actually returns what you expect.
Before you can run Logstash Filter Verifier you need to install
it. After covering that, let's start with a simple example and follow
up with reference documentation.
## Installing
All releases of Logstash Filter Verifier are published in binary form
for the most common platforms at
[github.com/magnusbaeck/logstash-filter-verifier/releases](https://github.com/magnusbaeck/logstash-filter-verifier/releases).
If you need to run the program on other platforms or if you want to
modify the program yourself you can build and use it on any platform
for which a recent [Go](https://golang.org/) compiler is
available. Pretty much any platform where Logstash runs should be
fine, including Windows.
Many Linux distributions make some version of the Go compiler easily
installable, but otherwise you can [download and install the latest
version](https://golang.org/dl/). The source code is written to use
[Go modules](https://github.com/golang/go/wiki/Modules) for dependency
management. You need at least least Go 1.16.x.
To just build an executable file you don't need anything but the Go
compiler; just clone the Logstash Filter Verifier repository and run
`go build` from the root directory of the cloned repostiory. If
successful you'll find an executable in the current directory.
One drawback of this is that the program won't get stamped with the
correct version number, so `logstash-filter-verifier --version` will
say "unknown"). To address this and make it easy to run tests and
static checks you need GNU make and other GNU tools.
The makefile can also be used to install Logstash Filter Verifier
centrally, by default in /usr/local/bin but you can change that by
modifying the PREFIX variable. For example, to install it in $HOME/bin
(which is probably in your shell's path) you can issue the following
command:
$ make install PREFIX=$HOME
## Standalone and Daemon mode (since Version 2.0)
Since version 2.0, there are two different modes, Logstash Filter Verifier
can be operated in.
1. **Standalone**: In this mode, for each test run a fresh instance of Logstash
is started in the background by Logstash Filter Verifier. If a user wants to
frequently execute test cases, this might be slow and tedious.
This has been to only mode available in versions prior to 2.0.
2. **Daemon**: In this mode, Logstash Filter Verifier is executed twice in
parallel (preferably in two different shells). One instance is the daemon.
The daemon starts and controls the Logstash instances (there might be
multiple). This daemon process is normally left running for the time the user
is working on the Logstash configuration and testing it with Logstash Filter
Verifier.
For each execution of the test cases, another instance Logstash Filter
Verifier is started (client). The client collects the current state of the
Logstash configuration as well as the test cases and passes them to the
daemon. The daemon reloads the configuration in one of the running Logstash
instances, executes the test cases and returns the result back to the client.
The client shows the results to the user and exits, while the daemon
continues to run and waits for the next client to submit a test execution
job.
## Examples
The examples that follow build upon each other and do not only show
how to use Logstash Filter Verifier to test that particular kind of
log. They also highlight how to deal with different features in logs.
### Syslog messages
Logstash is often used to parse syslog messages, so let's use that as
a first example.
Test case files are in JSON or YAML format and contain a single object
with about a handful of supported properties.
Sample with JSON format:
```json
{
"fields": {
"type": "syslog"
},
"testcases": [
{
"input": [
"Oct 6 20:55:29 myhost myprogram[31993]: This is a test message"
],
"expected": [
{
"@timestamp": "2015-10-06T20:55:29.000Z",
"host": "myhost",
"message": "This is a test message",
"pid": 31993,
"program": "myprogram",
"type": "syslog"
}
]
}
]
}
```
Sample with YAML format:
```yaml
fields:
type: "syslog"
testcases:
- input:
- "Oct 6 20:55:29 myhost myprogram[31993]: This is a test message"
expected:
- "@timestamp": "2015-10-06T20:55:29.000Z"
host: "myhost"
message: "This is a test message"
pid: 31993
program: "myprogram"
type: "syslog"
```
Most Logstash configurations contain filters for multiple kinds of
logs and uses conditions on field values to select which filters to
apply. Those field values are typically set in the input plugins. To
make Logstash treat the test events correctly we can "inject"
additional field values to make the test events look like the real
events to Logstash. In this example, `fields.type` is set to "syslog"
which means that the input events in the test cases in this file will
have that in their `type` field when they're passed to Logstash.
