24 Configure vcr
You can also get the default configuration variables via vcr_config_defaults()
#> $warn_on_empty_cassette
#> [1] TRUE
#>
#> $quiet
#> [1] TRUE
#>
#> $verbose_errors
#> [1] FALSE
#>
#> $write_disk_path
#> NULL
#>
#> $filter_query_parameters
#> NULL
#>
#> $filter_response_headers
#> NULL
#>
#> $filter_request_headers
#> NULL
#>
#> $filter_sensitive_data_regex
#> NULL
#>
#> $filter_sensitive_data
#> NULL
#>
#> $log_opts
#> $log_opts$file
#> [1] "vcr.log"
#>
#> $log_opts$log_prefix
#> [1] "Cassette"
#>
#> $log_opts$date
#> [1] TRUE
#>
#>
#> $log
#> [1] FALSE
#>
#> $linked_context
#> NULL
#>
#> $cassettes
#> list()
#>
#> $allow_http_connections_when_no_cassette
#> [1] FALSE
#>
#> $clean_outdated_http_interactions
#> [1] FALSE
#>
#> $re_record_interval
#> NULL
#>
#> $turned_off
#> [1] FALSE
#>
#> $preserve_exact_body_bytes
#> [1] FALSE
#>
#> $uri_parser
#> [1] "crul::url_parse"
#>
#> $ignore_request
#> NULL
#>
#> $ignore_localhost
#> [1] FALSE
#>
#> $ignore_hosts
#> NULL
#>
#> $persist_with
#> [1] "FileSystem"
#>
#> $json_pretty
#> [1] FALSE
#>
#> $serialize_with
#> [1] "yaml"
#>
#> $allow_unused_http_interactions
#> [1] TRUE
#>
#> $match_requests_on
#> [1] "method" "uri"
#>
#> $record
#> [1] "once"
#>
#> $dir
#> [1] "."These defaults are set when you load vcr - you can override any of them as described below.
24.1 Set configuration variables
Use vcr_configure() to set configuration variables.
For example, set a single variable:
vcr_configure(
dir = "foobar/vcr_cassettes"
)#> <vcr configuration>
#> Cassette Dir: foobar/vcr_cassettes
#> Record: once
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: method, uri
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:Or many at once:
vcr_configure(
dir = "foobar/vcr_cassettes",
record = "all"
)#> <vcr configuration>
#> Cassette Dir: foobar/vcr_cassettes
#> Record: all
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: method, uri
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3 Details on some of the config options
24.3.1 dir
Directory where cassettes are stored
vcr_configure(dir = "new/path")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: once
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: method, uri
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.2 record
The record mode
One of: ‘all’, ‘none’, ‘new_episodes’, ‘once’. See ?recording for info on the options
vcr_configure(record = "new_episodes")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: method, uri
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.3 match_requests_on
Customize how vcr matches requests
vcr_configure(match_requests_on = c('query', 'headers'))#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.4 allow_unused_http_interactions
Allow HTTP connections when no cassette
Default is TRUE, and thus does not error when http interactions are unused. You
can set to FALSE in which case vcr errors when a cassette is ejected and
not all http interactions have been used.
vcr_configure(allow_unused_http_interactions = FALSE)#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.5 serialize_with
Which serializer to use: “yaml” or “json”. Note that you can have multiple cassettes with the same name as long as they use different serializers; so if you only want one cassette for a given cassette name, make sure to not switch serializers, or clean up files you no longer need.
vcr_configure(serialize_with = "yaml")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.6 persist_with
Which persister to use. Right now only option is “FileSystem”
vcr_configure(persist_with = "FileSystem")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts:
#> ignore localhost?: FALSE
#> Write disk path:24.3.7 ignoring some requests
ignore_hosts
Specify particular hosts to ignore. By ignore, we mean that real HTTP requests to the ignored host will be allowed to occur, while all others will not.
vcr_configure(ignore_hosts = "google.com")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts: google.com
#> ignore localhost?: FALSE
#> Write disk path:ignore_localhost
Ignore all localhost requests
vcr_configure(ignore_localhost = TRUE)#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: crul::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts: google.com
#> ignore localhost?: TRUE
#> Write disk path:ignore_request
THIS DOESN’T WORK YET
How to ignore requests
For ignoring requests, you can for example, have real http requests go through (ignored by vcr) while other requests are handled by vcr. For example, let’s say you want requests to google.com to be ignored:
vcr_configure(ignore_hosts = "google.com")
use_cassette("foo_bar", {
crul::HttpClient$new("https://httpbin.org/get")$get()
crul::HttpClient$new("https://google.com")$get()
})The request to httpbin.org will be handled by vcr, a cassette created for the request/response to that url, while the google.com request will be ignored and not cached at all.
Note: ignoring requests only works for the crul package for now; it should work for httr and httr2 in a later vcr version.
