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Logbook: HTTP request and response logging

Logbook

Stability: Active Build Status Coverage Status Code Quality Javadoc Release Maven Central License

Logbook noun, /lɑɡ bʊk/: A book in which measurements from the ship's log are recorded, along with other salient details of the voyage.

Logbook is an extensible Java library to enable complete request and response logging for different client- and server-side technologies. It satisfies a special need by a) allowing web application developers to log any HTTP traffic that an application receives or sends b) in a way that makes it easy to persist and analyze it later. This can be useful for traditional log analysis, meeting audit requirements or investigating individual historic traffic issues.

Logbook is ready to use out of the box for most common setups. Even for uncommon applications and technologies, it should be simple to implement the necessary interfaces to connect a library/framework/etc. to it.

Features

  • Logging: of HTTP requests and responses, including the body; partial logging (no body) for unauthorized requests
  • Customization: of logging format, logging destination, and conditions that request to log
  • Support: for Servlet containers, Apache’s HTTP client, Square's OkHttp, and (via its elegant API) other frameworks
  • Optional obfuscation of sensitive data
  • Spring Boot Auto Configuration
  • Scalyr compatible
  • Sensible defaults

Dependencies

  • Java 8
  • Any build tool using Maven Central, or direct download
  • Servlet Container (optional)
  • Apache HTTP Client (optional)
  • OkHttp (optional)
  • Spring 4.x or 5.x (optional)
  • Spring Boot 1.x or 2.x (optional)
  • JAX-RS 2.x Client and Server (optional)

Installation

Add the following dependency to your project:

<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-core</artifactId>
    <version>${logbook.version}</version>
</dependency>

Additional modules/artifacts of Logbook always share the same version number.

Alternatively, you can import our bill of materials...

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.zalando</groupId>
      <artifactId>logbook-bom</artifactId>
      <version>${logbook.version}</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

... which allows you to omit versions:

<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-core</artifactId>
</dependency>
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-servlet</artifactId>
</dependency>
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-httpclient</artifactId>
</dependency>
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-jaxrs</artifactId>
</dependency>
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-okhttp</artifactId>
</dependency>
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-spring-boot-starter</artifactId>
</dependency>

The logbook logger must be configured to trace level in order to log the requests and responses. With Spring Boot 2 (using Logback) this can be accomplised by adding the following line to your application.properties

logging.level.org.zalando.logbook: TRACE

Usage

All integrations require an instance of Logbook which holds all configuration and wires all necessary parts together. You can either create one using all the defaults:

Logbook logbook = Logbook.create();

or create a customized version using the LogbookBuilder:

Logbook logbook = Logbook.builder()
    .condition(new CustomCondition())
    .rawRequestFilter(new CustomRawRequestFilter())
    .rawResponseFilter(new CustomRawResponseFilter())
    .queryFilter(new CustomQueryFilter())
    .headerFilter(new CustomHeaderFilter())
    .bodyFilter(new CustomBodyFilter())
    .requestFilter(new CustomRequestFilter())
    .responseFilter(new CustomResponseFilter())
    .formatter(new CustomHttpLogFormatter())
    .writer(new CustomHttpLogWriter())
    .build();

Phases

Logbook works in several different phases:

  1. Conditional,
  2. Filtering,
  3. Formatting and
  4. Writing

Each phase is represented by one or more interfaces that can be used for customization. Every phase has a sensible default.

Conditional

Logging HTTP messages and including their bodies is a rather expensive task, so it makes a lot of sense to disable logging for certain requests. A common use case would be to ignore health check requests from a load balancer, or any request to management endpoints typically issued by developers.

Defining a condition is as easy as writing a special Predicate that decides whether a request (and its corresponding response) should be logged or not. Alternatively you can use and combine predefined predicates:

Logbook logbook = Logbook.builder()
    .condition(exclude(
        requestTo("/health"),
        requestTo("/admin/**"),
        contentType("application/octet-stream"),
        header("X-Secret", newHashSet("1", "true")::contains)))
    .build();

Exclusion patterns, e.g. /admin/**, are loosely following Ant's style of path patterns without taking the the query string of the URL into consideration.