Next, in `input`, we define a single test string that we want to feed
through Logstash, and the `expected` array contains a one-element
array with the event we expect Logstash to emit for the given input.
The `testcases` array can contain multiple objects with `input` and
`expected` keys. For example, if we change the example above to
```yaml
fields:
type: "syslog"
testcases:
- input:
- "Oct 6 20:55:29 myhost myprogram[31993]: This is a test message"
expected:
- "@timestamp": "2015-10-06T20:55:29.000Z"
host: "myhost"
message: "This is a test message"
pid: 31993
program: "myprogram"
type: "syslog"
- input:
- "Oct 6 20:55:29 myhost myprogram: This is a test message"
expected:
- "@timestamp": "2015-10-06T20:55:29.000Z"
host: "myhost"
message: "This is a test message"
program: "myprogram"
type: "syslog"
```
we also test syslog messages that lack the bracketed pid after the
program name.
Note that UTC is the assumed timezone for input events to avoid
different behavior depending on the timezone of the machine where
Logstash Filter Verifier happens to run. This won't affect time
formats that include a timezone.
This command will run this test case file through Logstash Filter
Verifier (replace all "path/to" with the actual paths to the files,
obviously):
$ path/to/logstash-filter-verifier standalone path/to/syslog.json path/to/filters
If the test is successful, Logstash Filter Verifier will terminate
with a zero exit code and (almost) no output. If the test fails it'll
run `diff -u` (or some other command if you use the `--diff-command`
flag) to compare the pretty-printed JSON representation of the
expected and actual events.
The actual event emitted by Logstash will contain a `@version` field,
but since that field isn't interesting it's ignored by default when
reading the actual event. Hence we don't need to include it in the
expected event either. Additional fields can be ignored with the
`ignore` array property in the test case file (see details below).
### Beats messages
In [Beats](https://www.elastic.co/guide/en/beats/libbeat/current/beats-reference.html)
you can also specify fields to control the behavior of the Logstash pipeline.
An example in Beats config might look like this:
```yaml
- input_type: log
paths: ["/var/log/work/*.log"]
fields:
type: openlog
- input_type: log
paths: ["/var/log/trace/*.trc"]
fields:
type: trace
```
The Logstash configuration would then look like this to check the
given field:
```none
if ([fields][type] == "openlog") {
Do something for type openlog
```
But, in order to test the behavior with LFV you have to give it like so:
```none
{
"fields": {
"[fields][type]": "openlog"
},
```
The reason is, that Beats is inserting by default declared fields under a
root element `fields`, while the LFV is just considering it as a configuration
option.
Alternatively you can tell Beats to insert the configured fields on root:
```yaml
fields_under_root: true
```
### JSON messages
I always prefer to configure applications to emit JSON objects
whenever possible so that I don't have to write complex and/or
ambiguous grok expressions. Here's an example:
```json
{"message": "This is a test message", "client": "127.0.0.1", "host": "myhost", "time": "2015-10-06T20:55:29Z"}
```
When you feed events like this to Logstash it's likely that the
input used will have its codec set to "json_lines". This is something we
should mimic on the Logstash Filter Verifier side too. Use `codec` for
that:
Sample with JSON format:
```json
{
"fields": {
"type": "app"
},
"codec": "json_lines",
"ignore": ["host"],
"testcases": [
{
"input": [
"{\"message\": \"This is a test message\", \"client\": \"127.0.0.1\", \"time\": \"2015-10-06T20:55:29Z\"}"
],
"expected": [
{
"@timestamp": "2015-10-06T20:55:29.000Z",
"client": "localhost",
"clientip": "127.0.0.1",
"message": "This is a test message",
"type": "app"
}
]
}
]
}
```
Sample with YAML format:
```yaml
fields:
type: "app"
codec: "json_lines"
ignore:
- "host"
testcases:
- input:
- >
{
"message": "This is a test message",
"client": "127.0.0.1",
"time": "2015-10-06T20:55:29Z"
}
expected:
- "@timestamp": "2015-10-06T20:55:29.000Z"
client: "localhost"
clientip: "127.0.0.1"
message: "This is a test message"
type: "app"
```
There are a few points to be made here:
* The double quotes inside the string must be escaped when using JSON format.