24.3.8 uri_parse
Which uri parser to use
By default we use crul::url_parse, but you can use a different one. Remember
to pass in the function quoted, and namespaced.
vcr_configure(uri_parser = "urltools::url_parse")#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: urltools::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: FALSE
#> Logging?: FALSE
#> ignored hosts: google.com
#> ignore localhost?: TRUE
#> Write disk path:24.3.9 preserve_exact_body_bytes
Some HTTP servers are not well-behaved and respond with invalid data. Set
preserve_exact_body_bytes to TRUE to base64 encode the result body in
order to preserve the bytes exactly as-is. vcr does not do this by
default, since base64-encoding the string removes the human readability
of the cassette.
vcr_configure(preserve_exact_body_bytes = TRUE)#> <vcr configuration>
#> Cassette Dir: new/path
#> Record: new_episodes
#> Serialize with: yaml
#> URI Parser: urltools::url_parse
#> Match Requests on: query, headers
#> Preserve Bytes?: TRUE
#> Logging?: FALSE
#> ignored hosts: google.com
#> ignore localhost?: TRUE
#> Write disk path:24.3.10 filter_sensitive_data
A named list of values to replace. Sometimes your package or script is working with sensitive tokens/keys, which you do not want to accidentally share with the world.
Before recording (writing to a cassette) we do the replacement and then when reading from the cassette we do the reverse replacement to get back to the real data.
vcr_configure(
filter_sensitive_data = list("<some_api_key>" = Sys.getenv('MY_API_KEY'))
)Before recording to disk, the env var MY_API_KEY is retrieved from your machine,
and we find instances of it, and replace with <some_api_key>. When replaying
to create the HTTP response object we put the real value of the env var
back in place.
To target specific request or response headers see filter_request_headers
and filter_response_headers.
24.3.11 filter_request_headers
Expects a character vector or a named list. If a character vector, or any unnamed element in a list, the request header is removed before being written to the cassette.
If a named list is passed, the name is the header and the value is the value with which to replace the real value.
A request header you set to remove or replace is only removed/replaced
from the cassette, and any requests using a cassette, but will still be in
your crul, httr or httr2 response objects on a real request that creates the
cassette.
Examples:
vcr_configure(
filter_request_headers = "Authorization"
)
vcr_configure(
filter_request_headers = c("Authorization", "User-Agent")
)
vcr_configure(
filter_request_headers = list(Authorization = "<<<not-my-bearer-token>>>")
)24.3.12 filter_response_headers
Expects a character vector or a named list. If a character vector, or any unnamed element in a list, the response header is removed before being written to the cassette.
If a named list is passed, the name is the header and the value is the value with which to replace the real value.
A response header you set to remove or replace is only removed/replaced
from the cassette, and any requests using a cassette, but will still be in
your crul, httr or httr2 response objects on a real request that creates the
cassette.
Examples:
vcr_configure(
filter_response_headers = "server"
)
vcr_configure(
filter_response_headers = c("server", "date")
)
vcr_configure(
filter_response_headers = list(server = "fake-server")
)24.3.13 filter_query_parameters
Expects a character vector or a named list. If a character vector, or any unnamed element in a list, the query parameter is removed (both parameter name and value) before being written to the cassette.
If a named list is passed, the name is the query parameter name and the value is the value with which to replace the real value.
A response header you set to remove or replace is only removed/replaced
from the cassette, and any requests using a cassette, but will still be in
your crul, httr or httr2 response objects on a real request that creates the
cassette.
Beware of your match_requests_on option when using this filter. If you
filter out a query parameter it’s probably a bad idea to match on query
given that there is no way for vcr to restore the exact http request
from your cassette after one or more query parameters is removed or changed.
One way you could filter a query parameter and still match on query or
at least on the complete uri is to use replacement behavior (a named list),
but instead of list(a="b") use two values list(a=c("b","c")), where
“c” is the string to be stored in the cassette. You could of course replace
those values with values from environment variables so that you obscure
the real values if your code is public.
Examples:
# completely drop parameter "user"
vcr_configure(
filter_query_parameters = "user"
)
# completely drop parameters "user" and "api_key"
vcr_configure(
filter_query_parameters = c("user", "api_key")
)
# replace the value of parameter "api_key" with "fake-api-key"
# NOTE: in this case there's no way to put back any value on
# subsequent requests, so we have to match by dropping this
# parameter value before comparing URIs
vcr_configure(
filter_query_parameters = list(api_key = "fake-api-key")
)
# replace the value found at Sys.getenv("MY_API_KEY") of parameter
# "api_key" with the value "foo". When using a cassette on subsequent
# requests, we can replace "foo" with the value at Sys.getenv("MY_API_KEY")
# before doing the URI comparison
vcr_configure(
filter_query_parameters = list(api_key = c(Sys.getenv("MY_API_KEY"), "foo"))
)