Filtering

The goal of Filtering is to prevent the logging of certain sensitive parts of HTTP requests and responses. This usually includes the Authorization header, but could also apply to certain plaintext query or form parameters — e.g. password.

Logbook supports different types of filters:

Type Operates on Applies to Default
RawRequestFilter RawHttpRequest request binary/streams
RawResponseFilter RawHttpResponse response binary/streams
QueryFilter Query string request access_token
HeaderFilter Header (single key-value pair) both Authorization
BodyFilter Content-Type and body both n/a
RequestFilter HttpRequest request n/a
ResponseFilter HttpResponse response n/a

QueryFilter, HeaderFilter and BodyFilter are relatively high-level and should cover all needs in ~90% of all cases. For more complicated setups one should fallback to the low-level variants, i.e. RawRequestFilter and RawResponseFilter as well as RequestFilter and ResponseFilter respectively (in conjunction with ForwardingRawHttpRequest/ForwardingRawHttpResponse and ForwardingHttpRequest/ForwardingHttpResponse).

You can configure filters like this:

Logbook logbook = Logbook.builder()
    .rawRequestFilter(replaceBody(contentType("audio/*"), "mmh mmh mmh mmh"))
    .rawResponseFilter(replaceBody(contentType("*/*-stream"), "It just keeps going and going..."))
    .queryFilter(accessToken())
    .queryFilter(replaceQuery("password", "<secret>"))
    .headerFilter(authorization()) 
    .headerFilter(eachHeader("X-Secret"::equalsIgnoreCase, "<secret>"))
    .build();

You can configure as many filters as you want - they will run consecutively.

Correlation

Logbook uses a correlation id to correlate requests and responses. This allows match-related requests and responses that would usually be located in different places in the log file.

Formatting

Formatting defines how requests and responses will be transformed to strings basically. Formatters do not specify where requests and responses are logged to — writers do that work.

Logbook comes with two different default formatters: HTTP and JSON.

HTTP

HTTP is the default formatting style, provided by the DefaultHttpLogFormatter. It is primarily designed to be used for local development and debugging, not for production use. This is because it’s not as readily machine-readable as JSON.

Request
Incoming Request: 2d66e4bc-9a0d-11e5-a84c-1f39510f0d6b
GET http://example.org/test HTTP/1.1
Accept: application/json
Host: localhost
Content-Type: text/plain

Hello world!
Response
Outgoing Response: 2d66e4bc-9a0d-11e5-a84c-1f39510f0d6b
Duration: 25 ms
HTTP/1.1 200
Content-Type: application/json

{"value":"Hello world!"}
JSON

JSON is an alternative formatting style, provided by the JsonHttpLogFormatter. Unlike HTTP, it is primarily designed for production use — parsers and log consumers can easily consume it.

Request
{
  "origin": "remote",
  "type": "request",
  "correlation": "2d66e4bc-9a0d-11e5-a84c-1f39510f0d6b",
  "protocol": "HTTP/1.1",
  "sender": "127.0.0.1",
  "method": "GET",
  "path": "http://example.org/test",
  "headers": {
    "Accept": ["application/json"],
    "Content-Type": ["text/plain"]
  },
  "body": "Hello world!"
}
Response
{
  "origin": "local",
  "type": "response",
  "correlation": "2d66e4bc-9a0d-11e5-a84c-1f39510f0d6b",
  "duration": 25,
  "protocol": "HTTP/1.1",
  "status": 200,
  "headers": {
    "Content-Type": ["text/plain"]
  },
  "body": "Hello world!"
}

Note: Bodies of type application/json (and application/*+json) will be inlined into the resulting JSON tree. I.e., a JSON response body will not be escaped and represented as a string:

{
  "origin": "local",
  "type": "response",
  "correlation": "2d66e4bc-9a0d-11e5-a84c-1f39510f0d6b",
  "duration": 25,
  "protocol": "HTTP/1.1",
  "status": 200,
  "headers": {
    "Content-Type": ["application/json"]
  },
  "body": {
    "greeting": "Hello, world!"
  }
}
cURL

cURL is an alternative formatting style, provided by the CurlHttpLogFormatter which will render requests as executable cURL commands. Unlike JSON, it is primarily designed for humans.