YAML files sometimes require quoting too; for example if the value starts
with `[` or `{` or if a numeric value should be forced to be parsed as a
string.
* Together with the lack of a need to escape double quotes inside JSON
strings, the use of `>` to create folded lines in the YAML representation
makes the input JSON much easier to read.
* The filters being tested here use Logstash's [dns
filter](https://www.elastic.co/guide/en/logstash/current/plugins-filters-dns.html)
to transform the IP address in the `client` field into a hostname
and copy the original IP address into the `clientip` field. To avoid
future problems and flaky tests, pick a hostname or IP address for
the test case that will always resolve to the same thing. As in this
example, localhost and 127.0.0.1 should be safe picks.
* If the input event doesn't contain a `host` field, Logstash will add
such a field containing the name of the current host. To avoid test
cases that behave differently depending on the host where they're
run, we ignore that field with the `ignore` property.
### Version 2.0 (Daemon mode only)
With version 2.0 of Logstash Filter Verifier (Daemon mode) some new features
have been added:
* **Export of @metadata**:
There is out of the box support to let Logstash Filter Verifier export
the values in the (otherwise hidden) `@metadata` field of the event.
This allows to write test cases, which take the values in the `@metadata`
field into account. (see `export_metadata` in test case file reference)
* **Pipeline configuration**:
Logstash Filter Verifier in Daemon mode accepts complete Logstash pipelines
as configuration. This includes the localization of the Logstash configuration
files through the paths provided in the `pipelines.yml` file and replacing all
input and output filters with the respective parts to execute the tests.
* **Multiple pipelines**
The pipeline configuration may consist of multiple pipelines, that might be
linked ([pipeline to pipeline communication](https://www.elastic.co/guide/en/logstash/current/pipeline-to-pipeline.html))
or independent pipelines.
* **Plugin mock**
Plugin mock allows to replace (or remove) plugins in the Logstash
configuration under test, that do not work during or that would potentially
not produce the expected results test execution. Examples for such filter
plugins are mainly plugins, that perform some sort of call out to a third
party system, for example to look up data ([elasticsearch](https://www.elastic.co/guide/en/logstash/current/plugins-filters-elasticsearch.html),
[http](https://www.elastic.co/guide/en/logstash/current/plugins-filters-http.html),
[jdbc](https://www.elastic.co/guide/en/logstash/current/plugins-filters-jdbc_static.html),
[memcached](https://www.elastic.co/guide/en/logstash/current/plugins-filters-memcached.html)).
In order to to be able to produce reproducible results in the test cases,
these plugins can be replaced with mocks. In particular the [mutate](https://www.elastic.co/guide/en/logstash/current/plugins-filters-mutate.html)
and the [translate](https://www.elastic.co/guide/en/logstash/current/plugins-filters-translate.html)
filters have proven to be helpful as replacements.
Other use cases for mocks are:
* replace filters, that operate on environment variables, that need to be changed
between different test cases (see [#120](https://github.com/magnusbaeck/logstash-filter-verifier/issues/120)).
* replace pipeline input and output plugins in order to test pipelines in isolation.
In order to execute a test case in daemon mode, first the daemon needs to be
started (e.g. in its own terminal or shell):
$ path/to/logstash-filter-verifier daemon start
Next, a single test case run can be launched with (in second terminal/shell):
$ path/to/logstash-filter-verifier daemon run --pipeline path/to/pipelines.yml --pipeline-base base/path/of/logstash-configuration --testcase-dir path/to/testcases
The flag `--pipeline-base` is required, if the `pipelines.yml` file does use
relative paths for the actual logstash pipeline configuration.
