Debug Retrofit 2’s API Call with OkHttp Logging Interceptor

Retrofit 1 has a built-in log feature for debugging requests and responses. However, this feature was removed in Retrofit 2. Based on the community’s request, the developers of OkHttp made a logging interceptor.

OkHttp Logging Interceptor is an OkHttp interceptor that logs HTTP requests and response data.

You need to install OkHttp and its logging interceptor

implementation 'com.squareup.okhttp3:okhttp:4.0.1'
implementation 'com.squareup.okhttp3:logging-interceptor:4.0.1'

Here is my Retrofit code in Kotlin:

val interceptor = HttpLoggingInterceptor()
interceptor.level = HttpLoggingInterceptor.Level.BODY
val client = OkHttpClient.Builder().addInterceptor(interceptor).build()
val retrofit = Retrofit.Builder()
            .baseUrl("API_URL")
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .addConverterFactory(GsonConverterFactory.create())
            .client(client)
            .build()

How the log looks like:

019-08-12 11:33:21.387 2744-2862/com.company.testapp D/OkHttp: <-- 200 OK http://website/api/logout (140ms)
2019-08-12 11:33:21.387 2744-2862/com.company.testapp D/OkHttp: Date: Mon, 12 Aug 2019 04:33:24 GMT
2019-08-12 11:33:21.388 2744-2862/com.company.testapp D/OkHttp: Server: Apache/2.4.6 (CentOS) OpenSSL/1.0.1e-fips mod_fcgid/2.3.9 PHP/5.6.30 mod_python/3.5.0- Python/2.7.5
2019-08-12 11:33:21.388 2744-2862/com.company.testapp D/OkHttp: X-Powered-By: PHP/7.3.5
2019-08-12 11:33:21.388 2744-2862/com.company.testapp D/OkHttp: Cache-Control: no-cache, private
2019-08-12 11:33:21.388 2744-2862/com.company.testapp D/OkHttp: X-RateLimit-Limit: 60
2019-08-12 11:33:21.389 2744-2862/com.company.testapp D/OkHttp: X-RateLimit-Remaining: 59
2019-08-12 11:33:21.389 2744-2862/com.company.testapp D/OkHttp: Vary: Authorization
2019-08-12 11:33:21.389 2744-2862/com.company.testapp D/OkHttp: Keep-Alive: timeout=5, max=100
2019-08-12 11:33:21.390 2744-2862/com.company.testapp D/OkHttp: Connection: Keep-Alive
2019-08-12 11:33:21.390 2744-2862/com.company.testapp D/OkHttp: Transfer-Encoding: chunked
2019-08-12 11:33:21.391 2744-2862/com.company.testapp D/OkHttp: Content-Type: text/html; charset=UTF-8
2019-08-12 11:33:21.393 2744-2862/com.company.testapp D/OkHttp: You have been succesfully logged out!
2019-08-12 11:33:21.393 2744-2862/com.company.testapp D/OkHttp: <-- END HTTP (37-byte body)

The interceptor has 4 log levels: NONE, BASIC, HEADERS, BODY. The 2 log levels, HEADERS and BODY , have the potential to leak sensitive information such as “Authorization” or “Cookie” headers and the contents of the request and response bodies so don’t use them in a production release.