Request
curl -v -X GET 'http://localhost/test' -H 'Accept: application/json'
Response

See HTTP or provide own fallback for responses:

new CurlHttpLogFormatter(new JsonHttpLogFormatter());

Writing

Writing defines where formatted requests and responses are written to. Logbook comes with three implementations: Logger, Stream and Chunking.

Logger

By default, requests and responses are logged with an slf4j logger that uses the org.zalando.logbook.Logbook category and the log level trace. This can be customized:

Logbook logbook = Logbook.builder()
    .writer(new DefaultHttpLogWriter(
        LoggerFactory.getLogger("http.wire-log"), 
        Level.DEBUG))
    .build();
Stream

An alternative implementation is to log requests and responses to a PrintStream, e.g. System.out or System.err. This is usually a bad choice for running in production, but can sometimes be useful for short-term local development and/or investigation.

Logbook logbook = Logbook.builder()
    .writer(new StreamHttpLogWriter(System.err))
    .build();
Chunking

The ChunkingHttpLogWriter will split long messages into smaller chunks and will write them individually while delegating to another writer:

Logbook logbook = Logbook.builder()
    .writer(new ChunkingHttpLogWriter(1000, new DefaultHttpLogWriter()))
    .build();

Servlet

You’ll have to register the LogbookFilter as a Filter in your filter chain — either in your web.xml file (please note that the xml approach will use all the defaults and is not configurable):

<filter>
    <filter-name>LogbookFilter</filter-name>
    <filter-class>org.zalando.logbook.servlet.LogbookFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>LogbookFilter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>ASYNC</dispatcher>
    <dispatcher>ERROR</dispatcher>
</filter-mapping>

or programmatically, via the ServletContext:

context.addFilter("LogbookFilter", new LogbookFilter(logbook))
    .addMappingForUrlPatterns(EnumSet.of(REQUEST, ASYNC, ERROR), true, "/*"); 

The LogbookFilter will, by default, treat requests with a application/x-www-form-urlencoded body not different from any other request, i.e you will see the request body in the logs. The downside of this approach is that you won't be able to use any of the HttpServletRequest.getParameter*(..) methods. See issue #94 for some more details.

As of Logbook 1.5.0, you can now specify one of three strategies that define how Logbook deals with this situation by using the logbook.servlet.form-request system property:

Value Pros Cons
body (default) Body is logged Downstream code can not use getParameter*()
parameter Body is logged (but it's reconstructed from parameters) Downstream code can not use getInputStream()
off Downstream code can decide whether to use getInputStream() or getParameter*() Body is not logged

Security

Secure applications usually need a slightly different setup. You should generally avoid logging unauthorized requests, especially the body, because it quickly allows attackers to flood your logfile — and, consequently, your precious disk space. Assuming that your application handles authorization inside another filter, you have two choices:

  • Don't log unauthorized requests
  • Log unauthorized requests without the request body

You can easily achieve the former setup by placing the LogbookFilter after your security filter. The latter is a little bit more sophisticated. You’ll need two LogbookFilter instances — one before your security filter, and one after it:

context.addFilter("unauthorizedLogbookFilter", new LogbookFilter(logbook, Strategy.SECURITY))
    .addMappingForUrlPatterns(EnumSet.of(REQUEST, ASYNC, ERROR), true, "/*");
context.addFilter("securityFilter", new SecurityFilter())
    .addMappingForUrlPatterns(EnumSet.of(REQUEST), true, "/*");
context.addFilter("authorizedLogbookFilter", new LogbookFilter(logbook))
    .addMappingForUrlPatterns(EnumSet.of(REQUEST, ASYNC, ERROR), true, "/*");

The first logbook filter will log unauthorized requests only. The second filter will log authorized requests, as always.