If the Logstash configuration under test does not contain `id` attributes for
all plugins, the `--add-missing-id` flag instructs Logstash Filter Verifier to
add the missing `id` attributes on the fly.
As an example, we can execute the `basic_pipeline` test case from this
repository.
Let us assume, the following setup:
* The logstash filter verifier binary is available at `/usr/local/bin/logstash-fitler-verifier`.
* This repository is available at `/tmp/logstash-filter-verifier` (e.g. with `git clone https://github.com/magnusbaeck/logstash-filter-verifier `).
The command to run the `basic_pipeline` example would look like this (the daemon
needs to be started beforehand):
$ /usr/local/bin/logstash-fitler-verifier daemon run --pipeline /tmp/logstash-filter-verifier/testdata/basic_pipeline.yml --pipeline-base /tmp/logstash-filter-verifier/testdata/basic_pipeline --testcase-dir /tmp/logstash-filter-verifier/testdata/testcases/basic_pipeline --add-missing-id
More examples (e.g. multiple pipelines and plugin mock) can be found in the
`testcases/` folder of this repository.
## Test case file reference
### Standalone mode / Logstash Filter Verifier before version 2.0
Test case files are JSON files containing a single object. That object
may have the following properties:
* `codec`: A string with the codec configuration of the input plugin used
when executing the tests. This string will be included verbatim in the
Logstash configuration so it could either be just the name of the codec
plugin (normally `line` or `json_lines`) or include additional codec
options like e.g. `plain { charset => "ISO-8859-1" }`.
* `fields`: An object containing the fields that all input messages
should have. This is vital since filters typically are configured
based on the event's type and/or tags. Scalar values (strings,
numbers, and booleans) are supported, as are objects (containing
scalars, arrays and nested objects), arrays of scalars and nested arrays.
The only combination which is not allowed are objects within arrays.
A shorthand for defining nested fields is to use the Logstash's field
reference syntax (`[field][subfield]`), i.e.
`fields: {"[log][file][path]": "/tmp/test.log"}` is equivalent to
`fields: {"log": {"file": {"path": "/tmp/test.log"}}}`.
* `ignore`: An array with the names of the fields that should be
removed from the events that Logstash emit. This is for example
useful for dynamically generated fields whose contents can't be
predicted and hardwired into the test case file. If you need to exclude
individual subfields you can use Logstash's field reference syntax,
i.e. `[log][file][path]` will exclude that field but keep other subfields
of `log` like e.g. `[log][level]` and `[log][file][line]`.
* `testcases`: An array of test case objects, each having the following
contents:
* `input`: An array with the lines of input (each line being a string)
that should be fed to the Logstash process. If you use `json_lines` codec
you can use Logstash's syntax reference syntax for fields in the JSON
object, making
`{"message": "my message", "[log][file][path]": "/tmp/test.log"}`
equivalent to
`{"message": "my message", "log": {"file": {"path": "/tmp/test.log"}}}`.
* `expected`: An array of JSON objects with the events to be
expected. They will be compared to the actual events produced by the
Logstash process.
* `description`: An optional textual description of the test case, e.g.
useful as documentation. This text will be included in the program's
progress messages.
### Daemon mode
Test case files for the Daemon mode have the same fields as for Standalone mode
with the following changes/additions
Additional fields:
* `input_plugin`: The unique [ID](https://www.elastic.co/guide/en/logstash/7.10/plugins-inputs-file.html#plugins-inputs-file-id)
of the input plugin in the tested configuration, where the test input is
coming from. This is necessary, if a setup with multiple inputs is tested,
which either have different codecs or are part of different pipelines.
* `export_metadata`: Controls if the metadata of the event processed by Logstash
is returned. The metadata is contained in the field `[@metadata]` in the
Logstash event. If the metadata is exported, the respective fields are
compared with the expected result of the testcase as well. (default: false)
* `export_outputs`: Controls if the ID of the output, a particular event has
emitted by, is kept in the event or not. If this is enabled, the expected
event needs to contain a field named `_lfv_out_passed` which contains the ID
of the Logstash output.
* `testcases`:
* `fields`: Local fields, only added to the events of this test case. These
fields overwrite global fields.
Ignored / obsolete fields:
* `codec`
#### Plugin mock
The plugin mock config file (yaml) consists of an array of plugin mock elements.
Each plugin mock element consists for the plugin id that should be replaced as
well as the Logstash configuration string that should be used as the
replacement. This string might be empty. In this case, the mocked plugin is just
removed from the Logstash configuration.
Example:
```yaml
- id: removeme
- id: mockme
mock: |
mutate {
replace => {
"[message]" => "mocked"
}
}
```
Given the above plugin mock configuration, the plugin with the ID `removeme` is
removed from the Logstash configuration. The plugin with the ID `mockme` is
replaced with the given Logstash configuration.
## Migrating to the current test case file format
Originally the `input` and `expected` configuration keys were at the
top level of the test case file. They were later moved into the
`testcases` key.
To migrate test case files from the old to the new file format the
following command using [jq](https://stedolan.github.io/jq/) can be
used (run it in the directory containing the test case files):
```
for f in *.json ; do
jq '{ codec, fields, ignore, testcases:[[.input[]], [.expected[]]] | transpose | map({input: [.[0]], expected: [.[1]]})} | with_entries(select(.value != null))' $f > $f.migrated && mv $f.migrated $f
done
```
This command only works for test case files where there's a one-to-one
mapping between the elements of the `input` array and the elements of
the `expected` array. If you e.g. have drop and/or split filters in
your Logstash configuration you'll have to patch the converted test
case file by hand afterwards.
## Notes
### The `--sockets` flag (Standalone mode)
The command line flag `--sockets` allows to use unix domain sockets instead of
stdin to send the input to Logstash. The advantage of this approach is, that
it allows to process test case files in parallel to Logstash, instead of
starting a new Logstash instance for every test case file. Because Logstash
is known to start slowly, this increases the time needed significantly,
especially if there are lots of different test case files.
For the test cases to work properly together with the unix domain socket input,
the test case files need to include the property `codec` set to the value `line`
(or `json_lines`, if json formatted input should be processed).
### The `--logstash-arg` flag
The `--logstash-arg` flag is used to supply additional command line
arguments or flags for Logstash. Those arguments are not processed by
Logstash Filter Verifier other than just forwarding them to Logstash.
For flags consisting of a flag name and a value, for both a seperate
`--logstash-arg` in the correct order has to be provided. Because
values, starting with one or two dashes (`-`) are treated as flag by
Logstash Filter Verifier, for those flags the value _must_ not be
separated using a space but they have to be separated from the flag
with the equal sign (`=`).
For example to set the Logstash node name the following arguments have
to be provided to Logstash Filter Verifier:
--logstash-arg=--node.name --logstash-arg MyInstanceName
### Logstash compatibility
#### Standalone mode
Different versions of Logstash behave slightly differently and changes
in Logstash may require changes in Logstash Filter Verifier. Upon
startup, the program will attempt to auto-detect the version of
Logstash used and will use this information to adapt its own behavior.
Starting with Logstash 5.0 finding out the Logstash version is very
quick but in previous versions the version string was printed by Ruby
code in the JVM so it took several seconds. To avoid this you can use
the `--logstash-version` flag to tell Logstash Filter Verifier which
version of Logstash it should expect. Example:
logstash-filter-verifier standalone ... --logstash-version 2.4.0
#### Daemon mode
In order to use Logstash Filter Verifier in Daemon mode, at least Logstash
version 6.7.x is required. Older versions of Logstash are not supported and do
not work with Daemon mode.