HTTP Client

The logbook-httpclient module contains both an HttpRequestInterceptor and an HttpResponseInterceptor to use with the HttpClient:

CloseableHttpClient client = HttpClientBuilder.create()
        .addInterceptorFirst(new LogbookHttpRequestInterceptor(logbook))
        .addInterceptorFirst(new LogbookHttpResponseInterceptor())
        .build();

Since the LogbookHttpResponseInterceptor is incompatible with the HttpAsyncClient there is another way to log responses:

CloseableHttpAsyncClient client = HttpAsyncClientBuilder.create()
        .addInterceptorFirst(new LogbookHttpRequestInterceptor(logbook))
        .build();
        
// and then wrap your response consumer
client.execute(producer, new LogbookHttpAsyncResponseConsumer<>(consumer), callback)

JAX-RS

The logbook-jaxrs module contains:

  • a LogbookClientFilter for use with applications making HTTP requests
  client.register(new LogbookClientFilter(logbook));
  • a LogbookServerFilter for use with HTTP servers
  resourceConfig.register(new LogbookServerFilter(logbook));

OkHttp

The logbook-okhttp module contains an Interceptor to use with the OkHttpClient:

OkHttpClient client = new OkHttpClient.Builder()
        .addNetworkInterceptor(new LogbookInterceptor(logbook))
        .build();

Spring Boot Starter

Logbook comes with a convenient auto configuration for Spring Boot users. It sets up all of the following parts automatically with sensible defaults:

  • Servlet filter
  • Second Servlet filter for unauthorized requests (if Spring Security is detected)
  • Header-/Parameter-/Body-Filters
  • HTTP-/JSON-style formatter
  • Logging writer
Type Name Default
FilterRegistrationBean unauthorizedLogbookFilter Based on LogbookFilter
FilterRegistrationBean authorizedLogbookFilter Based on LogbookFilter
Logbook Based on condition, filters, formatter and writer
Predicate<RawHttpRequest> requestCondition No filter; is later combined with logbook.exclude
RawRequestFilter RawRequestFilters.defaultValue()
RawResponseFilter RawResponseFilters.defaultValue()
HeaderFilter Based on logbook.obfuscate.headers
QueryFilter Based on logbook.obfuscate.parameters
BodyFilter BodyFilters.defaultValue()
RequestFilter RequestFilter.none()
ResponseFilter ResponseFilter.none()
HttpLogFormatter JsonHttpLogFormatter
HttpLogWriter DefaultHttpLogWriter

Multiple filters are merged into one.

Configuration

The following tables show the available configuration:

Configuration Description Default
logbook.exclude Exclude certain URLs []
logbook.filter.enabled Enable the LogbookFilter(s) true
logbook.format.style Formatting style (http, json or curl) json
logbook.obfuscate.headers List of header names that need obfuscation [Authorization]
logbook.obfuscate.parameters List of parameter names that need obfuscation [access_token]
logbook.write.category Changes the category of the DefaultHttpLogWriter org.zalando.logbook.Logbook
logbook.write.level Changes the level of the DefaultHttpLogWriter TRACE
logbook.write.chunk-size Splits log lines into smaller chunks of size up-to chunk-size. 0 (disabled)
logbook.write.max-body-size Truncates the body up to max-body-size and appends .... -1 (disabled)
Example configuration
logbook:
    exclude:
        - /health
        - /admin/**
    filter.enabled: true
    format.style: http
    obfuscate:
        headers:
            - Authorization
            - X-Secret
        parameters:
            - access_token
            - password
    write:
        category: http.wire-log
        level: INFO
        chunk-size: 1000

Known Issues

The Logbook HTTP Client integration is handling gzip-compressed response entities incorrectly if the interceptor runs before a decompressing interceptor. Since logging compressed contents is not really helpful it's advised to register the logbook interceptor as the last interceptor in the chain.

Getting Help with Logbook

If you have questions, concerns, bug reports, etc., please file an issue in this repository's Issue Tracker.

Getting Involved/Contributing

To contribute, simply make a pull request and add a brief description (1-2 sentences) of your addition or change. For more details, check the contribution guidelines.

Alternatives

Logbook puts a big emphasis on logging the actual request/response body that was sent over the wire. The Apache HttpClient, among the following alternatives, is the only technology to support that.

Credits and References

Creative Commons (Attribution-Share Alike 3.0 Unported Grand Turk, a replica of a three-masted 6th rate frigate from Nelson's days - logbook and charts by JoJan is licensed under a Creative Commons (Attribution-Share Alike 3.0 Unported).