### Windows compatibility
Logstash Filter Verifier has been reported to work on Windows, but
this isn't tested by the author and it's not guaranteed to work. There
are a couple of known quirks that are easy to work around:
* It won't guess the location of your Logstash executable so you'll have
to manually provide it with the `--logstash-path` flag.
* The default value of the `--diff-command` is `diff -u` which won't work
on typical Windows machines. You'll have to explicitly select which diff
tool to use.
### Plugin ID (Daemon mode)
The Daemon mode of Logstash Filter Verifier expects each plugin in the Logstash
configuration to have a unique [ID](https://www.elastic.co/guide/en/logstash/current/plugins-filters-mutate.html#plugins-filters-mutate-id).
In order to test an existing Logstash configuration, which lacks these ID, there
are two options:
1. Permanently add the missing ID to the configuration. This can either be done
by hand or with the help of [`mustache`](https://github.com/breml/logstash-config).
mustache lint --auto-fix-id
2. Let Logstash Filter Verifier add the ID temporarily just for the execution
of the test cases by adding the flag `--add-missing-id`.
### Logstash Plugins
#### Clone (Filter)
LFV configures Logstash such that the ordering of the events while being
processed by the pipeline is ensured. In this regard, the [`clone` filter](https://www.elastic.co/guide/en/logstash/current/plugins-filters-clone.html)
is special, because it injects additional events into the processing pipeline.
The cloned events can be expected in the following order:
1. original event
2. clones of the event in the order of appearance in the `clones` attribute
of the `clone` filter.
### @metadata field
Events in Logstash have a special field called [`@metadata`](https://www.elastic.co/guide/en/logstash/master/event-dependent-configuration.html#metadata).
The contents of `@metadata` are not part of any of your events at output time.
LFV does make use of `@metadata` to store information, which is required to
control the processing of the events. To ensure the correct operation of LFV,
the Logstash configuration under test is not allowed to alter any field within
the `@metadata`, which start with `__lfv_`. For example the following fields
are used by LFV (not conclusive):
* `[@metadata][__lfv_id]`
* `[@metadata][__lfv_out_passed]`
These fields are also removed from `@metadata` even when the test case definition
does include `export_metadata`.
Additionally, all fields within `@metadata` starting with `__tmp_` are removed.
For debug purposes, the `--debug` flag may be passed, which prevents the
removal of the above mentioned fields.
## Development
### Dependencies
For a fully working development environment, the following tooling needs to be
present:
* Go compiler
* `make` command
* Proto buffer compiler (`protobuf-compiler`)
### Run Integration Tests
In order to run the integration tests, the following preparation is needed:
1. Run `go run . setup 8.12.1` to download Logstash version 8.12.1
2. Prepare a `logstash-filter-verifier.yml` config file, which points to the
downloaded Logstash version, e.g.
```yaml
---
loglevel: debug
logstash:
path: ./3rdparty/logstash-8.12.1-linux-x86_64/bin/logstash
keep-envs:
- TESTMODE
metadata-key: __metadata
```
3. Execute the integration tests by providing the respective env var:
`INTEGRATION_TEST=1 go test -v .`
or
```shell
export INTEGRATION_TEST=1
go test -v .
```
## Known limitations and future work
* Some log formats don't include all timestamp components. For
example, most syslog formats don't include the year. This should be
dealt with somehow.
* Logstash configurations, which remove the `@timestamp` field can not be tested
using the daemon mode (see [#151](https://github.com/magnusbaeck/logstash-filter-verifier/issues/151)).
* The maximum size of events, that can be processed is ~64KB (see [#169](https://github.com/magnusbaeck/logstash-filter-verifier/issues/169)).
## License
This software is copyright 2015–2021 by Magnus Bäck <> and
other contributors and licensed under the Apache 2.0 license. See the LICENSE
file for the full license text.